WO2018030143A1

WO2018030143A1 - Drive device and electric motor drive device

Info

Publication number: WO2018030143A1
Application number: PCT/JP2017/026808
Authority: WO
Inventors: 政道名和
Original assignee: 株式会社豊田自動織機
Priority date: 2016-08-08
Filing date: 2017-07-25
Publication date: 2018-02-15
Also published as: JP2018026897A

Abstract

The drive device comprises an electric motor, an inverter circuit, wiring for a multi-phase armature, a field circuit, an inverter control unit, and a field control unit. The field circuit is connected to a second end of a field winding via field wiring and is used to apply a field current to the field winding. The inverter control unit performs switching control with respect to upper arm switching components and lower arm switching components in respective arms for the multiple phases. The field control unit controls the field circuit such that the field current flows into the field winding when a neutral-point voltage, that is, a voltage at a neutral point of armature windings for the multiple phases, has a positive value.

Description

DRIVE DEVICE AND ELECTRIC MOTOR DRIVE DEVICE

The present invention relates to a drive device and an electric motor drive device.

For example, as shown in Patent Document 1, a driving device including an electric motor and an inverter circuit that drives the electric motor is known. Patent Document 1 discloses a field winding type electric motor having a three-phase armature winding and a field winding. In Patent Document 1, the inverter circuit has a three-phase arm, the three-phase arm has an upper arm switching element and a lower arm switching element, respectively, and by switching each switching element, The point which converts direct-current power into alternating current power is indicated. Further, Patent Document 1 discloses that the drive device has a boost converter as a field circuit and two field wirings that connect both ends of the field winding and the boost converter. Yes.

JP 2012-80776 A

Here, a ripple current may be generated in the inverter circuit due to switching of the switching element of the inverter circuit. When AC power including the ripple current is supplied to the armature winding, the controllability of the electric motor may be reduced.

In addition, in a configuration in which a field winding type electric motor is adopted as the electric motor, a field circuit and a field winding are provided separately from the armature wiring connecting the inverter circuit and the armature winding. A separate field wiring is required. For this reason, there is a concern that the routing of wiring becomes complicated or the manufacturing cost increases.

An object of the present invention is to provide a driving device and an electric motor driving device capable of reducing the ripple current while reducing the number of field wirings connecting the field circuit and the field winding of the electric motor. It is to be.

The first mode for achieving the above object provides a drive device. The drive device includes an electric motor, an inverter circuit, and a multi-phase armature wiring. The electric motor has three or more phases of armature windings and field windings that are star-connected. The inverter circuit is configured to convert DC power from a DC power source into AC power, and includes a plurality of phase arms provided for each of the plurality of armature windings. The multi-phase armature wiring connects the multi-phase arm and the multi-phase armature winding. Each of the arms of the plurality of phases is connected to the upper arm switching element connected to the high voltage side of the DC power source via a high voltage bus, and connected to the upper arm switching element in series and the DC connected via the low voltage bus And a lower arm switching element connected to the low voltage side of the power supply. The field winding has a first end connected to a neutral point of the multi-phase armature winding and a second end connected to a field wiring. The driving device includes a field circuit, an inverter control unit, and a field control unit. The field circuit is connected to the second end of the field winding via the field wiring, and is used to flow a field current through the field winding. The inverter control unit is configured to control switching of the upper arm switching element and the lower arm switching element in the plurality of phase arms. The field control unit controls the field circuit so that the field current flows through the field winding when a neutral point voltage, which is a neutral point voltage of the multi-phase armature winding, is positive. Is configured to do.

The second mode for achieving the above object provides an electric motor drive device. The electric motor drive device is connected to a star-connected multi-phase armature winding of three or more phases, a first end connected to a neutral point of the multi-phase armature winding, and a field wiring And an electric motor having a field winding having a second end. The electric motor drive device includes an inverter circuit configured to convert DC power from a DC power source into AC power. The inverter circuit has a multi-phase arm provided for each of the multi-phase armature windings. Each of the arms of the plurality of phases is connected to the upper arm switching element connected to the high voltage side of the DC power source via a high voltage bus, and connected to the upper arm switching element in series and the DC connected via the low voltage bus And a lower arm switching element connected to the low voltage side of the power supply. The electric motor driving device includes a field circuit, an inverter control unit, and a field control unit. The field circuit is connected to the second end of the field winding via the field wiring and is used to flow a field current through the field winding. The inverter control unit is configured to switch the upper arm switching element and the lower arm switching element in the plurality of phase arms. The field control unit controls the field circuit so that the field current flows through the field winding when a neutral point voltage, which is a neutral point voltage of the multi-phase armature winding, is positive. Is configured to do.

The block diagram which shows the outline | summary of a drive device. The circuit diagram of a drive circuit. The schematic diagram which shows the relationship between a switching pattern and the state of a field switching element. (A) is a waveform of a neutral point voltage, (b) is a time chart which shows the ON / OFF aspect of a field switching element. (A) is the waveform of the ripple current generated in the inverter circuit, (b) is the waveform of the amplitude current generated in the field winding, and (c) is supplied to the armature winding of a plurality of phases. Waveform of ripple current included in AC power.

Hereinafter, an embodiment of the present invention will be described. In the present embodiment, the drive device 10 is for in-vehicle use. For convenience of explanation, the following description will be made on the drive device 10 mounted on a vehicle.

As shown in FIG. 1, the drive device 10 includes an electric motor (rotary electric machine) 11 and an electric motor drive device 12 that drives the electric motor 11.
The electric motor 11 may be any motor as long as it is a vehicle-mounted motor mounted on a vehicle. The electric motor 11 is an arbitrary motor such as a traveling motor or a compressor motor. When the vehicle is a fuel cell vehicle, the electric motor 11 may be a motor that drives a pump that supplies hydrogen to the fuel cell.

The electric motor 11 includes a rotating shaft 21, a rotor 22, a stator core 23, a plurality of armature windings 24 u to 24 w, and a field winding 25.
The rotating shaft 21 is connected to the driving object 100. As the rotating shaft 21 rotates, the driving object 100 mounted on the vehicle is driven. The driving object 100 is arbitrary as long as it is driven by the rotating shaft 21. The driving object 100 is a compression mechanism that compresses fluid in, for example, a shaft connected to wheels or a compressor.

The rotor 22 is fixed to the rotating shaft 21, and the rotor 22 and the rotating shaft 21 rotate integrally. In the present embodiment, the rotor 22 has a plurality of field winding slots. In addition, the specific shape and material of the rotor 22 are arbitrary.

The stator core 23 has a hollow cylindrical shape, for example, and is provided on the outer side in the radial direction of the rotor 22. The stator core 23 has a plurality of armature winding slots arranged in the circumferential direction.
The multi-phase armature windings 24 u to 24 w are wound around the armature winding slot of the stator core 23. In the present embodiment, the multi-phase armature windings 24u to 24w are constituted by a u-phase armature winding 24u, a v-phase armature winding 24v, and a w-phase armature winding 24w. That is, the electric motor 11 in the present embodiment is a three-phase motor. When AC power, more specifically, three-phase AC power, is input to the multi-phase armature windings 24u to 24w, a magnetic field is generated, and the rotor 22 is rotated by the magnetic field. Thereby, the rotating shaft 21 rotates.

As shown in FIGS. 1 and 2, the multi-phase armature windings 24u to 24w have a star connection structure connected to each other at a neutral point N. Note that the winding mode of the multi-phase armature windings 24u to 24w with respect to the stator core 23 may be arbitrarily changed, such as concentrated winding or distributed winding.

The field winding 25 is wound around the field winding slot of the rotor 22. The field winding 25 is a magnetic field that interacts with the magnetic field formed by the multi-phase armature windings 24u to 24w when a field current Im that is a direct current in a certain direction flows through the field winding 25. Is configured to generate. For example, the field winding 25 is wound so as to generate a magnetic field that strengthens the magnetic field formed by the armature windings 24u to 24w of the plurality of phases when the field current Im flows through the field winding 25. ing. The configuration including the position of the field winding slot and the specific winding mode of the field winding 25 are arbitrary.

The field winding 25 has a first end 25a and a second end 25b. It can be said that the first end 25a and the second end 25b are a winding start portion and a winding end portion of the field winding 25, respectively. The first end 25a is connected to a neutral point N of the multiple-phase armature windings 24u to 24w.

As shown in FIGS. 1 and 2, the electric motor drive device 12 includes an inverter circuit 30 configured to drive the electric motor 11 and a field circuit for causing a field current Im to flow through the field winding 25. 40.

