JP5754609B2 - Power converter and its control device - Google Patents

Description

  The present invention relates to a power converter including a semiconductor switching element such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) having a parasitic diode, and a control device thereof.

In recent years, MOSFETs are widely used as semiconductor switching elements for power converters from the viewpoints of high-frequency driving, miniaturization, and high efficiency due to a short switching time and a decrease in on-resistance.
Here, since the parasitic diode of the MOSFET has a long reverse recovery time and a small reverse recovery tolerance, if the MOSFET is used in an inverter as it is, there is a risk that the reflux current will flow through the parasitic diode and destroy the MOSFET during reverse recovery. is there. For this reason, when a MOSFET is applied to an inverter, a freewheeling diode having a fast response speed is connected in reverse parallel to the MOSFET without using a parasitic diode of the MOSFET to secure a freewheeling current path.

9 and 10 are main circuit configuration diagrams of a conventional inverter using a MOSFET, and both are described in Patent Document 1.
First, the inverter of FIG. 9 is configured by connecting a full bridge circuit including four MOSFETs 110, 120, 130, and 140 to both ends of the DC power supply 101. MOSFETs 110, 120, 130, and 140 have parasitic diodes 111, 121, 131, and 141 and stray capacitances 112, 122, 132, and 142, respectively, and one semiconductor is formed by one MOSFET, the parasitic diode, and the stray capacitance. A switching element is configured.

Block diodes 113, 123, 133, and 143 are connected in series to the MOSFETs 110, 120, 130, and 140, respectively. The series connection circuit of these MOSFETs and block diodes includes freewheeling diodes 114, 124, 134, 144 are connected in antiparallel.
An inductive load 102 is connected between a connection point between the MOSFET 110 and the block diode 123 and a connection point between the MOSFET 130 and the block diode 143.

In the circuit of FIG. 9, the DC power of the DC power supply 101 can be converted into single-phase AC power and supplied to the inductive load 102 by appropriately turning on and off the MOSFETs 110, 120, 130, and 140.
For example, when the MOSFET 140 is turned on and the MOSFET 130 is turned off and the MOSFET 110 is turned on and the MOSFET 120 is turned off, the path of the DC power supply 101 → block diode 113 → MOSFET 110 → inductive load 102 → block diode 143 → MOSFET 140 → DC power supply 101 Current flows. Next, when the on / off states of the MOSFETs 110 and 120 are reversed, the return current flows through the path of the inductive load 102 → the block diode 143 → the MOSFET 140 → the return diode 124 → the inductive load 102.

The block diode 123 is for preventing the return current at this time from flowing into the parasitic diode 121. If the block diode 123 is not provided, the parasitic diode 121 has a small withstand capability at the time of reverse recovery. Will be. For this reason, the circuit is configured such that the return current from the inductive load 102 is blocked by the block diode 123 and does not flow to the parasitic diode 121 but flows to the return diode 124 having a fast response speed.
The operation of the other block diodes 113, 133, 143 and freewheeling diodes 114, 134, 144 is also the same as that of the block diode 123 and freewheeling diode 124 described above.

As described above, when the MOSFET 110 is turned on and the MOSFET 120 is turned off and the current flows through the path of the DC power supply 101 → the block diode 113 → the MOSFET 110 → the inductive load 102 → the block diode 143 → the MOSFET 140 → the DC power supply 101, The stray capacitance 122 is charged up to the voltage of the DC power supply 101. When the MOSFET 110 is turned off next time, the freewheeling diode 124 becomes conductive. Therefore, during the period until the MOSFET 120 is turned on (the period in which both the MOSFETs 110 and 120 are off), the voltage across the stray capacitance 122 (DC) is applied to the block diode 123. The voltage of the power supply 101 is applied.
Therefore, it is necessary to use a high-breakdown-voltage element that can withstand the DC power supply voltage for the block diode 123, and this is the same for the other block diodes 113, 133, and 143.

Therefore, in the inverter of FIG. 10, in addition to the configuration of FIG. 9, Zener diodes (constant voltage diodes) 115, 125, 135, 145 are connected in parallel to the block diodes 113, 123, 133, 143, respectively.
By configuring as shown in FIG. 10, for example, it is possible to prevent the voltage across the stray capacitance 122 from being applied to the block diode 123 when the free-wheeling diode 124 is conducting. Therefore, low breakdown voltage and low loss elements can be used for the block diodes 113, 123, 133, and 143.

