Power conversion device and motor module

Abstract

According to one embodiment, a power conversion device includes H-bridge circuits corresponding to respective phases of a motor, and an auxiliary circuit corresponding to at least one of the H-bridge circuits. The auxiliary circuit includes: a first rectifying element and a first inductor connected in series between a first connection point and a third connection point; a second rectifying element and a second inductor connected in series between the second connection point and the third connection point; a third rectifying element and a third inductor connected in series between the first connection point and the fourth connection point; a fourth rectifying element and a fourth inductor connected in series between the second connection point and the fourth connection point; the fifth switch is connected between the positive electrode of the power supply and the third connection point; a fifth rectifying element having a negative terminal connected to the third connection point and a positive terminal connected to a negative electrode of the power supply; a sixth rectifying element having a negative terminal connected to the positive electrode and a positive terminal connected to the fourth connection point; and a sixth switch connected between the negative electrode and the fourth connection point.

Description

Technical Field

[0001] The invention relates to a power conversion device and a motor module. Background Art

[0002] Patent document 1 discloses a driving control device for operating an induction motor having a three-phase stator winding and six lead terminals using two three-phase inverters. The driving control device controls the output voltage phases of the two inverters to be in phase when the induction motor is running at a low speed. In addition, when the induction motor is running at a high speed, the driving control device reverses the voltage phase of one inverter by 180 degrees and makes the output frequency of the two inverters 1 / 2 to reverse the phase rotation. Through this control, when switching from low-speed operation to high-speed operation, the number of poles of the induction motor is equivalently switched from 4 poles to 2 poles, so that the size of the induction motor will not be increased, and the torque shortage during high-speed operation can be eliminated. Prior art literature Patent Literature

[0003] Patent Document 1: Japanese Patent Application Publication No. 2002-136184 Summary of the invention Technical problem to be solved by the invention

[0004] In the technology disclosed in Patent Document 1, when each switch included in two inverters is switched, switching loss occurs, which causes a decrease in the driving efficiency of the induction motor. Technical means for solving technical problems

[0005] One embodiment of the power conversion device of the present invention includes: an H-bridge circuit corresponding to each phase of a motor having two N-phase terminal groups (N is an integer greater than or equal to 3); an auxiliary circuit corresponding to at least one of the H-bridge circuits; and a control unit that controls the H-bridge circuit and the auxiliary circuit, wherein the H-bridge circuit includes: a first branch including a first switch connected between a positive electrode of a power source and a first connection point and a second switch connected between a negative electrode of the power source and the first connection point; and a second branch including a third switch connected between the positive electrode and the second connection point and a fourth switch connected between the negative electrode and the second connection point, wherein the auxiliary circuit includes: a first rectifying element and a first inductor connected in series between the first connection point and the third connection point; and a second branch including a third switch connected between the positive electrode and the second connection point and a fourth switch connected between the negative electrode and the second connection point. A second rectifier element and a second inductor are connected in series between the first connection point and the fourth connection point; a third rectifier element and a third inductor are connected in series between the first connection point and the fourth connection point; a fourth rectifier element and a fourth inductor are connected in series between the second connection point and the fourth connection point; a fifth switch is connected between the positive electrode and the third connection point; a fifth rectifier element having a negative terminal connected to the third connection point and a positive terminal connected to the negative electrode; a sixth rectifier element having a negative terminal connected to the positive electrode and a positive terminal connected to the fourth connection point; and a sixth switch is connected between the negative electrode and the fourth connection point, the positive terminal of the first rectifier element and the positive terminal of the second rectifier element are located on one side of the third connection point, and the negative terminal of the third rectifier element and the negative terminal of the fourth rectifier element are located on one side of the fourth connection point.

[0006] One aspect of a motor module of the present invention includes a motor having two N-phase terminal groups (N is an integer equal to or greater than 3), and the power conversion device of the above aspect. Effects of the Invention

[0007] According to the above aspect of the present invention, it is possible to reduce the switching loss of each switch included in the H-bridge circuit corresponding to each motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a diagram schematically showing the structure of a power module 1 in this embodiment. Figure 2 1 is a diagram showing a circuit configuration of an H-bridge circuit BC corresponding to U and an auxiliary circuit SC corresponding to the H-bridge circuit BC. Figure 3 1 is a timing chart showing on-off timings of the first switch Tr1 , the second switch Tr2 , and the fifth switch Tr5 when current flows from the first connection point P1 to the motor 20 . Figure 4 Yes means Figure 3 The diagram shows the state of each switch and the direction of the current in the first period T1 within the PWM period TP. Figure 5 Yes means Figure 3 The diagram shows the state of each switch and the direction of the current in the second period T2 within the PWM period TP. Figure 6 Yes means Figure 3 The diagram shows the state of each switch and the direction of the current in the third period T3 within the PWM period TP. Figure 7 Yes means Figure 3 The diagram shows the state of each switch and the direction of the current in the fourth period T4 within the PWM period TP. Figure 8 Yes means Figure 3 The diagram shows the state of each switch and the direction of the current in the fifth period T5 within the PWM period TP. Fig. 9 1 is a timing chart showing on-off timings of the first switch Tr1 , the second switch Tr2 , and the sixth switch Tr6 when current flows from the first connection point P1 to the motor 20 . Fig.10 Yes means Fig. 9 The diagram shows the state of each switch and the direction of the current in the first period T11 within the PWM period TP. Fig.11 Yes means Fig. 9 The diagram shows the state of each switch and the direction of the current in the second period T12 within the PWM period TP. Fig.12 Yes means Fig. 9 The diagram shows the state of each switch and the direction of the current in the third period T13 within the PWM period TP. Fig.13 Yes means Fig. 9 The diagram shows the state of each switch and the direction of the current in the fourth period T14 within the PWM period TP. Fig.14 Yes means Fig. 9 The diagram shows the state of each switch and the direction of the current in the fifth period T15 within the PWM period TP. Fig.15 1 is a timing chart showing on-off timings of the first to fourth switches Tr1 to Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20 , respectively. Fig.16 Yes means Fig.15 The diagram shows the state of each switch and the direction of the current in the first period T21 within the PWM period TP. Fig.17 Yes means Fig.15 The diagram shows the state of each switch and the direction of the current in the second period T22 within the PWM period TP. Fig.18 Yes means Fig.15 The diagram shows the state of each switch and the direction of the current in the third period T23 within the PWM period TP. Fig.19 Yes means Fig.15 The diagram shows the state of each switch and the direction of the current in the fourth period T24 within the PWM period TP. Fig. 20 Yes means Fig.15 The diagram shows the state of each switch and the direction of the current in the fifth period T25 within the PWM period TP. Fig.21 1 is a timing diagram showing on-off timings of the first to fourth switches Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20 respectively and the on-period of the first switch Tr1 is shorter than the on-period of the third switch Tr3 within the PWM period TP. Fig. 22 Yes means Fig.21 The diagram shows the state of each switch and the direction of the current in the first period T31 within the PWM period TP. Fig.23 Yes means Fig.21 The diagram shows the state of each switch and the direction of the current in the second period T32 within the PWM period TP. Fig.24 Yes means Fig.21 The diagram shows the state of each switch and the direction of the current in the third period T33 within the PWM period TP. Fig.25 Yes means Fig.21 The diagram shows the state of each switch and the direction of the current in the fourth period T34 within the PWM period TP. Fig.26 Yes means Fig.21 The diagram shows the state of each switch and the direction of the current in the fifth period T35 within the PWM period TP. Fig. 27 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively, and within the PWM period TP, the length of the on-period of the first switch Tr1 is different from the length of the on-period of the third switch Tr3, and the center of the on-period of the first switch Tr1 and the center of the on-period of the third switch Tr3 are staggered from each other by half a PWM period. Fig.28 1 is a timing chart showing on-off timings of the first to fourth switches Tr1 to Tr4 and the sixth switch Tr6 when current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively. Fig.29 Yes means Fig.28 The diagram shows the state of each switch and the direction of the current in the first period T51 within the PWM period TP. Fig.30 Yes means Fig.28 The diagram shows the state of each switch and the direction of the current in the second period T52 within the PWM period TP. Fig.31 Yes means Fig.28 The diagram shows the state of each switch and the direction of the current in the third period T53 within the PWM period TP. Fig.32 Yes means Fig.28 The diagram shows the state of each switch and the direction of the current in the fourth period T54 within the PWM period TP. Fig.33 Yes means Fig.28 The diagram shows the state of each switch and the direction of the current in the fifth period T55 within the PWM period TP. Fig.34 1 is a timing diagram showing the on-off timings of the first to fourth switches Tr1 to Tr4 and the sixth switch Tr6 when current flows from the motor 20 to the first connection point P1 and the second connection point P2 respectively and the on-period of the second switch Tr2 is shorter than the on-period of the fourth switch Tr4 within the PWM period TP. Fig.35 Yes means Fig.34 The diagram shows the state of each switch and the direction of the current in the first period T61 within the PWM period TP. Fig.36 Yes means Fig.34 The diagram shows the state of each switch and the direction of the current in the second period T62 within the PWM period TP. Fig.37 Yes means Fig.34 The diagram shows the state of each switch and the direction of the current in the third period T63 within the PWM period TP. Fig.38 Yes means Fig.34 The diagram shows the state of each switch and the direction of the current in the fourth period T64 within the PWM period TP. Fig.39 Yes means Fig.34 The diagram shows the state of each switch and the direction of the current in the fifth period T65 within the PWM period TP. Fig.40 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the sixth switch Tr6 when the current flows from the motor 20 to the first connection point P1 and the second connection point P2 respectively, and within the PWM period TP, the length of the on-period of the second switch Tr2 is different from the length of the on-period of the fourth switch Tr4, and the center of the on-period of the second switch Tr2 and the center of the on-period of the fourth switch Tr4 are staggered from each other by half a PWM period. Fig.41 1 is a timing chart showing on-off timings of the first to sixth switches Tr1 to Tr6 when current flows from the first connection point P1 to the motor 20 and current flows from the motor 20 to the second connection point P2. Fig.42 Yes means Fig.41 The diagram shows the state of each switch and the direction of the current in the first period T81 within the PWM period TP. Fig.43 Yes means Fig.41 The diagram shows the state of each switch and the direction of the current in the second period T82 within the PWM period TP. Fig.44 Yes means Fig.41 The diagram shows the state of each switch and the direction of the current in the third period T83 within the PWM period TP. Fig.45 Yes means Fig.41 The diagram shows the state of each switch and the direction of the current in the fourth period T84 within the PWM period TP. Fig.46 Yes means Fig.41 The diagram shows the state of each switch and the direction of the current in the fifth period T85 within the PWM period TP. Fig.47 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the fifth switch Tr5 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, and the on-period of the first switch Tr1 is longer than the on-period of the fourth switch Tr4 within the PWM period TP. Fig.48 Yes means Fig.47 The diagram shows the state of each switch and the direction of the current in the first period T91 within the PWM period TP. Fig.49 Yes means Fig.47 The diagram shows the state of each switch and the direction of the current in the second period T92 within the PWM period TP. Fig.50 Yes means Fig.47The diagram shows the state of each switch and the direction of the current in the third period T93 within the PWM period TP. Fig.51 Yes means Fig.47 The diagram shows the state of each switch and the direction of the current in the fourth period T94 within the PWM period TP. Fig.52 Yes means Fig.47 The diagram shows the state of each switch and the direction of the current in the fifth period T95 within the PWM period TP. Fig.53 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, and the on-period of the first switch Tr1 is shorter than the on-period of the fourth switch Tr4 within the PWM period TP. Fig.54 It is a timing diagram showing the on-off timing of the first switch Tr1 to the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, and the length of the on-period of the first switch Tr1 and the length of the on-period of the fourth switch Tr4 are different within the PWM period TP, and the center of the on-period of the first switch Tr1 and the center of the on-period of the fourth switch Tr4 are staggered from each other by half a PWM period. Fig.55 It is a diagram showing a modification of the H-bridge circuit BC and the auxiliary circuit SC. DETAILED DESCRIPTION

[0009] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 Schematically shows the structure of the power module 1 in this embodiment. Figure 1 As shown, the motor module 1 includes a power conversion device 10 and a motor 20. The motor 20 has two N-phase terminal groups (N is an integer greater than 3). In this embodiment, as an example, N is 3. That is, the motor 20 is a three-phase motor having two three-phase terminal groups.

[0010] As one three-phase terminal group, the motor 20 has a first U-phase terminal 21u, a first V-phase terminal 21v, and a first W-phase terminal 21w. As another three-phase terminal group, the motor 20 has a second U-phase terminal 22u, a second V-phase terminal 22v, and a second W-phase terminal 22w. The motor 20 also has a first U-phase coil 23u, a first V-phase coil 23v, a first W-phase coil 23w, a second U-phase coil 24u, a second V-phase coil 24v, and a second W-phase coil 24w.