The inverter circuit 30 and the field circuit 40 are connected to the in-vehicle power storage device 101, and receive DC power from the in-vehicle power storage device 101. Specifically, drive device 10 includes a positive electrode bus LN1 connected to the positive electrode of in-vehicle power storage device 101, and a negative electrode bus LN2 connected to the negative electrode of in-vehicle power storage device 101. The inverter circuit 30 and the field circuit 40 are connected to the in-vehicle power storage device 101 via the positive electrode bus LN1 and the negative electrode bus LN2. Then, the DC power of the in-vehicle power storage device 101 is supplied to the inverter circuit 30 and the field circuit 40 through the positive bus LN1 and the negative bus LN2.

The in-vehicle power storage device 101 is arbitrary as long as it can charge and discharge DC power, and is, for example, a secondary battery or an electric double layer capacitor. In the present embodiment, the in-vehicle power storage device 101 corresponds to a DC power source. In other words, the positive bus LN1 corresponds to the high voltage bus (first bus) connected to the high voltage side of the DC power supply, and the negative bus LN2 corresponds to the low voltage bus (second bus) connected to the low voltage side of the DC power supply. Corresponding to

As shown in FIG. 2, the vehicle is provided with a smoothing capacitor C0 connected in parallel with the in-vehicle power storage device 101. In the present embodiment, the smoothing capacitor C0 is provided outside the driving device 10. However, it is not restricted to this, The drive device 10 may have the smoothing capacitor C0.

Incidentally, although illustration is omitted, the in-vehicle power storage device 101 is shared by the driving device 10 and other in-vehicle devices mounted on the vehicle. Specifically, the driving device 10 and other in-vehicle devices are connected to the in-vehicle power storage device 101 in parallel with each other. For this reason, if a ripple current Ir is generated in the inverter circuit 30, the ripple current Ir can be transmitted to the other in-vehicle devices through the positive electrode bus LN1 and the negative electrode bus LN2.

The inverter circuit 30 is configured to convert DC power from the in-vehicle power storage device 101 into AC power (three-phase AC power in the present embodiment).
As shown in FIG. 2, the inverter circuit 30 has a plurality of phase arms 31u to 31w provided for each of the plurality of phase armature windings 24u to 24w. Specifically, inverter circuit 30 corresponds to u-phase arm 31u corresponding to u-phase armature winding 24u, v-phase arm 31v corresponding to v-phase armature winding 24v, and w-phase armature winding 24w. W-phase arm 31w. The multiple-phase arms 31u to 31w have the same configuration.

The u-phase arm 31u has a u-phase upper arm switching element Qu1 and a u-phase lower arm switching element Qu2 that are connected in series with each other via a u-phase arm connection line 32u. The u-phase upper arm switching element Qu1 is connected to the positive electrode bus LN1, and is connected to the positive electrode of the in-vehicle power storage device 101 via the positive electrode bus LN1. The u-phase lower arm switching element Qu2 is connected to the negative electrode bus LN2, and is connected to the negative electrode of the in-vehicle power storage device 101 via the negative electrode bus LN2.

Similarly, the v-phase arm 31v has a v-phase upper arm switching element Qv1 and a v-phase lower arm switching element Qv2 connected in series with each other via a v-phase arm connection line 32v. The w-phase arm 31w has a w-phase upper arm switching element Qw1 and a w-phase lower arm switching element Qw2 connected in series with each other via a w-phase arm connection line 32w. Similar to the u-phase arm 31u, the v-phase arm 31v and the w-phase arm 31w are connected to the positive bus LN1 and the negative bus LN2, and are supplied with DC power from the in-vehicle power storage device 101.

Each switching element Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 is a power switching element such as an insulated gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor). However, each of the switching elements Qu1 to Qw2 is not limited to the IGBT, and may be any switching element. Note that the switching elements Qu1 to Qw2 have freewheeling diodes (body diodes) Du1 to Dw2.

As shown in FIGS. 1 and 2, the driving apparatus 10 includes a plurality of armature wirings LNu to LNw for connecting a plurality of arms 31u to 31w and a plurality of armature windings 24u to 24w. Yes. The armature wirings LNu to LNw connect the arm connection lines 32u to 32w and the armature windings 24u to 24w. The number of armature wirings LNu to LNw is the same as the number of phases of the armature windings 24u to 24w, and is three in this embodiment. In the present embodiment, the multiple-phase armature wirings LNu to LNw are configured by a u-phase armature wiring LNu, a v-phase armature wiring LNv, and a w-phase armature wiring LNw.

