TWI806989B - Power conversion device and air conditioner equipped with it - Google Patents

Abstract

To provide a simple configuration and low-loss power conversion device and the like. The inverter (100) is equipped with: a switching element driving circuit (20) that outputs a driving signal to the switching element (Qa, Qb); and a reverse voltage applying circuit (30a, 30b) that applies a reverse voltage to the parasitic diode (Da, Db) or flywheel diode of the switching element (Qa, Qb); A reverse voltage application signal is generated to a reverse voltage application circuit (30a, 30b).

Description

Power conversion device and air conditioner equipped with it

The present invention relates to power conversion devices and the like.

As a technique for reducing the loss of a power conversion device, for example, the technique described in Patent Document 1 is known. That is, Patent Document 1 discloses a power conversion device including flywheel diodes connected in antiparallel to a main circuit switching element, and a reverse voltage application circuit that applies a reverse voltage smaller than that of a DC voltage source to each flywheel diode when these flywheel diodes are turned off.

[Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Patent No. 4204534

In the technique described in Patent Document 1, the loss of the power conversion device is reduced by applying a reverse voltage to the flywheel diode from the reverse voltage application circuit as described above. However, in the patent In the technique described in Document 1, since a dedicated microcomputer is required to separately operate the main circuit switching control circuit and the reverse voltage application circuit, the number of parts and the manufacturing cost increase.

Therefore, the present invention makes it a subject to provide a simple configuration and a low-loss power conversion device and the like.

In order to solve the aforementioned problems, the power conversion device of the present invention is configured to include a reverse voltage driving circuit which is connected one-to-one to the reverse voltage applying circuit and is also connected to the switching element driving circuit, and generates a reverse voltage applying signal to the above reverse voltage applying circuit using a driving signal input from the switching element driving circuit to itself.

According to the present invention, it is possible to provide a simple configuration and a low-loss power conversion device and the like.

1: Compressor

2: Outdoor heat exchanger (condenser/evaporator)

3: Outdoor fan

4: Expansion valve

5: Indoor heat exchanger (evaporator/condenser)

6: Indoor fan

10: Inverter circuit (power conversion circuit)

10A: conversion circuit (power conversion circuit)

10u: 1st lead (switching lead)

10v: 2nd lead (toggle lead)

10w: 3rd lead (switch lead)

11, 12: Lead (switch lead)

20: Switching element drive circuit

30a, 30b: reverse voltage application circuit

40a, 40b: resonator (drive circuit for reverse voltage)

50, 50A: control circuit

60a: Turn-on delay circuit

70a: Power-on time setting circuit

100, 100A: inverter (power conversion device)

200: Converter (power conversion device)

Da, Db, Dc, Dd, De, Df: parasitic diodes

Da1, Db1, Dc1, Dd1, De1, Df1: Flywheel diodes

F: Refrigerant circuit

M: motor

Qa, Qc, Qe: switching elements (switching elements of the upper arm)

Qb, Qd, Qf: switching elements (switching elements of the lower arm)

W: air conditioner

ha: Wiring (the first wiring)

ma: wiring (second wiring)

[ Fig. 1 ] is a configuration diagram of an inverter as a power conversion device according to a first embodiment of the present invention.

[ Fig. 2 ] is a diagram for the reverse voltage application circuit, resonator, and conduction delay in the inverter of the power conversion device according to the first embodiment of the present invention. The circuit diagram showing the composition of the delay circuit and the power-on time setting circuit.

[ Fig. 3 ] is a time chart showing the operation related to the application of the reverse voltage to the inverter of the power conversion device according to the first embodiment of the present invention.

[ Fig. 4 ] is a configuration diagram of a converter of a power conversion device according to a second embodiment of the present invention.

[ Fig. 5 ] is a structural diagram of an air conditioner according to a third embodiment of the present invention.

[ Fig. 6 ] is a configuration diagram of an inverter of a power conversion device as a modified example of the present invention.

[First Embodiment] <The structure of the inverter>

FIG. 1 is a configuration diagram of an inverter 100 as a power conversion device according to a first embodiment. The inverter 100 is a power conversion device that converts DC voltage into AC voltage. In addition, as the DC power supply E shown in FIG. 1 , a three-phase AC voltage applied from an AC power supply (not shown) converted into a DC voltage by a converter (not shown) may also be used.

As shown in FIG. 1 , an inverter 100 is provided with a switching element drive circuit 20, reverse voltage application circuits 30a, 30b, resonators 40a, 40b (reverse voltage drive circuit), and a control circuit 50 in addition to an inverter circuit 10 (power conversion circuit) as a main circuit.