[0011] exist Figure 1 Although not shown in the figure, the motor 20 has a motor housing, a rotor and a stator housed in the motor housing. The rotor is a rotating body rotatably supported by a bearing member such as a rotor bearing inside the motor housing. The rotor has an output shaft, which is coaxially engaged with the rotor while passing through the radial inner side of the rotor in the axial direction. The stator is arranged inside the motor housing while surrounding the outer peripheral surface of the rotor, and generates the electromagnetic force required to rotate the rotor.

[0012] The first U-phase coil 23u, the first V-phase coil 23v, and the first W-phase coil 23w are respectively provided with excitation coils on the stator. One end of the first U-phase coil 23u is electrically connected to the first U-phase terminal 21u. One end of the first V-phase coil 23v is electrically connected to the first V-phase terminal 21v. One end of the first W-phase coil 23w is electrically connected to the first W-phase terminal 21w. The other end of the first U-phase coil 23u, the other end of the first V-phase coil 23v, and the other end of the first W-phase coil 23w are electrically connected to each other.

[0013] The second U-phase coil 24u, the second V-phase coil 24v, and the second W-phase coil 24w are respectively provided as excitation coils on the stator. One end of the second U-phase coil 24u is electrically connected to the second U-phase terminal 22u. One end of the second V-phase coil 24v is electrically connected to the second V-phase terminal 22v. One end of the second W-phase coil 24w is electrically connected to the second W-phase terminal 22w. The other end of the second U-phase coil 24u, the other end of the second V-phase coil 24v, and the other end of the second W-phase coil 24w are electrically connected to each other.

[0014] The power conversion device 10 controls the energization state of each coil included in the electric motor 20, thereby generating an electromagnetic force required to rotate the rotor. As the rotor rotates, the output shaft also rotates synchronously with the rotor.

[0015] The power conversion device 10 includes a first three-phase full-bridge circuit 11, a second three-phase full-bridge circuit 12, and a control unit 13. The first three-phase full-bridge circuit 11 is electrically connected to one three-phase terminal group of the motor 20. The second three-phase full-bridge circuit 12 is electrically connected to another three-phase terminal group of the motor 20. The first three-phase full-bridge circuit 11 and the second three-phase full-bridge circuit 12 are electrically connected to a DC power supply 30, respectively.

[0016] The first three-phase full-bridge circuit 11 and the second three-phase full-bridge circuit 12 coordinate operations according to the gate signals output from the control unit 13, thereby performing mutual conversion between DC power and three-phase AC power between the DC power supply 30 and the motor 20. For example, when the first three-phase full-bridge circuit 11 and the second three-phase full-bridge circuit 12 operate as a dual inverter, the power conversion device 10 converts the DC power provided by the DC power supply 30 into three-phase AC power and outputs it to the motor 20.

[0017] The first three-phase full-bridge circuit 11 has six switches, namely, three high-side switches and three low-side switches. The first three-phase full-bridge circuit 11 has a first U-phase high-side switch UH1, a first V-phase high-side switch VH1, a first W-phase high-side switch WH1, a first U-phase low-side switch UL1, a first V-phase low-side switch VL1, and a first W-phase low-side switch WL1. In the present embodiment, each switch included in the first three-phase full-bridge circuit 11 is, for example, an n-channel MOS-FET (Metal-Oxide-Semiconductor Field-Effect Transistor).

[0018] For example, IGBT (Insulated Gate Bipolar Transistor), JFET (Junction Field Effect Transistor), etc. can be used as each switch. Diodes are connected to these switches in reverse parallel. As described above, in the case of using MOS-FET as a switch, the body diode of the MOS-FET can also be used instead of the diode.

[0019] The drain terminal of the first U-phase high-side switch UH1, the drain terminal of the first V-phase high-side switch VH1, and the drain terminal of the first W-phase high-side switch WH1 are respectively electrically connected to the positive electrode of the DC power supply 30. The source terminal of the first U-phase low-side switch UL1, the source terminal of the first V-phase low-side switch VL1, and the source terminal of the first W-phase low-side switch WL1 are respectively electrically connected to the negative electrode of the DC power supply 30.

[0020] The source terminal of the first U-phase high-side switch UH1 is electrically connected to the first U-phase terminal 21u and the drain terminal of the first U-phase low-side switch UL1 , respectively.

[0021] The source terminal of the first V-phase high-side switch VH1 is electrically connected to the first V-phase terminal 21v and the drain terminal of the first V-phase low-side switch VL1 , respectively. That is, the source terminal of the first V-phase high-side switch VH1 is electrically connected to one end of the first V-phase coil 23v via the first V-phase terminal 21v.

[0022] The source terminal of the first W-phase high-side switch WH1 is electrically connected to the first W-phase terminal 21w and the drain terminal of the first W-phase low-side switch WL1 . That is, the source terminal of the first W-phase high-side switch WH1 is electrically connected to one end of the first W-phase coil 23w via the first W-phase terminal 21w.

[0023] Although in Figure 1Although not shown in the figure, the gate terminal of the first U-phase high-side switch UH1, the gate terminal of the first V-phase high-side switch VH1, and the gate terminal of the first W-phase high-side switch WH1 are electrically connected to the control unit 13. Similarly, the gate terminal of the first U-phase low-side switch UL1, the gate terminal of the first V-phase low-side switch VL1, and the gate terminal of the first W-phase low-side switch WL1 are electrically connected to the control unit 13.

[0024] The second three-phase full-bridge circuit 12 has six switches, namely, three high-side switches and three low-side switches. The second three-phase full-bridge circuit 12 has a second U-phase high-side switch UH2, a second V-phase high-side switch VH2, a second W-phase high-side switch WH2, a second U-phase low-side switch UL2, a second V-phase low-side switch VL2, and a second W-phase low-side switch WL2. In the present embodiment, each switch included in the second three-phase full-bridge circuit 12 is, for example, an n-channel MOS-FET.

[0025] The drain terminal of the second U-phase high-side switch UH2, the drain terminal of the second V-phase high-side switch VH2, and the drain terminal of the second W-phase high-side switch WH2 are respectively electrically connected to the positive electrode of the DC power supply 30. The source terminal of the second U-phase low-side switch UL2, the source terminal of the second V-phase low-side switch VL2, and the source terminal of the second W-phase low-side switch WL2 are respectively electrically connected to the negative electrode of the DC power supply 30.

[0026] The source terminal of the second U-phase high-side switch UH2 is electrically connected to the second U-phase terminal 22u and the drain terminal of the second U-phase low-side switch UL2, respectively. That is, the source terminal of the second U-phase high-side switch UH2 is electrically connected to the other end of the second U-phase coil 24u via the second U-phase terminal 22u.

[0027] The source terminal of the second V-phase high-side switch VH2 is electrically connected to the second V-phase terminal 22v and the drain terminal of the second V-phase low-side switch VL2, respectively. That is, the source terminal of the second V-phase high-side switch VH2 is electrically connected to the other end of the second V-phase coil 24v via the second V-phase terminal 22v.

[0028] The source terminal of the second W-phase high-side switch WH2 is electrically connected to the second W-phase terminal 22w and the drain terminal of the second W-phase low-side switch WL2, respectively. That is, the source terminal of the second W-phase high-side switch WH2 is electrically connected to the other end of the second W-phase coil 24w via the second W-phase terminal 22w.

[0029] Although in Figure 1Although not shown in the figure, the gate terminal of the second U-phase high-side switch UH2, the gate terminal of the second V-phase high-side switch VH2, and the gate terminal of the second W-phase high-side switch WH2 are respectively electrically connected to the control unit 13. Similarly, the gate terminal of the second U-phase low-side switch UL2, the gate terminal of the second V-phase low-side switch VL2, and the gate terminal of the second W-phase low-side switch WL2 are respectively electrically connected to the control unit 13.

[0030] The control unit 13 controls each switch included in the first three-phase full-bridge circuit 11 and the second three-phase full-bridge circuit 12. As an example, the control unit 13 is an MCU (Microcontroller Unit). The control unit 13 generates a gate signal required to control each switch by pulse width modulation, and outputs the gate signal to the gate terminal of each switch.

[0031] As can be understood from the above description, the power conversion device 10 includes H-bridge circuits corresponding to the respective motors 20. Figure 1 Although not shown in the figure, the power conversion device 10 further includes an auxiliary circuit corresponding to at least one of the H-bridge circuits. Hereinafter, the circuit configuration of the H-bridge circuit and the auxiliary circuit will be described using an H-bridge circuit corresponding to U and an auxiliary circuit corresponding to the H-bridge circuit as a representative example.

[0032] Figure 2 1 is a diagram showing the circuit structure of an H-bridge circuit BC corresponding to U and an auxiliary circuit SC corresponding to the H-bridge circuit BC. Figure 2 As shown, the H-bridge circuit BC includes a first branch U1 and a second branch U2. The first branch U1 includes a first switch Tr1 corresponding to the first U-phase high-side switch UH1 and a second switch Tr2 corresponding to the first U-phase low-side switch UL1. The second branch U2 includes a third switch Tr3 corresponding to the second U-phase high-side switch UH2 and a fourth switch Tr4 corresponding to the second U-phase low-side switch UL2.

[0033] The first switch Tr1 is electrically connected between the positive electrode of the DC power supply 30 and the first connection point P1. Specifically, the drain terminal of the first switch Tr1 is electrically connected to the positive electrode of the DC power supply 30, and the source terminal of the first switch Tr1 is electrically connected to the first connection point P1. The first connection point P1 is a node electrically connected to the first U-phase terminal 21u of the motor 20.

[0034] The second switch Tr2 is electrically connected between the negative electrode of the DC power source 30 and the first connection point P1. Specifically, the source terminal of the second switch Tr2 is electrically connected to the negative electrode of the DC power source 30, and the drain terminal of the second switch Tr2 is electrically connected to the first connection point P1.

[0035] The third switch Tr3 is electrically connected between the positive electrode of the DC power supply 30 and the second connection point P2. Specifically, the drain terminal of the third switch Tr3 is electrically connected to the positive electrode of the DC power supply 30, and the source terminal of the third switch Tr3 is electrically connected to the second connection point P2. The second connection point P2 is a node electrically connected to the second U-phase terminal 22u of the motor 20.

[0036] The fourth switch Tr4 is electrically connected between the negative electrode of the DC power source 30 and the second connection point P2. Specifically, the source terminal of the fourth switch Tr4 is electrically connected to the negative electrode of the DC power source 30, and the drain terminal of the fourth switch Tr4 is electrically connected to the second connection point P2.

[0037] The auxiliary circuit SC includes a first rectifying element D1, a second rectifying element D2, a third rectifying element D3, a fourth rectifying element D4, a fifth rectifying element D5, a sixth rectifying element D6, a first inductor L1, a second inductor L2, a third inductor L3, a fourth inductor L4, a fifth switch Tr5, and a sixth switch Tr6. For example, the first rectifying element D1 to the sixth rectifying element D6 are diodes, respectively. In addition, for example, the fifth switch Tr5 and the sixth switch Tr6 are n-channel MOS-FETs, respectively.

[0038] The first rectifying element D1 and the first inductor L1 are connected in series between the first connection point P1 and the third connection point P3. Specifically, the anode terminal of the first rectifying element D1 is electrically connected to the third connection point P3, and the cathode terminal of the first rectifying element D1 is electrically connected to one end of the first inductor L1. The other end of the first inductor L1 is electrically connected to the first connection point P1. The anode terminal is equivalent to the positive terminal, and the cathode terminal is equivalent to the negative terminal.

[0039] The second rectifying element D2 and the second inductor L2 are connected in series between the second connection point P2 and the third connection point P3. Specifically, the anode terminal of the second rectifying element D2 is electrically connected to the third connection point P3, and the cathode terminal of the second rectifying element D2 is electrically connected to one end of the second inductor L2. The other end of the second inductor L2 is electrically connected to the second connection point P2.

[0040] The third rectifying element D3 and the third inductor L3 are connected in series between the first connection point P1 and the fourth connection point P4. Specifically, the cathode terminal of the third rectifying element D3 is electrically connected to the fourth connection point P4, and the anode terminal of the third rectifying element D3 is electrically connected to one end of the third inductor L3. The other end of the third inductor L3 is electrically connected to the first connection point P1.

[0041] The fourth rectifying element D4 and the fourth inductor L4 are connected in series between the second connection point P2 and the fourth connection point P4. Specifically, the cathode terminal of the fourth rectifying element D4 is electrically connected to the fourth connection point P4, and the anode terminal of the fourth rectifying element D4 is electrically connected to one end of the fourth inductor L4. The other end of the fourth inductor L4 is electrically connected to the second connection point P2.