As shown in FIG. 2, the field circuit 40 is used to flow a field current Im through the field winding 25. The field circuit 40 includes a field diode Dm and a field switching element Qm connected to each other via a field connection line 41.

The anode of the field diode Dm is connected to the field connection line 41, and the cathode of the field diode Dm is connected to the positive electrode bus LN1.
The field switching element Qm is composed of, for example, an IGBT. The collector of field switching element Qm is connected to field connection line 41, and the emitter of field switching element Qm is connected to negative electrode bus LN2. That is, the field connection line 41 connects the field diode Dm and the field switching element Qm, more specifically, the anode of the field diode Dm and the collector of the field switching element Qm.

The driving device 10 includes a field wiring LNm that connects the field winding 25 and the field circuit 40. The field wiring LNm connects the second end 25 b of the field winding 25 and the field connection line 41 of the field circuit 40. In the present embodiment, there is one field wiring LNm.

According to such a configuration, since the first end 25a of the field winding 25 and the neutral point N are connected, the wiring for connecting the first end 25a and the field circuit 40 is omitted. As a result, the number of field wirings LNm is reduced.

As shown in FIGS. 1 and 2, the drive device 10 includes a control device 50 that controls the inverter circuit 30 and the field circuit 40. The control device 50 can be realized by, for example, one or more dedicated hardware circuits and / or one or more processors (control circuits) that operate according to a computer program (software). The processor includes a CPU and memories such as a RAM and a ROM, and the memory stores program codes or instructions configured to cause the processor to execute various processes, for example. Memory or computer readable media includes any available media that can be accessed by a general purpose or special purpose computer. Note that an inverter control unit 51 and a field control unit 52, which will be described later, as well as the control device 50 are one or more dedicated hardware circuits and / or one or more processors (control circuits) that operate according to a computer program (software). ) Can be realized.

The control device 50 is connected to the gates of the switching elements Qu1 to Qw2 of the inverter circuit 30 and the gate of the field switching element Qm of the field circuit 40, and the switching elements Qu1 to Qw2 and the field switching element Qm are individually connected. It is configured to be controllable.

The control device 50 includes an inverter control unit 51 configured to control switching of each of the switching elements Qu1 to Qw2, and a field control unit 52 configured to perform switching control of the field switching element Qm of the field circuit 40. I have.

The inverter control unit 51 sequentially switches the switching pattern that is a combination of ON / OFF of the upper arm switching elements Qu1 to Qw1 and the lower arm switching elements Qu2 to Qw2 in the multiple-phase arms 31u to 31w, so that the in-vehicle power storage device 101 The direct current power is converted into alternating current power.

The switching pattern will be described in detail below.
As shown in FIG. 3, a plurality (eight in this embodiment) of patterns P1 to P8 are set as switching patterns of the switching elements Qu1 to Qw2 that are sequentially switched. For example, the first pattern P1 is a switching pattern in which the upper arm switching elements Qu1 to Qw1 are turned off and the lower arm switching elements Qu2 to Qw2 are turned on. In the second pattern P2, the u-phase upper arm switching element Qu1, the v-phase lower arm switching element Qv2 and the w-phase lower arm switching element Qw2 are in the ON state, and the u-phase lower arm switching element Qu2 and the v-phase upper arm switching element Qv1. And a switching pattern in which the w-phase upper arm switching element Qw1 is in the OFF state.

The inverter control unit 51 switches the DC power (DC voltage) to AC power (three-phase AC voltage) by sequentially switching the switching patterns of the switching elements Qu1 to Qw2 while appropriately selecting from the plurality of patterns P1 to P8. ).

Further, the inverter control unit 51 is configured such that a target current value is input from the outside. Based on the input of the target current value from the outside, the inverter control unit 51 controls each of the switching elements Qu1 to Qw2 so that the AC power of the target current value is input to the plurality of armature windings 24u to 24w. PWM control is performed. Specifically, the inverter control unit 51 adjusts the execution period and the duty ratio of each switching pattern that is sequentially switched based on parameters such as a target current value and a DC voltage of the in-vehicle power storage device 101.

