JP2016220376A - Power supply device and air conditioner using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device that has a high efficiency and high reliability to in-rush current.SOLUTION: A power supply device 10 includes a rectification circuit unit having a first series connection circuit of rectifying diodes 11a and 11b, a second series connection circuit of switching elements 13a and 13b, and a smoothing capacitor 16. AC power is input via a reactor 14 in between a first series connection point of the first series connection circuit and a second series connection point of the second series connection circuit. The switching elements 13a and 13b convert AC power to DC power. The rectification circuit unit includes a third series connection circuit of rectifying diodes 12a and 12b connected in parallel to the second series connection circuit, and a coil 15 connected between the third series connection point of the third series connection circuit and the second series connection point of the second series connection circuit. An AC power source is connected between the first series connection point and the third series connection point via the reactor 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply device and an air conditioner using the same.

  A power supply device used for an air conditioner or the like has a function of rectifying and smoothing an AC voltage (power) received from an AC power supply into a DC voltage (power). In addition, the power supply device is required to have a power factor improvement function and a function to cope with an excessive inrush current generated when the power supply is turned on.

  As a basic circuit for rectifying and smoothing an alternating voltage (power) into a direct voltage (power), a so-called capacitor input rectifying and smoothing circuit including a diode bridge and a smoothing capacitor is known.

  Also, there is known a rectifying / smoothing circuit in which a part of the rectifier diode in the diode bridge is replaced with a switching element, a reactor is provided between the switching element and the AC power supply, and power factor improvement and loss reduction are performed by a boost chopper operation. . Furthermore, in this rectifying / smoothing circuit, a rectifying / smoothing circuit provided with a rectifying diode that bypasses the inrush current is known as a conventional technique for preventing an excessive inrush current generated when the power is turned on from flowing into the switching element and causing the element to fail. (For example, refer to Patent Document 1).

Japanese Patent Laying-Open No. 2004-72846 (FIG. 3)

  However, in the above prior art, it is possible to prevent a failure of the switching element due to inrush current, but by providing a rectifier diode for inrush current bypass, the boost chopper circuit functions effectively for loss reduction and power factor improvement. Becomes difficult. As a result, there is a problem in that the efficiency of the power supply device and its application equipment is reduced. This problem is particularly noticeable when the input voltage (power) is small.

  Therefore, the present invention provides a highly reliable power supply apparatus and an air conditioner that have high reliability against inrush current.

  In order to solve the above problems, a power supply device according to the present invention includes a first series connection circuit in which a first rectifier diode and a second rectifier diode are connected in series, and a first switching element having a reverse conduction function. And a second series connection circuit in which the second switching elements are connected in series are connected between the positive electrode and the negative electrode, a circuit unit connected in parallel, and a smoothing capacitor connected between the positive electrode and the negative electrode And the circuit unit includes a third series connection circuit in which the third rectification diode and the fourth rectification diode are connected in series and connected in parallel to the second series connection circuit, and an inductance element. And the AC power supply is connected to the first series connection point in the first series connection circuit and connected to the third series connection point in the third series connection circuit via the reactor. Is a third series connection point is connected to a second series connection point in the second series circuit via an inductance element.

  In order to solve the above-described problem, an air conditioner according to the present invention includes an electric compressor in which a compressor is driven by an AC electric motor, and a power supply device that supplies electric power to the electric compressor. The refrigerant compressed by the refrigerant circulates in the cooling / heating cycle, and the power supply device includes an inverter connected between the positive electrode and the negative electrode of the power supply device according to the present invention, and the electric power output from the inverter is supplied to the electric compressor. Is done.

  According to the present invention, an inrush current flowing through the switching element can be suppressed without reducing the efficiency. For this reason, both the reliability and efficiency of the power supply device and the air conditioner are improved.

  Problems, configurations, and effects other than those described above will become apparent from the following description of embodiments.

It is a circuit diagram which shows the power supply device which is Example 1 of this invention. It is a circuit diagram which shows the power supply device for an electric compressor drive which is Example 2 of this invention. The capacitor input rectification smoothing circuit which is the comparative example 1 is shown. The rectification smoothing circuit provided with the step-up chopper circuit which is the comparative example 2 is shown. The voltage waveform and current waveform on the input side of the capacitor input rectifying and smoothing circuit are shown. The voltage waveform and current waveform of the input side of a rectification smoothing circuit provided with a step-up chopper circuit are shown. The rectification smoothing circuit provided with the diode for inrush current bypass which is the comparative example 3 is shown. The rectification smoothing circuit provided with the step-up chopper circuit which is the comparative example 4 is shown. It is a circuit diagram which shows the power supply device which is Example 4 of this invention. It is a cycle block diagram of the air conditioner of Example 4. It is an external view of the outdoor unit of the air conditioner of Example 4.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals indicate the same constituent elements or constituent elements having similar functions.

  FIG. 1 is a circuit diagram showing a power supply device according to Embodiment 1 of the present invention.

  In FIG. 1, a power supply device 10 includes rectifier diodes 11a, 11b, 12a, and 12b that are first to fourth rectifier diodes, a coil 15, and switching elements 13a and 13b that are first and second switching elements, respectively. A circuit unit, a reactor 14, and a smoothing capacitor 16 are provided. Note that MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are applied as the switching elements 13a and 13b. The MOSFET has a reverse conduction function by a parasitic diode built in the element. For this reason, the MOSFET can be a path of inrush current, but according to the present embodiment, as will be described later, the inrush current flowing through the MOSFET is suppressed.