The inverter circuit 10 is a power conversion circuit that converts the DC voltage applied from the DC power supply E into a three-phase AC voltage, and applies the three-phase AC voltage to the motor M. The inverter circuit 10 includes a first lead 10u, a second lead 10v, and a third lead 10w.

The first lead 10u is a switching lead for connecting the switching element Qa of the upper arm and the switching element Qb of the lower arm. As such switching elements Qa and Qb, for example, MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) can be used. In addition, the same applies to other switching elements Qc, Qd, Qe, and Qf.

The drain of the switching element Qa is connected to the positive side of the DC power supply E, and the source is connected to the drain of the switching element Qb. Also, the source of the switching element Qb is grounded. A connection point P1 between the source of the switching element Qa and the drain of the switching element Qb is connected to the U-phase coil Lu of the motor M via the wiring u.

Similarly, the second lead 10v is provided with an upper arm switching element Qc and a lower arm switching element Qd. The connection point P2 of the switching elements Qc, Qd is connected to the V-phase winding line Lv of the motor M via the wiring v. Also, the third lead 10w is provided with an upper arm switching element Qe and a lower arm switching element Qf. The connection point P3 of the switching elements Qe, Qf is connected to the W-phase winding line Lw of the motor M via the wiring w.

The first lead 10u, the second lead 10v, and the third lead 10w are mutually connected in parallel. Also, the voltage Vd of the DC power supply E is applied to both ends of the first lead 10u, the second lead 10v, and the third lead 10w. However, by controlling based on PWM (PulseWidth Modulation) The ON/OFF of the switching elements Qa~Qf are switched in a specific way, so that the three-phase AC power is output to the motor M through the wiring u, v, w.

The switching element Qa has a parasitic diode Da inside it. The parasitic diode Da is part of the pn junction existing between the source and the drain of the switching element Qa, and is formed during the manufacturing process of the switching element Qa (for example, MOSFET). In addition, the same applies to other switching elements Qb to Qf.

The switching element drive circuit 20 is a circuit that outputs specific drive signals to the upper and lower pair of switching elements Qa, Qb, respectively, based on commands from the control circuit 50 . As shown in FIG. 1, the switching element drive circuit 20 is connected to the gate of the switching element Qa via the wiring ha (first wiring). That is, the switching element Qa corresponding to the reverse voltage application circuit 30a described later and the switching element driving circuit 20 in one-to-one correspondence are connected via the wiring ha. In addition, the switching element drive circuit 20 is also connected to the gate of the switching element Qb via the wiring hb (first wiring).

The resistor Ra shown in FIG. 1 is a gate circuit for adjusting the voltage of the drive signal output from the switching element drive circuit 20, and is provided at the wiring ha. In addition, the configuration of FIG. 1 is only one example, and the gate circuit of the switching element Qa is not limited to being constituted only by the resistor Ra.

The reverse voltage application circuit 30a is a circuit for applying a reverse voltage to the parasitic diode Da (or flywheel diode) of the switching element Qa, and is connected to the switching element Qa one-to-one. In addition, the so-called "Reverse voltage" refers to the reverse direction voltage of the parasitic diode Da. The reverse voltage application circuit 30a is connected to the source of the switching element Qa via the wiring ia, and is connected to the drain of the switching element Qa via the wiring ja.

The resonator 40a is a circuit that outputs a specific reverse voltage application signal to the reverse voltage application circuit 30a, and is connected to the reverse voltage application circuit 30a. As shown in FIG. 1 , the resonator 40a is connected one-to-one to the reverse voltage applying circuit 30a via the wiring ka, and is also connected to the switching element driving circuit 20 via the wiring ma and wiring ha (part) sequentially. In other words, the resonator 40a corresponding to the reverse voltage application circuit 30a described later and the wiring ha (first wiring) are connected via the wiring ma (second wiring).

Furthermore, the resonator 40a generates a reverse voltage application signal to the reverse voltage application circuit 30a using a drive signal input to itself from the switching element drive circuit 20 sequentially through the wiring ha (first wiring) and the wiring ma (second wiring). That is, the resonator 40a generates a specific reverse voltage application signal by passing the driving signal of the switching element Qa. This is one of the main features of the first embodiment.

In addition, the reverse voltage application circuit 30b and the resonator 40b are also connected to the switching element Qb of the lower arm. And, the driving signal generated by the switching element driving circuit 20 is output to the switching element Qb via hb, and is also output to the resonator 40b via the wiring hb (part) and the wiring mb sequentially.

Also, although not shown in FIG. 1, at the respective switching elements Qc, Qd, Qe, and Qf of the second lead 10v and the third lead 10w, there are also switching elements Qc, Qd, Qe, and Qf. Similar to the first lead 10u, a switching element drive circuit, a reverse voltage application circuit, a resonator, and the like are connected. In addition, the three switching element driving circuits 20, 20, 20 corresponding to the U phase, V phase, and W phase can be provided individually, and the switching element driving circuits 20, 20, 20 of the three phases can also be packaged into one body.

The control circuit 50 is, for example, a microcomputer (Microcomputer), although it is not shown in the figure, it is composed of electronic circuits including a CPU (Central Processing Unit), ROM (Read Only Memory), RAM (Random Access Memory), and various interfaces. Also, the program stored in the ROM is read out and developed in the RAM, and the CPU executes various processes. The control circuit 50 outputs a specific control signal based on PWM control to the switching element drive circuit 20 .

FIG. 2 is a circuit diagram showing the configuration of the reverse voltage applying circuit 30a, the resonator 40a, the conduction delay circuit 60a, and the conduction time setting circuit 70a. In addition, in FIG. 2 , the circuit related to the switching element Qa of the upper arm is illustrated, and the illustration of the circuits related to the other switching elements Qb to Qf (refer to FIG. 1 ) is omitted. In addition, in FIG. 1 which has already been described, illustration of the conduction delay circuit 60a and the conduction time setting circuit 70a is omitted.

As shown in FIG. 2 , the reverse voltage application circuit 30 a includes a diode 31 , switching means 32 , and a capacitor 33 . The diode 31 is an element for preventing the reverse flow of current, and is provided at the wiring ja. Diode 31, the anode is connected with the switching means 32, and the cathode The electrode is connected to the drain of the switching element Qa via the wiring ja.

The switching means 32 is an element for switching connection/disconnection between the capacitor 33 and the switching element Qa, and is provided at the wiring ja. Also, the on/off of the switching means 32 is switched by a signal from the "OUT" terminal of the resonator 40a. As such switching means 32, for example, a MOSFET is used.

The capacitor 33 is an element that applies a specific voltage as a reverse voltage to the parasitic diode Da when the switching means 32 is switched on. The positive side of the capacitor 33 is connected to the drain of the switching element Qa via the wiring ja, and the negative side is connected to the source of the switching element Qa via the wiring ia. In addition, a bootstrap circuit (not shown) for appropriately charging the capacitor 33 may be provided.

The resonator 40a is an electronic circuit that outputs a specific electrical signal from the "OUT" terminal to the switching means 32 in response to changes in the voltage applied between the "In" terminal and the "GND" terminal. In this embodiment, when the resonator 40a detects a dip in the rectangular wave voltage applied from the switching element drive circuit 20, it outputs an ON signal from the "OUT" terminal to the switching means 32 for a predetermined time.

As shown in FIG. 2 , the "In" terminal of the resonator 40a is connected to the switching element drive circuit 20 through the wiring ma and the wiring ha (part) in order, and the "GND" terminal is grounded. Also, a specific voltage Vcc is applied to the "Vcc" terminal of the resonator 40a via the energization time setting circuit 70a. The "OUT" terminal of the resonator 40a, It is connected to the gate of the MOSFET which is the switching means 32 via the wiring ka.

The turn-on delay circuit 60a is a circuit that sets a specific delay time from when the drive signal output from the switching element drive circuit 20 is turned off until the output of the reverse voltage application signal is started at the resonator 40a. In the example shown in FIG. 2, as the ON delay circuit 60a, an RC circuit in which a resistor 61 and a capacitor 62 are connected in an L-shape is provided at the wiring ma connecting the switching element drive circuit 20 and the resonator 40a.

To describe it concretely, the resistor 61 of the on-delay circuit 60a is provided at the wiring ma connecting the "In" terminal and the wiring ha. Also, the positive side of the capacitor 62 is provided on the "In" terminal side of the resistor 61 at the wiring ma, and the negative side of the capacitor 62 is grounded.

And, by appropriately setting the time constant of the turn-on delay circuit 60a in advance, the rectangular-wave driving signal output from the switching element driving circuit 20 is output to the resonator 40a with a specific delay time (on delay). Thereby, the optimum delay time can be preset in consideration of the characteristics of the switching element Qa and the parasitic diode Da in the design stage. In addition, the configuration of the turn-on delay circuit 60a shown in FIG. 2 is just one example, and is not limited thereto.

The energization time setting circuit 70a is a circuit for setting the energization time of the conduction signal output from the resonator 40a. In the example shown in Figure 2, the energization time setting circuit 70a is equipped with a resistor 71 and a diode 72, and capacitor 73. The resistor 71 and the diode 72 are connected in parallel, and a capacitor 73 is connected in series at the parallel connection. The positive side of the capacitor 73 is connected to the anode of the diode 72, and the negative side of the capacitor 73 is connected to the "Vcc" terminal of the resonator 40a.

