Power conversion device

Abstract

Provided is a power conversion device capable of reducing noise generated during temperature rise control of a battery. A power conversion device (10) is provided with: a rotating electric machine (40) having windings (41U, 41V, 41W, 41X, 41Y); an inverter (30) having a series connection of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL); and a capacitor (31) connected in parallel with the series connection body. This power conversion device is provided with: connection paths (60, 90, 90U, 90W) that electrically connect the negative electrode side of a first storage battery (21) and the positive electrode side of a second storage battery (22), among the first storage battery (21) and the second storage battery (22) connected in series, to a winding; and a control unit (70) that performs switching control of the upper arm switch and the lower arm switch such that a current flows between the first battery and the second battery via the inverter, the winding, and the connection path.

Description

[0001] This invention patent application is a divisional application of the invention patent application with international application number PCT / JP2020 / 001772, international application date January 20, 2020, application number 202080010745.X entering the Chinese national phase, and name “Power Conversion Device”. Technical Field

[0002] The present disclosure relates to a power conversion device including: a rotating electric machine having a winding; an inverter having a series connection of an upper arm switch and a lower arm switch; and a capacitor connected in parallel to the series connection. Background Art

[0003] As such a power conversion device, it is known to control the temperature rise of the battery by exchanging reactive power between the battery and the capacitor via an inverter, as shown in Patent Document 1. Specifically, when current flows from the battery to the capacitor, the inverter and the winding are used as a step-up chopper circuit, and when current flows from the capacitor to the battery, the inverter and the winding are used as a step-up chopper circuit. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent No. 5865736 Summary of the invention

[0005] In the power conversion device described in Patent Document 1, since reactive power is exchanged between the battery and the capacitor, the terminal voltage of the capacitor varies in proportion to the reactive power. Due to this variation, the terminal voltage of the capacitor may exceed the allowable upper limit value determined by the withstand voltage performance of the capacitor, thereby reducing the reliability of the capacitor.

[0006] On the other hand, due to the change of the terminal voltage of the capacitor, the terminal voltage of the capacitor may be excessively reduced. When the current flows from the battery to the capacitor via the inverter, the terminal voltage of the capacitor needs to be higher than the terminal voltage of the battery. Therefore, if the terminal voltage of the capacitor is excessively reduced, it may be impossible to control the current flowing from the battery to the capacitor to the desired command current.

[0007] In order to deal with the above-described problems, it is necessary to reduce the fluctuation of the terminal voltage of the capacitor. In order to reduce the fluctuation, a countermeasure of increasing the capacitance of the capacitor can be considered. However, in this case, the capacitor will be enlarged.

[0008] On the other hand, in order to reduce the fluctuation, in addition to increasing the capacitance of the capacitor, a countermeasure of increasing the frequency of the reactive power (pulsating current) is also considered. However, in this case, the noise increases and the NVH characteristics of the power conversion device deteriorate.

[0009] A main object of the present disclosure is to provide a power conversion device capable of reducing noise generated during temperature increase control of a storage battery.

[0010] The present invention discloses an electric power conversion device, comprising: a rotating electric machine, wherein the rotating electric machine has a winding; an inverter having a series connection of an upper arm switch and a lower arm switch; and A capacitor connected in parallel with the series connection body, comprising: a connection path that electrically connects a negative electrode side of the first storage battery and a positive electrode side of the second storage battery, of the first storage battery and the second storage battery connected in series, to the winding; and A control unit performs switching control of the upper arm switch and the lower arm switch so that a current flows between the first battery and the second battery via the inverter, the winding, and the connection path.

[0011] The capacity of a battery is much larger than that of a capacitor. Therefore, the increase or decrease in terminal voltage relative to the charge and discharge current of a battery is much smaller than the increase or decrease in terminal voltage relative to the charge and discharge current of a capacitor. Therefore, if power can be exchanged between batteries instead of between capacitors and batteries, the change in terminal voltage of the capacitor during temperature rise control can be reduced without increasing the switching frequency of the upper arm switch and the lower arm switch.

[0012] Therefore, in order to exchange power between batteries via an inverter, the present disclosure includes a connection path that electrically connects the negative side of the first battery and the positive side of the second battery in the first battery and the second battery connected in series to the winding of the rotating electric machine. In addition, in order to increase the temperature of the first battery and the second battery, the control unit of the present disclosure performs switching control of the upper arm switch and the lower arm switch so that current flows between the first battery and the second battery via the inverter, the winding and the connection path. As a result, the variation of the terminal voltage of the capacitor can be reduced without increasing the switching frequency of the upper arm switch and the lower arm switch. Therefore, according to the present disclosure described above, the noise generated during the temperature increase control of the first battery and the second battery can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The above objects, other objects, features and advantages of the present disclosure will become more apparent with reference to the accompanying drawings and the following detailed description. Figure 1 It is a configuration diagram of the power conversion device according to the first embodiment. Figure 2 It is a flowchart showing the processing steps of the control device. Figure 3 is a diagram showing an equivalent circuit. Figure 4 It is a functional block diagram of the control device. Figure 5 This is a diagram showing a method of setting a command current. Figure 6 This is a timing chart showing the transition of the switch control method and the like. Figure 7 It is a graph showing the simulation results. Figure 8 It is a diagram showing the simulation results of the comparative example. Fig. 9 This is a timing chart showing the transition of the control method of the switch and the like according to the first modification of the first embodiment. Fig.10 This is a timing chart showing the transition of the control method of the switch and the like according to the first modification of the first embodiment. Fig.11 This is a functional block diagram of a control device according to Modification 2 of the first embodiment. Fig.12 It is a timing diagram showing the hysteresis control method. Fig.13 It is a diagram showing a method of correcting a command current according to the second embodiment. Fig.14 This is a diagram showing a method of correcting the command current. Fig.15 This is a flowchart showing the processing procedure of the control device according to the third embodiment. Fig.16 It is a configuration diagram of a power conversion device according to a fourth embodiment. Fig.17 It is a configuration diagram of a power conversion device according to a fifth embodiment. Fig.18 It is a functional block diagram of the control device. Fig.19 This is a timing chart showing the transition of the switch control method and the like. Fig. 20 It is a graph showing the simulation results. Fig.21 This is a functional block diagram of a control device according to Modification 1 of the fifth embodiment. Fig. 22 It is a timing chart showing the transition of the control method of the switch and the like according to the second modification of the fifth embodiment. Fig.23It is a configuration diagram of a power conversion device according to a sixth embodiment. Fig.24 It is a configuration diagram of a power conversion device according to a seventh embodiment. DETAILED DESCRIPTION

[0014] <First embodiment> Hereinafter, a first embodiment of the power conversion device of the present disclosure will be described with reference to the drawings. In this embodiment, the power conversion device is installed in a vehicle.

[0015] like Figure 1 As shown, the power conversion device 10 includes an inverter 30 and a rotary electric machine 40. The power conversion device 10 has a function of exchanging electric power between the battery pack 20 and the rotary electric machine 40 via the inverter 30 in order to increase the temperature of the battery pack 20.

[0016] The rotating electric machine 40 is a three-phase synchronous machine, including a U-phase winding 41U, a V-phase winding 41V, and a W-phase winding 41W connected in star shape as stator windings. The respective phase windings 41U, 41V, and 41W are arranged in a manner that each is staggered by 120° in electrical angle. The rotating electric machine 40 is, for example, a permanent magnet synchronous machine. In the present embodiment, the rotating electric machine 40 is a vehicle-mounted main machine and is a driving power source for the vehicle.

[0017] The inverter 30 includes a series connection of upper arm switches QUH, QVH, QWH and lower arm switches QUL, QVL, QWL corresponding to the number of three phases. In the present embodiment, as each switch QUH, QVH, QWH, QUL, QVL, QWL, a voltage-controlled semiconductor switch element is used, specifically, an IGBT is used. Therefore, the high potential side terminal of each switch QUH, QVH, QWH, QUL, QVL, QWL is the collector, and the low potential side terminal is the emitter. For each switch QUH, QVH, QWH, QUL, QVL, QWL, each diode DUH, DVH, DWH, DUL, DVL, DWL as a freewheeling diode is connected in reverse parallel.

[0018] The emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL are connected to the first end of the U-phase winding 41U via a U-phase conductive component 32U such as a busbar. The emitter of the V-phase upper arm switch QVH and the collector of the V-phase lower arm switch QVL are connected to the first end of the V-phase winding 41V via a V-phase conductive component 32V such as a busbar. The emitter of the W-phase upper arm switch QWH and the collector of the W-phase lower arm switch QWL are connected to the first end of the W-phase winding 41W via a W-phase conductive component 32W such as a busbar. The second ends of the U-phase winding 41U, the V-phase winding 41V, and the W-phase winding 41W are connected to each other at the neutral point O. In addition, in the present embodiment, the number of turns of each phase winding 41U, 41V, and 41W is set to be the same. As a result, the inductance of each phase winding 41U, 41V, and 41W is set to be the same.

[0019] The collector of each upper arm switch QUH, QVH, QWH is connected to the positive terminal of the battery pack 20 via a positive-side bus bar Lp such as a bus bar. The emitter of each lower arm switch QUL, QVL, QWL is connected to the negative terminal of the battery pack 20 via a negative-side bus bar Ln such as a bus bar.

[0020] The power conversion device 10 includes a capacitor 31 that connects the positive-side bus line Lp and the negative-side bus line Ln. The capacitor 31 may be built in the inverter 30 or provided outside the inverter 30.

[0021] The battery pack 20 is configured as a series connection of battery cells as single batteries, and the terminal voltage is, for example, several hundred V. In the present embodiment, the terminal voltages (for example, rated voltages) of the battery cells constituting the battery pack 20 are set to be the same. As the battery cells, for example, secondary batteries such as lithium-ion batteries can be used.

[0022] In the present embodiment, a plurality of battery cells on the high potential side of the battery cells constituting the battery pack 20 are connected in series to form a first storage battery 21, and a plurality of battery cells on the low potential side are connected in series to form a second storage battery 22. That is, the battery pack 20 is divided into two blocks. In the present embodiment, the number of battery cells constituting the first storage battery 21 is the same as the number of battery cells constituting the second storage battery 22. Therefore, the terminal voltage (e.g., rated voltage) of the first storage battery 21 is the same as the terminal voltage (e.g., rated voltage) of the second storage battery 22.

[0023] In the battery pack 20 , an intermediate terminal B is connected to the negative electrode terminal of the first storage battery 21 and the positive electrode terminal of the second storage battery 22 .

[0024] The power conversion device 10 includes a monitoring unit 50 (corresponding to a voltage information detection unit). The monitoring unit 50 monitors the terminal voltage, SOC, SOH, temperature, and the like of each battery cell constituting the battery pack 20.

[0025] The power conversion device 10 includes a connection path 60 and a connection switch 61. The connection path 60 electrically connects the intermediate terminal B of the battery pack 20 to the neutral point O. The connection switch 61 is provided on the connection path 60. In the present embodiment, a relay is used as the connection switch 61. By setting the connection switch 61 to the on state, the intermediate terminal B and the neutral point O are electrically connected. On the other hand, by setting the connection switch 61 to the off state, the intermediate terminal B and the neutral point O are electrically disconnected.

[0026] The power conversion device 10 includes a current sensor 62 that detects a current flowing through the connection path 60. The detection value of the current sensor 62 is input to a control device 70 (corresponding to a control unit) included in the power conversion device 10.

[0027] The control device 70 is mainly composed of a microcomputer, and performs switching control of each switch constituting the inverter 30 so as to feedback-control the control amount of the rotary electric machine 40 to the command value. The control amount is, for example, torque.

[0028] The control device 70 performs on / off control of the connection switch 61 and can communicate with the monitoring unit 50. In addition, the control device 70 can communicate with a higher-level control device 80 provided outside the power conversion device 10. The higher-level control device 80 performs overall control of the vehicle.

[0029] The control device 70 implements various control functions by executing programs stored in a storage device included in the control device 70. The various functions may be implemented by an electronic circuit as hardware or by both hardware and software.

[0030] Next, the temperature increase control of the battery pack 20 executed by the control device 70 will be described. Figure 2 2 is a flowchart showing the procedure of the temperature increase control process. This process is repeatedly executed by the control device 70 at a predetermined control cycle, for example.

[0031] In step S10, it is determined whether there is a request to increase the temperature of the battery pack 20. For example, when it is determined that an instruction to increase the temperature of the battery pack 20 is issued from the upper control device 80, or when the temperature of the battery pack 20 detected by the monitoring unit 50 is lower than the threshold temperature, it can be determined that there is a request to increase the temperature. Here, the temperature compared with the threshold temperature can be, for example, the lowest temperature among the temperatures of the detected battery cells, or the average temperature of the battery cells calculated based on the temperatures of the detected battery cells.

[0032] In the present embodiment, a situation in which an affirmative determination is made in step S10 is conceivably a situation in which the vehicle is stopped before the rotary electric machine 40 is driven.

[0033] If it is determined in step S10 that there is no temperature increase request, the process proceeds to step S11 to determine whether there is a drive request for the rotary electric machine 40. In the present embodiment, the drive request includes a request to drive the rotary electric machine 40 to cause the vehicle to travel.

[0034] If it is determined in step S11 that there is no drive request, the process proceeds to step S12 and the standby mode is set. By setting this mode, the switches QUH to QWL of the inverter 30 are controlled to be turned off. Then, in step S13, the connection switch 61 is controlled to be turned off. As a result, the intermediate terminal B and the neutral point O are electrically disconnected.

[0035] When it is determined in step S11 that there is a drive request, the process proceeds to step S14 and sets the drive mode of the rotating motor 40. Then, in step S15, the connection switch 61 is controlled to be turned on. As a result, the intermediate terminal B is electrically connected to the neutral point O via the connection path 60. Thereafter, in step S16, the switching control of each switch QUH~QWL of the inverter 30 is performed to drive the rotating motor 40. As a result, the driving wheels of the vehicle rotate, thereby enabling the vehicle to travel. In addition, the switching control in step S16 can be implemented, for example, using a PWM or pulse mode based on a comparison of the magnitude of the command voltage applied to each phase winding 41U~41W and a carrier signal (e.g., a triangular wave signal).

[0036] If it is determined in step S10 that there is a temperature increase request, the process proceeds to step S17 and the temperature increase control mode is set. In step S18, the connection switch 61 is controlled to be turned on.

[0037] In step S19, temperature increase PWM control is performed to increase the temperature of the battery pack 20. This control will be described below.

[0038] Figure 3 (a) shows an equivalent circuit of the power conversion device 10 used in the temperature increase PWM control. Figure 3 In (a), each phase winding 41U to 41W is represented as winding 41, each upper arm switch QUH, QVH, QWH is represented as upper arm switch QH, and each upper arm diode DUH, DVH, DWH is represented as upper arm diode DH. In addition, each lower arm switch QUL, QVL, QWL is represented as lower arm switch QL, and each lower arm diode DUL, DVL, DWL is represented as lower arm diode DL.

[0039] Figure 3 The equivalent circuit of (a) can be shown as Figure 3 (b) is the equivalent circuit of . