JP7205314B2 - CONTROL DEVICE AND POWER CONVERSION DEVICE INCLUDING THE SAME - Google Patents

Description

TECHNICAL FIELD The present invention relates to a control device for controlling a plurality of power conversion modules cooled by a cooler, and a power converter including the same.

Power converters having power semiconductor devices are known (for example, Patent Documents 1 to 4). Technological innovations in power semiconductor devices, which are the main components of such power converters, have realized higher-speed switching operations, thereby reducing loss (eg, heat generation) generated from the power semiconductor devices. This makes it possible to simplify the cooler provided in the power converter for cooling the power semiconductor device.

In order to disperse the amount of heat generated by the power semiconductor devices, the power converter includes a power conversion circuit having a plurality of power semiconductor devices as one module (hereinafter sometimes referred to as a "power conversion module"). A parallel connection configuration may be adopted.

Patent No. 6094687 JP 2015-153766 A JP 2016-171610 A JP-A-8-33313

A conventional power conversion device cannot uniformly cool a plurality of power conversion modules, and temperature unevenness may occur among the power conversion modules. If temperature unevenness occurs among a plurality of power conversion modules, there is a problem that the output power of the power conversion device is rate-determined by the power conversion modules that are insufficiently cooled.

An object of the present invention is to provide a controller capable of suppressing temperature unevenness in a plurality of power conversion modules, and a power converter including the same.

In order to achieve the above object, a control device according to an aspect of the present invention adjusts the proportion of converted power borne by the plurality of power conversion modules so that the temperature difference between the plurality of power conversion modules connected in parallel is reduced. A storage unit that stores a value based on the total converted power of a plurality of power conversion modules in association with each other, and an adjustment unit that adjusts the current flowing through each of the plurality of power conversion modules based on the ratio stored in the storage unit. and

In order to achieve the above object, a power conversion apparatus according to an aspect of the present invention includes a plurality of power conversion modules connected in parallel, a cooling unit for cooling the plurality of power conversion modules, and a plurality of power conversion modules. a storage unit that stores a ratio of the converted power borne by the plurality of power conversion modules in association with a value based on the total converted power of the plurality of power conversion modules so that the temperature difference between the modules becomes small, and the storage unit and a control device having an adjustment unit that adjusts the current flowing through each of the plurality of power conversion modules based on the ratio stored in the power conversion module.

According to one aspect of the present invention, it is possible to suppress temperature unevenness among a plurality of power conversion modules.

BRIEF DESCRIPTION OF THE DRAWINGS It is a circuit block diagram which shows schematic structure of the power converter device by 1st Embodiment of this invention. 1 is a circuit block diagram showing a schematic configuration of a power conversion module provided in a power conversion device according to a first embodiment of the present invention; FIG. It is a figure which shows the schematic structure of the cooling part with which the power converter by 1st Embodiment of this invention was equipped. FIG. 4 is a diagram for explaining the power conversion device according to the first embodiment of the present invention, and is a graph showing an example of temperature characteristics of the power conversion module with respect to the load factor. FIG. 2 is a diagram for explaining the power conversion device according to the first embodiment of the present invention, and is a diagram showing an example of characteristics of a sharing coefficient with respect to a load factor stored in a storage unit provided in a power conversion module. FIG. 3 is a functional block diagram of main parts of a common module control circuit as a control device according to the first embodiment of the present invention; FIG. FIG. 3 is a circuit block diagram showing a schematic configuration of a power converter according to a second embodiment of the present invention; FIG. It is a figure explaining the power converter device by 2nd Embodiment of this invention, Comprising: It is a graph which shows an example of the temperature characteristic of the power conversion module with respect to a load factor. FIG. 10 is a diagram for explaining a power conversion device according to a second embodiment of the present invention, and is a diagram showing an example of characteristics of a sharing coefficient with respect to a load factor stored in a storage unit provided in a power conversion module; FIG. 10 is a functional block diagram of main parts of a common module control circuit as a control device according to a second embodiment of the present invention; It is a figure explaining the power converter device by 2nd Embodiment of this invention, Comprising: It is a graph which shows an example of the relationship between ambient temperature and maximum output power. It is a figure which shows the schematic structure of the cooling part with which the power converter by 3rd Embodiment of this invention was equipped.

[First embodiment]
(power converter)
A control device according to a first embodiment of the present invention and a power converter including the same will be described with reference to FIGS. 1 to 6. FIG. First, a schematic configuration of a power converter according to this embodiment will be described with reference to FIGS. 1 to 3. FIG. An inverter device that converts DC power into AC power will be described below as an example of the power conversion device according to the present embodiment.

As shown in FIG. 1, the power converter 1 according to this embodiment is connected between a DC power supply 8 and a load 9 . The power conversion device 1 converts DC power supplied from a DC power supply 8 into three-phase (U-phase, V-phase and W-phase) AC power, and supplies the U-phase, V-phase and W-phase AC power to a load 9. configured to supply

The power conversion device 1 includes a plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 connected in parallel. Power conversion modules 11 , 12 , 13 and 14 are connected in parallel between DC power supply 8 and load 9 .

The power conversion device 1 includes a common module control circuit (an example of a control device) 15 that controls the power conversion modules 11 , 12 , 13 and 14 . The power conversion device 1 includes a voltage detector 16 connected between the power conversion modules 11, 12, 13, and 14 and the DC power supply 8, and a load connected between the power conversion modules 11, 12, 13, and 14. and a voltage detection circuit 17 .

The voltage detector 16 is configured to detect the input voltage of the power converter 1 . That is, the voltage detector 16 is configured to detect the overall voltage input to the power conversion modules 11 , 12 , 13 and 14 . One input terminal of the voltage detector 16 is connected to the positive electrode side of the DC power supply 8 and to the positive electrode side input terminals of the power conversion modules 11 , 12 , 13 , and 14 . The other input terminal of the voltage detector 16 is connected to the negative input terminal of the DC power supply 8 and the negative input terminals of the power conversion modules 11 , 12 , 13 and 14 . An output terminal of the voltage detector 16 is connected to the common module control circuit 15 . As a result, the voltage detector 16 detects the input voltage input to the power converter 1, which is the voltage between the positive and negative sides of the DC power supply 8, and outputs the voltage detection signal Vpn to the common module control circuit 15. can be output.

The voltage detection circuit 17 is configured to detect the output voltage of the power converter 1 . That is, the voltage detection circuit 17 is configured to detect the U-phase, V-phase, and W-phase AC voltages output to the load 9 . The voltage detection circuit 17 includes a voltage detector 171 that detects a U-phase AC output voltage output from the power converter 1 and a voltage detector 172 that detects a V-phase AC output voltage output from the power converter 1 . and a voltage detector 173 for detecting the W-phase AC output voltage output from the power converter 1 . One input terminal of the voltage detector 171 is connected to each output terminal of the power conversion modules 11, 12, 13, and 14 to which a U-phase AC output voltage is output. One input terminal of the voltage detector 172 is connected to each output terminal of the power conversion modules 11, 12, 13, and 14 to which a V-phase AC output voltage is output. One input terminal of the voltage detector 173 is connected to each output terminal of the power conversion modules 11, 12, 13, and 14 to which a W-phase AC output voltage is output. The other terminals of voltage detectors 171, 172 and 173 are connected together. Output terminals of the voltage detectors 171 , 172 , 173 are connected to the common module control circuit 15 . As a result, the voltage detection circuit 17 detects an AC output voltage with a virtual neutral point at which the sum of the U-phase AC output voltage, the V-phase AC output voltage, and the W-phase AC output voltage is zero. be able to. Further, the voltage detection circuit 17 outputs a voltage detection signal Vu that is the detection result of the U-phase AC output voltage, a voltage detection signal Vv that is the detection result of the V-phase AC output voltage, and a detection result of the W-phase AC output voltage. A certain voltage detection signal Vw can be output to the common module control circuit 15 .

The power conversion module 11 detects the U-phase, V-phase, and W-phase AC output currents flowing between the load 9 and outputs the current detection signal Iu_11 of the U-phase, the current detection signal Iv_11 of the V-phase, and the current of the W-phase. It is configured to output the detection signal Iw_11 to the common module control circuit 15 . The power conversion module 12 detects the U-phase, V-phase, and W-phase AC output currents flowing between the load 9 and detects the current detection signal Iu_12 of the U phase, the current detection signal Iv_12 of the V phase, and the current of the W phase. It is configured to output the detection signal Iw_12 to the common module control circuit 15 . The power conversion module 13 detects each of the U-phase, V-phase, and W-phase AC output currents flowing between the load 9 and detects the current detection signal Iu_13 of the U phase, the current detection signal Iv_13 of the V phase, and the current of the W phase. It is configured to output the detection signal Iw_13 to the common module control circuit 15 . The power conversion module 14 detects the U-phase, V-phase, and W-phase AC output currents flowing between the load 9 and detects the current detection signal Iu_14 of the U phase, the current detection signal Iv_14 of the V phase, and the current of the W phase. It is configured to output the detection signal Iw_14 to the common module control circuit 15 .

The common module control circuit 15 receives a voltage detection signal Vpn input from the voltage detector 16, voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17, and current detection signals Iu_11 and Iu_11 input from the power conversion module 11. A control signal Sc_11 for controlling the power conversion module 11 is generated based on Iv_11 and Iw_11. The common module control circuit 15 detects the power based on the voltage detection signal Vpn, the voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17, and the current detection signals Iu_12, Iv_12, and Iw_12 input from the power conversion module 12. It is configured to generate a control signal Sc_12 for controlling the conversion module 12 . The common module control circuit 15 detects electric power based on the voltage detection signal Vpn, the voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17 and the current detection signals Iu_13, Iv_13, and Iw_13 input from the power conversion module 13. It is configured to generate a control signal Sc_13 for controlling the transformation module 13 . The common module control circuit 15 detects the power based on the voltage detection signal Vpn, the voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17, and the current detection signals Iu_14, Iv_14, and Iw_14 input from the power conversion module 14. It is arranged to generate a control signal Sc_14 for controlling the conversion module 14 . The common module control circuit 15 outputs the generated control signal Sc_11 to the power conversion module 11, outputs the generated control signal Sc_12 to the power conversion module 12, outputs the generated control signal Sc_13 to the power conversion module 13, and generates is configured to output the control signal Sc_<b>14 to the power conversion module 14 .

Next, the configuration of the power conversion module provided in the power converter 1 according to this embodiment will be described with reference to FIG. 1 and FIG. The power conversion modules 11, 12, 13, and 14 have the same configuration and are configured to exhibit the same function. For this reason, the configurations of the power conversion modules 11, 12, 13, and 14 will be described below by taking the power conversion module 11 as an example.

As shown in FIG. 2, the power conversion module 11 has a DC capacitor C connected between the positive and negative sides of the DC power supply 8, and an inverter section 111 connected in parallel to the DC capacitor C. there is The power conversion module 11 has an inverter section 111 as a power conversion circuit. The DC capacitor C is provided to stabilize the DC voltage output from the DC power supply 8 (that is, the input voltage input to the power conversion module 11).

The inverter unit 111 has semiconductor elements M1, M3, M5 connected to the positive side of the input voltage input from the DC power supply 8, and semiconductor elements M2, M4, M6 connected to the negative side of the input voltage. ing. The semiconductor element M1 and the semiconductor element M2 are connected in series between the positive electrode side and the negative electrode side of the DC power supply 8 . The semiconductor element M3 and the semiconductor element M4 are connected in series between the positive electrode side and the negative electrode side of the DC power supply 8 . The semiconductor element M5 and the semiconductor element M6 are connected in series between the positive electrode side and the negative electrode side of the DC power supply 8 . Semiconductor element M1 and semiconductor element M2, semiconductor element M3 and semiconductor element M4, semiconductor element M5 and semiconductor element M6, and DC capacitor C are connected in parallel.