<Operation of Inverter>

The control circuit 50 shown in FIG. 1 generates a PWM signal (Pulse Width Modulation) based on a comparison result between a reference sine wave signal (not shown) and a specific triangular wave (not shown). Based on this PWM signal, for example, at the switching element driving circuit 20 corresponding to the first lead 10u, a driving signal for a pair of upper and lower switching elements Qa, Qb is generated.

In addition, the driving signal of the switching element Qa of the upper arm and the driving signal of the switching element Qb of the lower arm are complementary (on/off slightly reversed). However, since a large short-circuit current flows when both switching elements Qa and Qb are temporarily turned on, a specific dead time is set so that such a short-circuit current does not flow. The aforementioned so-called inactive time is a period in which both the switching element Qa of the upper arm and the switching element Qb of the lower arm are in the OFF state. In addition, it is the same about other 2nd lead wire 10v and 3rd lead wire 10w.

Next, as one example, the reverse recovery current generated in the parasitic diode Da will be described. For example, when the switching elements Qa and Qd are turned on, the current flows through the switching element Qa, the U-phase coil Lu, the V-phase coil Lv of the motor M, and the switching element Qd in sequence.

Here, assuming that the reverse voltage application circuit 30a is not provided, since the voltage Vd (large reverse voltage) is applied to the parasitic diode Da of the upper arm at the moment when the switching element Qb of the lower arm is switched from off to on, a specific reverse recovery current is generated at the parasitic diode Da. Since this reverse return current flows through the switching element Qb of the lower arm, a large loss (switching loss) occurs in the switching element Qb. In order to suppress such loss, a reverse voltage application circuit 30a is provided.

In addition, the so-called "reverse recovery current" refers to the current flowing at the moment when the voltage applied to the parasitic diode Da (or flywheel diode) is switched from forward voltage to reverse voltage.

The reverse voltage applying circuit 30a applies a small reverse voltage to the parasitic diode Da of the upper arm immediately after the driving signal of the switching element Qa drops and enters a specific invalid time. Thereby, before the switching element Qb of the lower arm is switched from off to on, a small reverse recovery current flows intentionally through the parasitic diode Da of the upper arm.

As a result, the carriers (electrons or holes) that cause the reverse recovery current at the parasitic diode Da are exhausted. Thereby, even if the switching element Qb of the lower arm is switched on later, since almost no reverse recovery current flows in the parasitic diode Da, loss in the switching element Qb of the lower arm can be suppressed.

FIG. 3 is a timing chart showing the actions related to the application of the reverse voltage at the inverter 100 (refer to FIG. 1 and FIG. 2 as appropriate). From the top of FIG. 3 , sequentially for the driving signal of the switching element Qa of the upper arm, The driving signal of the switching element Qb of the lower arm, the signal output from the "OUT" terminal of the resonator 40a (refer to FIG. 2 ) and the signal output from the "OUT" terminal of the resonator 40b (refer to FIG. 2 ) are shown. Also, each horizontal axis in Fig. 3 represents time.

The "inactive time" shown in FIG. 3 is a period in which both switching elements Qa and Qb are in the OFF state. Actually, the "invalid time" is a very short time, however, in FIG. 3, the "invalid time" is described as a relatively long time for easy understanding.

The resonator 40a outputs an ON signal to the reverse voltage applying circuit 30a for a predetermined time when detecting a dip in the driving signal of the switching element Qa. That is, if the driving signal output from the switching element driving circuit 20 to the switching element Qa of the upper arm is switched from on to off (time t1), the resonator 40a detects the drop of the driving signal with a specific delay time Δta at the turn-on delay circuit 60a. After that, the output of the conduction signal from the resonator 40a is started (time t2).

If an ON signal is output from the "OUT" terminal of the resonator 40a (see FIG. 2 ) to the switching means 32 (see FIG. 2 ) of the reverse voltage applying circuit 30a, the switching means 32 is switched to conduction, and a specific reverse voltage is applied to the parasitic diode Da. In addition, this reverse voltage is smaller than the voltage Vd of the DC power supply E. That is, the voltage between the plates of the capacitor 62 shown in FIG. 2 is smaller than the voltage Vd of the DC power supply E. This is for suppressing the peak value of the reverse recovery current flowing in the parasitic diode Da.

If a reverse voltage is applied to the parasitic diode Da, a small reverse recovery current flows through the parasitic diode Da and the switching element Qb during the inactive time of the upper and lower pair of switching elements Qa, Qb. By this, the carriers (electrons or holes) present at the parasitic diode Da are temporarily almost depleted. Therefore, even if the switching element Qb of the lower arm is switched on afterwards and the voltage Vd is applied to the parasitic diode Da of the upper arm, a large reverse recovery current hardly flows. Thereby, the loss at the switching element Qb can be reduced.