  Note that, as shown in FIG. 9, a circuit in which a freewheeling diode is connected in antiparallel to a series connection circuit of a MOSFET and a block diode is also described in Patent Document 2. For this reason, also in the prior art described in Patent Document 2, it is required to increase the breakdown voltage of the block diode as in FIG.

Japanese Examined Patent Publication No. 6-34595 (column 2, line 4 to column 4, line 24, column 4, line 45 to column 6, line 9, FIGS. 1 and 2) Japanese Patent No. 3613332 (paragraphs [0014] to [0019], FIG. 1)

  The conventional inverters shown in FIG. 9 and FIG. 10 are useful because they can be operated without flowing the reflux current through the parasitic diode. However, according to these conventional techniques, there is a problem that the number of circuit components constituting the power converter increases, resulting in an increase in size and cost of the device.

Therefore, an object of the present invention is to provide a power converter that can be configured with a small number of parts. Another object of the present invention is to provide a power converter that enables cost reduction.
Furthermore, another object of the present invention is to provide an optimal control device for on / off control of the semiconductor switching element of the power converter.

The power converter of the present invention includes a full bridge circuit composed of four semiconductor switching elements having parasitic diodes, a diode bridge circuit composed of four freewheeling diodes, a direct current side of the full bridge circuit, and a direct current side of the diode bridge circuit. Positive and negative DC buses connected to each other, first and second block diodes provided on the positive and negative DC buses, respectively, and inductivity connected to the AC side of the full bridge circuit The inverter includes a load and a DC power source connected to the DC side of the diode bridge circuit. And while connecting the alternating current side of the full bridge circuit and the diode bridge circuit, connecting the first block diode in the reverse direction with respect to the parasitic diode of the semiconductor switching element connected to the positive direct current bus, and The second block diode is connected in the reverse direction to the parasitic diode of the semiconductor switching element connected to the negative DC bus.
Here, the semiconductor switching element is, for example, a MOSFET, and an element having a short reverse recovery time and a small stray capacitance, such as a SiC (Silicon Carbide) diode, is used as the free wheel diode.

Moreover, the power converter of this invention can also comprise a rectifier by connecting a DC load instead of the said DC power supply, and connecting a single phase AC power supply instead of the said inductive load.
Furthermore, a DC-DC converter can be configured by replacing the inductive load of the inverter and the single-phase AC power source of the rectifier with the primary winding and secondary winding of the transformer, respectively.

Note that the control device that controls the power converter performs on / off control of the semiconductor switching element by pulse width modulation control, for example.
The control device includes a comparator such as a comparator for comparing the voltage command value for the power converter and the carrier, an inverting unit for inverting the logic of the output signal of the comparing unit, an output signal of the comparing unit, and an output signal of the inverting unit. The first and second delay means such as an on-delay circuit for delaying the output signal are used, and the output signals of the first and second delay means are used as drive signals for the semiconductor switching elements of the power converter.

According to the present invention, it is not necessary to provide a block diode in each arm of the semiconductor switching element as shown in FIGS. 9 and 10, and it is sufficient to provide a block diode only on the positive and negative DC buses of the power converter. Further, as shown in FIG. 10, the power conversion operation can be performed while ensuring a return current path that does not pass through the parasitic diode of the semiconductor switching element without using a Zener diode.
For this reason, the number of parts constituting the circuit can be reduced as compared with the conventional case, and the configuration can be simplified, the device can be downsized, and the cost can be reduced.

It is a main circuit block diagram of the inverter which concerns on 1st Embodiment of this invention. It is a block diagram of the control apparatus which concerns on 1st Embodiment of this invention. It is a wave form diagram which shows the operation | movement of the inverter of FIG. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a wave form diagram which shows the operation | movement of the inverter of FIG. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the inverter which shows operation | movement of 1st Embodiment of this invention. It is a main circuit block diagram of the PWM rectifier which concerns on 2nd Embodiment of this invention. It is a main circuit block diagram of the DC-DC converter which concerns on 3rd Embodiment of this invention. It is a main circuit block diagram of the conventional inverter using MOSFET. It is a main circuit block diagram of the conventional inverter using MOSFET.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a main circuit configuration diagram showing a first embodiment of the present invention. As in FIGS. 9 and 10, the first embodiment relates to an inverter that converts DC power of a DC power source into single-phase AC power by turning on and off the MOSFET and supplies it to an inductive load such as a motor or a transformer. It is.