Semiconductor element M1 and semiconductor element M2 form, for example, a U-phase arm, semiconductor element M3 and semiconductor element M4 form, for example, a V-phase arm, and semiconductor element M5 and semiconductor element M6 form, for example, a W-phase arm. ing. Therefore, the inverter section 111 has a three-phase bridge circuit in which these U-phase arm, V-phase arm and W-phase arm are connected in parallel. The semiconductor elements M1, M3 and M5 constitute a high side switch, and the semiconductor elements M2, M4 and M6 constitute a low side switch.

The semiconductor element M1 has a switching element Q1 and a freewheeling diode D1 connected in anti-parallel to the switching element Q1. The semiconductor element M2 has a switching element Q2 and a freewheeling diode D2 connected in anti-parallel to the switching element Q2. The semiconductor element M3 has a switching element Q3 and a freewheeling diode D3 connected in anti-parallel to the switching element Q3. The semiconductor element M4 has a switching element Q4 and a freewheeling diode D4 connected in anti-parallel to the switching element Q4. The semiconductor element M5 has a switching element Q5 and a freewheeling diode D5 connected in anti-parallel to the switching element Q5. The semiconductor element M6 has a switching element Q6 and a freewheeling diode D6 connected in anti-parallel to the switching element Q6.

In this embodiment, the switching elements Q1, Q2, Q3, Q4, Q5, and Q6 are composed of, for example, MOSFETs (Metal Oxide Semiconductor Field Emission Transistors). The switching elements Q1, Q2, Q3, Q4, Q5, Q6 are semiconductor elements made of silicon carbon (SiC), for example. Note that the switching elements Q1, Q2, Q3, Q4, Q5, and Q6 are not limited to carbon silicon, and may include a wide bandgap semiconductor. A wide bandgap semiconductor device is a semiconductor device having a bandgap larger than that of a silicon semiconductor device, and includes, for example, SiC, GaN, diamond, gallium nitride-based materials, gallium oxide-based materials, AlN, AlGaN, or ZnO. element.

The power conversion module 11 has a gate drive circuit 112 that drives the switching elements Q1, Q2, Q3, Q4, Q5 and Q6. The gate drive circuit 112 has six output amplifiers (not shown). Each of the six output amplifiers has a signal output terminal and a reference potential terminal. The signal output terminals of the six output amplifiers are connected to the gate terminals of the switching elements Q1, Q2, Q3, Q4, Q5 and Q6 in a one-to-one relationship. The reference potential terminals of the six output amplifiers are connected to the source terminals of the switching elements Q1, Q2, Q3, Q4, Q5 and Q6 in a one-to-one relationship. The gate drive circuit 112 is also connected to the common module control circuit 15 . The gate drive circuit 112 is configured to receive the control signal Sc_11 from the common module control circuit 15 . Based on the control signal Sc_11 input from the common module control circuit 15, the gate drive circuit 112 generates drive signals for driving the switching elements Q1, Q2, Q3, Q4, Q5 and Q6, respectively. The gate drive circuit 112 individually outputs high-level or low-level drive signals between the gate terminals and source terminals of the switching elements Q1, Q2, Q3, Q4, Q5, and Q6. As a result, the switching elements Q1, Q2, Q3, Q4, Q5 and Q6 are independently driven to the ON state or the OFF state.

The drain terminal of the switching element Q1 is connected to the cathode terminal of the freewheeling diode D1. The drain terminal of the switching element Q1 and the cathode terminal of the freewheeling diode D1 are also connected to one electrode of the DC capacitor C and the positive electrode side of the DC power supply 8 . The source terminal of the switching element Q1 is connected to the anode terminal of the freewheeling diode D1.

The drain terminal of the switching element Q2 is connected to the cathode terminal of the freewheeling diode D2. The drain terminal of the switching element Q2 and the cathode terminal of the freewheeling diode D2 are also connected to the source terminal of the switching element Q1 and the anode terminal of the freewheeling diode D1. The source terminal of the switching element Q2 is connected to the anode terminal of the freewheeling diode D2. The source terminal of the switching element Q2 and the anode terminal of the freewheeling diode D2 are also connected to the other electrode of the DC capacitor C and the negative electrode side of the DC power supply 8 .

A connection between the source terminal of the switching element Q1 and the anode terminal of the freewheeling diode D1, and the drain terminal of the switching element Q2 and the cathode terminal of the freewheeling diode D2 is connected via an AC reactor Lu provided in the power conversion module 11. It is connected to load 9 .

A drain terminal of the switching element Q3 is connected to a cathode terminal of a freewheeling diode D3. The drain terminal of the switching element Q3 and the cathode terminal of the freewheeling diode D3 are also connected to one electrode of the DC capacitor C and the positive electrode side of the DC power supply 8 . The source terminal of the switching element Q3 is connected to the anode terminal of the freewheeling diode D3.

A drain terminal of the switching element Q4 is connected to a cathode terminal of a freewheeling diode D4. The drain terminal of the switching element Q4 and the cathode terminal of the freewheeling diode D4 are also connected to the source terminal of the switching element Q3 and the anode terminal of the freewheeling diode D3. A source terminal of the switching element Q4 is connected to an anode terminal of a freewheeling diode D4. The source terminal of the switching element Q4 and the anode terminal of the freewheeling diode D4 are also connected to the other electrode of the DC capacitor C and the negative electrode side of the DC power supply 8 .

A connecting portion between the source terminal of the switching element Q3 and the anode terminal of the freewheeling diode D3 and the drain terminal of the switching element Q4 and the cathode terminal of the freewheeling diode D4 is connected through an AC reactor Lv provided in the power conversion module 11. It is connected to load 9 .

A drain terminal of the switching element Q5 is connected to a cathode terminal of a freewheeling diode D5. The drain terminal of the switching element Q5 and the cathode terminal of the freewheeling diode D5 are also connected to one electrode of the DC capacitor C and the positive electrode side of the DC power supply 8 . A source terminal of the switching element Q5 is connected to an anode terminal of a freewheeling diode D5.

A source terminal of the switching element Q6 is connected to an anode terminal of a freewheeling diode D6. The drain terminal of the switching element Q6 and the cathode terminal of the freewheeling diode D6 are also connected to the source terminal of the switching element Q5 and the anode terminal of the freewheeling diode D5. A source terminal of the switching element Q6 is connected to an anode terminal of a freewheeling diode D6. The source terminal of the switching element Q6 and the anode terminal of the freewheeling diode D6 are also connected to the other electrode of the DC capacitor C and the negative electrode side of the DC power supply 8 .

A connection between the source terminal of the switching element Q5 and the anode terminal of the freewheeling diode D5, and the drain terminal of the switching element Q6 and the cathode terminal of the freewheeling diode D6 is connected through an AC reactor Lw provided in the power conversion module 11. It is connected to load 9 .

The power conversion module 11 includes a current detector 113u provided between the connection portion of the semiconductor elements M1 and M2 and the AC reactor Lu, and a current detector 113u provided between the connection portion of the semiconductor elements M3 and M4 and the AC reactor Lv. and a current detector 113w provided between the connecting portion of the semiconductor element M5 and the semiconductor element M6 and the AC reactor Lw. The current detector 113 u is configured to detect a U-phase alternating current flowing between the power conversion module 11 and the load 9 and output a current detection signal Iu_11 of the alternating current to the common module control circuit 15 . . The current detector 113v is configured to detect a V-phase alternating current flowing between the power conversion module 11 and the load 9 and output a current detection signal Iv_11 of the alternating current to the common module control circuit 15. . The current detector 113w is configured to detect a W-phase AC current flowing between the power conversion module 11 and the load 9 and output a current detection signal Iw_11 of the AC current to the common module control circuit 15. .

As shown in FIG. 3 , the power converter 1 includes a cooling unit 18 that cools a plurality of (four in this embodiment) power conversion modules 11 , 12 , 13 and 14 . The cooling unit 18 is composed of, for example, a natural air cooling heat sink. The cooling unit 18 cools the power conversion modules 11, 12, 13, 14 by dissipating loss (that is, heat) generated in the power conversion modules 11, 12, 13, 14 to the atmosphere. The cooling part 18 is made of metal such as aluminum or copper.

The cooling section 18 has a base section 181 on which the power conversion modules 11, 12, 13 and 14 are mounted. Power conversion modules 11 , 12 , 13 , 14 are thermally joined to base portion 181 . The power conversion modules 11 , 12 , 13 , 14 are mounted on the base portion 181 with substantially equal intervals therebetween.

The cooling section 18 has a plurality of heat radiation fins 182 extending from the rear surface of the mounting surface of the base section 181 on which the power conversion modules 11, 12, 13 and 14 are mounted. Each of the plurality of radiation fins 182 has a thin rectangular parallelepiped shape. A plurality of radiation fins 182 are arranged with a predetermined gap therebetween. The base portion 181 and the plurality of heat radiation fins 182 are formed integrally, for example.

The power conversion modules 11, 12, 13, and 14 and the cooling unit 18 are installed inside a housing (not shown) provided in the power conversion device 1 with a plurality of heat radiation fins 182 arranged in a horizontal direction. . The cooling unit 18 cools the power conversion modules 11, 12, 13, 14 by natural air cooling. Therefore, as shown in FIG. 3, the direction of the natural convection NC generated in the plurality of radiation fins 182 is from the bottom to the top. As a result, temperature unevenness occurs in the cooling section 18 such that the temperature is higher on the upper side than on the lower side.

As shown in FIG. 3, the power conversion modules 11 and 13 are mounted on the upper side of the base portion 181, for example, and the power conversion modules 12 and 14 are mounted on the lower side of the base portion 181, for example. Therefore, in the power conversion device 1 , the temperature of the power conversion modules 11 and 13 tends to be higher than that of the power conversion modules 12 and 14 due to the temperature unevenness of the cooling unit 18 .

(Control device)
Next, the control device according to the present embodiment will be described using FIGS. 4 to 6 while referring to FIGS. 1 to 3. FIG. A common module control circuit 15 (see FIG. 1), which corresponds to an example of the control device according to this embodiment, is configured to control the power conversion modules 11, 12, 13, and 14 (see FIG. 1). The common module control circuit 15 receives the voltage detection signal Vpn input from the voltage detector 16 (see FIG. 1), the voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17 (see FIG. 1), the power conversion module Current detection signals Iu_11 to Iw_11 input from 11, current detection signals Iu_12 to Iw_12 input from the power conversion module 12, current detection signals Iu_13 to Iw_13 input from the power conversion module 13, and input from the power conversion module 14 A function of outputting control signals Sc_11, Sc_12, Sc_13, and Sc_14 calculated based on the current detection signals Iu_14 to Iw_14 to the power conversion modules 11, 12, 13, and 14 is exhibited. Thereby, the common module control circuit 15 can individually adjust the ratio of the converted power borne by the power conversion modules 11, 12, 13, and 14 in real time.

Here, P_11 is the converted power borne by the power conversion module 11, P_12 is the converted power borne by the power conversion module 12, P_13 is the converted power borne by the power conversion module 13, and P_14 is the converted power borne by the power conversion module 14. Then, the converted power Ptol output by the power electronics device 1 can be defined as the following equation (1).
P_tol=P_11+P_12+P_13+P_14 (1)

Further, here, the converted powers P_11, P_12, P_13, and P_14 introduce a sharing coefficient (an example of the ratio of the converted power borne by the plurality of power conversion modules) α_11, α_12, α_13, and α_14 ranging from 0 to 1. , can be defined by the following equations (2) to (5).
P_11=(α_11/4)×P_tol (2)
P_12=(α_12/4)×P_tol (3)
P_13=(α_13/4)×P_tol (4)
P_14=(α_14/4)×P_tol (5)

In Expression (2), “α_11” indicates the sharing coefficient of the converted power P_11 borne by the power conversion module 11 . In Expression (3), “α_12” indicates the sharing coefficient of the converted power P_12 borne by the power conversion module 12 . In Expression (4), “α_13” indicates the sharing coefficient of the converted power P_13 borne by the power conversion module 13 . In Equation (5), “α_14” indicates the sharing coefficient of the converted power P_14 borne by the power conversion module 14 .