Here, as shown in FIGS. 3 and 4A, the switching pattern includes a positive pattern in which the neutral point voltage Ve, which is a voltage at the neutral point N, is positive (+), and a neutral point voltage Ve. Negative patterns that are negative (-). Specifically, the positive patterns are the third pattern P3, the fifth pattern P5, the seventh pattern P7, and the eighth pattern P8. As shown in FIG. 4A, the neutral point voltage Ve is maximum when the pattern is the eighth pattern P8, and the neutral point voltage Ve when the pattern is the eighth pattern P8 is the DC voltage of the in-vehicle power storage device 101. 1/2 of this. The neutral point voltages Ve in the case of the third pattern P3, the fifth pattern P5, and the seventh pattern P7 are the same.

The negative patterns are the first pattern P1, the second pattern P2, the fourth pattern P4, and the sixth pattern P6. As shown in FIG. 4A, the neutral point voltage Ve is minimum when the pattern is the first pattern P1, and the absolute value of the neutral point voltage Ve when the pattern is the first pattern P1 is the in-vehicle power storage device 101. ½ of the direct current voltage. The neutral point voltages Ve in the second pattern P2, the fourth pattern P4, and the sixth pattern P6 are the same.

According to such a configuration, as the switching pattern is sequentially switched among the plurality of patterns P1 to P8, as shown in FIG. 4A, the neutral point voltage Ve periodically changes. Specifically, a period in which the neutral point voltage Ve is positive and a period in which the neutral point voltage Ve is negative are alternately switched. The neutral point voltage Ve being positive means that the neutral point voltage Ve is higher than the ground, and the neutral point voltage Ve being negative means that the neutral point voltage Ve is lower than the ground. Means.

The field controller 52 controls the field circuit 40 (specifically, the field switching element Qm) so that the field current Im flows through the field winding 25 when the neutral point voltage Ve is positive. It is configured. Specifically, the field control unit 52 turns on the field switching element Qm when the switching pattern is a positive pattern.

In the present embodiment, as shown in FIG. 4B, the field control unit 52 maintains the field switching element Qm in the ON state over a period in which the neutral point voltage Ve is positive, and the neutral point voltage Ve. The field switching element Qm is maintained in the OFF state over a period in which is negative. Thereby, the positive / negative of the neutral point voltage Ve and ON / OFF of the field switching element Qm are synchronizing. In other words, the period during which the neutral point voltage Ve is positive coincides with the period during which the field switching element Qm is in the ON state.

As already explained, the polarity of the neutral point voltage Ve is periodically switched. For this reason, the field switching element Qm is periodically turned ON / OFF. The switching frequency of the field switching element Qm corresponds to the switching frequency of each of the switching elements Qu1 to Qw2.

In practice, the inverter control unit 51 sets a dead time when switching the switching pattern. That is, the inverter control unit 51 switches the switching pattern from the current pattern to another pattern through the dead time. The field control unit 52 turns off the field switching element Qm during the dead time.

Next, the operation of the present embodiment will be described with reference to FIGS. 5 (a) to 5 (c). 5A shows the waveform of the ripple current Ir generated in the inverter circuit 30, and FIG. 5B shows the waveform of the amplitude current Ia generated in the field winding 25. FIG. c) is a waveform of the ripple current Ir included in the AC power supplied to the multi-phase armature windings 24u to 24w.

The field current Im, which is a unidirectional current, flows through the field winding 25 when the field switching element Qm is turned on under the condition that the neutral point voltage Ve is positive. As a result, a magnetic field is formed in the field winding 25, and the magnetic field generated from the multiple-phase armature windings 24u to 24w is strengthened by the magnetic field. Thereby, the torque of the electric motor 11 can be increased.

Incidentally, a back electromotive force is generated in the field winding 25 immediately after the field switching element Qm is turned OFF. In this case, the field current Im resulting from the back electromotive force flows through the field diode Dm. As a result, it is difficult for the back electromotive force to become excessively high, for example, a situation where the back electromotive force exceeds the withstand voltage of the field switching element Qm.

Here, in each of the switching elements Qu1 to Qw2, switching control in which switching patterns are sequentially switched is performed. Therefore, as shown in FIG. 5A, a ripple current Ir corresponding to the switching frequency of each of the switching elements Qu1 to Qw2 is generated in the inverter circuit 30. The frequency of the ripple current Ir is higher than the frequency of the AC power supplied to the multiple-phase armature windings 24u to 24w.

Incidentally, when the field winding 25 is not provided or when the switching control of the field switching element Qm is not performed even if the field winding 25 is provided, the ripple current Ir is It is superimposed on the output current of the inverter circuit 30 as it is. The superimposed ripple current Ir is propagated to the plural-phase armature windings 24u to 24w. That is, when the field winding 25 is not provided, or when the switching control of the field switching element Qm as described above is not performed even if the field winding 25 is provided, the inverter circuit 30 includes The amplitude of the ripple current Ir generated in this way is equal to the amplitude of the ripple current Ir flowing through the multiple-phase armature windings 24u to 24w.

On the other hand, in this embodiment, since the field switching element Qm is turned on when the neutral point voltage Ve is positive, in synchronization with the periodic positive / negative switching of the neutral point voltage Ve, The field switching element Qm is periodically turned ON / OFF (switching). Therefore, as shown in FIG. 5B, an amplitude current Ia is also generated in the field winding 25. That is, the field current Im includes a direct current component and an alternating current component (amplitude current Ia). The amplitude current Ia has a phase opposite to that of the ripple current Ir. For this reason, the ripple current Ir and the amplitude current Ia cancel each other. Thereby, as shown in FIG.5 (c), the ripple current Ir is reduced. Specifically, the amplitude of the ripple current Ir becomes small, and preferably “0”.

According to the embodiment described above in detail, the following effects are obtained.
(1) The driving device 10 includes a field winding type electric motor 11 having a plurality of armature windings 24u to 24w and field windings 25 connected in a star shape, and an in-vehicle power storage device 101 as a DC power source. And an inverter circuit 30 for converting DC power from the AC power into AC power. The inverter circuit 30 has a plurality of phase arms 31u to 31w provided for each of the plurality of phase armature windings 24u to 24w. The multiple-phase arms 31u to 31w are connected to the positive electrode of the in-vehicle power storage device 101 via the positive electrode bus LN1 and the upper arm switching elements Qu1 to Qw1 connected to the positive electrode of the in-vehicle power storage device 101, and the in-vehicle power storage device 101 via the negative electrode bus LN2. A plurality of lower arm switching elements Qu2-Qw2 connected to the negative electrode. The field winding 25 has a first end 25a connected to the neutral point N of the multi-phase armature windings 24u to 24w, and a second end 25b connected to the field wiring LNm. Yes.

In such a configuration, the driving device 10 is connected to the second end 25b of the field winding 25 via the field wiring LNm, and is used for flowing a field current Im through the field winding 25. 40. The drive apparatus 10 is configured so that the field current Im flows in the field winding 25 when the neutral point voltage Ve is positive and the inverter control unit 51 configured to perform switching control of the switching elements Qu1 to Qw2. And a field control unit 52 configured to control the field circuit 40.

According to this configuration, since the first end 25a of the field winding 25 is connected to the neutral point N, it is not necessary to connect the first end 25a and the field circuit 40. Thereby, as the field wiring LNm, it is only necessary to connect both the first end 25a and the second end 25b of the field winding 25 to the field circuit 40 instead of both the first end 25a and the second end 25b. The number of wirings LNm can be reduced.

In addition, when the neutral point voltage Ve is positive, the field current Im flows through the field winding 25, so that an amplitude current Ia is generated in the field winding 25. The amplitude current Ia is a current having an opposite phase to the ripple current Ir generated in the inverter circuit 30. As a result, the ripple current Ir and the amplitude current Ia cancel each other, so that the ripple current Ir is reduced. Therefore, the ripple current Ir can be reduced while reducing the number of the field wirings LNm.

The effect of the drive device 10 will be described in further detail. In the drive device 10, a field winding type is adopted as the electric motor 11. The field winding type electric motor 11 can realize both a reduction in size and an improvement in torque as compared with a normal electric motor having no field winding 25. However, because of the characteristics of the field winding type electric motor 11, the field wiring LNm is required separately from the multi-phase armature wirings LNu to LNw, and therefore the number of wirings for connecting the electric motor 11 and various circuits. The inconvenience of an increase in In particular, the field wiring LNm tends to be more expensive than the field connection line 41 in the field circuit 40 or the multi-phase arm connection lines 32u to 32w in the inverter circuit 30, and is routed. Tends to be cumbersome.

In contrast, according to the present embodiment, by connecting the neutral point N and the field winding 25, an increase in the number of wires, which is a peculiar inconvenience in the field winding type electric motor 11, can be suppressed. . And, by controlling the field circuit 40 as described above, the ripple current Ir can be reduced by using the configuration for suppressing the increase in the number of wirings, which is different from the reduction in the number of field wirings LNm. An effect can be obtained.

(2) The field circuit 40 includes a field diode Dm having a cathode connected to the positive bus LN1, a field switching element Qm connected to the negative bus LN2, an anode of the field diode Dm, and a field switching element. And a field connection line 41 for connecting Qm. The field wiring LNm is connected to the field connection line 41.

In such a configuration, the field control unit 52 controls the field switching element Qm so that the field current Im flows through the field winding 25 when the neutral point voltage Ve is positive. According to such a configuration, the field current Im can be supplied to or stopped from the field winding 25 by the control of the field switching element Qm. Thereby, control of the field current Im can be performed suitably.

In addition, if the field current Im is stopped in a situation where the field current Im flows, a counter electromotive force is generated in the field winding 25. In this regard, according to the present embodiment, since the field current Im caused by the counter electromotive force flows through the field diode Dm, it is possible to suppress the counter electromotive force from becoming excessively high.

(3) The inverter control unit 51 sequentially switches the switching pattern that is a combination of ON / OFF of the upper arm switching elements Qu1 to Qw1 and the lower arm switching elements Qu2 to Qw2 in the multi-phase arms 31u to 31w. The switching pattern includes a positive pattern in which the neutral point voltage Ve is positive and a negative pattern in which the neutral point voltage Ve is negative.

In such a configuration, the field controller 52 controls the field circuit 40 (field switching element Qm) so that the field current Im flows through the field winding 25 when the switching pattern is a positive pattern. According to such a configuration, the neutral point voltage Ve is positive without providing a voltage sensor for detecting the neutral point voltage Ve or calculating the neutral point voltage Ve based on the three-phase AC voltage. In this case, the field current Im can flow through the field winding 25. Thereby, the effect (1) can be obtained relatively easily.

(4) The drive device 10 is for in-vehicle use, and the inverter circuit 30 is configured to convert DC power of the in-vehicle power storage device 101 into AC power.
According to such a configuration, the ripple current Ir can be reduced while reducing the number of field wirings LNm in the in-vehicle drive device 10. Thereby, the drive target object 100 mounted in the vehicle can be suitably driven using the drive device 10.

In particular, the in-vehicle power storage device 101 may be shared by the driving device 10 and other in-vehicle devices. In this case, the ripple current Ir generated in the inverter circuit 30 can flow out of the drive device 10 and propagate to the other on-vehicle equipment. Then, in the other in-vehicle devices, there may be a problem that malfunction occurs or a filter circuit is necessary. On the other hand, in the present embodiment, as described above, the ripple current Ir can be reduced, so that the above inconvenience can be suppressed.

In addition, you may change the said embodiment as follows.
The field circuit 40 is not limited to that of the embodiment and is arbitrary. For example, an IGBT or MOSFET having a body diode as the field diode Dm may be provided.

In the embodiment, the field control unit 52 is configured to determine whether the neutral point voltage Ve is positive from the switching pattern, but is not limited thereto. For example, the field control unit 52 may periodically calculate the neutral point voltage Ve from the three-phase AC voltage and determine whether or not the calculated neutral point voltage Ve is positive. The drive device 10 includes a voltage sensor that detects the neutral point voltage Ve, and the field control unit 52 determines whether the neutral point voltage Ve is positive based on the detection result of the voltage sensor. Also good.

○ The period in which the neutral point voltage Ve is positive and the period in which the field switching element Qm is in the ON state may not completely match. The field control unit 52 may turn on the field switching element Qm for a part of the period in which the neutral point voltage Ve is positive. In other words, the field control unit 52 may control the field circuit 40 so that the field current Im flows in at least a part of the period in which the neutral point voltage Ve is positive.

For example, the field control unit 52 sets the field switching element Qm so that the field current Im flows only when a predetermined specific pattern (for example, the eighth pattern P8) among the plurality of positive patterns is set as the switching pattern. It may be turned on. In this case, when the switching pattern is other than the specific pattern, the field control unit 52 may turn off the field switching element Qm so that the field current Im does not flow.