  As shown in FIG. 1, the anode of the rectifier diode 11a and the cathode of the rectifier diode 11b are connected, and the rectifier diodes 11a and 11b are connected in series. The cathode of the rectifier diode 11 a is connected to the direct current positive electrode side wiring 101, and the anode of the rectifier diode 11 b is connected to the direct current negative electrode side wiring 102. Further, the anode of the rectifier diode 12a and the cathode of the rectifier diode 12b are connected, and the rectifier diodes 12a and 12b are connected in series. The cathode of the rectifier diode 12 a is connected to the direct current positive electrode side wiring 101, and the anode of the rectifier diode 12 b is connected to the direct current negative electrode side wiring 102.

  The first output terminal (upper side in FIG. 1) of the single-phase AC power supply 201 is connected to the series connection point P3 of the rectifier diode 12a and the rectifier diode 12b via the reactor 14, and the first output terminal of the single-phase AC power supply 201 is connected. The two output terminals (lower side in FIG. 1) are directly connected to a series connection point P1 between the rectifier diode 11a and the rectifier diode 11b. Therefore, the rectifier diodes 11a, 11b, 12a, 12b and the smoothing capacitor 16 constitute a so-called capacitor input rectification smoothing circuit. For this reason, this embodiment can output a smoothed DC voltage (power) without performing the synchronous rectification operation by the step-up chopper circuit including the switching elements 13a and 13b. That is, in the present embodiment, the AC voltage (power) input from the single-phase AC power source 201 is rectified by the diode bridge circuit including the rectifier diodes 11a, 11b, 12a, and 12b, and the positive-side wiring 101 and the negative-side wiring A voltage (power) mainly including the rectified direct current component is supplied to 102. A voltage (power) mainly composed of a direct current component supplied to the positive electrode side wiring 101 and the negative electrode side wiring 102 is converted into a DC voltage smoothed by the action of the smoothing capacitor 16, and the smoothed DC voltage (power) is obtained. Is supplied to the load 202.

  However, there is a section in which no current flows in a region where the input AC voltage is small. This is because, since the rectifier diode has a diffusion potential at the PN junction, no current flows when the voltage is small (approximately 0.7 to 0.8 V or less) even in the forward direction. If there is a section where current does not flow in this way, the difference between the current waveform and the sine waveform increases, and the power factor decreases.

  On the other hand, in this embodiment, the power factor is improved by the reactor 14 as follows. The reactor 14 has an action of accumulating and releasing electric energy. Further, the reactor 14 has an action of generating a counter electromotive force when a current flows. The action of these reactors 14 suppresses a steep change in current and releases the stored energy even when the input voltage decreases, thereby reducing the slope and maximum value of the input current. As a result, the waveform of the current flowing through the rectifier circuit section is relatively close to a sine wave, and the power factor is improved. The power factor improvement effect by the reactor 14 is effective even when the switching elements 13a and 13b are not switched and do not perform the power factor correction operation.

  In the present embodiment, the switching elements 13a and 13b, the reactor 14, the coil 15, and the rectifier diodes 11a and 11b further constitute a boost chopper circuit. More specifically, the source of the switching element 13a and the drain of the switching element 13b are connected, and the switching elements 13a and 13b are connected in series. The drain of the switching element 13 a is connected to the positive electrode side wiring 101, and the source of the switching element 13 b is connected to the negative electrode side wiring 102. The coil 15 is connected between the series connection point P2 of the switching elements 13a and 13b and the series connection point P3 of the rectifier diodes 12a and 12b. Therefore, the series connection point P2 of the switching elements 13a and 13b is connected to the first output terminal (upper side in FIG. 1) of the AC power supply 201 through the coil 15 and the reactor 14. Further, the series connection point P1 of the rectifier diodes 11a and 11b in the rectifier circuit is connected to the second AC output terminal (lower side in FIG. 1) of the AC power supply 201 as described above.

  Therefore, in this embodiment, the AC power from the AC power source 201 passes through the reactor 14 between the series connection point P1 of the diodes 11a and 11b and the series connection point P2 of the switching elements 13a and 13b. Is input. At this time, the AC power supply 201 is connected between the series connection point P1 of the diodes 11a and 11b and the series connection point P3 of the diodes 12a and 12b via the reactor 14, and further through the coil 15 to the switching elements 13a and 13b. Connected to the series connection point P2. That is, in this embodiment, AC power is input to the rectifier circuit portion of the boost chopper circuit via the reactor 14 and the coil 15.

  Here, the reactor 14 and the coil 15 are inductance elements in the step-up chopper circuit. In this embodiment, the inductance value of the coil 15 is set to a value smaller than the inductance value of the reactor 14. For example, the inductance of the coil 15 and the inductance of the reactor 14 are set to several tens of μH and several mH, respectively. For this reason, only the reactor 14 of the reactor 14 and the coil 15 substantially functions as a boosting inductance element in the boosting chopper circuit. In the step-up chopper circuit, the coil 15 functions as a conductor for connecting the reactor 14 to the series connection point P2 of the switching elements 13a and 13b. Other functions of the coil 15 in the power supply device of this embodiment will be described later.

  The boosting chopper circuit according to the first embodiment has a boosting function, a synchronous rectification function, and a function for improving the power factor, as will be described below.

  In this embodiment, when the boosting operation, the synchronous rectification operation, and the power factor correction operation are performed, the switching elements 13a and 13b are repeatedly short-circuited, that is, turned on / off repeatedly (this is referred to as complementary symmetric operation). By repeating this on / off, electric energy is accumulated and released in the reactor 14.

  When the switching element 13b is turned on in the positive half cycle of the single-phase AC power supply 201, the first output terminal (upper side in FIG. 1) of the single-phase AC power supply 201, the reactor 14, the switching element 13b, the diode 11b, and the single-phase AC A current flows through the path of the second output terminal (lower side in FIG. 1) of the power supply 201, and electric energy is accumulated in the reactor 14. At this time, a current due to the inductance of the reactor 14 and the voltage of the single-phase AC power source 201 flows through the reactor 14. Since the smoothing capacitor 16 is not included in the path, this current flows even in a section where the voltage of the AC power supply 201 is lower than the voltage of the smoothing capacitor 16. For this reason, since a current waveform becomes a substantially sine wave shape, a power factor is improved.

  Next, when the switching element 13b is turned off and the switching element 13a is turned on, the electrical energy accumulated in the reactor 14 is released through the path of the reactor 14, the coil 15, the switching element 13a, the smoothing capacitor 16, and the rectifier diode 11b. A current flows through this path. As a result, the smoothing capacitor 16 is charged to a voltage higher than the power supply voltage. That is, the boosting operation is performed in the power supply device of the first embodiment. Here, a current path including the rectifier diode 12a is also conceivable. However, since the on-resistance of the switching element 13a is smaller than that of the rectifier diode 12a and the inductance of the coil 15 is smaller than that of the reactor 14 as described above, the rectifier diode 12a. It is difficult for current to flow through. That is, the rectifier diode 12a does not function so much in the rectifier circuit, and instead the switching element 13a performs a so-called synchronous rectification operation. For this reason, the power loss of a rectifier circuit part can be reduced. In particular, when the input AC voltage (power) is small and the output DC voltage (power) is small, the power loss reduction effect by the synchronous rectification operation is large.

  Further, when the switching element 13a is turned on in the negative half cycle of the single-phase AC power supply 201, the second output terminal of the single-phase AC power supply 201, the diode 11a, the switching element 13a, the reactor 14, the single-phase AC power supply 201 first. A current flows through the path of the output terminal, and electric energy is accumulated in the reactor 14. At this time, similarly to the positive half cycle of the single-phase AC power supply 201, the current waveform becomes a substantially sinusoidal shape, so that the power factor is improved.

  Next, when the switching element 13a is turned off and the switching element 13b is turned on, the electrical energy accumulated in the reactor 14 is released through the path of the rectifier diode 11a, the smoothing capacitor 16, the switching element 13b, and the reactor 14, and this path Current flows through Thereby, the boosting operation is performed as in the positive half cycle of the single-phase AC power supply 201. Further, since the ON resistance of the switching element 13b is smaller than that of the rectifier diode 12a and the inductance of the coil 15 is smaller than that of the reactor 14, it is difficult for current to flow through the rectifier diode 12b. That is, the rectifier diode 12b does not function so much in the rectifier circuit, and instead, the switching element 13b performs a so-called synchronous rectification operation. For this reason, the power loss of a rectifier circuit part can be reduced.

  In this embodiment, MOSFETs are used as the switching elements 13a and 13b. However, when the MOSFET is on, a PN junction such as a diode is not present in the current path including the channel in the MOSFET element. Since it is not included, the on-resistance can be sufficiently lower than the diodes 12a and 12b. For this reason, in the synchronous rectification operation, no current flows through the diodes 12a and 12b, and the entire current can flow through the switching elements 13a and 13b, so that power loss in the rectification operation can be reduced.

  Moreover, the power loss of the power supply device can be reduced by applying a super junction MOSFET having a lower on-resistance as the MOSFET.

  In FIG. 1, a diode is connected in antiparallel to the switching elements 13a and 13b. This is a parasitic diode formed inside the MOSFET. In the ON state of the MOSFET, current flows in a region including a channel having a low resistance, and almost no current flows in the parasitic diode as in the diodes 12a and 12b.

  In order for the synchronous rectification operation to function sufficiently, the inductance of the coil 15 is preferably smaller than the inductance of the reactor 14 as in this embodiment. For example, the inductance of the reactor 14 is preferably set to 1 mH or more and less than 10 mH, and the inductance of the coil 15 is preferably set to 10 μH or more and less than 100 μH. Thus, during normal operation, that is, when the boost chopper circuit performs normal operation, the impedance of the rectifier diode 12a is larger than the series impedance of the switching element 13a and the coil 15, and the impedance of the rectifier diode 12b is the same as that of the switching element 13b. It becomes larger than the series impedance of the coil 15. That is, for the same current during normal operation, the voltage drop of the rectifier diode 12a is larger than the voltage drop of the series connection of the switching element 13a and the coil 15, and the voltage drop of the rectifier diode 12b is It becomes larger than the voltage drop of 15 series connection. For this reason, during normal operation, a current can be reliably passed through the switching elements 13a and 13b.

  In this embodiment, particularly in the low current region where the back electromotive force of the coil 15 is small, the power loss reduction effect by the synchronous rectification operation is high. When the current increases and the back electromotive force of the coil 15 increases, there is a possibility that the synchronous rectification operation is not sufficient. On the other hand, in this embodiment, the rectification operation is performed by the rectification circuit including the diode bridge circuit including the rectification diodes 11a and 11b in the rectification circuit unit of the boost chopper circuit and the rectification diodes 12a and 12b that do not contribute to the synchronous rectification operation. Secured. At this time, the voltage drop of the switching element increases in proportion to the current, but the increase in the voltage drop of the rectifier diode is suppressed by the non-linearity of the current / voltage characteristics of the rectifier diode. Increase is suppressed.

  As described above, the boost chopper circuit according to the first embodiment includes a synchronous rectification function and a power factor correction function in addition to the boost function by complementary on / off control of the switching elements 13a and 13b. The switching elements 13a and 13b are ON / OFF controlled by giving a control signal to the control terminal (gate terminal) of the switching element by a control circuit not shown in FIG. The control circuit creates a control signal by, for example, a pulse width modulation (PWM) method. In this case, the first embodiment performs the boosting operation, the synchronous rectification operation, and the power factor correction operation according to the pulse width and timing of the control signal. In the boost chopper circuit, the magnitude of the output DC voltage can be changed by adjusting the ON period and OFF period of the pulse.

  Next, the inrush current suppression function of the coil 15 will be described. Although both the reactor 14 and the coil 15 are inductance elements, both have different inductance values and main functions (the reactor 14 boosts and improves the power factor, and the coil 15 suppresses inrush current). For the sake of clarity, another name is used for convenience.

  In the circuit of FIG. 1, an inrush current flows from the AC power source 201 to the smoothing capacitor 16 through the rectifier diodes 11a, 11b, 12a, and 12b when the power is turned on. For example, when a positive half-cycle voltage is input, an inrush current flows through a path including the reactor 14, the rectifier diode 12a, the smoothing capacitor 16, and the rectifier diode 11b. Here, since the forward direction of the built-in diodes of the switching elements 13a and 13b is the direction in which the inrush current flows, the inrush current may also flow through the switching elements 13a and 13b even when the switching elements 13a and 13b are in the off state. There is.

  Therefore, in this embodiment, the coil 15, that is, the inductance element is inserted into the inrush current path via the switching element 13a or 13b. Since the back electromotive force is generated in response to the steep change of the inrush current due to the inductance of the coil 15, the inrush current flowing through the switching elements 13a and 13b is suppressed.

  Further, in the inrush current path, the switching elements 13a and 13b are connected in parallel with the rectifier diodes 12a and 12b via the coil 15, respectively. Therefore, the inrush current is generated from the switching element and the diodes 12a and 12b. Is shunted to the rectifier circuit. That is, the inrush current is bypassed by the diodes 12a and 12b. Thereby, it is suppressed that an excessive inrush current flows into switching element 13a, 13b and a rectifier circuit.

  In this way, the inrush current flowing through the switching elements 13a and 13b and the rectifier circuit is suppressed by the suppression of the inrush current flowing through the switching elements 13a and 13b by the coil 15 and the shunting of the inrush current by the switching element and the rectifier circuit. Failure of the switching element and the rectifier diode can be prevented.

  The inductance of the coil 15 is preferably set to 10 μH or more and less than 100 μH. Thereby, with respect to the inrush current, the impedance of the rectifier diode 12a is smaller than the series impedance of the switching element 13a and the coil 15, and the impedance of the rectifier diode 12b is smaller than the series impedance of the switching element 13b and the coil 15. . That is, for the same inrush current, the voltage drop of the rectifier diode 12a is smaller than the voltage drop of the series connection of the switching element 13a and the coil 15, and the voltage drop of the rectifier diode 12b is series of the switching element 13b and the coil 15. Less than the voltage drop of the connection. For this reason, inrush current can be reliably bypassed to the rectifier diodes 12a and 12b.

  As described above, according to the first embodiment, the rectifier diodes 12a and 12b serving as a bypass for the inrush current are provided, and between the connection point P3 of the rectifier diodes 12a and 12b and the connection point P2 of the switching elements 13a and 13b. By connecting the coil 15 having a small inductance to the rush current, the inrush current flowing through the switching elements 13a and 13b is suppressed. Thereby, failure of the switching elements 13a and 13b due to inrush current can be prevented. Further, during normal operation, current flows through a current path including the switching elements 13a and 13b. Thereby, even if the rectifier diodes 12a and 12b are provided, the synchronous rectification operation and the power factor correction operation accompanying the on / off operation of the switching elements 13a and 13b in the step-up chopper operation are not hindered by the rectifier diodes 12a and 12b. It becomes effective. Therefore, the power supply device is less likely to fail with respect to the inrush current, and the reliability is improved, and the loss is reduced and the efficiency is improved.

  Hereinafter, in order to clarify the effect of the first embodiment of the present invention described above, a comparative example and problems thereof will be described. The problems described below are solved by the first embodiment as described above.

  FIG. 3 shows a capacitor input rectifying and smoothing circuit that receives an AC power supply and generates a DC voltage (power) as Comparative Example 1. FIG. 5 shows voltage waveforms and current waveforms on the input side of the capacitor input rectifying and smoothing circuit shown in FIG.

  As shown in FIG. 3, in the first comparative example, a rectifier circuit is configured from a diode bridge including rectifier diodes 11a, 11b, 12a, and 12b. The AC power supply 201 supplies AC voltage (electric power) to a pair of AC input terminals of the rectifier circuit. The rectifier circuit (rectifier diodes 11a, 11b, 12a, 12b) rectifies an AC voltage and supplies a voltage (power) mainly composed of a DC component to the smoothing capacitor 16 via the positive electrode side wiring 101 and the negative electrode side wiring 102. . The voltage (power) smoothed by the smoothing capacitor 16 is supplied to the load 202.

  In the first comparative example, as illustrated in FIG. 5, the current 1002 does not flow in a section where the voltage 1001 applied to the pair of AC input terminals is lower than the voltage of the smoothing capacitor 16. For this reason, the difference between the current waveform and the sine wave increases, and the power factor decreases.

  FIG. 4 shows a rectifying / smoothing circuit including a step-up chopper circuit as a second comparative example. FIG. 6 shows a voltage waveform and a current waveform on the input side of the rectifying / smoothing circuit of the second comparative example.

  As shown in FIG. 4, in this comparative example 2, a part of the rectifier circuit in comparative example 1 (FIG. 3), that is, the rectifier diodes 12a and 12b are replaced with switching elements 13a and 13b, and the switching elements 13a and 13b and the AC power supply are replaced. The reactor 14 is provided between the two. As a result, the second comparative example performs the boost chopper operation and also performs the power factor correction operation along with the boost chopper operation.

  In the reactor 14, a current due to the inductance and the input power supply voltage flows. This current flows regardless of the magnitude of the voltage of the smoothing capacitor 16 along with the step-up chopper operation. As a result, as shown in FIG. 6, the current 1003 can flow even when the voltage 1001 of the AC power supply 201 is lower than the voltage of the smoothing capacitor 16. That is, by storing and releasing the electrical energy in the reactor 14, a current flows even in a section where the input voltage of the AC power supply 201 is small. For this reason, since the waveform of the current 1003 can be made sinusoidal, the power factor is improved.

  In Comparative Example 2, since the smoothing capacitor 16 is not charged when the power is turned on, an inrush current flows when the power is turned on. Therefore, as the rectifier diodes 11a and 11b, diodes having a non-repetitive surge withstand capability that can withstand this inrush current are used. However, since the switching elements 13a and 13b have a surge resistance lower than that of the rectifier diode, there is a possibility that the switching elements 13a and 13b may break down when an excessive inrush current flows.

  FIG. 7 shows a rectifying / smoothing circuit including an inrush current bypass diode as a third comparative example.

  As shown in FIG. 7, in this comparative example 3, rectifier diodes 11c and 11d serving as a bypass of the inrush current are provided in order to suppress the inrush current flowing through the switching elements 13a and 13b.

  However, in Comparative Example 3, due to the counter electromotive force generated in the reactor 14, the power supply current flows through the rectifier diodes 11c and 11d even in the normal operation. For this reason, even if the switching elements 13a and 13b are used, it is difficult to sufficiently reduce the power loss of the power supply device.

  FIG. 8 shows a rectifying / smoothing circuit including a step-up chopper circuit as a fourth comparative example.

  In the present comparative example 4, as shown in FIG. 8, the rectifier circuit composed of the rectifier diodes 11a to 11d rectifies an AC voltage, and a voltage mainly composed of a DC component is applied to the positive side wiring 111 and the negative side wiring 102. Output. A step-up chopper circuit including a reactor 24, a switching element 26, and a reverse blocking diode 25 provided at the subsequent stage of the rectifier circuit outputs a DC voltage (power) to the smoothing capacitor 16 by a step-up operation and performs a power factor improvement operation. Then, voltage (electric power) is supplied to the load 202 from the positive electrode side wiring 121 and the negative electrode side wiring 102 at both ends of the smoothing capacitor 16.

  Here, operations of the step-up chopper circuit and the reverse blocking diode 5 will be described.

  As shown in FIG. 8, when the output terminal of the rectifier circuit that outputs the full-wave rectified voltage is short-circuited by the reactor 24 via the switching element 26, a current depending on the voltage and the inductance of the reactor 24 flows. This current flows regardless of the voltage of the smoothing capacitor 16 by the reverse blocking diode 25 connected between the connection point of the reactor 24 and the switching element 26 and the high potential side of the smoothing capacitor 16. For this reason, even when the voltage of the AC power supply 201 is lower than the voltage of the smoothing capacitor 16, a current can flow, and a current waveform as shown in FIG. 6 can be obtained.

  When the switching element 26 is turned off, no current flows through the switching element 26, but the current in the reactor 24 cannot be changed steeply (in this case, decreased) due to the action of the inductance. Therefore, the reactor 24 generates a counter electromotive force in order to keep the current flowing, and flows a current for charging the smoothing capacitor 16 via the reverse blocking diode 25. By repeating this operation, the current waveform can be made sinusoidal.

  Although this comparative example 4 is not a circuit configuration that should be considered for suppressing the inrush current to the switching element, the AC power supply voltage is rectified only by the rectifier diode, and the reverse blocking diode 25 is required. It is difficult to reduce.

  FIG. 2 is a circuit diagram showing a power supply device for driving an electric compressor according to a second embodiment of the present invention. Hereinafter, differences from the first embodiment will be mainly described, and the description of the same components as those of the first embodiment will be omitted.

  In the power supply device 20 in FIG. 2, the DC input side of the inverter 17 is connected to the DC output of the power supply device 10 of the first embodiment shown in FIG. Thereby, the DC voltage (power) output to both ends of the smoothing capacitor 16 is converted by the inverter 17 into an AC voltage (power) having a variable frequency and voltage. That is, the power supply device 10 (FIG. 1) according to the first embodiment is a power supply device that receives an AC voltage (power) from an AC power supply and outputs a DC voltage (power), whereas the power supply device according to the second embodiment. Reference numeral 20 denotes a power supply device that receives an AC voltage (power) from a commercial AC power source or the like and outputs an AC voltage (power).

  In FIG. 2, the inverter 17 includes switching elements 18a, 18b, 18c, 18d, 18e, and 18f made of MOSFET. The switching element 18a as the upper arm and the switching element 18b as the lower arm constitute a U-phase switching leg. The switching element 18c as the upper arm and the switching element 18d as the lower arm constitute a V-phase switching leg. Further, the switching element 18e serving as the upper arm and the switching element 18f serving as the lower arm constitute a W-phase switching leg.

  The high-potential side and the low-potential side of the U-phase, V-phase, and W-phase switching legs are connected to the positive-side wiring 101 and the negative-side wiring 102 to which the smoothing capacitor 16 is connected, respectively. As a result, the inverter 17 is supplied with a DC voltage (electric power) using the power supply device 10 (FIG. 1) of the first embodiment as a DC power source.

  The switching elements 18a, 18b, 18c, 18d, 18e, and 18f send predetermined control signals to control terminals (gate terminals) of the switching elements 18a, 18b, 18c, 18d, 18e, and 18f from a control circuit (not shown). By giving, on / off control is performed. Thus, a three-phase AC voltage (power) is output from the U-phase, V-phase, and W-phase switching legs by the U-phase AC output 103U, the V-phase AC output 103V, and the W-phase AC output 103W, respectively. .

  The three-phase AC voltage (power) output from the inverter 17 becomes a variable frequency by changing the timing of on / off control of the switching elements 18a, 18b, 18c, 18d, 18e, and 18f by the control circuit. . Further, the magnitude of the DC voltage across the smoothing capacitor 16 can be varied by changing the timing of on / off control of the switching elements 13a and 13b of the boost chopper circuit. As a result, the voltage amplitude of the three-phase AC voltage (power) output from the inverter 17 becomes variable.

  The three-phase AC voltage (voltage) output from the inverter 17 is supplied to the electric compressor 203 in which the compressor is driven by the three-phase AC motor. As the three-phase AC motor, for example, a permanent magnet synchronous motor is applied.

  As a control circuit of the inverter 17, for example, a PWM control circuit is applied. The control circuit for the inverter 17 and the control circuit for controlling the switching of the switching elements 13a and 13b on the DC power supply side are preferably integrated control circuits. Thereby, as a whole control circuit of the power supply device 20, the control circuit can be reduced in size, or the control accuracy can be improved.

  As described above, according to the second embodiment, the DC power supply of the inverter 17 is configured by the power supply device according to the first embodiment. Therefore, the power supply device that outputs a three-phase AC with a variable voltage and a variable frequency This makes it difficult to break down and improves reliability, while reducing loss and improving efficiency.

  The switching element constituting the inverter 17 is not limited to a MOSFET but may be an IGBT (Insulated Gate Bipolar Transistor) or a super junction MOSFET.

  FIG. 9 shows a circuit diagram of a power supply device according to Embodiment 3 of the present invention. Hereinafter, differences from the first embodiment will be mainly described, and the description of the same components as those of the first embodiment will be omitted.

  Unlike the first embodiment (FIG. 1), the AC power source of the third embodiment is a three-phase AC power source 301. For this reason, the power supply device 10 includes two rectifier diodes (11a and 11b in FIG. 1), two switching elements (13a and 13b in FIG. 1), and two rectifier diodes (for inrush current bypass) ( In FIG. 1, there are provided three rectifier circuit sections each including 12 a and 12 b) and a coil (15 in FIG. 1) for suppressing an inrush current flowing in the switching element according to the number of phases of the AC power source. A three-phase AC voltage (power) is input from the three-phase AC power supply 301 to the three rectifier circuit units via the three reactors 14a, 14b, and 14c.

  That is, in the third embodiment, as shown in FIG. 9, the rectification diodes 11a and 11b, the switching elements 13a and 13b, the rectification diodes 12a and 12b for bypassing the inrush current, and the switching elements 13a and 13b flow. A first rectifier circuit portion including a coil 15a for suppressing an inrush current, rectifier diodes 11c and 11d, switching elements 13c and 13d, rectifier diodes 12c and 12d for bypassing the inrush current, and a switching element 13c, A second rectifier circuit portion including a coil 15b for suppressing an inrush current flowing in 13d, rectifier diodes 11e and 11f, switching elements 13e and 13f, rectifier diodes 12e and 12f for bypassing the inrush current, and switching Suppresses inrush current flowing through the elements 13e and 13f It includes a third rectifier circuit consisting of a yl 15c, a.

  The first, second, and third rectifier circuit units are respectively connected to the U-phase terminal of the three-phase AC power supply 301 via the reactor 14a, the V-phase terminal via the reactor 14b, and the W-phase terminal via the reactor 14c. And three-phase AC voltage (electric power) is input. Each rectifier circuit unit operates in the same manner as in the first embodiment, so that the power supply device 10 in the third embodiment converts the three-phase AC voltage (power) input from the three-phase AC power source into a DC voltage (power). And output. The output DC voltage (electric power) is supplied to the load 202.

  In addition, about Example 3, the line voltage between the U-phase terminal and the V-phase terminal of the three-phase AC power supply 301, the line voltage between the V-phase terminal and the W-phase terminal, and between the W-phase terminal and the U-phase terminal Are respectively input to the first rectifier circuit unit, the second rectifier circuit unit, and the third rectifier circuit unit in the power supply device 10.

  According to the power supply device of the third embodiment, as in the first embodiment, the rectifier diodes 12a to 12f are provided to bypass the rush current, and the rush current that flows to the switching elements 13a to 13f by the coils 15a to 15c having a small inductance is provided. Current is suppressed. Thereby, failure of switching elements 13a-13f by inrush current can be prevented. Further, during normal operation, a current flows through a current path including the switching elements 13a to 13f. Thereby, the synchronous rectification operation and the power factor correction operation associated with the on / off operation of the switching elements 13a to 13f in the step-up chopper operation are effective without being hindered by the rush current bypass rectifier diodes 12a to 12f. Therefore, a power supply device that outputs a DC voltage (electric power) using an AC power supply as a three-phase AC power supply has improved reliability with respect to inrush current, reduced loss, and improved efficiency.

  Next, an air conditioner that is Embodiment 4 of the present invention will be described.

  The air conditioner of the fourth embodiment is shown in FIG. 2 as an electric compressor in which the compressor is driven by a three-phase AC motor and a power supply device that supplies a three-phase AC voltage (electric power) to the electric compressor. The power supply device 20 of Example 2 is provided. Note that the electric compressor included in the air conditioner of the fourth embodiment corresponds to the electric compressor 203 in FIG.

  Hereinafter, the air conditioner of the fourth embodiment will be further described with reference to FIGS. 10 and 11.

  FIG. 10 is a configuration diagram of the cooling and heating cycle of the air conditioner according to the fourth embodiment. The air conditioner includes an indoor heat exchanger 51, an outdoor heat exchanger 52, a compressor 53, an expansion valve 54, a four-way valve 55, an indoor blower fan 56, and an outdoor blower fan 57. The compressor 53, the outdoor heat exchanger 52, the outdoor blower fan (propeller fan) 57, and the expansion valve 54 are disposed in the outdoor unit (see FIG. 11), and the indoor heat exchanger 51 and the indoor blower fan 56 are indoor units (not shown). )).

  During the cooling operation, the high-temperature and high-pressure refrigerant discharged from the compressor 53 flows into the outdoor heat exchanger 52 through the four-way valve 55. The refrigerant flowing into the outdoor heat exchanger 52 is condensed and becomes liquid refrigerant by exchanging heat with outdoor air sent by the outdoor blower fan 57. The liquid refrigerant passes through the expansion valve 54 to become a low-temperature and low-pressure two-phase refrigerant and flows into the indoor heat exchanger 51. The low-temperature and low-pressure two-phase refrigerant that has flowed into the indoor heat exchanger 51 exchanges heat with the indoor air sent by the indoor blower fan 56. At this time, the indoor air sent to the indoor heat exchanger 51 is cooled by the low-temperature and low-pressure two-phase refrigerant that has flowed into the indoor heat exchanger 51, and is discharged into the room from a blower outlet (not shown). Since the air discharged into the room from the air outlet (not shown) is lower than the temperature of the air at the air inlet (not shown), the room temperature can be lowered. The refrigerant heat-exchanged by the indoor heat exchanger 51 returns to the compressor 53 again via the four-way valve 55.

  During the heating operation, the high-temperature and high-pressure refrigerant discharged from the compressor 53 flows into the indoor heat exchanger 51 through the four-way valve 55. Then, it passes through the four-way valve 55 and the outdoor heat exchanger 52 and returns to the compressor 53 via the four-way valve 55.

  FIG. 11 is an external view of an outdoor unit of an air conditioner according to the fourth embodiment. The space in the outdoor unit is divided into a compressor chamber A in which the compressor 53 is installed and a blower chamber B in which the outdoor blower fan 57 is installed, with the partition plate 70 interposed therebetween. An electrical component 79 such as a power supply device that drives the compressor 53 is accommodated in the electrical box and is located between the compressor 53 and the upper lid 80 and across the compressor chamber A and the blower chamber B. is set up. Further, the electrical component 79 is located above the partition plate 70 and is supported by the partition plate 70.

  The outdoor air is sucked from the rear side of the outdoor unit by the outdoor blower fan 57, passes through the outdoor heat exchanger 52, and then blown out from the front side (front panel 81) of the outdoor unit.

  When a three-phase AC voltage (power) having a variable voltage and a variable frequency is supplied to the compressor 53, that is, a three-phase AC motor included in the electric compressor, by the power supply device 20 of the second embodiment, the three-phase AC motor rotates. The compressor 53 is driven by the AC motor. Thereby, the air conditioner performs cooling and heating operations as described above.

  According to the air conditioner of the fourth embodiment, even if an inrush current occurs in the power supply device of the compressor, it becomes difficult to break down and the reliability is improved. Moreover, since loss is reduced and efficiency is improved, energy saving of the air conditioner can be achieved.

  In addition, this invention is not limited to embodiment mentioned above, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  For example, the DC power supply unit in the second embodiment may be replaced with the power supply device in the third embodiment. In addition, the power supply device according to the second embodiment is not limited to driving an electric compressor, but can be applied to various devices driven by an electric motor. Moreover, the power supply apparatus of Example 1 and Example 3 can supply direct-current voltage (electric power) with respect to the various apparatus which uses not only an inverter but direct-current power. Furthermore, the power supply apparatus of Example 1 and Example 3 can be applied not only to an air conditioner but also as a DC power supply unit for various devices. Further, the switching elements 13a and 13b of the step-up chopper circuit are not limited to MOSFETs but may be IGBTs having a reverse conduction function.

10, 20 Power supply devices 11a, 11b, 11c, 11d, 11e, 11f Rectifier diodes 12a, 12b, 12c, 12d, 12e, 12f Rectifier diodes 13a, 13b, 13c, 13d, 13e, 13f Switching elements 14, 14a, 14b, 14c Reactor 15, 15a, 15b, 15c Coil 16 Smoothing capacitor 17 Inverter 18a, 18b, 18c, 18d, 18e, 18f Switching element 51 Indoor heat exchanger 52 Outdoor heat exchanger 53 Compressor 54 Expansion valve 55 Four-way valve 56 Indoor ventilation Fan 57 Outdoor fan 70 Partition plate 79 Electrical component 80 Upper lid 81 Front panel 101 Positive side wiring 102 Negative side wiring 201 AC power source 202 Load 203 Electric compressor 301 Three-phase AC power source

Claims (10)

A first series connection circuit in which a first rectifier diode and a second rectifier diode are connected in series; a first switching element having a reverse conduction function; and a second switching element in which a second switching element is connected in series. A series connection circuit is connected between the positive electrode and the negative electrode, and a circuit unit connected in parallel;
A smoothing capacitor connected between the positive electrode and the negative electrode;
With
The circuit section is
A third series connection circuit in which a third rectification diode and a fourth rectification diode are connected in series and connected in parallel to the second series connection circuit;
An inductance element;
Have
An alternating current power source is connected to the first series connection point in the first series connection circuit, and is connected to the third series connection point in the third series connection circuit via a reactor,
The power supply apparatus, wherein the third series connection point is connected to a second series connection point in the second series connection circuit via the inductance element. The power supply device according to claim 1,
The power supply apparatus according to claim 1, wherein an inductance value of the inductance element is smaller than an inductance value of the reactor. In the power supply device according to claim 2,
An inductance value of the inductance element is 10 μH or more and less than 100 μH, and an inductance value of the reactor is 1 mH or more and less than 10 mH. The power supply device according to claim 1,
For the same inrush current, the voltage drop of the third rectifier diode is smaller than the voltage drop due to the first switching element and the inductance element,
And the power supply device characterized by the voltage drop of said 3rd rectifier diode being larger than the voltage drop by said 1st switching element and said inductance element with respect to the same electric current at the time of normal operation.   2. The power supply device according to claim 1, wherein the first switching element and the second switching element are controlled to be turned on and off in a complementary manner. The power supply device according to claim 1,
The AC power is single-phase and includes only one circuit unit. The power supply device according to claim 1,
A power supply apparatus comprising a plurality of the circuit units equal to the number of phases of the AC power. The power supply device according to claim 1,
The power supply device further comprises an inverter connected between the positive electrode and the negative electrode.   2. The power supply device according to claim 1, wherein the first switching element and the second switching element are MOSFETs. An electric compressor whose compressor is driven by an AC motor;
A power supply for supplying power to the electric compressor;
With
In the air conditioner in which the refrigerant compressed by the electric compressor circulates in an air conditioning cycle,
The power supply is
A first series connection circuit in which a first rectifier diode and a second rectifier diode are connected in series; a first switching element having a reverse conduction function; and a second switching element in which a second switching element is connected in series. A series connection circuit is connected between the positive electrode and the negative electrode, and a circuit unit connected in parallel;
A smoothing capacitor connected between the positive electrode and the negative electrode;
With
The circuit section is
A third series connection circuit in which a third rectification diode and a fourth rectification diode are connected in series and connected in parallel to the second series connection circuit;
An inductance element;
Have
An alternating current power source is connected to the first series connection point in the first series connection circuit, and is connected to the third series connection point in the third series connection circuit via a reactor,
The third series connection point is connected to the second series connection point in the second series connection circuit via the inductance element,
Furthermore, an inverter connected between the positive electrode and the negative electrode,
The air conditioner characterized in that the electric power output from the inverter is supplied to the electric compressor.

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