The converted power Ptol output by the power converter 1 is a required value determined by an external factor (for example, the load 9 (see FIG. 1)). The converted power Ptol output by the power conversion device 1 is a value that fluctuates according to the state of an external factor (for example, the load 9) and is not a fixed value. Since the converted power Ptol is a variable value, the converted powers P_11, P_12, P_13, and P_14 need to be changed according to the state of external factors (for example, the load 9). The power converter 1 is configured to change the values of the converted powers P_11, P_12, P_13 and P_14 by appropriately changing the sharing coefficients α_11, α_12, α_13 and α_14.

FIG. 4 shows the characteristics of the temperature of the four power conversion modules 11, 12, 13, and 14 (hereinafter, the temperature of the power conversion modules may be referred to as "module temperature") with respect to the load factor LF in the power converter 1. An example is shown. The load factor is the ratio of the converted power Ptol output by the power converter 1 at a predetermined point in time to the maximum required value determined by an external factor (the load 9 in this embodiment). The converted power Ptol output by the power converter 1 includes the converted power P_11 borne by the power conversion module 11, the converted power P_12 borne by the power conversion module 12, the converted power P_13 borne by the power conversion module 13, and the power conversion module 14. It is the sum of the converted power P_14 to be borne (hereinafter sometimes referred to as "total converted power") (see formula (1)). Therefore, the load factor corresponds to an example of a value based on the total converted power of the plurality of (four in this embodiment) power conversion modules 11 , 12 , 13 and 14 .

The horizontal axis of the graph shown in FIG. 4 represents the load factor LF [p. u. ], and the vertical axis of the graph indicates the module temperature Tm [° C.] of the power conversion module. “TCup” shown in FIG. 4 indicates the temperature characteristics of the power conversion modules 11 and 13 mounted on the upper side of the cooling section 18 . “TCbo” shown in FIG. 4 indicates temperature characteristics of the power conversion modules 12 and 14 mounted on the lower side of the cooling section 18 . "TRup" shown in FIG. 4 is a reference example of the temperature characteristics of the power conversion module, which is mounted on the upper side of the cooling unit 18 and has a constant sharing coefficient (for example, "1"). shows the temperature characteristics of "TRbo" shown in FIG. 4 is a reference example of the temperature characteristics of the power conversion module, which is mounted on the lower side of the cooling unit 18 and has a constant sharing coefficient (for example, "1"). shows the temperature characteristics of

It can be assumed that the power conversion modules 11 and 13 mounted on the upper side of the cooling section 18 have substantially the same temperature. Therefore, in FIG. 4, both the temperature characteristics of the power conversion modules 11 and 13 are represented by the temperature characteristics TCup. Similarly, the power conversion modules 12 and 14 mounted on the lower side of the cooling section 18 can be considered to have approximately the same temperature. Therefore, in FIG. 4, both the temperature characteristics of the power conversion modules 11 and 13 are represented by the temperature characteristics TCbo.

The cooling unit 18 provided in the power converter 1 radiates heat to the atmosphere by natural convection NC. Therefore, the temperature of the air flowing through the cooling section 18 rises significantly from the lower side of the cooling section 18 corresponding to the windward side to the upper side of the cooling section 18 corresponding to the leeward side. As a result, as shown in FIG. 4, in the power converter 1, the module temperature of the power conversion modules 11 and 13 arranged on the leeward side is higher than that of the power conversion modules 12 and 14 arranged on the windward side. tend to become

When the conversion power sharing coefficients borne by the power conversion modules are all constant (for example, "1") regardless of the load factor LF, the power conversion modules are shown by temperature characteristics TRup and temperature characteristics TRbo in FIG. temperature Tm linearly increases from the initial temperature Tma as the load factor LF increases. The initial temperature Tma is set to the highest initial temperature assumed as the ambient temperature of the power conversion modules 11 , 12 , 13 and 14 . A power conversion module arranged on the upper side (downwind side) of the cooling section 18 has a higher module temperature Tm than a power conversion module arranged on the lower side (windward side) of the cooling section 18 . Therefore, the power conversion module arranged on the upper side (downwind side) of the cooling unit 18 has a load factor LF of 1 [p. u. ], the module temperature Tm reaches the upper limit value Tml. Therefore, even though the module temperature Tm of the power conversion module arranged on the lower side (windward side) of the cooling unit 18 is lower than the upper limit value Tml, the output converted power of the power converter 1 is The power conversion module arranged on the upper side (downwind side) of the unit 18 limits the speed.

As indicated by the temperature characteristic TRbo in FIG. 4, the module temperature Tm of the power conversion module arranged on the lower side (windward side) of the cooling unit 18 does not reach the upper limit value Tml when the value of the load factor LF is LFa. . For this reason, the power conversion module arranged on the lower side (windward side) of the cooling unit 18 has room for further increasing the load factor LF.

Therefore, in the power converter 1 according to the present embodiment, the value of the load factor LF is 1 [p. u. ], the power conversion modules 11 and 13 having a relatively high module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 share It is configured to reduce the coefficients α_11, α_13 to values less than one. Further, in the power converter 1, the module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 is relatively low with the predetermined value LFb of the load factor LF as the boundary value. It is configured to increase the sharing coefficients α_12, α_14 of the power conversion modules 12, 14 to a value greater than one. Here, the predetermined value LFb is set to a value of the load factor LF (for example, a value smaller than LFa) at which the module temperature Tm of any of the power conversion modules 11, 12, 13, and 14 does not reach the upper limit value Tml.

As a result, as indicated by the temperature characteristic TCup in FIG. In the conversion modules 11 and 13, the rate of increase of the module temperature Tm is smaller when the load factor LF is equal to or greater than the predetermined value LFb than when the load factor LF is between 0 and the predetermined value LFb. On the other hand, as indicated by the temperature characteristic TCbo in FIG. Modules 12 and 14 have a higher rate of increase in module temperature Tm when the load factor is equal to or greater than the predetermined value LFb than when the load factor is between 0 and the predetermined value LFb. Thereby, the power conversion device 1 can reduce the temperature difference of the module temperature Tm between the power conversion modules 11 and 13 and the power conversion modules 12 and 14 when the load factor LF is equal to or higher than the predetermined value LFb.

The module temperatures Tm of the power conversion modules 11, 12, 13, and 14 are all when the value of the load factor LF is 1 [p. u. ], the upper limit value Tml is reached. As a result, the output converted power of the power conversion device 1 is prevented from being restricted by the power conversion modules 11 and 13 arranged on the upper side (downwind side) of the cooling unit 18, and the power conversion device 1 can output If the converted power Ptol is 1 [p. u. ] can be increased.

FIG. 5 shows the characteristics of the sharing coefficients α_11, α_12, α_13, and α_14 of the converted power P_11, P_12, P_13, and P_14 borne by the four power conversion modules 11, 12, 13, and 14 with respect to the load factor LF of the power converter 1. shows an example. The horizontal axis of the graph shown in FIG. 5 represents the load factor LF [p. u. ], and the vertical axis of the graph indicates the allocation coefficient. “SCup” shown in FIG. 5 indicates the characteristics of the sharing coefficients of the power conversion modules 11 and 13 mounted on the upper side of the cooling unit 18 (hereinafter sometimes referred to as “sharing coefficient characteristics”). “SCbo” shown in FIG. 5 indicates the sharing coefficient characteristics of the power conversion modules 12 and 14 mounted on the lower side of the cooling unit 18 . "SR" shown in FIG. 5 is a reference example of the sharing coefficient characteristics of the power conversion module, and indicates the characteristics of the sharing coefficient when the sharing coefficient is constant (for example, "1") with respect to the load factor. .

When the load factor LF reaches a predetermined value LFb (<1) [p. u. ] or more 1 [p. u. ] Since the power conversion modules 11, 12, 13, and 14 have non-linear temperature characteristics of the module temperature Tm in the following range, the power conversion modules 11, 12, 13, and 14, as shown in FIG. When the rate LF reaches the predetermined value LFb [p. u. ] or more 1 [p. u. ] It has the characteristic that the allocation coefficient increases or decreases in the following range. More specifically, the distribution coefficient characteristic with respect to the load factor LF is that of the four power conversion modules 11, 12, 13, and 14, the power conversion module that is mounted on the upper side of the cooling unit 18 and has a relatively high module temperature Tm. 11 and 13 are different from the power conversion modules 12 and 14 which are mounted on the lower side of the cooling section 18 and have a relatively low module temperature Tm. The sharing coefficients α_11 and α_13 of the power conversion modules 11 and 13 are such that the load factor FL is 0 [p. u. ] or more than the predetermined value LFb [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb [p. u. ] or more 1 [p. u. ] has a sharing coefficient characteristic SCup that decreases in the following range. On the other hand, the sharing coefficients α_12 and α_14 of the power conversion modules 12 and 14 are such that the load factor LF is 0 [p. u. ] or more than the predetermined value LFb [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb [p. u. ] or more 1 [p. u. ] has an allotment coefficient characteristic SCbo that increases in the following range.

When the power conversion modules 11 and 13 have a load factor of a predetermined value LFb[p. u. ] to 1 [p. u. ], and when the load factor is 1 [p. u. ] has a sharing coefficient characteristic SCup whose value is α−(α−<1). When the power conversion modules 12 and 14 have a load factor of a predetermined value LFb [p. u. ] to 1 [p. u. ], and when the load factor is 1 [p. u. ] has a sharing coefficient characteristic SCbo whose value is α+(α+>1).

As in the reference example of the sharing coefficient characteristic of the power conversion module shown in FIG. 5, when the sharing coefficient is constant (eg, "1") with respect to the load factor LF, the load factor If the value of LF is 1 [p. u. ], the module temperature Tm of one of the plurality of power conversion modules becomes the upper limit value Tml. On the other hand, in the present embodiment, the power conversion modules 11 and 13 with relatively high module temperature Tm have a predetermined value LFb[p. u. ] or more 1 [p. u. ], the apportionment coefficients α_11 and α_13 are set to be smaller than "1", for example, within the following range. Therefore, the converted powers P_11 and P_13 borne by the power conversion modules 11 and 13 are smaller than when the sharing coefficients α_11 and α_13 are "1" (see formulas (2) and (4)). Since the loss (heat) generated in the power conversion modules 11 and 13 is also reduced by reducing the converted powers P_11 and P_13, the module temperature Tm of the power conversion modules 11 and 13 is suppressed.

On the other hand, in the power conversion modules 12 and 14 having relatively low module temperatures Tm, for example, the module temperature Tm at a load factor value of LPa is lower than the upper limit value Tml (see FIG. 4). Therefore, the power conversion modules 12 and 14 have enough margin to increase the converted powers P_12 and P14 more than when the sharing coefficients α_12 and α_14 are "1", for example. Therefore, in the present embodiment, the predetermined value LFb[p. u. ] or more 1 [p. u. ] The sharing coefficients α_12 and α_14 are set to be larger than, for example, "1" within the following range. The converted powers P_12 and P_14 borne by the power conversion modules 12 and 14 are larger than when the sharing coefficients α_12 and α_14 are "1" (see formulas (3) and (5)). As a result, the converted powers P_12 and P_14 borne by the power conversion modules 12 and 14 increase, so that the reduction in the converted powers P_11 and P_13 borne by the power conversion modules 11 and 13 can be compensated. As a result, the power conversion device 1 can supply the load 9 with the converted power Ptal that satisfies the demand value of the load 9 . Also, in this case, the loss (heat) generated in the power conversion modules 12 and 14 increases, and the module temperature Tm of the power conversion modules 12 and 14 rises. However, the module temperature Tm of the power conversion modules 12 and 14 is such that the load factor LF is a predetermined value LFa [p. u. ] to 1 [p. u. ], which is lower than the upper limit value Tml and has a margin. Therefore, even if the power conversion modules 12 and 14 generate loss (heat), the module temperature Tm of the power conversion modules 12 and 14 remains at the predetermined value LFa [p. u. ] to 1 [p. u. ] does not reach the upper limit value Tml.