In FIG. 1, the anode of the first block diode 55 is connected to the positive electrode of the DC power source 1 via a positive DC bus 100P, and the second electrode is connected to the negative electrode of the DC power source 1 via a negative DC bus 100N. The cathode of the block diode 56 is connected. The cathode of the block diode 55 and the anode of the block diode 56 are connected to a pair of DC terminals of a full bridge circuit composed of four MOSFETs 10, 20, 30 and 40. An inductive load 2 is connected between the pair of AC terminals of the full bridge circuit.
The MOSFETs 10, 20, 30, and 40 have parasitic diodes 11, 21, 31, and 41 and stray capacitances 12, 22, 32, and 42, respectively. Here, the first block diode 55 is connected to the parasitic diodes 11 and 31 in the reverse direction, and the second block diode 56 is connected to the parasitic diodes 21 and 41 in the reverse direction.

Further, a series connection circuit of the freewheeling diodes 51 and 52 and a series connection circuit of the freewheeling diodes 53 and 54 are connected in parallel to the DC power supply 1. These free-wheeling diodes 51 to 54 constitute a diode bridge circuit, and a pair of DC terminals of the diode bridge circuit are connected to both ends of the DC power supply 1.
The series connection point of the reflux diodes 51 and 52 is connected to the series connection point of the MOSFETs 10 and 20, and the series connection point of the reflux diodes 53 and 54 is connected to the series connection point of the MOSFETs 30 and 40. That is, the pair of AC terminals of the diode bridge circuit is connected to the pair of AC terminals of the full bridge circuit composed of the MOSFETs 10, 20, 30, and 40.
As the free wheel diodes 51 to 54, it is desirable to use SiC (Silicon Carbide) diodes having a short reverse recovery time and a small stray capacitance.

  In the inverter configured as described above, the path of the return current by the inductive load 2 can be secured by the return diodes 51, 52, 53, and 54. In addition, by including a first block diode 55 connected in the reverse direction to the parasitic diodes 11 and 31, and a second block diode 56 connected in the reverse direction to the parasitic diodes 21 and 41, It is possible to prevent the return current from flowing through the parasitic diodes 11, 21, 31, 41, and to prevent the MOSFETs 10, 20, 30, 40 from being destroyed by the reverse recovery current of the parasitic diodes 11, 21, 31, 41. .

FIG. 2 is a configuration diagram of a control device that performs pulse width modulation (PWM) control on the inverter of FIG. 1.
In FIG. 2, 61 is a comparing means for comparing the voltage command value V ^* for the inverter with the triangular wave carrier CA. The output pulse of the comparison means 61 is directly input to the first on-delay circuit 63 as a delay means, and is also input to the second on-delay circuit 64 via the inversion circuit 62. These on-delay circuit 63 and 64, the input pulse time (dead time) _{t d} only delays is intended to be turned on, provided to prevent simultaneous ON, turned on simultaneously MOSFET30,40 of MOSFET10,20 ing. The output pulse of the first on-delay circuit 63 is output as the gate signal of the MOSFETs 10 and 40, and the output pulse of the second on-delay circuit 64 is output as the gate signal of the MOSFETs 20 and 30, respectively.

Next, the operation of the inverter of FIG. 1 will be described in detail with reference to FIGS. 3, 4A to 4E, 5, and 6A to 6E.
3, the voltage command value ^{V *} and the carrier CA to the inverter, the gate signal of MOSFET10,20,30,40, the applied voltage _{V o} to the inductive load 2, the inductive load 2 of the load current (arrow in FIG. 1 the direction is a positive direction) shows the I _o, the load current I _o is flowing in the positive direction.
4A, 4B, 4C, 4D, and 4E correspond to the periods (1), (2), (3), (4), and (5) in FIG. 3, respectively. .

First, in FIG. 4A (period (1) in FIG. 3), the MOSFETs 10 and 40 are turned on, and the voltage E _dc of the DC power source 1 is applied to the inductive load 2 (V _o = E _dc ). As a result, the load current _Io increases. 4A to 4E, the MOSFET in the on state is surrounded by a circle, and the path of the load current _Io is indicated by a broken line.

Next, in FIG. 4B (period (2) in FIG. 3), the MOSFETs 10 and 40 are turned off. At this time, MOSFET20,30 also because of the off-period (2) is a dead time _{t d.} Therefore, the DC power supply voltage is not applied to the inductive load 2, the energy stored in the inductive load 2 is released via the freewheeling diode 53, the direct current power supply 1, and the freewheeling diode 52, and the load current _Io is gradually increased. It will decrease to. Here, since the block diode 56 is connected in the reverse direction with respect to the parasitic diode 21 and the block diode 55 is connected in the reverse direction with respect to the parasitic diode 31, the return current flows through the parasitic diodes 21 and 31. Absent. For this reason, reverse recovery current does not flow through the parasitic diodes 21 and 31, and there is no possibility that the MOSFETs 20 and 30 are destroyed.