[0042] The fifth rectifying element D5 has a cathode terminal electrically connected to the third connection point P3 and an anode terminal electrically connected to the negative electrode of the DC power supply 30. The sixth rectifying element D6 has a cathode terminal electrically connected to the positive electrode of the DC power supply 30 and an anode terminal electrically connected to the fourth connection point P4.

[0043] The fifth switch Tr5 is electrically connected between the positive electrode of the DC power source 30 and the third connection point P3. Specifically, the drain terminal of the fifth switch Tr5 is electrically connected to the positive electrode of the DC power source 30, and the source terminal of the fifth switch Tr5 is electrically connected to the third connection point P3.

[0044] The sixth switch Tr6 is electrically connected between the negative electrode of the DC power source 30 and the fourth connection point P4. Specifically, the source terminal of the sixth switch Tr6 is electrically connected to the negative electrode of the DC power source 30, and the drain terminal of the sixth switch Tr6 is electrically connected to the fourth connection point P4.

[0045] The control section 13 controls the H-bridge circuit BC and the auxiliary circuit SC. The control section 13 controls the first switch Tr1 to the fourth switch Tr4 included in the H-bridge circuit BC and the fifth switch Tr5 and the sixth switch Tr6 included in the auxiliary circuit SC.

[0046] As described above, in the auxiliary circuit SC, the anode terminal of the first rectifier element D1 and the anode terminal of the second rectifier element D2 are located on one side of the third connection point P3. If the condition that the anode terminal of the first rectifier element D1 is located on one side of the third connection point P3 is satisfied, the position of the first rectifier element D1 and the position of the first inductor L1 may be swapped. Similarly, if the condition that the anode terminal of the second rectifier element D2 is located on one side of the third connection point P3 is satisfied, the position of the second rectifier element D2 and the position of the second inductor L2 may be swapped.

[0047] In the auxiliary circuit SC, the cathode terminal of the third rectifier element D3 and the cathode terminal of the fourth rectifier element D4 are located on one side of the fourth connection point P4. If the condition that the cathode terminal of the third rectifier element D3 is located on one side of the fourth connection point P4 is satisfied, the position of the third rectifier element D3 and the position of the third inductor L3 may be swapped. Similarly, if the condition that the cathode terminal of the fourth rectifier element D4 is located on one side of the fourth connection point P4 is satisfied, the position of the fourth rectifier element D4 and the position of the fourth inductor L4 may be swapped.

[0048] The above is a description of the structure of the motor module 1. The operation of the control unit 13 provided in the power conversion device 10 will be described in detail below. In the following, for the sake of convenience, the operation of the control unit 13 will be described with reference to the H-bridge circuit BC corresponding to U among the H-bridge circuits corresponding to the motor 20 and the auxiliary circuit SC corresponding to the H-bridge circuit BC, but it should be noted that the same operation is also applicable to the V phase and the W phase.

[0049] The control unit 13 has: a first mode in which the first branch U1 and the second branch U2 output voltages having the same phase; and a second mode in which the first branch U1 and the second branch U2 output voltages having opposite phases. For example, the control unit 13 operates in the first mode when the motor 20 is running at a low speed, and operates in the second mode when the motor 20 is running at a high speed. Through this control, when switching from low-speed operation to high-speed operation, the number of poles of the motor 20 is equivalently switched from 4 poles to 2 poles, so that the size of the motor 20 will not be increased, and the torque shortage during high-speed operation can be eliminated.

[0050] As described above, the control of switching the number of poles according to the rotation speed of the motor 20 is disclosed in Patent Document 1, and therefore a detailed description is omitted in this embodiment. In this embodiment, the operation performed by the control unit 13 in each mode to achieve soft switching to reduce the switching loss of at least one of the first switch Tr1 to the fourth switch Tr4 included in the H-bridge circuit BC is described in detail. In the following description, the operation performed by the control unit 13 to achieve soft switching is sometimes referred to as "soft switching operation".

[0051] First, before describing each embodiment of the soft switching action, a basic soft switching action as a basic soft switching action is described. As the basic soft switching action, the control unit 13 performs at least one of a first action of turning on the fifth switch Tr5 for a first time before turning on at least one of the first switch Tr1 and the third switch Tr3 within one control cycle of pulse width modulation, and a second action of turning on the sixth switch Tr6 for a second time before turning on at least one of the second switch Tr2 and the fourth switch Tr4 within one control cycle of pulse width modulation. Hereinafter, one control cycle of pulse width modulation may be referred to as a "PWM (Pulse Width Modulation) cycle".

[0052] Figure 3 1 is a timing diagram showing the on-off timing of the first switch Tr1, the second switch Tr2 and the fifth switch Tr5 when the current flows from the first connection point P1 of the first branch U1 to the motor 20. Figure 3As shown, when the current flows from the first connection point P1 to the motor 20, the first action is to turn on the fifth switch Tr5 for a first time before turning on the first switch Tr1 within the PWM period TP. Figure 3 In the example, the state of the second branch U2 is set to unrestricted.

[0053] Figure 4 Yes means Figure 3 1 and 1 , which are diagrams showing the states of the switches and the direction of the current in the first period T1 within the PWM cycle TP. In the following, for ease of explanation, the current flowing to the upper side of each circuit diagram is sometimes referred to as "upward current", the current flowing to the lower side of each circuit diagram is sometimes referred to as "downward current", the current flowing to the right side of each circuit diagram is sometimes referred to as "rightward current", and the current flowing to the left side of each circuit diagram is sometimes referred to as "leftward current".

[0054] like Figure 4 As shown, in the first period T1, the first switch Tr1 is turned off, the second switch Tr2 is turned on, and the fifth switch Tr5 is turned off. In the first period T1, an upward current flows through the second switch Tr2, and the current flows from the first connection point P1 to the motor 20. In the first period T1, the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30.

[0055] Figure 5 Yes means Figure 3 The state of each switch and the direction of the current in the second period T2 within the PWM cycle TP shown in FIG. Figure 5 As shown, in the second period T2, the first switch Tr1 is turned off, the second switch Tr2 is turned on, and the fifth switch Tr5 is turned on. In the second period T2, when the fifth switch Tr5 is turned on, the potential of the third connection point P3 of the auxiliary circuit SC is substantially equal to the positive electrode potential of the DC power supply 30, so the rightward current flows through the first inductor L1. In the second period T2, when the rightward current flowing through the first inductor L1 is greater than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the second switch Tr2. The second period T2 corresponds to the first time when the fifth switch Tr5 is set to be turned on.

[0056] Figure 6 Yes means Figure 3 The state of each switch and the direction of the current in the third period T3 within the PWM cycle TP shown in FIG. Figure 6As shown, in the third period T3, the first switch Tr1 is turned off, the second switch Tr2 is turned on, and the fifth switch Tr5 is turned off. In the third period T3, when the fifth switch Tr5 is turned off, the downward current flowing to the second switch Tr2 is transferred from the fifth switch Tr5 to the fifth rectifying element D5, and the upward current flows through the fifth rectifying element D5. In the third period T3, the potential of the third connection point P3 is substantially equal to the negative electrode potential of the DC power supply 30.

[0057] Figure 7 Yes means Figure 3 The state of each switch and the direction of the current in the fourth period T4 within the PWM cycle TP shown in FIG. Figure 7 As shown, in the fourth period T4, the first switch Tr1 is turned off, the second switch Tr2 is turned off, and the fifth switch Tr5 is turned off. In the fourth period T4, when the second switch Tr2 is turned off, the current flowing through the fifth rectifying element D5 and the first inductor L1 is transferred from the second switch Tr2 to the first switch Tr1, and the upward current flows through the body diode of the first switch Tr1. In the fourth period T4, since the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30, the voltage across the first switch Tr1 is substantially zero. The voltage across the first switch Tr1 is the potential difference between the drain terminal and the source terminal. In the fourth period T4, since a reverse voltage is applied to the first inductor L1, the rightward current flowing through the first inductor L1 gradually decreases.

[0058] Figure 8 Yes means Figure 3 The state of each switch and the direction of the current in the fifth period T5 of the PWM cycle TP are shown in FIG. Figure 8 As shown, in the fifth period T5, the first switch Tr1 is turned on, the second switch Tr2 is turned off, and the fifth switch Tr5 is turned off. In the fifth period T5, as the current flowing through the first inductor L1 decreases, the upward current flowing through the first switch Tr1 also decreases. Then, when the current flowing through the first inductor L1 is less than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the first switch Tr1. When the current flowing through the first inductor L1 is zero, the current flowing downward through the first switch Tr1 is consistent with the current flowing from the first connection point P1 to the motor 20.

[0059] As described above, the control unit 13 performs the first operation of turning on the fifth switch Tr5 for the first time before turning on the first switch Tr1 within the PWM period TP when the current flows from the first connection point P1 to the motor 20. Thus, before the first switch Tr1 is turned on, the voltage across the first switch Tr1 is substantially zero. That is, the control unit 13 performs the first operation described above to achieve soft switching of the first switch Tr1, thereby reducing the switching loss of the first switch Tr1.

[0060] When the current flows from the second connection point P2 to the motor 20, the first action is to turn on the fifth switch Tr5 for a first time before turning on the third switch Tr3 within the PWM period TP. That is, when the current flows from the second connection point P2 to the motor 20, the control unit 13 performs the first action of turning on the fifth switch Tr5 for a first time before turning on the third switch Tr3 within the PWM period TP. As a result, before the third switch Tr3 is turned on, the voltage across the third switch Tr3 is substantially zero. That is, by performing the first action described above by the control unit 13, soft switching of the third switch Tr3 is achieved, and the switching loss of the third switch Tr3 can be reduced.

[0061] Fig. 9 1 is a timing chart showing the on-off timing of the first switch Tr1, the second switch Tr2 and the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20. Fig. 9 As shown, when the current flows from the motor 20 to the first connection point P1, the second action is to turn on the sixth switch Tr6 for a second time before turning on the second switch Tr2 within the PWM period TP. Fig. 9 In the example, the state of the second branch U2 is set to unrestricted.

[0062] Fig.10 Yes means Fig. 9 The state of each switch and the direction of the current in the first period T11 within the PWM cycle TP shown in FIG. Fig.10 As shown, in the first period T11, the first switch Tr1 is turned on, the second switch Tr2 is turned off, and the sixth switch Tr6 is turned off. In the first period T11, the current flows from the motor 20 to the first connection point P1, and the upward current flows through the first switch Tr1. In the first period T11, the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30.

[0063] Fig.11 Yes means Fig. 9 The state of each switch and the direction of the current in the second period T12 within the PWM cycle TP shown in FIG. Fig.11 As shown, in the second period T12, the first switch Tr1 is turned on, the second switch Tr2 is turned off, and the sixth switch Tr6 is turned on. In the second period T12, when the sixth switch Tr6 is turned on, the potential of the fourth connection point P4 of the auxiliary circuit SC is substantially equal to the negative electrode potential of the DC power supply 30, so the rightward current flows through the third inductor L3. In the second period T12, when the rightward current flowing through the third inductor L3 is greater than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the first switch Tr1. The second period T12 corresponds to the second time when the sixth switch Tr6 is set to be turned on.

[0064] Fig.12 Yes means Fig. 9 The state of each switch and the direction of the current in the third period T13 within the PWM cycle TP shown in FIG. Fig.12 As shown, in the third period T13, the first switch Tr1 is turned on, the second switch Tr2 is turned off, and the sixth switch Tr6 is turned off. In the third period T13, when the sixth switch Tr6 is turned off, the rightward current flowing to the third inductor L3 is diverted from the sixth switch Tr6 to the sixth rectifying element D6, and the upward current flows through the sixth rectifying element D6. In the third period T13, the potential of the fourth connection point P4 is substantially equal to the positive electrode potential of the DC power supply 30.

[0065] Fig.13 Yes means Fig. 9 The state of each switch and the direction of the current in the fourth period T14 within the PWM cycle TP shown in FIG. Fig.13 As shown, in the fourth period T14, the first switch Tr1 is turned off, the second switch Tr2 is turned off, and the sixth switch Tr6 is turned off. In the fourth period T14, when the first switch Tr1 is turned off, the current flowing through the third inductor L3 and the sixth rectifying element D6 is transferred from the first switch Tr1 to the second switch Tr2, and the upward current flows through the body diode of the second switch Tr2. In the fourth period T14, since the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30, the voltage across the second switch Tr2 is substantially zero. In the fourth period T14, since a reverse voltage is applied to the third inductor L3, the rightward current flowing through the third inductor L3 gradually decreases.

[0066] Fig.14 Yes means Fig. 9 The state of each switch and the direction of the current in the fifth period T15 of the PWM cycle TP are shown in FIG. Fig.14 As shown, in the fifth period T15, the first switch Tr1 is turned off, the second switch Tr2 is turned on, and the sixth switch Tr6 is turned off. In the fifth period T15, as the current flowing through the third inductor L3 decreases, the upward current flowing through the second switch Tr2 also decreases. Then, when the current flowing through the third inductor L3 is less than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the second switch Tr2. When the current flowing through the third inductor L3 is zero, the current flowing downward through the second switch Tr2 is consistent with the current flowing from the motor 20 to the first connection point P1.