In addition, for example, the field control unit 52 calculates the target value in consideration of the operation status of the electric motor 11 and the neutral point voltage Ve is set so that the field current Im approaches (preferably matches) the target value. The ON period of the field switching element Qm during the positive period may be adjusted. That is, the field controller 52 may be configured to control the field current Im by adjusting the ON period of the field switching element Qm during the period in which the neutral point voltage Ve is positive.

The field winding 25 may be wound around the stator core 23 instead of the rotor 22.
A permanent magnet may be provided on the rotor 22 or the stator core 23, or there may be no permanent magnet.

○ The number of phases of the armature winding may be three or more, for example, four or five phases.
The switching elements Qu1 to Qw2 and the field switching element Qm are not limited to IGBTs but may be MOSFETs or the like. The field switching element Qm and each of the switching elements Qu1 to Qw2 may be different types of switching elements.

(Circle) the drive device 10 is not restricted to vehicle-mounted use, You may be used for another use.
O You may combine embodiment and each other example suitably.

Claims

An electric motor having three or more phases of armature windings and field windings connected in a star shape;
An inverter circuit configured to convert DC power from a DC power source into AC power, the inverter circuit having a plurality of arm provided for each of the plurality of armature windings;
A driving device comprising: a plurality of armature wirings connecting the plurality of phase arm and the plurality of armature windings;
Each of the arms of the plurality of phases is connected to the upper arm switching element connected to the high voltage side of the DC power source via a high voltage bus, and connected to the upper arm switching element in series and the DC connected via the low voltage bus A lower arm switching element connected to the low voltage side of the power source,
The field winding has a first end connected to a neutral point of the armature winding of the plurality of phases, and a second end connected to a field wiring,
The driving device includes:
A field circuit connected to the second end of the field winding via the field wiring and used to flow a field current through the field winding;
An inverter control unit configured to control switching of the upper arm switching element and the lower arm switching element in the arms of the plurality of phases;
The field circuit is configured to control the field current so that the field current flows through the field winding when a neutral point voltage that is a neutral point voltage of the multi-phase armature winding is positive. Field control unit,
A drive device comprising:
The field circuit is
A field diode having a cathode connected to the high-voltage bus;
A field switching element connected to the low-voltage bus;
A field connection line connecting the anode of the field diode and the field switching element;
Have
The field wiring is connected to the field connection line,
The field control unit is configured to control the field switching element such that the field current flows through the field winding when the neutral point voltage is positive. Drive device.
The inverter control unit is configured to sequentially switch a switching pattern that is a combination of ON / OFF of the upper arm switching element and the lower arm switching element in the multi-phase arm,
The switching pattern is:
A positive pattern in which the neutral point voltage is positive;
A negative pattern in which the neutral point voltage is negative;
Including
The field control unit is configured to control the field circuit so that the field current flows through the field winding when the switching pattern is the positive pattern. 2. The drive device according to 2.
The drive device is for in-vehicle use,
The DC power supply is an in-vehicle power storage device,
The high-voltage bus is a positive bus connected to the positive electrode of the in-vehicle power storage device,
The drive device according to any one of claims 1 to 3, wherein the low-voltage bus is a negative bus connected to a negative electrode of the in-vehicle power storage device.
5. The field control unit according to claim 1, wherein the field control unit is configured to control a field current by adjusting an ON period of a field switching element during a period in which the neutral point voltage is positive. The driving device according to claim 1.
A star-connected multi-phase armature winding of three or more phases, a first end connected to the neutral point of the multi-phase armature winding, and a second end connected to the field wiring An electric motor driving device configured to drive an electric motor including a field winding having:
Comprising an inverter circuit configured to convert DC power from a DC power source into AC power, the inverter circuit having a plurality of arms provided for each of the plurality of armature windings;
Each of the arms of the plurality of phases is connected to the upper arm switching element connected to the high voltage side of the DC power source via a high voltage bus, and connected to the upper arm switching element in series and the DC connected via the low voltage bus A lower arm switching element connected to the low voltage side of the power source,
The electric motor driving device is:
A field circuit connected to the second end of the field winding via the field wiring and used to pass a field current through the field winding;
An inverter control unit configured to switch the upper arm switching element and the lower arm switching element in the arms of the plurality of phases;
The field circuit is configured to control the field current so that the field current flows through the field winding when a neutral point voltage that is a neutral point voltage of the multi-phase armature winding is positive. And an electric field motor control unit.