A sharing coefficient is an example of a ratio of converted power borne by a plurality of power conversion modules. Also, the load factor corresponds to an example of a value based on the total converted power of a plurality of power conversion modules. Therefore, the sharing coefficient characteristic, which is the characteristic in which the sharing coefficient corresponds to the load factor, is the characteristic in which the ratio of the converted power borne by the plurality of power conversion modules corresponds to the value based on the total converted power of the plurality of power conversion modules. corresponds to an example of Furthermore, the sharing coefficient characteristics SCup and SCbo in this embodiment are set so that the temperature difference between the power conversion modules 11, 12, 13 and 14 becomes small. For this reason, the sharing coefficient characteristics SCup, SCbo are the total conversion ratio of the plurality of power conversion modules so that the temperature difference between the plurality of power conversion modules connected in parallel is reduced. This corresponds to an example of characteristics corresponding to values based on electric power.

The sharing coefficient characteristics SCup and SCbo with respect to the load factor LF of the power converter 1 shown in FIG. The predetermined value LFb of the load factor depends on the structure of the cooling unit 18 (for example, the size and the shape of the radiation fins 182), the mounting state of the power conversion modules 11, 12, 13, and 14 (placement and thermal resistance with the base unit 181). etc.). Further, the predetermined value LFb of the load factor LF is determined by the power conversion modules (power conversion modules 11 and 13 in this embodiment) that tend to be relatively hot and the power conversion modules (this power conversion module) that tend to be lower in temperature than the power conversion modules. In the embodiment, the temperature difference between the module temperature Tm and the power conversion modules 12, 14) may be set to a value equal to or greater than a predetermined value. The predetermined value LFb of the load factor is, for example, 0.9 [p. u. ] may be set. The sharing coefficient characteristics SCup, SCbo and the predetermined value LFb of the load factor are stored, for example, in a storage section (details will be described later) provided in the common module control circuit 15 (see FIG. 1).

Next, the configuration of the main part of the control device according to the present embodiment will be described using FIG. 6 while referring to FIGS. 1 to 5. FIG. FIG. 6 is a functional block diagram showing an example of a main part of a common module control circuit (an example of a control device) 15 provided in the power converter 1. As shown in FIG. The common module control circuit 15 causes the power conversion modules 11, 12, 13, and 14 to share the load factor of the power converter 1 according to the sharing coefficients α_11, α_12, α_13, and α_14. It is configured to individually control the conversion power of each of the 14. The common module control circuit 15 has a conversion power control section that controls conversion power for each of the power conversion modules 11, 12, 13, and 14. FIG. The conversion power control unit has the same configuration in each of the power conversion modules 11, 12, 13, and 14, and exhibits the same function. For this reason, the configuration of each conversion power control unit of the power conversion modules 11, 12, 13, and 14 will be described below by taking the conversion power control unit of the power conversion module 11 as an example. Note that FIG. 6 shows the conversion power control unit 100 of the power conversion module 11 .

As shown in FIG. 6 , the conversion power control section 100 provided in the common module control circuit 15 has an integrated control section 101 . The integrated control unit 101 is a functional block that controls the common module control circuit 15 in an integrated manner. The integrated control unit 101 is shared by the respective conversion power control units of the power conversion modules 11 , 12 , 13 and 14 . A d-axis current Id_ref, a q-axis current Iq_ref, and a maximum required current Idq_ref, which are required values of an external factor (the load 9 in this embodiment) input from the outside of the common module control circuit 15, for example, are input to the integrated control unit 101. be done. The d-axis current Id_ref and the q-axis current Iq_ref are currents currently required to drive the load 9, for example. The d-axis current Id_ref and the q-axis current Iq_ref are obtained when the load factor value of the power converter 1 is 1 [p. u. ] corresponds to the required value in any value other than The maximum requested current Idq_ref is the maximum current required to drive the load 9 . The maximum requested current Idq_ref is obtained when the value of the load factor of the power converter 1 is 1 [p. u. ] value. Although details will be described later, the integrated control unit 101 determines the current load of the power conversion device 1 based on the d-axis current Id_ref, the q-axis current Iq_ref, and the maximum required current Idq_ref input from the outside of the common module control circuit 15. configured to calculate a rate.

The integrated control unit 101 is configured to calculate the current load factor LF using the following equation (6) based on the input d-axis current Id_ref, q-axis current Iq_ref, and maximum requested current Idq_ref. there is Note that in equation (6), the load factor LF, the d-axis current Id_ref, the q-axis current Iq_ref, and the maximum required current Idq_ref are represented only by symbols.
LF=√(Id_ref ² +Iq_ref ² )/Idq_ref (6)

Although the details will be described later, the storage unit 102 stores shared coefficient characteristics SCup, SCbo, etc. of the power conversion module 11 . The integrated control unit 101 is configured to read from the storage unit 102 the allotment coefficient α_11 of the power conversion module 11 corresponding to the calculated load factor LF.

The conversion power control unit 100 detects the U-phase voltage detection signal Vu and the V-phase voltage detection signal Vu detected by the voltage detectors 171, 172, and 173 (see FIG. 2) provided in the voltage detection circuit 17 (see FIG. 2). It has a coordinate conversion unit 151 that converts the signal Vv and the W-phase voltage detection signal Vw into dq coordinate components to generate the d-axis system voltage Vd and the q-axis system voltage Vq. The coordinate conversion unit 151 is shared by the conversion power control units of the power conversion modules 11 , 12 , 13 and 14 .

The conversion power control unit 100 outputs a U-phase current detection signal Iu_11, a V-phase current detection signal Iv_11, and a W-phase current detection signal Iw_11 detected by the current detectors 113u, 113v, and 113w provided in the power conversion module 11. to dq coordinate components to generate d-axis current Id_11 and q-axis current Iq_11.

The conversion power control unit 100 performs power conversion by performing an arithmetic operation on the d-axis current Id_ref and the q-axis current Iq_ref input from the outside and the sharing coefficient α_11 of the power conversion module 11 based on the d-axis current Id_ref and the q-axis current Iq_ref. It has a current command value generator 150 that generates a d-axis current command value Id_11_ref and a q-axis current command value Iq_11_ref for the module 11 .

More specifically, as shown in FIG. 6, the current command value generation unit 150 generates the sharing coefficient characteristics SCup of the power conversion modules 11 and 13, the sharing coefficient characteristics SCbo of the power conversion modules 12 and 14 (see FIG. 5), and It has a storage unit 102 that stores a predetermined value LFb of the load factor of the power converter 1 and the like. That is, the storage unit 102 storing the sharing coefficient characteristics SCup, SCbo stores the ratio of the converted power borne by the plurality of power conversion modules so that the temperature difference between the plurality of power conversion modules connected in parallel is reduced. It corresponds to an example of a storage unit that stores a value based on the total converted power of the conversion module in association with the value. Storage unit 102 is shared by conversion power control units of power conversion modules 11 , 12 , 13 , and 14 . The storage unit 102 is connected to the integrated control unit 101 . As a result, the integrated control unit 101 can access the storage unit 102 and read the sharing coefficient characteristics SCup, SCbo, etc. of the power conversion modules 11, 12, 13, 14 stored in the storage unit 102. there is

The current command value generator 150 has a first divider 150a to which the d-axis current Id_ref is input, and a second divider 150b to which the q-axis current Iq_ref is input. The first division unit 150a is configured to divide the d-axis current Id_ref by the number of power conversion modules provided in the power converter 1 (four in this embodiment). The second division unit 150b is configured to divide the q-axis current Iq_ref by the number of power conversion modules provided in the power converter 1 (four in this embodiment).

The current command value generation unit 150 integrates the division signal input from the first division unit 150a and the signal including the information of the sharing coefficient α_11 input from the overall control unit 101, and generates the d-axis current command value ID_11_ref. It has a first integration unit 150c that outputs. Further, the current command value generation unit 150 integrates the division signal input from the second division unit 150b and the signal including the information of the sharing coefficient α_11 input from the integrated control unit 101, and obtains the q-axis current command value. It has a second integrator 150d that outputs Iq_11_ref. Thus, the current command value generation unit 150 generates the d-axis current command value Id_11_ref and the q-axis current command value Iq_11_ref based on the sharing coefficient α_11 corresponding to an example of the ratio of the converted power borne by the plurality of power conversion modules. is configured to The d-axis current command value Id_11_ref and the q-axis current command value Iq_11_ref are used to adjust the current flowing through the power conversion module 11 (AC output currents of U-phase, V-phase and W-phase).

Although not shown, the current command value generation units provided in the conversion power control units for the power conversion modules 12, 13, and 14 similarly generate the d-axis current command values based on the sharing coefficients α_12, α_13, and α_14. and q-axis current command values. Therefore, the current command value generation unit provided in the power conversion control unit is based on the ratio of the converted power P_11, P_12, P_13, P_14 borne by the power conversion modules 11, 12, 13, and 14 stored in the storage unit 102. corresponds to an example of an adjustment unit that adjusts the current flowing through each of the power conversion modules 11 , 12 , 13 , and 14 .

The conversion power control unit 100 calculates the deviation between the d-axis current command value Id_11_ref and the q-axis current command value Iq_11_ref output by the current command value generation unit 150 and the d-axis current Id_11 and the q-axis current Iq_11 output by the coordinate conversion unit 152. It has a deviation calculation unit 153 for calculating each. The deviation calculation unit 153 performs first subtraction for subtracting the d-axis current Id input from the coordinate conversion unit 152 from the d-axis current command value Id_11_ref input from the first integration unit 150c provided in the current command value generation unit 150. It has a portion 153a. The deviation calculation unit 153 also has a second subtraction unit 153b that subtracts the q-axis current Iq input from the coordinate conversion unit 152 from the q-axis current command value Iq_11_ref input from the second integration unit 150d. In this way, the deviation calculation unit 153 calculates the current command value generated by the current command value generation unit 150 and the current detection signals Iu_11, Iu_11, The difference between Iv_11 and Iw_11 is calculated. The current detection signals Iu, Iv, and Iw detected by the current detectors 113u, 113v, and 113w are U-phase, V-phase, and W-phase AC currents flowing between the power conversion module 11 and the load 9 . For this reason, the conversion power control unit 100 performs current feedback control in the deviation calculation unit 153 so that the current detection signals Iu_11, Iv_11, and Iw_11 (that is, the U phase and V current flowing between the power conversion module 11 and the load 9 phase and W-phase AC currents) are controlled to the values of the d-axis current command value Id_11_ref and the q-axis current command value Iq_21_ref.

The conversion power control unit 100 has a PI control unit 154 that performs proportional integral calculation on the signal output from the deviation calculation unit 153 . The PI control section 154 has a first PI control section 154 a that performs proportional integral control on the subtraction signal input from the first subtraction section 153 a provided in the deviation calculation section 153 . The PI control section 154 also has a second PI control section 154 b that performs proportional integral control on the subtraction signal input from the second subtraction section 153 b of the deviation calculation section 153 . The proportional calculation performed in each of the first PI control section 154a and the second PI control section 154b includes a parameter for converting the unit of the calculation result in the deviation calculation section 153 from current to voltage. Therefore, the signals output from the first PI control section 154a and the second PI control section 154b can be calculated with signals in voltage units.

The conversion power control unit 100 has a voltage drop calculation unit 155 that calculates voltage drops caused by the AC reactors Lu, Lv, and Lw (see FIG. 2) provided in the power conversion module 11 . The voltage drop calculation unit 155 includes a first calculation unit 155a that calculates a voltage drop due to the d-axis current Id input from the coordinate conversion unit 152, and a voltage drop due to the q-axis current Iq that is input from the coordinate conversion unit 152. and a second calculation unit 155b. “L” shown in FIG. 6 indicates a composite reactor of the AC reactors Lu, Lv, and Lw, and “ω” indicates the angular frequency of the three-phase AC voltage output by the power conversion module 11 .

The conversion power control unit 100 has a voltage addition unit 156 that adds or subtracts the voltage signal output by the PI control unit 154 and the d-axis system voltage Vd and the q-axis system voltage Vq output by the coordinate conversion unit 151 . The voltage addition unit 156 adds the voltage signal related to the d-axis input from the first PI control unit 154a provided in the PI control unit 154 and the d-axis system voltage Vd output from the coordinate conversion unit 151. It has a first adder 156a. The voltage addition unit 156 adds the voltage signal related to the q-axis input from the second PI control unit 154b provided in the PI control unit 154 and the q-axis system voltage Vq output from the coordinate conversion unit 151. It has a second adder 156b.

The voltage signal output from the PI control unit 154 is a signal based on the deviation between the d-axis current command value Id_11_ref and the q-axis current command value Iq_11_ref and the d-axis current Id_11 and the q-axis current Iq_11. That is, the voltage signal output from PI control section 154 is a signal based on the deviation between the current command value and the current detection value. Therefore, the voltage signal output from the first PI control unit 154a becomes a positive value when the d-axis current command value Id_11_ref is greater than the d-axis current Id_11, and the d-axis current command value Id_11_ref is d It becomes a negative value when it is smaller than the shaft current Id_11. Similarly, the voltage signal output from the second PI control unit 154b becomes a positive value when the q-axis current command value Iq_11_ref is larger than the q-axis current Iq_11, and the q-axis current command value Iq_11_ref is q It has a negative value when it is smaller than the shaft current Iq_11.

Therefore, when the voltage signal output from the first PI control unit 154a is positive, the first addition unit 156a adds the voltage signal to the d-axis system voltage Vd. On the other hand, when the voltage signal output from the first PI control unit 154a is negative, the first addition unit 156a adds the negative voltage signal to the d-axis system voltage Vd. Subtract the voltage signal from Vd. Similarly, when the voltage signal output from the second PI control unit 154b is positive, the second addition unit 156b adds the voltage signal to the q-axis system voltage Vq. On the other hand, when the voltage signal output from the second PI control unit 154b is negative, the second addition unit 156b adds the negative voltage signal to the q-axis system voltage Vq. The voltage signal is subtracted from Vq.

The conversion power control unit 100 has an addition/subtraction unit 157 that adds/subtracts the signal output from the voltage addition unit 156 and the signal output from the voltage drop calculation unit 155 . The addition/subtraction unit 157 adds the signal input from the first addition unit 157a provided in the voltage addition unit 156 and the signal input from the second calculation unit 155b of the voltage drop calculation unit 155 to the first addition unit 157a. have. The first adder 157a adds the signal input from the first adder 157a and the signal input from the second calculator 155b to generate the q-axis voltage command value on the dq coordinates.

The addition/subtraction unit 157 reverses the polarities of the signal input from the second addition unit 156b provided in the voltage addition unit 156 and the signal output from the first calculation unit 155a provided in the voltage drop calculation unit 155. It has a second adder 157b for adding the inverted signal. The second addition unit 157b adds the signal input from the second addition unit 156b and the inverted signal obtained by inverting the polarity of the signal output from the first calculation unit 155a, thereby obtaining the signal from the second addition unit 156b. A calculation equivalent to subtracting the signal input from the first calculation unit 155a from the input signal is executed to generate the d-axis voltage command value on the dq coordinates.

The conversion power control unit 100 converts the d-axis voltage command value and the q-axis voltage command value on the dq coordinates input from the addition/subtraction unit 157 into three-phase quantities, and outputs U-phase, V-phase, and W-phase output voltages. It has a coordinate conversion unit 158 that generates command values. That is, the coordinate conversion unit 158 outputs an output voltage command value to follow the U-phase AC output voltage generated by the power conversion module 11, an output voltage command value to follow the V-phase AC output voltage, and a W-phase AC output voltage. and an output voltage command value that causes the output voltage to follow.

The conversion power control unit 100 has a voltage command value standardizing unit 159 that standardizes the output voltage command value output by the coordinate transforming unit 158 . The voltage command value referencing unit 159 has a dividing unit 159a that halves the signal level of the voltage detection signal Vpn input from the voltage detector 16 (see FIG. 2). The voltage command value standardization unit 159 divides the output voltage command value input from the coordinate conversion unit 158 by the voltage level of the division signal input from the division unit 159a to standardize the output voltage command value. have. The standardization unit 159b standardizes each of the U-phase output voltage command value, the V-phase output voltage command value, and the W-phase output voltage command value input from the coordinate conversion unit 158 .

The conversion power control unit 100 pulse-width-modulates the standardized output voltage command values for the U-phase, the V-phase, and the W-phase input from the voltage command value standardization unit 159, and outputs the output voltage command values to the gate drive circuit 112. (refer to FIG. 2). The pulse width modulation unit 103 generates a control signal Sc_11 including information on gate pulse signals for driving the switching elements Q1 to Q6 provided in the power conversion module 11, and transmits the generated control signal Sc_11 to the gate drive circuit 112. output to

The common module control circuit 15 includes a storage unit 102 that stores the sharing coefficient characteristics SCup of the power conversion modules 11 and 13 and the sharing coefficient characteristics SCbo of the power conversion modules 12 and 14 . Further, the common module control circuit 15 controls the power conversion modules 11, 12, 13, 13, 13 based on the sharing coefficients α_11, α_12, α_13, α_14 obtained by referring to the sharing coefficient characteristics SCup, SCbo stored in the storage unit 102. 14 is provided with a current command value generation unit 150 corresponding to an example of an adjustment unit that adjusts the current flowing through each of the . The sharing coefficient characteristics SCup and SCbo are set so that the temperature difference between the power conversion modules 11, 12, 13 and 14 connected in parallel is small. Therefore, the common module control circuit 15 controls the currents flowing through the power conversion modules 11, 12, 13, and 14 based on the sharing coefficients α_11, α_12, α_13, and α_14 obtained by referring to the sharing coefficient characteristics SCup, SCbo. By adjusting the temperature difference between the power conversion modules 11, 12, 13 and 14 can be suppressed. The power conversion device 1 including the common module control circuit 15 can similarly suppress temperature differences among the power conversion modules 11 , 12 , 13 and 14 .

By the way, among the component parts of the conventional power converter, the forced air cooling fan of the cooler has a shorter life than the other components, so periodic replacement is required and the reliability of the power converter is lowered. end up Therefore, in some cases, conventional power converters are required to eliminate the need for maintenance work for the cooler by adopting a natural air cooling system that omits a fan for forced air cooling. Due to recent technological innovations in power semiconductor devices, smaller natural air-cooled power converters have been realized.

In order to apply natural air cooling to a power converter with a large conversion capacity, it is necessary to connect power semiconductor devices in parallel or connect multiple power conversion modules in parallel in order to disperse the amount of heat generated by the power semiconductor devices. It is realistic to adopt a configuration that Since power conversion modules are small, it is simple and practical to mount a plurality of power conversion modules on the same cooler (for example, a heat sink).

However, in the natural air cooling system, the heat of the heat sink is radiated by natural convection, so temperature unevenness on the same heat sink cannot be ignored. That is, in natural convection, the difference in temperature between the air in which natural convection occurs is large between the windward side and the leeward side, so the surface temperature of the heat sink also tends to increase toward the leeward side. Therefore, the cooling performance of the natural air cooling system differs depending on the location of each power conversion module. In particular, when the load to which power is supplied by the power conversion device is a heavy load, some of the power conversion modules may reach the temperature upper limit, limiting the output power of the power conversion device. Patent Literature 1 and Patent Literature 2 disclose a method of equalizing the cooling performance given to each power conversion module.

Patent Literature 1 discloses a cooling device including a first power conversion module and a second power conversion module having a larger area of thermal connection with a heat sink than the first power conversion module. Furthermore, in Patent Document 1, by arranging the first power conversion module on the windward side of the heat sink and the second power conversion module on the leeward side, the thermal resistance between the second power conversion module and the heat sink is , is lower than the thermal resistance of the first power conversion module and the heat sink, and the unevenness of the cooling performance due to the cooler itself can be offset as much as possible.

Patent Literature 2 discloses a cooling device in which the power conversion modules are arranged in a staggered manner on a heat sink so that the cooling performance given to each power conversion module is made uniform as much as possible.

The cooling device described in Patent Literature 1 requires power conversion modules having a plurality of types of different structures, so there is a problem of high cost. The cooling device described in Patent Literature 2 has a problem that the cooling device becomes large because there is a wasted space in which the power conversion module cannot be mounted on the heat sink.

On the other hand, the common module control circuit 15 and the power converter 1 according to the present embodiment change the sharing coefficient according to the places where the power conversion modules 11, 12, 13, and 14 are arranged on the cooling unit 18. Therefore, the loss generated in the power conversion modules 11, 12, 13, and 14 is adjusted. As a result, the common module control circuit 15 and the power conversion device 1 can suppress temperature variations among the power conversion modules 11 , 12 , 13 , and 14 and prevent output power limitation of the power conversion device 1 .

Further, in the common module control circuit 15 and the power conversion device 1, the power conversion modules 11, 12, 13 and 14 can have the same structure (size, shape, etc.). Thereby, cost reduction of the common module control circuit 15 and the power converter 1 can be achieved. Furthermore, since the common module control circuit 15 and the power conversion device 1 can mount the power conversion modules 11, 12, 13, and 14 in the cooling unit 18 without creating a wasteful space, miniaturization can be achieved.

As described above, the common module control circuit 15 according to this embodiment controls the power conversion modules 11, 12, 13, and 14 so that the temperature difference between the power conversion modules 11, 12, 13, and 14 connected in parallel is reduced. A storage unit 102 that stores a ratio of the converted power to be borne in association with a value based on the total converted power of the plurality of power conversion modules 11, 12, 13, and 14; A current command value generation unit 150 is provided to adjust the current flowing through each of the conversion modules 11 , 12 , 13 , 14 .

Further, the power conversion device 1 according to the present embodiment includes power conversion modules 11, 12, 13, and 14 connected in parallel, a cooling unit 18 for cooling the power conversion modules 11, 12, 13, and 14, and a common module control circuit. 15.

The common module control circuit 15 and the power converter 1 having such a configuration are configured so that the temperature difference between the power conversion modules 11, 12, 13, and 14 is small. It is possible to adjust the current flowing through each of the power conversion modules 11, 12, 13, and 14 based on the ratio of the converted power borne by (that is, the sharing coefficient). As a result, the common module control circuit 15 and the power conversion device 1 reduce the output power of the power conversion modules whose temperature tends to be relatively high, thereby suppressing loss (that is, heat generation). By increasing the output power of the power conversion module, which tends to be expensive, the output power amount of the entire power converter 1 can be maintained. As a result, the common module control circuit 15 and the power converter 1 can suppress the temperature unevenness of the power conversion modules 11 , 12 , 13 , 14 . As a result, the common module control circuit 15 and the power converter 1 can prevent the overall output power from being rate-determined by any one of the power conversion modules 11 , 12 , 13 , and 14 .

[Second embodiment]
A control device according to a second embodiment of the present invention and a power converter including the same will be described with reference to FIGS. 7 to 11. FIG. Concerning the control device according to the present embodiment and the power conversion device including the same, the same reference numerals are given to the constituent elements having the same actions and functions as those of the common module control circuit 15 and the power conversion device 1 according to the first embodiment. Detailed description is omitted.

(power converter)
First, the schematic configuration of the power converter according to the present embodiment will be described using FIG. 7 while referring to FIGS. 2 and 3. FIG.

As shown in FIG. 7, the power conversion device 3 according to the present embodiment includes an ambient temperature detector (detector example) 28 is provided. The ambient temperature detector 30 is configured to output to the common module control circuit 35 a temperature detection signal Ta, which is a signal containing information on the detected temperature. Here, the air that flows into the cooling section 18 is air that flows due to natural convection NC in the cooling section 18, for example. As the ambient temperature detector 30 that detects the temperature of the air flowing into the cooling section 18, for example, a detector that employs a thermocouple as a temperature detection section is exemplified. As the ambient temperature detector 30 that detects the temperature from which the temperature of the air flowing into the cooling unit 18 can be estimated, for example, a detector that employs a resistance temperature device as a temperature detection unit is exemplified.

Based on the temperature detection signal Ta input from the ambient temperature detector 30, the common module control circuit 35 can change the sharing coefficient corresponding to an example of the ratio of the converted power shared by the plurality of power conversion modules. It has the same configuration as the common module control circuit 15 according to the first embodiment except that it is configured in the same manner as the common module control circuit 15, and exhibits the same functions.

The power conversion modules 11, 12, 13, 14, voltage detector 16, and voltage detection circuit 17 in the present embodiment are similar to the power conversion modules 11, 12, 13, 14, voltage detector 16, and voltage detection in the first embodiment. Since it has the same configuration as the circuit 17 and exhibits the same function, the description is omitted.

(Control device)
Next, the control device according to the present embodiment will be described using FIGS. 8 to 11 while referring to FIGS. 2, 3 and 7. FIG. A common module control circuit 35 (see FIG. 7), which corresponds to an example of the control device according to the present embodiment, is configured to control the power conversion modules 11, 12, 13, and 14 (see FIG. 1). The common module control circuit 15 receives the voltage detection signal Vpn input from the voltage detector 16 (see FIG. 1), the voltage detection signals Vu, Vv, and Vw input from the voltage detection circuit 17 (see FIG. 1), the power conversion module Current detection signals Iu_11 to Iw_11 input from 11, current detection signals Iu_12 to Iw_12 input from the power conversion module 12, current detection signals Iu_13 to Iw_13 input from the power conversion module 13, input from the power conversion module 14 A function of outputting control signals Sc_11, Sc_12, Sc_13, and Sc_14 calculated based on the current detection signals Iu_14 to Iw_14 and the temperature detection signal Ta input from the ambient temperature detector 30 to the power conversion modules 11, 12, 13, and 14. It is designed to work. Thereby, the common module control circuit 35 can individually adjust the ratio of the converted power borne by the power conversion modules 11, 12, 13, and 14 in real time, taking into consideration the ambient temperature.

FIG. 8 shows an example of module temperature characteristics of the four power conversion modules 11 , 12 , 13 and 14 with respect to the load factor LF in the power conversion device 3 . The horizontal axis of the graph shown in FIG. 8 represents the load factor LF [p. u. ], and the vertical axis of the graph indicates the module temperature Tm [° C.] of the power conversion module. “TCup1” and “TCup2” shown in FIG. 8 indicate temperature characteristics of the power conversion modules 11 and 13 mounted on the upper side of the cooling section 18 . “TCup1” indicates the characteristics when the value of the module temperature Tm (initial temperature) is Tma1 (for example, 40° C.) when the value of the load factor LF is 0, and “TCup2” indicates the characteristics when the initial temperature value of the module temperature Tm is The characteristics for Tma2 (for example, 60° C.) are shown. “TCbo1” and “TCbo2” shown in FIG. 8 indicate temperature characteristics of the power conversion modules 12 and 14 mounted on the lower side of the cooling section 18 . “TCbo1” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma1 (eg, 40° C.), and “TCbo2” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma2 (eg, 60° C.). showing characteristics. “TRup1” and “TRup2” shown in FIG. 8 are reference examples of the temperature characteristics of the power conversion module, and are mounted on the upper side of the cooling unit 18 and have a constant sharing coefficient (for example, “1”). shows the temperature characteristics of the power conversion module. “TRup1” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma1 (eg, 40° C.), and “TRup2” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma2 (eg, 60° C.). showing characteristics. "TRbo1" and "TRbo2" shown in FIG. 8 are reference examples of the temperature characteristics of the power conversion module, are mounted on the lower side of the cooling unit 18, and have a constant sharing coefficient (for example, "1"). 3 shows the temperature characteristics of the power conversion module in the case of FIG. “TRbo1” indicates the temperature characteristic of the power conversion module when the initial temperature value of the module temperature Tm is Tma1 (eg, 40° C.); °C) shows the temperature characteristics of the power conversion module.

As shown in FIG. 8, the temperature characteristics TCup1, TCbo1, TRup1, and TRbo1 when the initial temperature value of the module temperature Tm is Tma1 (for example, 40° C.) are the temperature characteristics TCup, TCbo, TRup, and It has the same characteristics as TRbo. Therefore, when the initial temperature value of the module temperature Tm is Tm1, the value of the load factor LF is 1 [p. u. ], the power conversion modules 11 and 13 having a relatively high module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 share The coefficients α_11 and α_13 are set to decrease to values less than one. Further, with a predetermined value LFb1 of the load factor LF as a boundary value, the power conversion modules 12 and 14 having a relatively low module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 is set to increase to a value greater than one. Here, predetermined value LFb1 is set to a value of load factor LF at which module temperature Tmp of power conversion modules 11, 12, 13, and 14 does not reach upper limit value Tml. For example, the predetermined value LFb1 is set to a value smaller than the value LFa1 of the load factor LF at which the power conversion modules 11 and 13 having relatively high module temperatures Tm reach the upper limit value Tml when the sharing coefficient is set to a constant value. be.

As a result, as shown by the temperature characteristic TCup1 in FIG. 8, among the four power conversion modules 11, 12, 13, and 14, the power is mounted on the upper side of the cooling unit 18 and the module temperature Tm is relatively high. In the conversion modules 11 and 13, the rate of increase in the module temperature Tm is smaller when the load factor LF is equal to or greater than the predetermined value LFb1 than when the load factor LF is between 0 and the predetermined value LFb1. On the other hand, as indicated by the temperature characteristic TCbo1 in FIG. Modules 12 and 14 have a higher rate of increase in module temperature Tm when the load factor is greater than or equal to the predetermined value LFb1 than when the load factor is between 0 and the predetermined value LFb1. Thereby, the power conversion device 3 can reduce the temperature difference in the module temperature Tm between the power conversion modules 11 and 13 and the power conversion modules 12 and 14 when the load factor LF is equal to or higher than the predetermined value LFb1.

As shown in FIG. 8, when the initial temperature value of the module temperature Tm is Tm2 (>Tm1), the conversion power sharing coefficients borne by the respective power conversion modules are all constant regardless of the load factor LF (for example, "1 ), the temperature Tm of the power conversion module linearly increases from the initial temperature Tma2 as the load factor LF increases, as indicated by the temperature characteristics TRup2 and TRbo2 in FIG. The initial temperature Tma2 is a temperature higher than the maximum initial temperature assumed as the ambient temperature of the power conversion modules 11 , 12 , 13 and 14 . A power conversion module arranged on the upper side (downwind side) of the cooling section 18 has a higher module temperature Tm than a power conversion module arranged on the lower side (windward side) of the cooling section 18 . Therefore, the power conversion module arranged on the upper side (downwind side) of the cooling unit 18 has a load factor LF of 1 [p. u. ], the module temperature Tm reaches the upper limit value Tml at a value LFa2 (<LFa1). Therefore, even though the module temperature Tm of the power conversion module arranged on the lower side (windward side) of the cooling unit 18 is lower than the upper limit value Tml, the output converted power of the power conversion device 3 is The power conversion module arranged on the upper side (downwind side) of the unit 18 limits the speed.

As indicated by the temperature characteristic TRbo2 in FIG. 8, the module temperature Tm of the power conversion module arranged on the lower side (windward side) of the cooling unit 18 does not reach the upper limit value Tml when the value of the load factor LF is LFa2. . For this reason, the power conversion module arranged on the lower side (windward side) of the cooling unit 18 has room for further increasing the load factor LF. However, when the initial temperature value of the module temperature Tm is Tm2 (>Tm1), the module temperature Tm of the power conversion module arranged on the lower side (windward side) of the cooling unit 18 also has a load factor LF value of 1 [ p. u. ], the module temperature Tm reaches the upper limit value Tml at a value LFa3 (>LFa2).

Therefore, similarly to the case where the initial temperature value of the module temperature Tm is Tm1, also when the initial temperature value of the module temperature Tm is Tm2, the value of the load factor LF is 1 [p. u. ], the power conversion modules 11 and 13 having a relatively high module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13, and 14 share The coefficients α_11 and α_13 are set to decrease to values less than one. Further, with a predetermined value LFb2 of the load factor LF as a boundary value, the power conversion modules 12 and 14 having a relatively low module temperature Tm among the plurality of (four in this embodiment) power conversion modules 11, 12, 13 and 14 is set to increase to a value greater than one. Here, predetermined value LFb2 is set to a value of load factor LF at which module temperature Tm of none of power conversion modules 11, 12, 13, and 14 does not reach upper limit value Tml. For example, the predetermined value LFb2 is set to a value smaller than the value LFa2 of the load factor LF at which the power conversion modules 11 and 13 having relatively high module temperatures Tm reach the upper limit value Tml when the sharing coefficient is set to a constant value. be.

As a result, as shown by the temperature characteristic TCup2 in FIG. 8, among the four power conversion modules 11, 12, 13, and 14, the power is mounted on the upper side of the cooling unit 18 and the module temperature Tm is relatively high. In the conversion modules 11 and 13, the rate of increase in the module temperature Tm is smaller when the load factor LF is equal to or greater than the predetermined value LFb2 than when the load factor LF is between 0 and the predetermined value LFb2. On the other hand, as indicated by the temperature characteristic TCbo2 in FIG. Modules 12 and 14 have a higher rate of increase in module temperature Tm when the load factor is equal to or greater than the predetermined value LFb2 than when the load factor is between 0 and the predetermined value LFb2. As a result, the power conversion device 3 can reduce the temperature difference in the module temperature Tm between the power conversion modules 11 and 13 and the power conversion modules 12 and 14 when the load factor LF is equal to or higher than the predetermined value LFb2.

In this way, even if the initial temperature value of the module temperature Tm is the initial temperature Tm2 that is higher than the maximum initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, and 14, the power conversion module 11 , 13 and the module temperature Tm between the power conversion modules 12, 14 can be reduced. However, the module temperature Tm of the power conversion modules 11, 12, 13, and 14 is 1 [p. u. ], the upper limit value Tml is reached at a limit value LFc (for example, 0.7). Therefore, when the initial temperature value of the module temperature Tm is higher than the maximum initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, and 14, the power conversion device 3 operates at a load factor LF is designed to limit the range of

FIG. 9 shows the characteristics of the sharing coefficients α_11, α_12, α_13, and α_14 of the converted power P_11, P_12, P_13, and P_14 borne by the four power conversion modules 11, 12, 13, and 14 with respect to the load factor LF of the power converter 3. shows an example. The horizontal axis of the graph shown in FIG. 9 represents the load factor LF [p. u. ], and the vertical axis of the graph indicates the allocation coefficient. “SCup1” and “SCup2” shown in FIG. 9 indicate the sharing coefficient characteristics of the power conversion modules 11 and 13 mounted on the upper side of the cooling section 18 . “SCup1” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma1 (eg, 40° C.), and “SCup2” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma2 (eg, 60° C.). showing characteristics. “SCbo1” and “SCbo2” shown in FIG. 9 indicate the sharing coefficient characteristics of the power conversion modules 12 and 14 mounted on the lower side of the cooling section 18 . “SCbo1” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma1 (eg, 40° C.), and “SCbo2” indicates the characteristics when the initial temperature value of the module temperature Tm is Tma2 (eg, 60° C.). showing characteristics.

As shown in FIG. 9, when the initial temperature of the module temperature Tm is an initial temperature Tma1 (for example, 40° C.) below the highest initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, and 14, the sharing coefficient The characteristics SCup1 and SCbo1 have the same characteristics as the sharing coefficient characteristics SCup and SCbo in the first embodiment. Therefore, when the initial temperature value of the module temperature Tm is Tma1, the sharing coefficients α_11 and α_13 of the power conversion modules 11 and 13 are such that the load factor FL is 0 [p. u. ] or more predetermined value LFb1 [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb1 [p. u. ] or more 1 [p. u. ] has a sharing coefficient characteristic SCup1 that decreases in the following range. On the other hand, the sharing coefficients α_12 and α_14 of the power conversion modules 12 and 14 are such that the load factor LF is 0 [p. u. ] or more predetermined value LFb1 [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb1 [p. u. ] or more 1 [p. u. ] has an allotment coefficient characteristic SCbo1 that increases in the following range.

When the power conversion modules 11 and 13 have a load factor of a predetermined value LFb1[p. u. ] to 1 [p. u. ], and when the load factor is 1 [p. u. ] has a sharing coefficient characteristic SCup1 whose value is α−(α−<1). When the power conversion modules 12 and 14 have a load factor of a predetermined value LFb1[p. u. ] to 1 [p. u. ], and when the load factor is 1 [p. u. ] has a distribution coefficient characteristic SCbo1 whose value is α+(α+>1).

As shown in FIG. 9, when the initial temperature of the module temperature Tm is an initial temperature Tma2 (for example, 60° C.) higher than the maximum initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, and 14, the sharing The coefficient characteristics SCup2 and SCbo2 are such that the maximum value of the load factor LF is 1 [p. u. ] It has a characteristic that is less than When the initial temperature value of the module temperature Tm is Tma2, the sharing coefficients α_11 and α_13 of the power conversion modules 11 and 13 are such that the load factor FL is 0 [p. u. ] or more than the predetermined value LFb2 [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb2 [p. u. ] and the limit value LFc (<1) [p. u. ] has a sharing coefficient characteristic SCup2 that decreases in the following range. On the other hand, the sharing coefficients α_12 and α_14 of the power conversion modules 12 and 14 are such that the load factor LF is 0 [p. u. ] or more than the predetermined value LFb2 [p. u. ] is a constant value α1 (for example, “1”), and a predetermined value LFb2 [p. u. ] and the limit value LFc [p. u. ] has an allotment coefficient characteristic SCbo2 that increases in the following range.

In the power conversion modules 11 and 13, the load factor LF is a predetermined value LFb2 [p. u. ] to the limit value LFc [p. u. ], and the limit value LFc [p. u. ] has a sharing coefficient characteristic SCup2 whose value is α−(α−<1). In the power conversion modules 12 and 14, the load factor LF is a predetermined value LFb2 [p. u. ] to the limit value LFc [p. u. ], and the load factor LF reaches the limit value LFc [p. u. ] has a sharing coefficient characteristic SCbo2 whose value is α+(α+>1).

Thus, under the condition that the initial temperature of the module temperature Tm exceeds the maximum initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, 14, the maximum load factor is 1 [p. u. ], the transition of the allocation coefficient will be different. The sharing coefficient characteristic SCup2 has such a characteristic that the sharing coefficient characteristic SCup1 shifts in the direction of decreasing the load factor LF. The sharing factor characteristic SCbo2 has such a characteristic that the sharing factor characteristic SCbo1 is shifted in the direction of decreasing the load factor LF. Therefore, when the initial temperature of the module temperature Tm is different, even if the load factor is the same, the sharing coefficient changes when the value of the load factor LF is between the predetermined value Fb2 and the limit value LFc. That is, the sharing coefficient corresponding to an example of the ratio of the converted power borne by the plurality of power conversion modules is the ambient temperature (air temperature) of the power conversion modules 11, 12, 13, and 14 detected by the ambient temperature detector 30. example) or the ambient temperature can be estimated. The distribution coefficient characteristics of the power conversion modules 11, 12, 13, and 14 with respect to the load factor LF of the power converter 3 and the ambient temperature shown in FIG. It is obtained by calculation by simulation.

The predetermined value FLb1 of the load factor LF may be set to any value less than or equal to LFa1. The predetermined value FLb1 of the load factor LF may be set, for example, to a value 10% lower than the value LFa1 of the load factor LF. The predetermined value FLb2 of the load factor LF may be set to any value less than or equal to LFa2 for the load factor LF. The predetermined value FLb2 of the load factor LF may be set to a value 10% lower than the value LFa2 of the load factor LF, for example. Also, when the maximum value of the load factor LF is 1 [p. u. ] is a unique value with which the load factor can be maximized, with the sharing factor and the load factor as parameters. When the maximum value of the load factor LF is 1 [p. u. ] can be obtained by measuring before the power conversion device 3 is put into actual operation or by searching for the sharing coefficient and the load factor as parameters through an operation simulation of the power conversion device 3 .

The sharing coefficient characteristics SCup1, SCbo1, SCup2, SCbo2, the predetermined values LFb1, LFb2 of the load factor LF, and the limit value LFc of the load factor LF are stored in, for example, a storage unit (details are (to be described later).

Next, the configuration of the main part of the control device according to the present embodiment will be described using FIG. 10 while referring to FIGS. 7 to 9. FIG. FIG. 10 is a functional block diagram showing an example of a main part of a common module control circuit (an example of a control device) 35 provided in the power converter 3. As shown in FIG. The common module control circuit 35 causes the power conversion modules 11, 12, 13, and 14 to share the load factor LF of the power converter 3 according to the sharing coefficients α_11, α_12, α_13, and α_14. , 14 are individually controlled. The common module control circuit 35 has a conversion power control section that controls conversion power for each of the power conversion modules 11 , 12 , 13 and 14 . The conversion power control unit has the same configuration in each of the power conversion modules 11, 12, 13, and 14, and exhibits the same function. For this reason, the configuration of each conversion power control unit of the power conversion modules 11, 12, 13, and 14 will be described below by taking the conversion power control unit of the power conversion module 11 as an example. Note that FIG. 10 shows the conversion power control unit 300 of the power conversion module 11 .

As shown in FIG. 10, the conversion power control unit 300 provided in the common module control circuit 35 is the same as the common module control circuit according to the first embodiment, except that the overall control unit 301 and the storage unit 302 have different configurations. It has the same configuration as the conversion power control section 100 provided in 15, and exhibits the same function.

As shown in FIG. 10, the integrated control unit 301 includes a d-axis current Id_ref, which is a request value of an external factor input from outside the common module control circuit 35 (in this embodiment, the load 9 (see FIG. 7)), In addition to the q-axis current Iq_ref and the maximum requested current Idq_ref, the temperature detection signal Ta output by the ambient temperature detector 30 (see FIG. 7) is input.

The storage unit 302 provided in the common module control circuit 35 stores shared coefficient characteristics SCup1, SCbo1, SCup2, SCbo2, and the like. Therefore, the sharing coefficients stored in the storage unit 302 and corresponding to an example of the ratio of the converted power borne by the plurality of power conversion modules are the power conversion modules 11, 12, 13, and 14 detected by the ambient temperature detector 30. ambient temperature (an example of air temperature) or a temperature detection value that can estimate the ambient temperature.

For example, the integrated control unit 301 refers to the sharing coefficient characteristic based on the initial temperature of the module temperature Tm corresponding to the temperature detection signal Ta input from the ambient temperature detector 30, and calculates the current time calculated using the above equation (6). The sharing coefficient α_11 corresponding to the load factor LF at is read out from the storage unit 302 . For example, when the initial temperature value of the module temperature Tm corresponding to the temperature detection signal Ta input from the ambient temperature detector 30 is Tma2, the overall control unit 301 changes the sharing coefficient characteristic SCup2 stored in the storage unit 302 to Tma2. , and reads out the allotment coefficient α_11 corresponding to the current load factor LF calculated using the above equation (6).

Thus, in this embodiment, the temperature detection signal Ta input from the ambient temperature detector 30, that is, the ambient temperature of the power conversion module 11 is reflected in the sharing coefficient read by the integrated control unit 301 . Therefore, the conversion power control unit 300, from the current command value generation unit 150 to the pulse width modulation unit 103, operates in the same manner as the conversion power control unit 100 in the first embodiment, so that the ambient temperature of the power conversion module 11 can be generated and output to the gate driving circuit 112 (see FIG. 2).

Next, the relationship between the ambient temperature and the maximum output power of the power converter according to this embodiment will be explained using FIG. Here, the maximum output power of the power converter corresponds to the maximum load factor. FIG. 11 is a graph showing an example of the relationship between the ambient temperature and the maximum output power of the power conversion device 3. In FIG. The horizontal axis of the graph shown in FIG. 11 indicates the ambient temperature [° C.], and the vertical axis of the graph indicates the maximum output power [%]. A power characteristic MP1 shown in FIG. 11 indicates the characteristic of the maximum output power of the power conversion device 3 when the sharing coefficients of the power conversion modules 11, 12, 13, and 14 are changed. A power characteristic MP2 shown in FIG. 11 indicates the characteristic of the maximum output power of the power converter when the sharing coefficients of the power conversion modules 11, 12, 13, and 14 are not changed (when the sharing coefficients are fixed values). .

As shown by the power characteristic MP1 in FIG. 11, when the sharing coefficients of the power conversion modules 11, 12, 13, and 14 are changed, the operating range of the power converter 3 is the maximum output power when the ambient temperature is up to 40°C. 100%. The power characteristic MP1 also corresponds to the operating range of the power converter 1 according to the first embodiment.

As shown by the power characteristic MP1 in FIG. 11, when the sharing coefficients of the power conversion modules 11, 12, 13, and 14 are changed and the ambient temperature is 60° C., the operating range of the power converter 3 is the maximum output power. up to 70%. In this way, the power conversion device 3 can cope with derating with respect to the ambient temperature by limiting the operating range. The power conversion device 3 continuously or intermittently updates the appropriate sharing coefficient according to the ambient temperature within the operating range of 70% of the maximum output power. As a result, the power electronics device 3 can obtain a larger maximum output power than when the sharing coefficient is a fixed value (see power characteristic MP2).

As described above, the common module control circuit 35 according to the present embodiment controls the power conversion modules 11, 12, 13, and 14 so that the temperature difference between the power conversion modules 11, 12, 13, and 14 connected in parallel is reduced. A storage unit 302 that stores a ratio of the converted power to be borne in association with a value based on the total converted power of the plurality of power conversion modules 11, 12, 13, and 14; A current command value generation unit 150 is provided to adjust the current flowing through each of the conversion modules 11 , 12 , 13 , 14 .

The power conversion device 3 according to the present embodiment includes power conversion modules 11, 12, 13, and 14 connected in parallel, a cooling unit 18 for cooling the power conversion modules 11, 12, 13, and 14, and a common module control circuit. 35.

The common module control circuit 35 and the power converter 3 having such configurations can obtain the same effects as the common module control circuit 15 and the power converter 1 according to the first embodiment.

In addition, the power conversion device 3 according to the present embodiment includes an ambient temperature detector (detection An example of a vessel) 28 is provided. The common module control circuit 35 and the power conversion device 3 can change the sharing coefficient according to the detected ambient temperature of the power conversion modules 11 , 12 , 13 and 14 detected by the ambient temperature detector 30 . As a result, the common module control circuit 35 and the power conversion device 3 can cope with derating with respect to the ambient temperature by adjusting the operating range according to the initial ambient temperature of the power conversion modules 11, 12, 13, and 14. can be done.

[Third embodiment]
A control device and a power conversion device according to a third embodiment of the present invention will be described with reference to FIG. The power converter according to this embodiment is characterized in that the cooling unit is divided individually for each of the plurality of power conversion modules or divided for each part of the plurality of power conversion modules. Concerning the control device according to the present embodiment and the power conversion device including the same, the same reference numerals are given to the constituent elements having the same actions and functions as those of the common module control circuit 15 and the power conversion device 1 according to the first embodiment. Detailed description is omitted.

As shown in FIG. 12, the power converter according to this embodiment includes a cooling section 18 divided into four parts. In this embodiment, the cooling unit 18 is individually divided for each power conversion module 11, 12, 13, 14 as cooling units 18a, 18b, 18c, 18d.

The power conversion module 11 is mounted in the cooling unit 18a, the power conversion module 12 is mounted in the cooling unit 18b, the power conversion module 13 is mounted in the cooling unit 18c, and the power conversion module is mounted in the cooling unit 18d. A module 14 is mounted.

The cooling units 18a, 18b, 18c and 18d have base portions 181a, 181b, 181c and 181d on which the power conversion modules 11, 12, 13 and 14 are mounted. The power conversion modules 11, 12, 13, 14 are thermally joined to the base portions 181a, 181b, 181c, 181d. The cooling units 18a, 18b, 18c, 18d are composed of a plurality of radiation fins 182a, 182b extending from the rear surface of the mounting surface of the base units 181a, 181b, 181c, 181d on which the power conversion modules 11, 12, 13, 14 are mounted. , 182c and 182d. Each of the plurality of radiation fins 182a, 182b, 182c, 182d has a thin rectangular parallelepiped shape. The plurality of radiation fins 182a are arranged with a predetermined gap therebetween. The plurality of radiation fins 182b are arranged with a predetermined gap therebetween. The plurality of radiation fins 182c are arranged with a predetermined gap therebetween. A plurality of radiation fins 182d are arranged with a predetermined gap therebetween. The base portions 181a, 181b, 181c, 181d and the plurality of radiation fins 182a, 182b, 182c, 182d are formed integrally, for example.

The cooling portions 18a, 18b, 18c, 18d are arranged at approximately equal intervals. The cooling units 18a and 18b are arranged side by side in the vertical direction, and the cooling units 18c and 18d are arranged side by side in the vertical direction. The cooling units 18a and 18c are arranged side by side in the left-right direction, and the cooling units 18b and 18d are arranged side by side in the left-right direction. The cooling units 18a and 18c are installed inside a housing (not shown) provided in the power converter, with a plurality of radiation fins 182a and 182c arranged horizontally. The cooling units 18b and 18d are installed inside a housing (not shown) provided in the power conversion device 3 with a plurality of heat radiation fins 182b and 182d arranged horizontally. The cooling units 18a, 18b, 18c, 18d cool the power conversion modules 11, 12, 13, 14 by natural air cooling. Therefore, as shown in FIG. 12, the direction of the natural convection NC generated in the plurality of radiation fins 182a, 182b, 182c, and 182d is from the bottom to the top. As a result, the temperature of the cooling portions 18a and 18c becomes higher than that of the cooling portions 18b and 18d.

However, the common module control circuits 15 and 35 and the power conversion devices 1 and 3 according to the first and second embodiments can be applied to the control device and the power conversion device according to the present embodiment. As a result, the control device and the power converter according to the present embodiment can control the power conversion module 11 by the same method as the common module control circuits 15 and 35 and the power converters 1 and 3 according to the first embodiment or the second embodiment. , 12, 13, and 14, temperature unevenness of the power conversion modules 11, 12, 13, and 14 can be suppressed.

The present invention is not limited to the above embodiment, and various modifications are possible.
The control device and the power conversion device according to the first to third embodiments have a current command value generation unit, and current (that is, load factor ), but the present invention is not limited to this. For example, the control device and the power conversion device are not limited to the method of adjusting the output current command value, and according to the control purpose of the power supply device, appropriately through other physical quantities such as the torque command value and the input current command value. Of course, the current (that is, load factor) flowing through each of the power conversion modules may be adjusted. Furthermore, the control device and the power conversion device may, of course, adjust the time for which the current flows instead of adjusting the current amount of the current flowing through each of the plurality of power conversion modules.

In the above-described first to third embodiments, the DC-AC converter (two-level inverter) is used as an example of the power converter, but the present invention is not limited to this. For example, other converters such as DC-DC converters and AC-DC converters can be applied as the power conversion device according to the present invention. By adjusting the load factor borne by the plurality of power conversion modules provided in these converters via a value having a causal relationship with the load factor, the control device according to the first to third embodiments And the same effect as the power converter can be obtained.

In the first embodiment and the second embodiment, the power conversion modules 11 and 13 arranged on the upper side of the cooling section 18 have the same temperature characteristics and sharing coefficient characteristics, and are arranged on the lower side of the cooling section 18. Although the power conversion modules 12 and 13 are assumed to have the same temperature characteristics and sharing coefficient characteristics, the present invention is not limited to this. For example, the power conversion modules 11, 12, 13, and 14 each have different temperature characteristics and sharing coefficient characteristics, and the sharing coefficient and the current flowing through each power conversion module (that is, the load factor) are individually controlled by the above-described method. But of course it's fine.

The distribution coefficient characteristic in the first embodiment is set such that the load factor value changes in a curve between a predetermined value LFb and 1 in order to mitigate sudden temperature changes. Further, the sharing system general characteristic in the second embodiment is such that the value of the load factor is between the predetermined value LFb1 and 1 or between the predetermined value LFb2 and the limit value LFc, in order to mitigate sudden temperature changes. It is set to change in a curvilinear manner. However, the present invention is not limited to this. For example, the sharing factor characteristics may be set to increase or decrease between them linearly or stepwise. Alternatively, the sharing factor characteristic may be set to increase or decrease by a combination of at least two of curvilinear, linear and stepped changes therebetween.

When the initial temperature of the module temperature Tm is lower than the highest initial temperature assumed as the ambient temperature of the power conversion modules 11, 12, 13, and 14, the control device and the power conversion device according to the present invention provide the load factor It may be configured to be able to select whether or not to change the allotment coefficient according to. When the initial temperature of the module temperature Tm is lower than the highest initial temperature assumed as the ambient temperature of the plurality of power conversion modules, the module temperature of the power conversion module having a relatively high temperature among the plurality of power conversion modules is , the value of the load factor is 1.0 [p. u. ] may not reach the upper limit. Therefore, in the control device and power conversion device according to the present invention, the module temperature of the power conversion module, which is relatively high, is such that the load factor value is 1.0 [p. u. ], a threshold of the initial temperature may be set for determining whether or not the temperature reaches the upper limit. The control device and the power conversion device according to the present invention change the sharing coefficient according to the load factor when the initial temperature exceeds the threshold, and keep the sharing coefficient constant when the initial temperature is equal to or less than the threshold. , may be configured to be switchable.

In the third embodiment, the cooling unit 18 is divided individually as the cooling units 18a, 18b, 18c, and 18d for each of the power conversion modules 11, 12, 13, and 14, but the present invention is not limited to this. . For example, the cooling unit 18 may be divided for each part of the plurality of power conversion modules. Specifically, for example, of the power conversion modules 11, 12, 13, and 14, the cooling unit 18 sets the upper power conversion modules 11 and 13 as a set, and the lower power conversion modules 12 and 14 as a set. The set may be vertically divided into two. Further, the cooling unit 18 includes the power conversion modules 11, 12 arranged on the left side of the power conversion modules 11, 12, 13, 14 as a group, and the power conversion modules 13, 14 arranged on the right side as a group. may be divided into two in the left and right direction. Also, the cooling unit 18 may be divided into two by one of the power conversion modules 11, 12, 13, and 14 and the remaining three. Furthermore, the cooling unit 18 may be divided into three by one of the power conversion modules 11, 12, 13, and 14, the remaining one, and the remaining two.

In the above-described first to third embodiments, the natural air cooling system is described as an example of the cooling system, but the present invention is not limited to this. For example, the present invention can be applied to a forced air cooling system or a water cooling system. In the case of water cooling, the ambient temperature detector 30 is configured to detect the temperature of water used as a cooling medium or a temperature from which the temperature of water used as a cooling medium can be estimated.

In the first to third embodiments, the number of power conversion modules provided in the power conversion device is four, but the present invention is not limited to this. The same effect can be obtained even if the number of power conversion modules is two, three, or five or more.

In the first to third embodiments, the switching elements Q1 to Q6 are composed of MOSFETs, but the present invention is not limited to this. For example, the switching elements Q1-Q6 may be other power semiconductor devices such as IGBTs (Insulated Gate Bipolar Transistors).

The scope of the invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that achieve equivalent effects for which the invention is intended. Furthermore, the scope of the present invention is not limited to the combination of inventive features defined by the claims, but is defined by any desired combination of the specific features of each and every disclosed feature. sell.

1, 3 power conversion device 8 DC power supply 9 loads 11, 12, 13, 14 power conversion modules 15, 35 common module control circuits 16, 171, 172, 173 voltage detector 17 voltage detection circuits 18, 18a, 18b, 18c, 18d Cooling unit 30 Ambient temperature detectors 100, 300 Conversion power control units 101, 310 Integrated control units 102, 302 Storage unit 103 Pulse width modulation unit 111 Inverter unit 112 Gate drive circuits 113u, 113v, 113w Current detector 150 Current command value Generation unit 150a First division unit 150b Second division unit 150c First integration unit 150d Second integration unit 151, 152, 158 Coordinate conversion unit 153 Deviation calculation unit 153a First subtraction unit 153b Second subtraction unit 154 PI control unit 154a One PI control unit 154b Second PI control unit 155 Voltage drop calculation unit 155a First calculation unit 155b Second calculation unit 156 Voltage addition units 156a, 157a First addition units 156b, 157b Second addition unit 157 Addition/subtraction unit 159 Voltage command value Reference section 159a Division section 159b Reference section 181, 181a, 181b, 181c, 181d Base section 182, 182a, 182b, 182c, 182d Radiation fin C DC capacitors D1, D2, D3, D4, D5, D6 Freewheeling diode Lu , Lv, Lw AC reactors M1, M2, M3, M4, M5, M6 Semiconductor elements Q1, Q2, Q3, Q4, Q5, Q6 Switching elements

Claims (7)

A ratio of converted power borne by the plurality of power conversion modules is stored in association with a value based on the total converted power of the plurality of power conversion modules so that a temperature difference between the plurality of power conversion modules connected in parallel is reduced. a storage unit;
and an adjustment unit that adjusts currents flowing through each of the plurality of power conversion modules based on the ratio stored in the storage unit. The ratio stored in the storage unit is the temperature of a cooling medium flowing into a cooling unit that cools the plurality of power conversion modules, or the cooling detected by a detector that detects a temperature that can estimate the temperature of the cooling medium. 2. The control device according to claim 1, wherein the temperature of the medium or the temperature of the cooling medium is changed according to a temperature detection value that can be estimated. 3. The control device according to claim 1, wherein the ratio is set so that the temperature difference between the plurality of power conversion modules is small within a range at least in which the total converted power is equal to or greater than a predetermined value. . The predetermined value is based on the converted power at which at least one of the plurality of power conversion modules reaches the upper limit temperature when the plurality of power conversion modules output the total converted power without changing the ratio. 4. A control device as claimed in claim 3, characterized in that it is determined. a plurality of power conversion modules connected in parallel;
a cooling unit that cools the plurality of power conversion modules;
a storage unit that stores a ratio of the converted power borne by the plurality of power conversion modules so as to reduce the temperature difference among the plurality of power conversion modules in association with a value based on the total converted power of the plurality of power conversion modules; and a control device having an adjustment unit that adjusts the current flowing through each of the plurality of power conversion modules based on the ratio stored in the storage unit. The power converter according to claim 5, wherein the cooling unit is divided individually for each of the plurality of power conversion modules or divided for each part of the plurality of power conversion modules. A detector that detects the temperature of the cooling medium flowing into the cooling unit or the temperature that can estimate the temperature of the cooling medium,
7. The method according to claim 5, wherein the ratio stored in the storage unit changes depending on the temperature of the cooling medium detected by the detector or a detected temperature value that can estimate the temperature of the cooling medium. A power converter as described.

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