[0067] As described above, the control unit 13 performs the second operation of turning on the sixth switch Tr6 for the second time before turning on the second switch Tr2 within the PWM period TP when the current flows from the motor 20 to the first connection point P1. Thus, before the second switch Tr2 is turned on, the voltage across the second switch Tr2 is substantially zero. That is, by performing the second operation described above by the control unit 13, soft switching of the second switch Tr2 is achieved, and the switching loss of the second switch Tr2 can be reduced.

[0068] When the current flows from the motor 20 to the second connection point P2, the second operation is to turn on the sixth switch Tr6 for the second time before turning on the fourth switch Tr4 within the PWM period TP. That is, the control unit 13 performs the second operation of turning on the sixth switch Tr6 for the second time before turning on the fourth switch Tr4 within the PWM period TP when the current flows from the motor 20 to the second connection point P2. Thus, before the fourth switch Tr4 is turned on, the voltage across the fourth switch Tr4 is substantially zero. That is, by performing the second operation described above by the control unit 13, soft switching of the fourth switch Tr4 is achieved, and the switching loss of the fourth switch Tr4 can be reduced.

[0069] Based on the above basic soft switching operation, various embodiments of the soft switching operation are described below.

[0070] [Example 1] Fig.15 1 is a timing chart showing on-off timings of the first to fourth switches Tr1 to Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20 , respectively. Fig.15 Also shown are changes in the currents of the first inductor L1 and the second inductor L2 , the currents of the first switch Tr1 and the third switch Tr3 , and the voltages across the first switch Tr1 and the third switch Tr3 .

[0071] exist Fig.15 In FIG. 1 , I_L1 represents the current of the first inductor L1, I_L2 represents the current of the second inductor L2, I_Tr1 represents the current of the first switch Tr1, I_Tr3 represents the current of the third switch Tr3, V_Tr1 represents the voltage across the first switch Tr1, and V_Tr3 represents the voltage across the third switch Tr3.

[0072] like Fig.15As shown, when current flows from the first connection point P1 and the second connection point P2 to the motor 20, the control unit 13 turns on both the first switch Tr1 and the third switch Tr3 at the first timing, and performs the first action before the first timing within the PWM period TP. In other words, when current flows from the first connection point P1 and the second connection point P2 to the motor 20, the control unit 13 performs the first action of turning on the fifth switch Tr5 for the first time before turning on the first switch Tr1 and the third switch Tr3 at the same time within the PWM period TP.

[0073] Fig.16 Yes means Fig.15 The state of each switch and the direction of the current in the first period T21 of the PWM cycle TP are shown in FIG. Fig.16 As shown, in the first period T21, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned on, and the fifth switch Tr5 is turned off. In the first period T21, an upward current flows through the second switch Tr2 and the fourth switch Tr4, and the current flows from the first connection point P1 and the second connection point P2 to the motor 20. In the first period T21, the potentials of the first connection point P1 and the second connection point P2 are respectively substantially equal to the potential of the negative electrode of the DC power supply 30.

[0074] Fig.17 Yes means Fig.15 The state of each switch and the direction of the current in the second period T22 of the PWM cycle TP are shown in FIG. Fig.17 As shown, in the second period T22, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned on, and the fifth switch Tr5 is turned on. In the second period T22, when the fifth switch Tr5 becomes turned on, the potential of the third connection point P3 is substantially equal to the positive electrode potential of the DC power supply 30, so the rightward current flows through the first inductor L1 and the second inductor L2. In the second period T22, when the rightward current flowing through the first inductor L1 is greater than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the second switch Tr2. In addition, in the second period T22, when the rightward current flowing through the second inductor L2 is greater than the current flowing from the second connection point P2 to the motor 20, the downward current flows through the fourth switch Tr4. The second period T22 corresponds to the first time when the fifth switch Tr5 is set to be turned on.

[0075] Fig.18 Yes means Fig.15 The state of each switch and the direction of the current in the third period T23 within the PWM cycle TP shown in FIG. Fig.18As shown, in the third period T23, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned on, and the fifth switch Tr5 is turned off. In the third period T23, when the fifth switch Tr5 is turned off, the downward current flowing to the second switch Tr2 is transferred from the fifth switch Tr5 to the fifth rectifying element D5, and the upward current flows through the fifth rectifying element D5. In the third period T23, the potential of the third connection point P3 is substantially equal to the negative electrode potential of the DC power supply 30.

[0076] Fig.19 Yes means Fig.15 The state of each switch and the direction of the current in the fourth period T24 within the PWM cycle TP shown in FIG. Fig.19 As shown, in the fourth period T24, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned off, and the fifth switch Tr5 is turned off. In the fourth period T24, when the second switch Tr2 and the fourth switch Tr4 are turned off, the current flowing through the first inductor L1 is transferred from the second switch Tr2 to the first switch Tr1, and the current flowing through the second inductor L2 is transferred from the fourth switch Tr4 to the third switch Tr3, and the upward current flows through the body diodes of the first switch Tr1 and the third switch Tr3. In addition, in the fourth period T24, since the potentials of the first connection point P1 and the second connection point P2 are substantially equal to the positive electrode potential of the DC power supply 30, the voltages across the first switch Tr1 and the third switch Tr3 are substantially zero. In the fourth period T24, since the reverse voltage is applied to the first inductor L1 and the second inductor L2, the rightward current flowing through the first inductor L1 and the second inductor L2 gradually decreases.

[0077] Fig. 20 Yes means Fig.15 The state of each switch and the direction of the current in the fifth period T25 of the PWM cycle TP are shown in FIG. Fig. 20 As shown, in the fifth period T25, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the fifth switch Tr5 is turned off. In the fifth period T25, as the current flowing through the first inductor L1 and the second inductor L2 decreases, the upward current flowing through the first switch Tr1 and the third switch Tr3 also decreases. Then, when the current flowing through the first inductor L1 is less than the current flowing from the first connection point P1 to the motor 20, and the current flowing through the second inductor L2 is less than the current flowing from the second connection point P2 to the motor 20, the downward current flows through the first switch Tr1 and the third switch Tr3. When the current flowing through the first inductor L1 is zero, the current flowing downward through the first switch Tr1 is consistent with the current flowing from the first connection point P1 to the motor 20. In addition, when the current flowing through the second inductor L2 is zero, the current flowing downward through the third switch Tr3 is consistent with the current flowing from the second connection point P2 to the motor 20.

[0078] As described above, as a first action when current flows from the first connection point P1 and the second connection point P2 to the motor 20, the control unit 13 turns off the first switch Tr1 and the third switch Tr3, turns on the second switch Tr2 and the fourth switch Tr4, and turns off the fifth switch Tr5 in the first period T21 from the turn-on timing of the second switch Tr2 and the fourth switch Tr4 to the turn-on timing of the fifth switch Tr5. Then, the control unit 13 turns off the first switch Tr1 and the third switch Tr3 , turns on the second switch Tr2 and the fourth switch Tr4 , and turns on the fifth switch Tr5 in the second period T22 which is a period after the first period T21 and corresponds to the first time. Then, in the third period T23 after the second period T22 , the control unit 13 turns off the first switch Tr1 and the third switch Tr3 , turns on the second switch Tr2 and the fourth switch Tr4 , and turns off the fifth switch Tr5 . Furthermore, the control unit 13 turns off the first switch Tr1 and the third switch Tr3 , turns off the second switch Tr2 and the fourth switch Tr4 , and turns off the fifth switch Tr5 in the fourth period T24 from the end timing of the third period T23 to the turn-on timing of the first switch Tr1 and the third switch Tr3 .

[0079] As described above, the control unit 13 performs a first operation of turning on the fifth switch Tr5 for a first time before turning on the first switch Tr1 and the third switch Tr3 at the same time within the PWM period TP when the current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively. Thus, before the first switch Tr1 and the third switch Tr3 are turned on at the same time, the voltages across the first switch Tr1 and the third switch Tr3 are substantially zero. Therefore, when the current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively, the control unit 13 performs the above-mentioned soft switching operation to realize soft switching of the first switch Tr1 and the third switch Tr3, thereby reducing the switching loss of the first switch Tr1 and the third switch Tr3. Thus, by synchronizing the turn-on timings of the first switch Tr1 and the third switch Tr3 , soft switching can be achieved in both the first arm U1 and the second arm U2 . The switching elements included in the auxiliary circuit SC are only the fifth switch Tr5 and the sixth switch Tr6. Through the auxiliary circuit SC, soft switching can be performed on both the first branch U1 and the second branch U2. Therefore, the auxiliary circuit SC, the driving circuit of the auxiliary circuit SC and the control signal of the auxiliary circuit SC can be simplified, which can achieve circuit cost reduction and circuit area reduction.

[0080] The above-mentioned embodiment 1 is an example of soft switching action in the case where the first branch U1 and the second branch U2 output voltages of the same phase, and currents flow from the first connection point P1 and the second connection point P2 to the motor 20. However, in the case where the number of poles is switched during the rotation of the motor 20, the output voltage of the first branch U1 and the output voltage of the second branch U2 are not simply in the same phase or opposite phase, and different duty ratios may occur in the first branch U1 and the second branch U2.

[0081] Since the switching control of the number of poles is performed in a short time, even if the operation of the auxiliary circuit SC is stopped during the switching control of the number of poles, and hard switching of each switch included in the H-bridge circuit BC is performed, the switching loss does not increase. However, as described in the following embodiment 2, by operating the auxiliary circuit SC in synchronization with one of the first branch U1 and the second branch U2, the switching loss can be suppressed as much as possible.

[0082] [Example 2] Fig.21 1 is a timing diagram showing on-off timings of the first to fourth switches Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20 respectively and the on-period of the first switch Tr1 is shorter than the on-period of the third switch Tr3 within the PWM period TP.

[0083] Thus, when current flows from the first connection point P1 and the second connection point P2 to the motor 20 respectively, and the length of the on-period of the first switch Tr1 is different from the length of the on-period of the third switch Tr3 within the PWM period TP, the control unit 13 turns on the other switch at the second timing when one of the first switch Tr1 and the third switch Tr3 is turned on and the other is turned off, and performs the first action before the second timing within the PWM period TP.

[0084] exist Fig.21 In the illustrated example, the control unit 13 turns on the fifth switch Tr5 for a first time before a second timing at which the first switch Tr1 is turned on in a state where the third switch Tr3 is turned on and the first switch Tr1 is turned off within the PWM period TP.

[0085] Fig. 22 Yes means Fig.21 FIG. 1 is a diagram showing the state of each switch and the direction of the current in the first period T31 within the PWM cycle TP. Fig. 22 As shown, in the first period T31, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned off. In the first period T31, the upward current flows through the second switch Tr2, and the downward current flows through the third switch Tr3, and the current flows from the first connection point P1 and the second connection point P2 to the motor 20. In the first period T31, the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30, and the potential of the second connection point P2 is substantially equal to the positive electrode potential of the DC power supply 30.

[0086] Fig.23 Yes means Fig.21 The state of each switch and the direction of the current in the second period T32 of the PWM cycle TP are shown in FIG. Fig.23 As shown, in the second period T32, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned on. In the second period T32, when the fifth switch Tr5 becomes turned on, the potential of the third connection point P3 is substantially equal to the positive electrode potential of the DC power supply 30, so the rightward current flows through the first inductor L1. In the second period T32, when the rightward current flowing through the first inductor L1 is greater than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the second switch Tr2. The second period T32 corresponds to the first time when the fifth switch Tr5 is set to be turned on.

[0087] Fig.24 Yes means Fig.21 The state of each switch and the direction of the current in the third period T33 within the PWM cycle TP shown in FIG. Fig.24 As shown, in the third period T33, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned off. In the third period T33, when the fifth switch Tr5 is turned off, the downward current flowing to the second switch Tr2 is transferred from the fifth switch Tr5 to the fifth rectifying element D5, and the upward current flows to the fifth rectifying element D5. In the third period T33, the potential of the third connection point P3 is substantially equal to the negative electrode potential of the DC power supply 30.

[0088] Fig.25 Yes means Fig.21 The state of each switch and the direction of the current in the fourth period T34 within the PWM cycle TP shown in FIG. Fig.25As shown, in the fourth period T34, the first switch Tr1, the second switch Tr2 and the fourth switch Tr4 are turned off, the third switch Tr3 is turned on, and the fifth switch Tr5 is turned off. In the fourth period T34, when the second switch Tr2 is turned off, the current flowing through the first inductor L1 is transferred from the second switch Tr2 to the first switch Tr1, and the upward current flows through the body diode of the first switch Tr1. In addition, in the fourth period T34, since the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30, the voltage across the first switch Tr1 is substantially zero. In the fourth period T34, since a reverse voltage is applied to the first inductor L1, the rightward current flowing through the first inductor L1 gradually decreases.

[0089] Fig.26 Yes means Fig.21 The state of each switch and the direction of the current in the fifth period T35 of the PWM cycle TP are shown in FIG. Fig.26 As shown, in the fifth period T35, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the fifth switch Tr5 is turned off. In the fifth period T35, as the current flowing through the first inductor L1 decreases, the upward current flowing through the first switch Tr1 also decreases. Then, when the current flowing through the first inductor L1 is less than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the first switch Tr1. When the current flowing through the first inductor L1 is zero, the current flowing downward through the first switch Tr1 coincides with the current flowing from the first connection point P1 to the motor 20 .

[0090] As described above, the control unit 13 turns on the fifth switch Tr5 for a first time before the second timing of turning on the first switch Tr1 in a state where the third switch Tr3 is turned on and the first switch Tr1 is turned off within the PWM period TP. Thus, before the first switch Tr1 is turned on, the voltage across the first switch Tr1 is substantially zero. Therefore, when current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively, and the on-period of the first switch Tr1 is shorter than the on-period of the third switch Tr3 within the PWM period TP, the control unit 13 performs the above-mentioned soft switching operation, thereby realizing soft switching of the first switch Tr1 and reducing the switching loss of the first switch Tr1.

[0091] Fig. 27It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the fifth switch Tr5 when current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively, and within the PWM period TP, the length of the on-period of the first switch Tr1 is different from the length of the on-period of the third switch Tr3, and the center of the on-period of the first switch Tr1 and the center of the on-period of the third switch Tr3 are staggered from each other by half a PWM period.

[0092] exist Fig. 27 In the example shown, the control unit 13 turns on the fifth switch Tr5 for a first time before turning on the first switch Tr1 during the period T41 within the PWM period TP, when the third switch Tr3 is turned on and the first switch Tr1 is turned off. Fig. 27 In the illustrated example, the control unit 13 turns on the fifth switch Tr5 for a first time before turning on the third switch Tr3 in a state where the first switch Tr1 is turned on and the third switch Tr3 is turned off during a period T42 within the PWM period TP.

[0093] Thus, before the first switch Tr1 is turned on, the voltage across the first switch Tr1 is substantially zero, and before the third switch Tr3 is turned on, the voltage across the third switch Tr3 is substantially zero. Therefore, when current flows from the first connection point P1 and the second connection point P2 to the motor 20, respectively, and within the PWM period TP, the length of the on-period of the first switch Tr1 is different from the length of the on-period of the third switch Tr3, and the center of the on-period of the first switch Tr1 and the center of the on-period of the third switch Tr3 are offset from each other by half a PWM period, the control unit 13 performs the above-mentioned soft switching operation, and the soft switching of the first switch Tr1 and the third switch Tr3 is realized, so that the switching loss of the first switch Tr1 and the third switch Tr3 can be reduced.

[0094] [Example 3] Fig.28 1 is a timing chart showing on-off timings of the first to fourth switches Tr1 to Tr4 and the sixth switch Tr6 when current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively. Fig.28 Also shown are changes in the currents of the third inductor L3 and the fourth inductor L4 , the currents of the second switch Tr2 and the fourth switch Tr4 , and the voltages across the second switch Tr2 and the fourth switch Tr4 .

[0095] exist Fig.28, I_L3 represents the current of the third inductor L3, I_L4 represents the current of the fourth inductor L4, I_Tr2 represents the current of the second switch Tr2, I_Tr4 represents the current of the fourth switch Tr4, V_Tr2 represents the voltage across the second switch Tr2, and V_Tr4 represents the voltage across the fourth switch Tr4.

[0096] like Fig.28 As shown, the control unit 13 turns on both the second switch Tr1 and the fourth switch Tr4 at the third timing when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, and performs the second operation before the third timing within the PWM period TP. In other words, the control unit 13 performs the second operation of turning on the sixth switch Tr6 for the second time before turning on the second switch Tr2 and the fourth switch Tr4 at the same time within the PWM period TP when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively.

[0097] Fig.29 Yes means Fig.28 FIG. 1 is a diagram showing the state of each switch and the direction of the current in the first period T51 within the PWM cycle TP. Fig.29 As shown, in the first period T51, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the sixth switch Tr6 is turned off. In the first period T51, the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, and the upward current flows to the first switch Tr1 and the third switch Tr3. In the first period T51, the potentials of the first connection point P1 and the second connection point P2 are respectively substantially equal to the positive electrode potential of the DC power supply 30.

[0098] Fig.30 Yes means Fig.28 The state of each switch and the direction of the current in the second period T52 within the PWM cycle TP shown in FIG. Fig.30As shown, in the second period T52, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the sixth switch Tr6 is turned on. In the second period T52, when the sixth switch Tr6 becomes turned on, the potential of the fourth connection point P4 is substantially equal to the negative electrode potential of the DC power supply 30, so that the rightward current flows through the third inductor L3 and the fourth inductor L4. In the second period T52, when the rightward current flowing through the third inductor L3 is greater than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the first switch Tr1. In addition, in the second period T52, when the rightward current flowing through the fourth inductor L4 is greater than the current flowing from the motor 20 to the second connection point P2, the downward current flows through the third switch Tr3. The second period T52 corresponds to the second time when the sixth switch Tr6 is set to be turned on.

[0099] Fig.31 Yes means Fig.28 The state of each switch and the direction of the current in the third period T53 within the PWM cycle TP shown in FIG. Fig.31 As shown, in the third period T53, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the sixth switch Tr6 is turned off. In the third period T53, when the sixth switch Tr6 is turned off, the rightward current flowing to the third inductor L3 and the fourth inductor L4 is diverted from the sixth switch Tr6 to the sixth rectifying element D6, and the upward current flows through the sixth rectifying element D6. In the third period T53, the potential of the fourth connection point P4 is substantially equal to the positive electrode potential of the DC power supply 30.

[0100] Fig.32 Yes means Fig.28 The state of each switch and the direction of the current in the fourth period T54 within the PWM cycle TP shown in FIG. Fig.32 As shown, in the fourth period T54, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned off, and the sixth switch Tr6 is turned off. In the fourth period T54, when the first switch Tr1 and the third switch Tr3 are turned off, the current flowing through the sixth rectifying element D6 is transferred from the first switch Tr1 to the second switch Tr2, and from the third switch Tr3 to the fourth switch Tr4, and the upward current flows through the body diodes of the second switch Tr2 and the fourth switch Tr4. In the fourth period T54, since the potentials of the first connection point P1 and the second connection point P2 are respectively substantially equal to the negative electrode potential of the DC power supply 30, the voltages across the second switch Tr2 and the fourth switch Tr4 are substantially zero. In the fourth period T54, since the reverse voltage is applied to the third inductor L3 and the fourth inductor L4, the rightward current flowing through the third inductor L3 and the fourth inductor L4 gradually decreases.

[0101] Fig.33 Yes means Fig.28 The state of each switch and the direction of the current in the fifth period T55 of the PWM cycle TP are shown in FIG. Fig.33 As shown, in the fifth period T55, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned on, and the sixth switch Tr6 is turned off. In the fifth period T55, as the current flowing through the third inductor L3 and the fourth inductor L4 decreases, the upward current flowing through the second switch Tr2 and the fourth switch Tr4 also decreases. Then, when the current flowing through the third inductor L3 is less than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the second switch Tr2. In addition, when the current flowing through the fourth inductor L4 is less than the current flowing from the motor 20 to the second connection point P2, the downward current flows through the fourth switch Tr4. When the current flowing through the third inductor L3 is zero, the current flowing downward through the second switch Tr2 is consistent with the current flowing from the motor 20 to the first connection point P1. In addition, when the current flowing through the fourth inductor L4 is zero, the current flowing downward through the fourth switch Tr4 is consistent with the current flowing from the motor 20 to the second connection point P2.

[0102] As described above, as the second operation when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, the control unit 13 turns on the first switch Tr1 and the third switch Tr3, turns off the second switch Tr2 and the fourth switch Tr4, and turns off the sixth switch Tr6 in the fifth period from the turn-on timing of the first switch Tr1 and the third switch Tr3 to the turn-on timing of the sixth switch Tr6. The first period T51 corresponds to the fifth period. Then, the control unit 13 turns on the first switch Tr1 and the third switch Tr3 , turns off the second switch Tr2 and the fourth switch Tr4 , and turns on the sixth switch Tr6 in a sixth period that is a period after the fifth period and corresponds to the second time. The second period T52 corresponds to the sixth period. Then, in the seventh period following the sixth period, the control unit 13 turns on the first switch Tr1 and the third switch Tr3, turns off the second switch Tr2 and the fourth switch Tr4, and turns off the sixth switch Tr6. The third period T53 corresponds to the seventh period. Furthermore, the control unit 13 turns off the first switch Tr1 and the third switch Tr3, turns off the second switch Tr2 and the fourth switch Tr4, and turns off the sixth switch Tr6 in the eighth period from the end timing of the seventh period to the turn-on timing of the second switch Tr2 and the fourth switch Tr4. The fourth period T54 corresponds to the eighth period.

[0103] As described above, the control unit 13 performs the second operation of turning on the sixth switch Tr6 for the second time before turning on the second switch Tr2 and the fourth switch Tr4 at the same time within the PWM period TP when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively. Thus, before the second switch Tr2 and the fourth switch Tr4 are turned on at the same time, the voltages across the second switch Tr2 and the fourth switch Tr4 are substantially zero. Therefore, when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, the control unit 13 performs the above-mentioned soft switching operation to realize soft switching of the second switch Tr2 and the fourth switch Tr4, thereby reducing the switching loss of the second switch Tr2 and the fourth switch Tr4. Thus, by synchronizing the turn-on timings of the second switch Tr2 and the fourth switch Tr4 , soft switching can be achieved in both the first arm U1 and the second arm U2 . The switching elements included in the auxiliary circuit SC are only the fifth switch Tr5 and the sixth switch Tr6. Through the auxiliary circuit SC, soft switching can be performed on both the first branch U1 and the second branch U2. Therefore, the auxiliary circuit SC, the driving circuit of the auxiliary circuit SC and the control signal of the auxiliary circuit SC can be simplified, which can achieve circuit cost reduction and circuit area reduction.

[0104] The above-mentioned embodiment 3 is an example of soft switching operation in the case where the first branch U1 and the second branch U2 output voltages of the same phase, and current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively. However, as described above, in the case where the number of poles is switched during the rotation of the motor 20, the output voltage of the first branch U1 and the output voltage of the second branch U2 are not simply in the same phase or opposite phase, and a state where the duty ratio is different will also occur in the first branch U1 and the second branch U2. As described in the following embodiment 4, even in the above case, by making the auxiliary circuit SC operate synchronously with one of the first branch U1 and the second branch U2, the switching loss can be suppressed as much as possible.

[0105] [Example 4] Fig.34 1 is a timing diagram showing the on-off timings of the first to fourth switches Tr1 to Tr4 and the sixth switch Tr6 when current flows from the motor 20 to the first connection point P1 and the second connection point P2 respectively and the on-period of the second switch Tr2 is shorter than the on-period of the fourth switch Tr4 within the PWM period TP.

[0106] Thus, when current flows from the motor 20 to the first connection point P1 and the second connection point P2 respectively, and the length of the on-period of the second switch Tr2 is different from the length of the on-period of the fourth switch Tr4 within the PWM period TP, the control unit 13 turns on the other switch at the fourth timing when one of the second switch Tr2 and the fourth switch Tr4 is turned on and the other is turned off, and performs the second action before the fourth timing within the PWM period TP.

[0107] exist Fig.34 In the illustrated example, the control unit 13 turns on the sixth switch Tr6 for a second time before a fourth timing at which the second switch Tr2 is turned on, in a state in which the fourth switch Tr4 is turned on and the second switch Tr2 is turned off.

[0108] Fig.35 Yes means Fig.34 FIG. 1 is a diagram showing the state of each switch and the direction of the current in the first period T61 within the PWM cycle TP. Fig.35 As shown, in the first period T61, the first switch Tr1 and the fourth switch Tr4 are turned on, the second switch Tr2 and the third switch Tr3 are turned off, and the sixth switch Tr6 is turned off. In the first period T61, the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, the upward current flows through the first switch Tr1, and the downward current flows through the fourth switch Tr4. In the first period T61, the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30, and the potential of the second connection point P2 is substantially equal to the negative electrode potential of the DC power supply 30.

[0109] Fig.36 Yes means Fig.34 FIG. 1 is a diagram showing the state of each switch and the direction of the current in the second period T62 within the PWM cycle TP. Fig.36 As shown, in the second period T62, the first switch Tr1 and the fourth switch Tr4 are turned on, the second switch Tr2 and the third switch Tr3 are turned off, and the sixth switch Tr6 is turned on. In the second period T62, when the sixth switch Tr6 is turned on, the potential of the fourth connection point P4 is substantially equal to the negative electrode potential of the DC power supply 30, so the rightward current flows through the third inductor L3. In the second period T62, when the rightward current flowing through the third inductor L3 is greater than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the first switch Tr1. The second period T62 corresponds to the second time when the sixth switch Tr6 is set to be turned on.

[0110] Fig.37 Yes means Fig.34 The state of each switch and the direction of the current in the third period T63 within the PWM cycle TP shown in FIG. Fig.37As shown, in the third period T63, the first switch Tr1 and the fourth switch Tr4 are turned on, the second switch Tr2 and the third switch Tr3 are turned off, and the sixth switch Tr6 is turned off. In the third period T63, when the sixth switch Tr6 is turned off, the rightward current flowing to the third inductor L3 is diverted from the sixth switch Tr6 to the sixth rectifying element D6, and the upward current flows through the sixth rectifying element D6. In the third period T63, the potential of the fourth connection point P4 is substantially equal to the positive electrode potential of the DC power supply 30.

[0111] Fig.38 Yes means Fig.34 The state of each switch and the direction of the current in the fourth period T64 within the PWM cycle TP shown in FIG. Fig.38 As shown, in the fourth period T64, the fourth switch Tr4 is turned on, the first switch Tr1, the second switch Tr2 and the third switch Tr3 are turned off, and the sixth switch Tr6 is turned off. In the fourth period T64, when the first switch Tr1 is turned off, the current flowing through the sixth rectifying element D6 is transferred from the first switch Tr1 to the second switch Tr2, and the upward current flows through the body diode of the second switch Tr2. In the fourth period T64, since the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30, the voltage across the second switch Tr2 is substantially zero. In the fourth period T64, since a reverse voltage is applied to the third inductor L3, the rightward current flowing through the third inductor L3 gradually decreases.

[0112] Fig.39 Yes means Fig.34 The state of each switch and the direction of the current in the fifth period T65 of the PWM cycle TP are shown in FIG. Fig.39 As shown, in the fifth period T65, the first switch Tr1 and the third switch Tr3 are turned off, the second switch Tr2 and the fourth switch Tr4 are turned on, and the sixth switch Tr6 is turned off. In the fifth period T65, as the current flowing through the third inductor L3 decreases, the upward current flowing through the second switch Tr2 also decreases. Then, when the current flowing through the third inductor L3 is less than the current flowing from the motor 20 to the first connection point P1, the downward current flows through the second switch Tr2. When the current flowing through the third inductor L3 is zero, the current flowing downward through the second switch Tr2 coincides with the current flowing from the motor 20 to the first connection point P1.

[0113] As described above, the control unit 13 turns on the sixth switch Tr6 for the second time before the fourth timing at which the second switch Tr2 is turned on, in the state where the fourth switch Tr4 is turned on and the second switch Tr2 is turned off, within the PWM period TP. Thus, before the second switch Tr2 is turned on, the voltage across the second switch Tr2 is substantially zero. Therefore, when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, and the on-period of the second switch Tr2 is shorter than the on-period of the fourth switch Tr4 within the PWM period TP, the control unit 13 performs the above-mentioned soft switching operation, thereby realizing soft switching of the second switch Tr2 and reducing the switching loss of the second switch Tr2.

[0114] Fig.40 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the sixth switch Tr6 when the current flows from the motor 20 to the first connection point P1 and the second connection point P2 respectively, and within the PWM period TP, the length of the on-period of the second switch Tr2 is different from the length of the on-period of the fourth switch Tr4, and the center of the on-period of the second switch Tr2 and the center of the on-period of the fourth switch Tr4 are staggered from each other by half a PWM period.

[0115] exist Fig.40 In the example shown, the control unit 13 turns on the sixth switch Tr6 for a second time before turning on the second switch Tr2 during the period T71 within the PWM period TP, while the fourth switch Tr4 is turned on and the second switch Tr2 is turned off. Fig.40 In the illustrated example, the control unit 13 turns on the fourth switch Tr4 for a second time before turning on the fourth switch Tr4 in a state where the second switch Tr2 is turned on and the fourth switch Tr4 is turned off during a period T72 in the PWM period TP.

[0116] Thus, before the second switch Tr2 is turned on, the voltage across the second switch Tr2 is substantially zero, and before the fourth switch Tr4 is turned on, the voltage across the fourth switch Tr4 is substantially zero. Therefore, when the current flows from the motor 20 to the first connection point P1 and the second connection point P2, respectively, and within the PWM period TP, the length of the on-period of the second switch Tr2 is different from the length of the on-period of the fourth switch Tr4, and the center of the on-period of the second switch Tr2 and the center of the on-period of the fourth switch Tr4 are offset from each other by half a PWM period, the control unit 13 performs the above-mentioned soft switching operation, and the soft switching of the second switch Tr2 and the fourth switch Tr4 is realized, so that the switching loss of the second switch Tr2 and the fourth switch Tr4 can be reduced.

[0117] [Example 5] Fig.411 is a timing diagram showing the on-off timing of the first switch Tr1 to the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2. Embodiment 5 is an example of soft switching action in the case where the first branch U1 and the second branch U2 output voltages of opposite phases, the current flows from the first connection point P1 to the motor 20, and the current flows from the motor 20 to the second connection point P2. Fig.41 Also shown are changes in the currents of the first inductor L1 and the fourth inductor L4 , the currents of the first switch Tr1 and the fourth switch Tr4 , and the voltages across the first switch Tr1 and the fourth switch Tr4 .

[0118] exist Fig.41 In FIG. 1 , I_L1 represents the current of the first inductor L1, and I_L4 represents the current of the fourth inductor L4. I_Tr1 represents the current of the first switch Tr1, and I_Tr4 represents the current of the fourth switch Tr4. V_Tr1 represents the voltage across the first switch Tr1, and V_Tr4 represents the voltage across the fourth switch Tr4.

[0119] like Fig.41 As shown, the control unit 13 turns on both the first switch Tr1 and the fourth switch Tr4 at the fifth timing when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, and performs the first action and the second action simultaneously before the fifth timing within the PWM period TP.

[0120] In other words, when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, the control unit 13 simultaneously performs a first action of turning on the fifth switch Tr5 for a first time and a second action of turning on the sixth switch Tr6 for a second time within the PWM period TP before simultaneously turning on the first switch Tr1 and the fourth switch Tr4. In this case, the first time is equal to the second time.

[0121] Fig.42 Yes means Fig.41 The state of each switch and the direction of the current in the first period T81 of the PWM cycle TP are shown in FIG. Fig.42As shown, in the first period T81, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 and the sixth switch Tr6 are turned off. In the first period T81, the upward current flows through the second switch Tr2, and the current flows from the first connection point P1 to the motor 20. In addition, in the first period T81, the current flows from the motor 20 to the second connection point P2, and the upward current flows to the third switch Tr3. In the first period T81, the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30, and the potential of the second connection point P2 is substantially equal to the positive electrode potential of the DC power supply 30.

[0122] Fig.43 Yes means Fig.41 The state of each switch and the direction of the current in the second period T82 within the PWM cycle TP shown in FIG. Fig.43 As shown, in the second period T82, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 and the sixth switch Tr6 are turned on. In the second period T82, when the fifth switch Tr5 and the sixth switch Tr6 are turned on, the potential of the third connection point P3 is substantially equal to the positive electrode potential of the DC power supply 30, and the potential of the fourth connection point P4 is substantially equal to the negative electrode potential of the DC power supply 30, so that the rightward current flows through the first inductor L1 and the fourth inductor L4. In the second period T82, when the rightward current flowing through the first inductor L1 is greater than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the second switch Tr2. In addition, in the second period T82, when the rightward current flowing through the fourth inductor L4 is greater than the current flowing from the motor 20 to the second connection point P2, the downward current flows through the third switch Tr3. The second period T82 corresponds to a first time when the fifth switch Tr5 is turned on, and corresponds to a second time when the sixth switch Tr6 is turned on.

[0123] Fig.44 Yes means Fig.41 The state of each switch and the direction of the current in the third period T83 within the PWM cycle TP shown in FIG. Fig.44As shown, in the third period T83, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 and the sixth switch Tr6 are turned off. In the third period T83, when the fifth switch Tr5 is turned off, the rightward current flowing to the first inductor L1 is diverted from the fifth switch Tr5 to the fifth rectifying element D5, and the upward current flows through the fifth rectifying element D5. In addition, in the third period T83, when the sixth switch Tr6 is turned off, the rightward current flowing to the fourth inductor L4 is diverted from the sixth switch Tr6 to the sixth rectifying element D6, and the upward current flows to the sixth rectifying element D6. In the third period T83, the potential of the third connection point P3 is substantially equal to the negative electrode potential of the DC power supply 30, and the potential of the fourth connection point P4 is substantially equal to the positive electrode potential of the DC power supply 30.

[0124] Fig.45 Yes means Fig.41 The state of each switch and the direction of the current in the fourth period T84 within the PWM cycle TP shown in FIG. Fig.45 As shown, in the fourth period T84, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned off, and the fifth switch Tr5 and the sixth switch Tr6 are turned off. In the fourth period T84, when the second switch Tr2 is turned off, the current flowing through the first inductor L1 is transferred from the second switch Tr2 to the first switch Tr1, and the upward current flows through the body diode of the first switch Tr1. In addition, in the fourth period T84, when the third switch Tr3 is turned off, the current flowing through the fourth inductor L4 is transferred from the third switch Tr3 to the fourth switch Tr4, and the upward current flows through the body diode of the fourth switch Tr4. In the fourth period T84, since the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30, and the potential of the second connection point P2 is substantially equal to the negative electrode potential of the DC power supply 30, the voltages across the first switch Tr1 and the fourth switch Tr4 are substantially zero. In the fourth period T84 , since voltages in opposite directions are applied to the first inductor L1 and the fourth inductor L4 , the rightward current flowing through the first inductor L1 and the fourth inductor L4 gradually decreases.

[0125] Fig.46 Yes means Fig.41 The state of each switch and the direction of the current in the fifth period T85 of the PWM cycle TP are shown in FIG. Fig.46As shown, in the fifth period T85, the first switch Tr1 and the fourth switch Tr4 are turned on, the second switch Tr2 and the third switch Tr3 are turned off, and the fifth switch Tr5 and the sixth switch Tr6 are turned off. In the fifth period T85, as the current flowing through the first inductor L1 and the fourth inductor L4 decreases, the upward current flowing through the first switch Tr1 and the fourth switch Tr4 also decreases. Then, when the current flowing through the first inductor L1 is less than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the first switch Tr1. In addition, when the current flowing through the fourth inductor L4 is less than the current flowing from the motor 20 to the second connection point P2, the downward current flows through the fourth switch Tr4. When the current flowing through the first inductor L1 is zero, the current flowing through the first switch Tr1 is consistent with the current flowing from the first connection point P1 to the motor 20. In addition, when the current flowing through the fourth inductor L4 is zero, the current flowing through the fourth switch Tr4 is consistent with the current flowing from the motor 20 to the second connection point P2.

[0126] As described above, when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2 , the control unit 13 performs the first operation and the second operation simultaneously. That is, in the ninth period from the turn-on timing of the second switch Tr2 and the third switch Tr3 to the turn-on timing of the fifth switch Tr5 and the sixth switch Tr6, the control unit 13 turns off the first switch Tr1 and the fourth switch Tr4, turns on the second switch Tr2 and the third switch Tr3, and turns off the fifth switch Tr5 and the sixth switch Tr6. The first period T81 corresponds to the ninth period. Then, the control unit 13 turns off the first switch Tr1 and the fourth switch Tr4, turns on the second switch Tr2 and the third switch Tr3, and turns on the fifth switch Tr5 and the sixth switch Tr6 in the tenth period which is the period after the ninth period and corresponds to the first time. The second period T82 corresponds to the tenth period. Then, in the eleventh period following the tenth period, the control unit 13 turns off the first switch Tr1 and the fourth switch Tr4, turns on the second switch Tr2 and the third switch Tr3, and turns off the fifth switch Tr5 and the sixth switch Tr6. The third period T83 corresponds to the eleventh period. Furthermore, the control unit 13 turns off the first switch Tr1 and the fourth switch Tr4, turns off the second switch Tr2 and the third switch Tr3, and turns off the fifth switch Tr5 and the sixth switch Tr6 in the twelfth period from the end timing of the eleventh period to the turn-on timing of the first switch Tr1 and the fourth switch Tr4. The fourth period T84 corresponds to the twelfth period.

[0127] As described above, when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, the control unit 13 simultaneously performs a first action of turning on the fifth switch Tr5 for a first time and a second action of turning on the sixth switch Tr6 for a second time before turning on the first switch Tr1 and the fourth switch Tr4 at the same time within the PWM period TP. Thus, before the first switch Tr1 and the fourth switch Tr4 are turned on at the same time, the voltage across the first switch Tr1 and the fourth switch Tr4 is substantially zero. Therefore, when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, the control unit 13 performs the above-mentioned soft switching action to realize soft switching of the first switch Tr1 and the fourth switch Tr4, and the switching loss of the first switch Tr1 and the fourth switch Tr4 can be reduced. Thus, by synchronizing the turn-on timings of the first switch Tr1 and the fourth switch Tr4 , soft switching can be achieved in both the first arm U1 and the second arm U2 . The switching elements included in the auxiliary circuit SC are only the fifth switch Tr5 and the sixth switch Tr6. Through the auxiliary circuit SC, soft switching can be performed on both the first branch U1 and the second branch U2. Therefore, the auxiliary circuit SC, the driving circuit of the auxiliary circuit SC and the control signal of the auxiliary circuit SC can be simplified, which can achieve circuit cost reduction and circuit area reduction.

[0128] When the current flows from the second connection point P2 to the motor 20 and the current flows from the motor 20 to the first connection point P1, in the description of Example 5, the first branch U1, the first connection point P1 and the third connection point P3 are respectively replaced by the second branch U2, the second connection point P2 and the fourth connection point P4, the first switch Tr1 and the fourth switch Tr4 are respectively replaced by the second switch Tr2 and the third switch Tr3, and the first inductor L1 and the fourth inductor L4 are respectively replaced by the second inductor L2 and the third inductor L3.

[0129] Embodiment 5 is an example of soft switching operation in the case where the first branch U1 and the second branch U2 output voltages of opposite phases, current flows from the first connection point P1 to the motor 20, and current flows from the motor 20 to the second connection point P2. As described above, in the case where the number of poles is switched during the rotation of the motor 20, the output voltage of the first branch U1 and the output voltage of the second branch U2 are not simply in the same phase or opposite phase relationship, and a state where the duty ratio is different between the first branch U1 and the second branch U2 occurs. However, as described in the following embodiment 6, even in this case, by operating the auxiliary circuit SC synchronously with one of the first branch U1 and the second branch U2, the switching loss can be suppressed as much as possible.

[0130] [Example 6] Fig.47 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the fifth switch Tr5 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2, and the on-period of the first switch Tr1 is longer than the on-period of the fourth switch Tr4 within the PWM period TP.

[0131] Thus, when current flows from the first connection point P1 to the motor 20 and current flows from the motor 20 to the second connection point P2, and the length of the on-period of the first switch Tr1 is different from the length of the on-period of the fourth switch Tr4 within the PWM period TP, the control unit 13 turns on the first switch Tr1 at the sixth timing when the first switch Tr1 is turned off and the fourth switch Tr4 is turned off, and performs the first action before the sixth timing within the PWM period TP.

[0132] exist Fig.47 In the illustrated example, the control unit 13 turns on the fifth switch Tr5 for a first time before a sixth timing at which the first switch Tr1 is turned on in a state where the first switch Tr1 and the fourth switch Tr4 are turned off within the PWM period TP.

[0133] Fig.48 Yes means Fig.47 The state of each switch and the direction of the current in the first period T91 of the PWM cycle TP are shown in FIG. Fig.48 As shown, in the first period T91, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned off. In the first period T91, the upward current flows through the second switch Tr2, and the current flows from the first connection point P1 to the motor 20. In addition, in the first period T91, the current flows from the motor 20 to the second connection point P2, and the upward current flows through the third switch Tr3. In the first period T91, the potential of the first connection point P1 is substantially equal to the negative electrode potential of the DC power supply 30, and the potential of the second connection point P2 is substantially equal to the positive electrode potential of the DC power supply 30.

[0134] Fig.49 Yes means Fig.47 The state of each switch and the direction of the current in the second period T92 within the PWM cycle TP shown in FIG. Fig.49As shown, in the second period T92, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned on. In the second period T92, when the fifth switch Tr5 is turned on, the potential of the third connection point P3 is substantially equal to the positive electrode potential of the DC power supply 30, so the rightward current flows through the first inductor L1. In the second period T92, when the rightward current flowing through the first inductor L1 is greater than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the second switch Tr2. The second period T92 corresponds to the first time when the fifth switch Tr5 is set to be turned on.

[0135] Fig.50 Yes means Fig.47 The state of each switch and the direction of the current in the third period T93 within the PWM cycle TP shown in FIG. Fig.50 As shown, in the third period T93, the first switch Tr1 and the fourth switch Tr4 are turned off, the second switch Tr2 and the third switch Tr3 are turned on, and the fifth switch Tr5 is turned off. In the third period T93, when the fifth switch Tr5 is turned off, the downward current flowing through the second switch Tr2 is transferred from the fifth switch Tr5 to the fifth rectifying element D5, and the upward current flows through the fifth rectifying element D5. In the third period T93, the potential of the third connection point P3 is substantially equal to the negative electrode potential of the DC power supply 30.

[0136] Fig.51 Yes means Fig.47 The state of each switch and the direction of the current in the fourth period T94 within the PWM cycle TP shown in FIG. Fig.51 As shown, in the fourth period T94, the first switch Tr1, the second switch Tr2 and the fourth switch Tr4 are turned off, the third switch Tr3 is turned on, and the fifth switch Tr5 is turned off. In the fourth period T94, when the second switch Tr2 is turned off, the current flowing through the first inductor L1 is transferred from the second switch Tr2 to the first switch Tr1, and the upward current flows through the body diode of the first switch Tr1. In the fourth period T94, since the potential of the first connection point P1 is substantially equal to the positive electrode potential of the DC power supply 30, the voltage across the first switch Tr1 is substantially zero. In the fourth period T94, since a reverse voltage is applied to the first inductor L1, the rightward current flowing through the first inductor L1 gradually decreases.

[0137] Fig.52 Yes means Fig.47 The state of each switch and the direction of the current in the fifth period T95 of the PWM cycle TP are shown in FIG. Fig.52As shown, in the fifth period T95, the first switch Tr1 and the third switch Tr3 are turned on, the second switch Tr2 and the fourth switch Tr4 are turned off, and the fifth switch Tr5 is turned off. In the fifth period T95, as the current flowing through the first inductor L1 decreases, the upward current flowing through the first switch Tr1 also decreases. Then, when the current flowing through the first inductor L1 is less than the current flowing from the first connection point P1 to the motor 20, the downward current flows through the first switch Tr1. When the current flowing through the first inductor L1 is zero, the current flowing downward through the first switch Tr1 coincides with the current flowing from the first connection point P1 to the motor 20 .

[0138] As described above, when the current flows from the first connection point P1 to the motor 20, and the current flows from the motor 20 to the second connection point P2, and the on-period of the first switch Tr1 is longer than the on-period of the fourth switch Tr4 in the PWM period TP, the control unit 13 turns on the fifth switch Tr5 for a first time before turning on the first switch Tr1 in a state where the first switch Tr1 is turned off and the fourth switch Tr4 is turned off in the PWM period TP. Thus, before the first switch Tr1 is turned on, the voltage across the first switch Tr1 is substantially zero. Therefore, when the current flows from the first connection point P1 to the motor 20, and the current flows from the motor 20 to the second connection point P2, and the on-period of the first switch Tr1 is longer than the on-period of the fourth switch Tr4 in the PWM period TP, the control unit 13 performs the above-mentioned soft switching operation, realizes the soft switching of the first switch Tr1, and can reduce the switching loss of the first switch Tr1.

[0139] Fig.53 It is a timing diagram showing the on-off timing of the first switch Tr1 to the fourth switch Tr4 and the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20 and the current flows from the motor 20 to the second connection point P2 and the on-period of the first switch Tr1 is shorter than the on-period of the fourth switch Tr4 within the PWM period TP.

[0140] exist Fig.53 In the example shown, the control unit 13 turns on the fourth switch Tr4 at the seventh timing while the first switch Tr1 is turned off and the fourth switch Tr4 is turned off, and performs the second action before the seventh timing within the PWM period TP. In other words, the control unit 13 performs the second action of turning on the sixth switch Tr6 for the second time before turning on the fourth switch Tr4 within the PWM period TP while the first switch Tr1 is turned off and the fourth switch Tr4 is turned off.

[0141] Therefore, before the fourth switch Tr4 is turned on, the voltage across the fourth switch Tr4 is substantially zero. Fig.53In the illustrated example, the control unit 13 performs the above-described soft switching operation to realize soft switching of the fourth switch Tr4 , thereby reducing the switching loss of the fourth switch Tr4 .

[0142] Fig.54 It is a timing diagram showing the on-off timing of the first switch Tr1 to the sixth switch Tr6 when the current flows from the first connection point P1 to the motor 20, and the current flows from the motor 20 to the second connection point P2, and the length of the on-period of the first switch Tr1 and the length of the on-period of the fourth switch Tr4 are different within the PWM period TP, and the center of the on-period of the first switch Tr1 and the center of the on-period of the fourth switch Tr4 are offset from each other by half a PWM period.

[0143] exist Fig.54 In the example shown, the control unit 13 performs a first operation of turning on the fifth switch Tr5 for a first time before turning on the first switch Tr1 in a state where the third switch Tr3 is turned on and the first switch Tr1 is turned off within the PWM period TP. Fig.54 In the example shown, the control unit 13 performs a second operation of turning on the sixth switch Tr6 for a second time before turning on the fourth switch Tr4 in a state where the first switch Tr1 is turned off and the fourth switch Tr4 is turned off within the PWM period TP.

[0144] Thus, before the first switch Tr1 is turned on, the voltage across the first switch Tr1 is substantially zero, and before the fourth switch Tr4 is turned on, the voltage across the fourth switch Tr4 is substantially zero. Fig.54 In the illustrated example, the control unit 13 performs the above-described soft switching operation to realize soft switching of the first switch Tr1 and the fourth switch Tr4 , thereby reducing switching losses of the first switch Tr1 and the fourth switch Tr4 .

[0145] When the current flows from the second connection point P2 to the motor 20 and the current flows from the motor 20 to the first connection point P1, in the description of Example 6, the first branch U1, the first connection point P1 and the third connection point P3 are respectively replaced by the second branch U2, the second connection point P2 and the fourth connection point P4, the first switch Tr1 and the fourth switch Tr4 are respectively replaced by the second switch Tr2 and the third switch Tr3, and the first inductor L1 and the fourth inductor L4 are respectively replaced by the second inductor L2 and the third inductor L3.

[0146] [Modifications] The present invention is not limited to the above-described embodiments, and the various configurations described in this specification can be appropriately combined within a range that does not contradict each other.

[0147] Fig.551 is a diagram showing a modified example of an H-bridge circuit BC and an auxiliary circuit SC. The H-bridge circuit BC may include a first capacitor connected in parallel to at least one of the first to fourth switches Tr1 to Tr4. Fig.55 In the modified example shown, the first capacitor C1 is connected in parallel with the first switch Tr1, the first capacitor C2 is connected in parallel with the second switch Tr2, the first capacitor C3 is connected in parallel with the third switch Tr3, and the first capacitor C4 is connected in parallel with the fourth switch Tr4. By adopting such a structure, the turn-off loss of the first switch Tr1 to the fourth switch Tr4 can also be reduced.

[0148] In addition, the auxiliary circuit SC may include a second capacitor connected in parallel with at least one of the fifth switch Tr5 and the sixth switch Tr5. Fig.55 In the variation shown, the second capacitor C5 is connected in parallel with the fifth switch Tr5, and the second capacitor C6 is connected in parallel with the sixth switch Tr6. By adopting such a structure, the turn-off loss of the fifth switch Tr5 to the sixth switch Tr6 can also be reduced. The capacitor can be connected in parallel to at least one of the fifth rectifying element D5 and the sixth rectifying element D6.

[0149] In the above embodiment, the motor 20 having a structure in which the neutral point of the first U-phase coil 23u, the first V-phase coil 23v, and the first W-phase coil 23w are electrically isolated from the neutral point of the second U-phase coil 24u, the second V-phase coil 24v, and the second W-phase coil 24w is illustrated. The present invention is not limited to this, and a motor having a structure in which the neutral point of the first U-phase coil 23u, the first V-phase coil 23v, and the first W-phase coil 23w are electrically connected to the neutral point of the second U-phase coil 24u, the second V-phase coil 24v, and the second W-phase coil 24w may be used.