And, the conduction signal output from the "OUT" terminal (refer to FIG. 2 ) of the resonator 40a is continued for a specific time based on the energization time setting circuit 70a (time t2~t4). As a result, the conduction state of the switching means 32 (refer to FIG. 2 ) of the reverse voltage applying circuit 30a is also continued during the period from time t2 to t4. In addition, the timing of switching the switching means 32 from on to off may be after a specific time Δtb elapses from the end of the inactive time (time t1-t3), or may be approximately at the same time as the end of the inactive time.

In this way, since the reverse voltage application signal is output during the inactive time of the switching elements Qa, Qb, it is possible to appropriately suppress the reverse return current at the parasitic diode Da.

The action of the re-vibrator 40b on the other side is also the same as that of the re-vibrator 40a on one side. That is, although the period is not shown in FIG. 3 , when the drop of the driving signal of the switching element Qb is detected with a specific delay time, the reverse voltage applying circuit 30b is turned on from the "OUT" terminal of the resonator 40b. The number is output at a specific time. As a result, a small reverse voltage is applied to the parasitic diode Db of the switching element Qb of the lower arm, and a small reverse recovery current flows during the inactive time. In addition, it is the same about other 2nd lead wire 10v and 3rd lead wire 10w.

<Effect>

According to the first embodiment, for example, before the switching element Qb of the lower arm is switched on, the reverse voltage applying circuit 30a is configured to apply a reverse voltage to the parasitic diode Da to intentionally flow a small reverse recovery current. Therefore, when the switching element Qb of the lower arm is switched on and the voltage Vd is applied to the parasitic diode Da, it is possible to suppress the flow of a large reverse recovery current. Thereby, the switching loss in the inverter 100 is reduced, and the efficiency can be improved. In addition, it is also possible to suppress the resonance phenomenon or the occurrence of surge voltage caused by the noise accompanying the reverse recovery current.

Moreover, according to the first embodiment, the resonators 40a and 40b generate reverse voltage application signals by flowing the drive signal from the switching element drive circuit 20 . Therefore, since there is no need to separately prepare a microcomputer provided with dedicated pins (not shown) connected to the resonators 40a, 40b, the number of parts and manufacturing cost can be reduced. In this way, according to the first embodiment, it is possible to provide an inverter 100 with a simple configuration and low loss.

[Second Embodiment]

In the second embodiment, a converter 200 (see FIG. 4 ) including a reverse voltage application circuit 30 a and the like will be described. In addition, the configuration and operation of the reverse voltage application circuit 30a, resonator 40a, conduction delay circuit 60a (refer to FIG. 2, not shown in FIG. 4) and energization time setting circuit 70a (refer to FIG. 2, not shown in FIG. 4) are the same as those of the first embodiment. Therefore, the description will be given for the parts that are different from those of the first embodiment, and the description will be omitted for the parts that overlap.

FIG. 4 is a configuration diagram of a converter 200 as a power conversion device according to a second embodiment. The converter 200 shown in FIG. 4 is a power conversion device that converts an AC voltage applied from an AC power supply G into a DC voltage. As shown in FIG. 4, the converter 200, in addition to the conversion circuit 10A as the main circuit, also includes a reactance L1, a smoothing capacitor C1, a switching element drive circuit 20, reverse voltage application circuits 30a, 30b, reoscillators 40a, 40b, and a control circuit 50A.

The conversion circuit 10A includes four switching elements Qa, Qb, Qc, and Qd connected in a bridge form. The input side of the conversion circuit 10A is connected to the AC power supply G, and the output side is connected to the inverter 100 . In addition, the inverter 100 has the same configuration as that of the first embodiment (refer to FIG. 1 ).

The switching element Qa is, for example, a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) with a parasitic diode Da inside. In addition, the same applies to other switching elements Qb, Qc, and Qd.

The conversion circuit 10A shown in Fig. 4 is for converting the AC voltage The circuit for converting to DC voltage has lead wires 11 and 12. One of the lead wires 11 is a switching lead wire formed by connecting the switching element Qa of the upper arm and the switching element Qb of the lower arm. Also, the lead wire 12 of the other side is also the same. And, one of the lead wires 11 and the other of the lead wires 12 are configured to be connected in parallel.

At one of the leads 11, the source of the switching element Qa and the drain of the switching element Qb are connected, and their connection point N1 is connected to the AC power supply G through the wiring p1. The source of the switching element Qc and the drain of the switching element Qd are connected to the other lead 12, and the connection point N2 thereof is connected to the AC power supply G via the wiring p2.

The drain of the switching element Qa and the drain of the switching element Qc are connected to each other, and their connection point N3 is connected to the inverter 100 through the wiring p3. In addition, the source of the switching element Qb and the source of the switching element Qd are connected to each other, and their connection point N4 is connected to the inverter 100 through the wiring p4 and grounded.

The reactance L1 stores the power supplied from the AC power supply G as energy, and releases the energy to boost the voltage or improve the power factor. The reactance L1 is provided at the wiring p1 connecting the AC power supply G and the conversion circuit 10A.

The smoothing capacitor C1 smoothes the voltage applied from the conversion circuit 10A. In the smoothing capacitor C1, the positive side is connected to the wiring p3, and the negative side is connected to the wiring p4.

The control circuit 50A is, for example, a microcomputer, and for switching The component replacement drive circuit 20 outputs specific control signals. Note that, since the processing performed by the control circuit 50A is well known, description thereof will be omitted.

Furthermore, the resonator 40a generates a reverse voltage application signal by flowing the driving signal from the switching element driving circuit 20 to the switching element Qa. The reverse voltage applying circuit 30a applies a small reverse voltage to the parasitic diode Da during the inactive time of the switching elements Qa, Qb based on the aforementioned reverse voltage applying signal. Thereby, while achieving simplification of the converter 200, switching loss can be reduced.

In addition, in FIG. 4, although the switching element driving circuit 20, the reverse voltage application circuits 30a, 30b, and the resonators 40a, 40b connected to one of the lead wires 11 are shown, the same circuit is also connected to the other lead wire 12.

<Effect>

According to the second embodiment, the resonators 40a, 40b use the driving signal from the switching element driving circuit 20 to generate the reverse voltage application signal. Thereby, the converter 200 with a simple structure and low loss can be provided.

[third embodiment]

In the third embodiment, an air conditioner W (refer to FIG. 5 ) including the inverter 100 (refer to FIG. 1 ) described in the first embodiment and the converter 200 (refer to FIG. 4 ) described in the second embodiment will be described. bright. In addition, the configuration of the inverter 100 is the same as that of the first embodiment, and the configuration of the converter 200 is the same as that of the second embodiment, and therefore descriptions thereof will be omitted.

Fig. 5 is a structural diagram of an air conditioner W according to a third embodiment. An air conditioner W is a machine that performs specific air conditioning. Hereinafter, although the air conditioner W is mainly performed as a person who performs cooling operation, it demonstrates, However, It is not limited to this. As shown in FIG. 5 , the air conditioner W includes a compressor 1, an outdoor heat exchanger 2, an outdoor fan 3, an expansion valve 4, an indoor heat exchanger 5, an indoor fan 6, an inverter 100, and a converter 200. Also, the refrigerant circuit F shown in FIG. 5 has a structure in which the compressor 1, the outdoor heat exchanger 2, the expansion valve 4, and the indoor heat exchanger 5 are sequentially connected in a loop through a pipe q.

The compressor 1 is a machine for compressing the refrigerant of the gas device, and has a motor M as a driving source. In addition, although it is omitted in FIG. 5 , an accumulator for separating the refrigerant into gas and liquid is provided on the suction side of the compressor 1 .

The inverter 100 and the converter 200 are power conversion devices that perform specific power conversion and output the converted power to the motor M of the compressor 1 . The outdoor heat exchanger 2 is a heat exchanger for exchanging heat between the refrigerant flowing through its heat pipe (not shown) and the outside air sent in from the outdoor fan 3 . The outdoor fan 3 is a fan that sends outside air into the outdoor heat exchanger 2 and is installed near the outdoor heat exchanger 2 .

The expansion valve 4 is used to pass through the outdoor heat exchanger 2 (condensing Device) made a condensed refrigerant decompression valve. On the other hand, the refrigerant decompressed by the expansion valve 4 is guided to the indoor heat exchanger 5 (evaporator).

The indoor heat exchanger 5 is a heat exchanger for exchanging heat between the refrigerant flowing through its heat pipe (not shown) and the indoor air (air in the air-conditioned space) sent in from the indoor fan 6 . The indoor fan 6 is a fan that sends indoor air into the indoor heat exchanger 5 and is installed near the indoor heat exchanger 5 .

In the example shown in FIG. 5, the compressor 1, the outdoor heat exchanger 2, the outdoor fan 3, the inverter 100, and the converter 200 are installed at the outdoor unit Uo. On the other hand, the indoor heat exchanger 5 and the indoor fan 6 are provided at the indoor unit Ui.

And, for example, in air-cooling operation, at the refrigerant circuit F, the refrigerant is circulated in a refrigeration cycle through the compressor 1, the outdoor heat exchanger 2 (condenser), the expansion valve 4, and the indoor heat exchanger 5 (evaporator) in sequence.

In addition, the configuration of the air conditioner W is not limited to the example shown in FIG. 5 . For example, a four-way valve (not shown) for switching the flow path of the refrigerant may be provided in the refrigerant circuit F. In this configuration, during heating operation, the refrigerant is circulated in a refrigeration cycle through the compressor 1, the indoor heat exchanger 5 (condenser), the expansion valve 4, and the outdoor heat exchanger 2 (evaporator) in sequence. That is to say, in the refrigerant circuit F in which the refrigerant circulates through the compressor 1, the "condenser", the "expansion valve" and the "evaporator" in sequence, one of the "condenser" and the "evaporator" is the chamber The other side of the external heat exchanger 2 is the indoor heat exchanger 5 .

<Effect>

According to the third embodiment, the air conditioner W includes the inverter 100 having the same configuration as the first embodiment, and also includes the converter 200 having the same configuration as the second embodiment. Thereby, an air conditioner W with high energy efficiency (APF: Annual Performance Factor) and high reliability can be provided.

≪Modification≫

Although the inverter 100 (see FIG. 1 ), the converter 200 (see FIG. 4 ), and the air conditioner W (see FIG. 5 ) of the present invention have been described above based on the respective embodiments, the present invention is not limited to these descriptions, and various modifications are possible. For example, it is also possible to add flywheel diodes Da1 to Df1 (refer to FIG. 6 ) to the configuration described in the first embodiment as described below.

FIG. 6 is a configuration diagram of an inverter 100A as a modified example of a power conversion device. As shown in FIG. 6, a flywheel diode Da1 may be connected in antiparallel to the switching element Qa. In this configuration, the reverse voltage generated by the reverse voltage applying circuit 30a is applied to the parasitic diode Da, and is also applied to the flywheel diode Da1. In addition, the same applies to the flywheel diodes Db1 to Df1 connected to other switching elements Qb to Qf. According to the structure shown in Figure 6, since it can suppress the reverse recovery current at the parasitic diodes Da~Df control, and can also suppress the reverse recovery current at the flywheel diodes Da1~Df1, therefore, it is possible to simplify the structure of the inverter 100A and reduce the loss. In addition, this point is also the same with respect to the converter 200 (refer FIG. 4) of 2nd Embodiment.

In addition, in the first embodiment, although the switching elements Qa to Qf (refer to FIG. 1 ) are all described as MOSFETs, the description is not limited thereto. For example, the switching elements Qa˜Qf can also be other types of elements such as IGBT (Insulated Gate Bipolor Transisto). In addition, as the switching elements Qa to Qf, elements of different types may be mixed. In addition, it may also be a configuration in which flywheel diodes are connected in antiparallel to switching elements of the type that do not have parasitic diodes. In addition, this point is also the same about 2nd Embodiment and 3rd Embodiment.

In addition, in the first embodiment, the case where the inverter 100 (see FIG. 1 ) is a two-level three-phase inverter has been described, but it is not limited thereto. For example, the configuration of the first embodiment can also be applied to a three-level inverter, and can also be applied to a single-phase inverter. In addition, the structure of the converter 200 (refer FIG. 4) demonstrated in 2nd Embodiment is only one example, and it is not limited to this.

In addition, in the third embodiment, the air conditioner W (refer to FIG. 5 ) including the inverter 100 (refer to FIG. 1 ) described in the first embodiment and the converter 200 (refer to FIG. 4 ) described in the second embodiment has been described, but it is not limited thereto. as well as That is, it is also possible to apply only one of 1st Embodiment and 2nd Embodiment to the air conditioner W.

In addition, in the third embodiment, although the indoor unit Ui (refer to FIG. 5 ) and the outdoor unit Uo (refer to FIG. 5 ) are described as air conditioners W each having one configuration, the system is not limited thereto. For example, each of the embodiments can be applied to a multiple-type air conditioner including a plurality of outdoor units.

Also, in the third embodiment, the air conditioner W (refer to FIG. 5 ) provided with the inverter 100 and the converter 200 has been described, but it can also be applied to other appliances such as refrigerators, water heaters, and washing machines.

Furthermore, the embodiments are described in detail for the sake of easy understanding of the present invention, and the present invention is not limited to the ones including all the described configurations. In addition, addition, deletion, and replacement of other configurations can be performed on a part of the configurations of the embodiments. In addition, the above-mentioned mechanisms and configurations represent those considered necessary for the explanation, and not all the mechanisms and configurations are absolutely indicated on the finished product.

10: Inverter circuit (power conversion circuit)

10u: 1st lead (switching lead)

10v: 2nd lead (toggle lead)

10w: 3rd lead (switch lead)

20: Switching element drive circuit

30a, 30b: reverse voltage application circuit

40a, 40b: resonator (drive circuit for reverse voltage)

50: Control circuit

100: Inverter (power conversion device)

Da, Db, Dc, Dd, De, Df: parasitic diodes

E: DC power supply

M: motor

Qa, Qc, Qe: switching elements (switching elements of the upper arm)

Qb, Qd, Qf: switching elements (switching elements of the lower arm)

ha: Wiring (the first wiring)

hb: Wiring

ma: wiring (second wiring)

mb: Wiring

ia, ja, ka: Wiring

Ra: resistance

P1, P2, P3: connection points

Lu: U phase coil

Lv: V-phase winding wire

Lw:W phase winding wire

u, v, w: Wiring

Vd: Voltage

Claims (7)

A power conversion device is characterized in that it is provided with: a power conversion circuit having a switching lead for connecting a switching element of an upper arm and a switching element of a lower arm; each of the aforementioned switching elements is provided with a parasitic diode, or a flywheel diode system is connected in anti-parallel at each of the aforementioned switching elements; connected, and apply a reverse voltage to the aforementioned parasitic diode or the aforementioned flywheel diode of the aforementioned switching element; and the driving circuit for reverse voltage is connected one-to-one with the aforementioned reverse voltage applying circuit, and is also connected to the aforementioned switching element driving circuit, and uses the aforementioned driving signal input from the aforementioned switching element driving circuit to itself to generate a reverse voltage applying signal to the aforementioned reverse voltage applying circuit; Parallel connections formed by electronic components and diodes connected in parallel, and capacitors connected in series with the aforementioned parallel connections, The positive side of the capacitor is connected to the anode of the diode, and the negative side of the capacitor is connected to the power supply terminal of the reverse voltage drive circuit. The power conversion device described in claim 1, wherein the switching element corresponding one-to-one to the reverse voltage applying circuit and the switching element driving circuit are connected via a first wiring, the driving circuit for reverse voltage corresponding to the reverse voltage applying circuit one-to-one and the first wiring are connected via a second wiring, and the driving circuit for reverse voltage uses the above-mentioned input from the switching element driving circuit sequentially via the first wiring and the second wiring to itself. driving signal to generate the aforementioned reverse voltage application signal. The power conversion device as described in claim 1 of the scope of the patent application further includes: a turn-on delay circuit that sets a specific delay time from when the drive signal output by the switching element drive circuit is set until the output of the reverse voltage application signal is started at the drive circuit for reverse voltage, and the conduction delay circuit is provided to drive the switch element. The circuit and the aforementioned reverse voltage are used as the wiring for connection with the drive circuit. In the power conversion device described in claim 1, the reverse voltage application signal is turned on during a specific dead time when both the switching element of the upper arm and the switching element of the lower arm are turned off. The power conversion device as described in any one of items 1 to 4 of the scope of application, wherein the aforementioned power conversion circuit is equipped with a plurality of the aforementioned switching leads connected in parallel, and is an inverter circuit that converts DC voltage into AC voltage. The power conversion device as described in any one of items 1 to 4 of the scope of application, wherein the aforementioned power conversion circuit is equipped with a plurality of the aforementioned switching leads connected in parallel, and is a conversion circuit that converts AC voltage into DC voltage. An air conditioner, characterized in that it includes: a refrigerant circuit that circulates the refrigerant through a compressor, a condenser, an expansion valve, and an evaporator in sequence; and performs specific power conversion, and converts the power converted circuit to the previous The motor of the compressor is used as an output power conversion device. The power conversion device is equipped with: a power conversion circuit with switching leads that connect the switching elements of the upper arm and the switching elements of the lower arm. connected one-to-one with the aforementioned switching element, and apply a reverse voltage to the aforementioned parasitic diode or the aforementioned flywheel diode of the aforementioned switching element; and a driving circuit for reverse voltage, which is connected one-to-one to the aforementioned reverse voltage applying circuit, and is also connected to the aforementioned switching element driving circuit, and uses the aforementioned driving signal input from the aforementioned switching element driving circuit to itself to generate a reverse voltage applying signal to the aforementioned reverse voltage applying circuit; The setting circuit is equipped with a parallel connection formed by connecting the electronic components and the diode in parallel, and a capacitor connected in series with the parallel connection, and the positive side of the capacitor is connected to the anode of the diode Then, the negative side of the aforementioned capacitor is connected to the power supply terminal of the aforementioned reverse voltage driving circuit.