In FIG. 4C (period (3) in FIG. 3), the MOSFETs 20 and 30 are turned on, the voltage (−E _dc ) of the DC power supply 1 is applied to the inductive load 2 (V _o = −E _dc ), and the load current I _o further decreases. However, since the block diode 55 is connected in series with the MOSFET 30 and the block diode 55 is connected in series with the MOSFET 20, the reflux current does not flow through these MOSFETs 20 and 30.

In FIG. 4D (period (4) in FIG. 3), the MOSFETs 20 and 30 are turned off. At this time, since the well off MOSFET10,40, this period (4) is a dead time _{t d.} At this time, as in FIG. 4B (period (2) in FIG. 3), the DC power supply voltage is not applied to the inductive load 2, and the energy accumulated in the inductive load 2 is the return diode 53, the DC power supply 1, It is discharged via the freewheeling diode 52, and the load current _Io further decreases. Further, due to the action of the block diodes 55 and 56, no reverse current flows through the parasitic diodes 21 and 31, so reverse recovery does not occur, and there is no possibility that the MOSFETs 20 and 30 are destroyed.

In FIG. 4E (period (5) in FIG. 3), the MOSFETs 10 and 40 are turned on, so that the voltage E _dc of the DC power supply 1 is applied to the inductive load 2 (V _o = E _dc ). As a result, the load current _Io increases.
Here, when the MOSFETs 10 and 40 are turned on, the free-wheeling diodes 52 and 53 surrounded by circles in FIG. 4E are turned off, so that reverse recovery current flows through these free-wheeling diodes 52 and 53. However, the reverse recovery loss can be reduced by using SiC diodes as the free-wheeling diodes 51 to 54 by using a reverse recovery time and a small stray capacitance as compared with a silicon diode.

5, the voltage command value ^{V *} and the carrier CA to the inverter, the gate signal of MOSFET10,20,30,40, the applied voltage _{V o} to the inductive load 2, the inductive load 2 of the load current (arrow in FIG. 1 the direction is a positive direction) shows the I _o, the load current I _o is flowing in the negative direction.
6A, FIG. 6B, FIG. 6C, FIG. 6D, and FIG. 6E correspond to the periods (1), (2), (3), (4), and (5) in FIG. .

First, in FIG. 6A (period (1) in FIG. 5), the MOSFETs 20 and 30 are turned on, and the voltage (−E _dc ) of the DC power source 1 is applied to the inductive load 2 (V _o = −E _dc ). As a result, the load current _Io increases in the negative direction. In FIGS. 6A to 6E, the MOSFET in the on state is surrounded by a circle, and the path of the load current _Io is indicated by a broken line.

Next, in FIG. 6B (period (2) in FIG. 5), the MOSFETs 20 and 30 are turned off. At this time, MOSFET10,40 also because of the off-period (2) is a dead time _{t d.} Therefore, the DC power supply voltage is not applied to the inductive load 2, the energy stored in the inductive load 2 is released via the freewheeling diode 51, the direct current power supply 1, and the freewheeling diode 54, and the load current _Io is gradually increased. It will decrease to. Here, since the block diode 56 is connected in the reverse direction with respect to the parasitic diode 11 and the block diode 55 is connected in the reverse direction with respect to the parasitic diode 41, the return current flows through the parasitic diodes 11 and 41. Absent. For this reason, reverse recovery current does not flow through the parasitic diodes 11 and 41, and there is no possibility that the MOSFETs 10 and 40 are destroyed.

In FIG. 6C (period (3) in FIG. 5), the MOSFETs 10 and 40 are turned on, the voltage E _dc of the DC power source 1 is applied to the inductive load 2 (V _o = E _dc ), and the load current I _o further decreases. I will do it. However, since the block diode 55 is connected in series to the MOSFET 10 and the block diode 55 is connected in series to the MOSFET 40, the reflux current does not flow through these MOSFETs 10 and 40.

In FIG. 6D (period (4) in FIG. 5), the MOSFETs 10 and 40 are turned off. At this time, since the well off MOSFET20,30, this period (4) is a dead time _{t d.} At this time, as in FIG. 6B (period (2) in FIG. 5), the DC power supply voltage is not applied to the inductive load 2, and the energy accumulated in the inductive load 2 is the return diode 51, the DC power supply 1, It is discharged via the freewheeling diode 54, and the load current _Io further decreases. Further, due to the action of the block diodes 55 and 56, no reverse current flows through the parasitic diodes 11 and 41, so that reverse recovery does not occur, and there is no possibility that the MOSFETs 10 and 40 are destroyed.

In FIG. 6E (period (5) in FIG. 5), since the MOSFETs 20 and 30 are turned on, the voltage (−E _dc ) of the DC power supply 1 is applied to the inductive load 2 (V _o = −E _dc ). . As a result, the load current _Io increases in the negative direction.
Here, when the MOSFETs 20 and 30 are turned on, the freewheeling diodes 51 and 54 surrounded by circles in FIG. 6E are turned off, and thus reverse freewheeling current flows through these freewheeling diodes 51 and 54. However, the reverse recovery loss can be reduced by using SiC diodes as the free-wheeling diodes 51 to 54 by using a reverse recovery time and a small stray capacitance as compared with a silicon diode.

  As described above, according to the present embodiment, the parasitic diodes 11, 21, 31, 41 can operate without flowing reverse recovery current, and the MOSFETs 10, 20, 30, 40 are prevented from being destroyed due to reverse recovery loss. be able to.

  Next, FIG. 7 is a main circuit configuration diagram showing a second embodiment of the present invention. In FIG. 7, the same circuit components as those in FIG. 1 are denoted by the same reference numerals as those in FIG. In FIG. 7, the MOSFETs 10, 20, 30, and 40 are shown by simplified switches. However, the MOSFETs 10, 20, 30, and 40 are the parasitic diodes 11, 21, 31, and 41, and the stray capacitances, as in the first example. 12, 22, 32, and 42, respectively.

  In the second embodiment, a DC load 80 is connected instead of the DC power source 1 in FIG. 1, and a single-phase AC power source 70 and AC reactors 111 and 112 are connected instead of the inductive load 2 in FIG. That is, the power converter of the second embodiment is a PWM rectifier that rectifies AC power of the single-phase AC power supply 70 and converts it into DC power by turning on and off the MOSFETs 10, 20, 30, and 40 of FIG. It is composed.

  In the second embodiment, the DC power supplied from the single-phase AC power supply 70 to the DC load 80 is adjusted by turning on / off the MOSFETs 10, 20, 30, and 40, and the input power factor is controlled to 1. Further, due to the action of the block diodes 55 and 56, the return current flowing through the single-phase AC power supply 70 does not flow to the parasitic diodes of the MOSFETs 10, 20, 30, and 40 as in the first embodiment. , 20, 30, 40 can be prevented.

FIG. 8 is a main circuit configuration diagram showing a third embodiment of the present invention. In FIG. 8, the same circuit components as those in FIGS. 1 and 7 are denoted by the same reference numerals as those in FIGS.
In the third embodiment, a DC-AC converter circuit (inverter) 200 configured almost in the same manner as in FIG. 1 and an AC-DC converter circuit (PWM rectifier) 300 configured in the same manner as in FIG. As a whole circuit, a DC-DC converter is configured by connecting via the.

  That is, a primary winding 91 of a transformer 90 is connected to the AC output side of the DC-AC conversion circuit 200, and a pair of AC terminals of a full bridge circuit composed of MOSFETs 10A, 20A, 30A, 40A is connected to the secondary winding 92. And a pair of AC terminals of a diode bridge circuit composed of reflux diodes 51A, 52A, 53A, 54A such as SiC diodes are connected. Also, block diodes 55A and 56A are respectively connected to the positive DC bus 100PA and the negative DC bus 100NA between the full bridge circuit and the diode bridge circuit with the polarities shown in the figure, and a pair of DC of the diode bridge circuit. A DC load 81 is connected between the terminals.

  In the third embodiment, the DC power of the DC power source 1 is converted into AC power by turning on and off the MOSFETs 10, 20, 30, and 40 of the DC-AC converter circuit 200, and the AC power input through the transformer 90 is converted. The DC power is converted into DC power by turning on and off the MOSFETs 10A, 20A, 30A, and 40A of the AC-DC conversion circuit 300 and supplied to the DC load 81. Also in the third embodiment, as described in the first and second embodiments, the return current does not flow to the parasitic diode of each MOSFET due to the action of the block diodes 55, 56, 55A, 56A. The destruction of the MOSFET can be prevented.

  In the third embodiment, the DC power supply 1 and the DC load 81 are replaced with, for example, a secondary battery, thereby converting power between the DC high voltage of one secondary battery and the DC low voltage of the other secondary battery. It is also possible to configure a bidirectional DC-DC converter that performs the above.

  INDUSTRIAL APPLICABILITY The present invention can be used for various power converters and control devices for converting DC power to AC power by converting a semiconductor switching element having a parasitic diode to AC power, or converting AC power to DC power. .

1: DC power supply 2: Inductive load 10, 10A, 20, 20A, 30, 30A, 40, 40A: MOSFET
11, 21, 31, 41: Parasitic diodes 12, 22, 32, 42: stray capacitances 51, 51A, 52, 52A, 53, 53A, 54, 54A: freewheeling diodes 55, 55A, 56, 56A: block diodes 61: Comparator 62: Inversion circuit 63, 64: On-delay circuit 70: Single-phase AC power supply 80, 81: DC load 90: Transformer 91: Primary winding 92: Secondary winding 100P, 100PA: Positive DC bus 100N, 100NA: Negative DC bus 111, 112: AC reactor 200: DC-AC converter circuit 300: AC-DC converter circuit

Claims (10)

A full bridge circuit consisting of four semiconductor switching elements having parasitic diodes;
A diode bridge circuit consisting of four freewheeling diodes;
A positive DC bus and a negative DC bus connecting the pair of DC terminals of the full bridge circuit and the pair of DC terminals of the diode bridge circuit, respectively.
A first block diode provided on the positive DC bus;
A second block diode provided on the negative DC bus;
An inductive load connected between a pair of AC terminals of the full bridge circuit;
A DC power source connected between a pair of DC terminals of the diode bridge circuit;
With
While connecting a pair of AC terminals of the full bridge circuit and a pair of AC terminals of the diode bridge circuit,
A first block diode is connected in a reverse direction with respect to the parasitic diode of the semiconductor switching element connected to the positive DC bus, and the parasitic diode of the semiconductor switching element connected to the negative DC bus is connected to the parasitic diode of the semiconductor switching element connected to the negative DC bus. A power converter characterized by connecting the second block diode in the opposite direction. A full bridge circuit consisting of four semiconductor switching elements having parasitic diodes;
A diode bridge circuit consisting of four freewheeling diodes;
A positive DC bus and a negative DC bus connecting the pair of DC terminals of the full bridge circuit and the pair of DC terminals of the diode bridge circuit, respectively.
A first block diode provided on the positive DC bus;
A second block diode provided on the negative DC bus;
A single-phase AC power source connected between a pair of AC terminals of the full bridge circuit;
A DC load connected between a pair of DC terminals of the diode bridge circuit;
With
While connecting a pair of AC terminals of the full bridge circuit and a pair of AC terminals of the diode bridge circuit,
A first block diode is connected in a reverse direction with respect to the parasitic diode of the semiconductor switching element connected to the positive DC bus, and the parasitic diode of the semiconductor switching element connected to the negative DC bus is connected to the parasitic diode of the semiconductor switching element connected to the negative DC bus. A power converter characterized by connecting the second block diode in the opposite direction.   A power having a transformer primary winding connected instead of the inductive load according to claim 1, and a secondary winding of the transformer connected instead of the single-phase AC power source according to claim 2 converter. In the power converter given in any 1 paragraph of Claims 1-3,
The power converter, wherein the semiconductor switching element is a MOSFET. In the power converter given in any 1 paragraph of Claims 1-3,
A power converter using a diode having a short reverse recovery time and a small stray capacitance as the freewheeling diode. The power converter according to claim 4, wherein
A power converter using a diode having a short reverse recovery time and a small stray capacitance as the freewheeling diode. The power converter according to claim 5, wherein
The power converter, wherein the reflux diode is a SiC diode. The power converter according to claim 6, wherein
The power converter, wherein the reflux diode is a SiC diode. In the control apparatus which carries out on-off control of the semiconductor switching element of the power converter given in any 1 paragraph of Claims 1-3,
A power converter control device comprising means for controlling the semiconductor switching element for pulse width modulation. The control device according to claim 9,
Comparison means for comparing the voltage command value for the power converter and the carrier,
First delay means for delaying the output signal of the comparison means;
Second delay means for delaying an inverted signal of the output signal of the comparison means;
With
The power converter control apparatus, wherein output signals of the first and second delay means are used as drive signals for the semiconductor switching element.

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