[0150] The present technology may also adopt the following structure. (1) The power conversion device includes: an H-bridge circuit, which corresponds to each phase of an electric motor having two N-phase terminal groups (N is an integer greater than 3); an auxiliary circuit, which corresponds to at least one of the H-bridge circuits; and a control unit, which controls the H-bridge circuit and the auxiliary circuit, the H-bridge circuit includes: a first branch, the first branch includes a first switch connected between the positive electrode of the power supply and a first connection point and a second switch connected between the negative electrode of the power supply and the first connection point; and a second branch, the second branch includes a third switch connected between the positive electrode and the second connection point and a fourth switch connected between the negative electrode and the second connection point, the auxiliary circuit includes: a first rectifier element and a first inductor connected in series between the first connection point and the third connection point; a first inductor connected in series between the second connection point and the third connection point; and a second inductor connected in series between the second connection point and the third connection point. A second rectifier element and a second inductor are connected in series between the first connection point and the fourth connection point; a third rectifier element and a third inductor are connected in series between the first connection point and the fourth connection point; a fourth rectifier element and a fourth inductor are connected in series between the second connection point and the fourth connection point; a fifth switch is connected between the positive electrode and the third connection point; a fifth rectifier element having a negative terminal connected to the third connection point and a positive terminal connected to the negative electrode; a sixth rectifier element having a negative terminal connected to the positive electrode and a positive terminal connected to the fourth connection point; and a sixth switch is connected between the negative electrode and the fourth connection point, the positive terminal of the first rectifier element and the positive terminal of the second rectifier element are located on one side of the third connection point, and the negative terminal of the third rectifier element and the negative terminal of the fourth rectifier element are located on one side of the fourth connection point. (2) In the power conversion device described in (1), the control unit performs at least one of a first action of turning on the fifth switch for a first time before turning on at least one of the first switch and the third switch within one control cycle of pulse width modulation, and a second action of turning on the sixth switch for a second time before turning on at least one of the second switch and the fourth switch within the one control cycle. (3) In the power conversion device described in (2), when current flows from the first connection point to the motor, the first action is an action of turning on the fifth switch for the first time before turning on the first switch within the one control cycle, and when current flows from the second connection point to the motor, the first action is an action of turning on the fifth switch for the first time before turning on the third switch within the one control cycle.(4) In the power conversion device described in (2), when current flows from the motor to the first connection point, the second action is an action of turning on the sixth switch for the second time before turning on the second switch within the one control cycle, and when current flows from the motor to the second connection point, the second action is an action of turning on the sixth switch for the second time before turning on the fourth switch within the one control cycle. (5) In the power conversion device described in (3), when current flows from the first connection point and the second connection point to the motor, the control unit turns on both the first switch and the third switch at a first timing, and performs the first action before the first timing within the one control cycle. (6) In the power conversion device described in (5), the control unit performs the following actions when performing the first action: in a first period from the turn-on timing of the second switch and the fourth switch to the turn-on timing of the fifth switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned off; in a second period which is a period after the first period and corresponds to the first time, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned on; in a third period after the second period, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned off; in a fourth period from the end timing of the third period to the turn-on timing of the first switch and the third switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned off, and the fifth switch is turned off. (7) In the power conversion device described in (3), when current flows from both the first connection point and the second connection point to the motor, the control unit turns on the other switch at a second timing while one of the first switch and the third switch is turned on and the other switch is turned off, and performs the first action before the second timing within the one control cycle. (8) In the power conversion device described in (4), when current flows from the motor to both the first connection point and the second connection point, the control unit turns on the second switch and the fourth switch at a third timing while current flows from the motor to both the first connection point and the second connection point, and performs the second action before the third timing within the one control cycle.(9) In the power conversion device described in (8), when performing the second action, the control unit performs the following actions: in a fifth period from the turn-on timing of the first switch and the third switch to the turn-on timing of the sixth switch, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned off; in a sixth period which is a period after the fifth period and corresponds to the second time, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned on; in a seventh period after the sixth period, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned off; in an eighth period from the end timing of the seventh period to the turn-on timing of the second switch and the fourth switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned off, and the sixth switch is turned off. (10) In the power conversion device described in (4), when current flows from the motor to the first connection point and the second connection point respectively, the control unit turns on the second switch at a fourth timing when one of the second switch and the fourth switch is turned on and the other switch is turned off, and performs the second action before the fourth timing within the one control cycle. (11) In the power conversion device described in (2), when current flows from the first connection point to the motor and current flows from the motor to the second connection point, the control unit turns on both the first switch and the fourth switch at a fifth timing, and performs the first action and the second action simultaneously within the one control cycle before the fifth timing, and the first time is equal to the second time.(12) In the power conversion device described in (11), when the control unit performs the first action and the second action simultaneously, the control unit performs the following actions: in a ninth period from the turn-on timing of the second switch and the third switch to the turn-on timing of the fifth switch and the sixth switch, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned off; in a tenth period which is a period after the ninth period and corresponds to the first time, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned on; in an eleventh period after the tenth period, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned off; in a twelfth period from the end timing of the eleventh period to the turn-on timing of the first switch and the fourth switch, the first switch and the fourth switch are turned off, the second switch and the third switch are turned off, and the fifth switch and the sixth switch are turned off. (13) The power conversion device described in (2), wherein the control unit turns on the first switch at a sixth timing when the current flows from the first connection point to the motor and the current flows from the motor to the second connection point, while the first switch is turned off and the fourth switch is turned off, and performs the first action before the sixth timing within the one control cycle. (14) The power conversion device described in (2), wherein the control unit turns on the fourth switch at a seventh timing when the current flows from the first connection point to the motor and the current flows from the motor to the second connection point, while the first switch is turned off and the fourth switch is turned off, and performs the second action before the seventh timing within the one control cycle. (15) The power conversion device described in any one of (1) to (14), wherein the control unit has a first mode in which the first branch and the second branch output voltages of the same phase, and a second mode in which the first branch and the second branch output voltages of opposite phases. (16) A power conversion device as described in any one of (1) to (15), wherein the H-bridge circuit includes a first capacitor connected in parallel with at least one of the first to fourth switches. (17) A power conversion device as described in any one of (1) to (16), wherein the auxiliary circuit includes a second capacitor connected in parallel with at least one of the fifth and sixth switches. (18) A motor module, comprising: a motor having two N-phase terminal groups (N is an integer greater than or equal to 3), and a power conversion device as described in any one of (1) to (17).

Claims

1. A power conversion device, characterized in that: include: An H-bridge circuit corresponding to each of the motors having two N-phase terminal groups (N is an integer greater than or equal to 3); an auxiliary circuit corresponding to at least one of the H-bridge circuits; as well as a control unit for controlling the H-bridge circuit and the auxiliary circuit, The H-bridge circuit comprises: a first branch comprising a first switch connected between a positive electrode of a power source and a first connection point, and a second switch connected between a negative electrode of the power source and the first connection point; and The second branch includes a third switch connected between the positive electrode and the second connection point, and a fourth switch connected between the negative electrode and the second connection point, and the auxiliary circuit includes: a first rectifying element and a first inductor connected in series between the first connection point and a third connection point; a second rectifying element and a second inductor connected in series between the second connection point and the third connection point; a third rectifying element and a third inductor connected in series between the first connection point and the fourth connection point; a fourth rectifying element and a fourth inductor connected in series between the second connection point and the fourth connection point; a fifth switch connected between the positive electrode and the third connection point; a fifth rectifying element having a negative terminal connected to the third connection point and a positive terminal connected to the negative electrode; a sixth rectifying element having a negative terminal connected to the positive electrode and a positive terminal connected to the fourth connection point; and a sixth switch connected between the negative electrode and the fourth connection point, The positive terminal of the first rectifying element and the positive terminal of the second rectifying element are located on one side of the third connection point, A negative terminal of the third rectifying element and a negative terminal of the fourth rectifying element are located on one side of the fourth connection point.

2. The power conversion device according to claim 1, characterized in that: The control unit performs at least one of a first action of turning on the fifth switch for a first time before turning on at least one of the first switch and the third switch within one control cycle of pulse width modulation, and a second action of turning on the sixth switch for a second time before turning on at least one of the second switch and the fourth switch within the one control cycle.

3. The power conversion device according to claim 2, characterized in that: When current flows from the first connection point to the motor, the first action is to turn on the fifth switch for the first time before turning on the first switch within the one control cycle. When current flows from the second connection point to the motor, the first operation is an operation of turning on the fifth switch for the first time before turning on the third switch within the one control cycle.

4. The power conversion device according to claim 2, characterized in that: When current flows from the motor to the first connection point, the second operation is to turn on the sixth switch for the second time before turning on the second switch within the one control cycle. When current flows from the motor to the second connection point, the second operation is an operation of turning on the sixth switch for the second time before turning on the fourth switch within the one control cycle.

5. The power conversion device according to claim 3, characterized in that: The control unit turns on both the first switch and the third switch at a first timing when current flows from the first connection point and the second connection point to the motor, and performs the first operation before the first timing within the one control cycle.

6. The power conversion device according to claim 5, characterized in that: When the control unit performs the first action, the control unit performs the following actions: During a first period from the turn-on timing of the second switch and the fourth switch to the turn-on timing of the fifth switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned off; In a second period that is a period after the first period and corresponds to the first time, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned on; In a third period after the second period, the first switch and the third switch are turned off, the second switch and the fourth switch are turned on, and the fifth switch is turned off; In a fourth period from the end timing of the third period to the turn-on timing of the first switch and the third switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned off, and the fifth switch is turned off.

7. The power conversion device according to claim 3, characterized in that: When current flows to the motor from both the first connection point and the second connection point, the control unit turns on the other switch at a second timing while one of the first switch and the third switch is turned on and the other switch is turned off, and performs the first action before the second timing within the one control cycle.

8. The power conversion device according to claim 4, characterized in that: The control unit turns on both the second switch and the fourth switch at a third timing when current flows from the motor to the first connection point and the second connection point, respectively, and performs the second operation before the third timing within the one control cycle.

9. The power conversion device according to claim 8, characterized in that: When the control unit performs the second action, the control unit performs the following actions: In a fifth period from the turn-on timing of the first switch and the third switch to the turn-on timing of the sixth switch, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned off; In a sixth period which is a period after the fifth period and corresponds to the second time, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned on; In a seventh period after the sixth period, the first switch and the third switch are turned on, the second switch and the fourth switch are turned off, and the sixth switch is turned off; In an eighth period from the end timing of the seventh period to the turn-on timing of the second switch and the fourth switch, the first switch and the third switch are turned off, the second switch and the fourth switch are turned off, and the sixth switch is turned off.

10. The power conversion device according to claim 4, characterized in that: When current flows from the motor to the first connection point and the second connection point respectively, the control unit turns on the other switch at a fourth timing while one of the second switch and the fourth switch is turned on and the other is turned off, and performs the second action before the fourth timing within the one control cycle.

11. The power conversion device according to claim 2, characterized in that: The control unit turns on both the first switch and the fourth switch at a fifth timing when current flows from the first connection point to the motor and current flows from the motor to the second connection point, and performs the first action and the second action simultaneously before the fifth timing within the one control cycle. The first time is equal to the second time.

12. The power conversion device according to claim 11, characterized in that: When the control unit performs the first action and the second action simultaneously, the control unit performs the following actions: In a ninth period from the turn-on timing of the second switch and the third switch to the turn-on timing of the fifth switch and the sixth switch, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned off; In a tenth period which is a period after the ninth period and corresponds to the first time, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned on; In an eleventh period after the tenth period, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the fifth switch and the sixth switch are turned off; In a twelfth period from the end timing of the eleventh period to the turn-on timing of the first switch and the fourth switch, the first switch and the fourth switch are turned off, the second switch and the third switch are turned off, and the fifth switch and the sixth switch are turned off.

13. The power conversion device according to claim 2, characterized in that: When current flows from the first connection point to the motor and current flows from the motor to the second connection point, the control unit turns on the first switch at a sixth timing in a state where the first switch is turned off and the fourth switch is turned off, and performs the first action before the sixth timing within the one control cycle.

14. The power conversion device according to claim 2, characterized in that: When current flows from the first connection point to the motor and current flows from the motor to the second connection point, the control unit turns on the fourth switch at a seventh timing in a state where the first switch is turned off and the fourth switch is turned off, and performs the second action before the seventh timing within the one control cycle.

15. The power conversion device according to any one of claims 1 to 14, characterized in that: The control unit has a first mode in which the first branch and the second branch output voltages of the same phase, and a second mode in which the first branch and the second branch output voltages of opposite phases.

16. The power conversion device according to any one of claims 1 to 14, characterized in that: The H-bridge circuit includes a first capacitor connected in parallel with at least one of the first to fourth switches.

17. The power conversion device according to claim 16, characterized in that: The auxiliary circuit includes a second capacitor connected in parallel with at least one of the fifth switch and the sixth switch.

18. A motor module, characterized in that: include: A motor having two N-phase terminal groups (N is an integer greater than 3); as well as The power conversion device according to any one of claims 1 to 14.

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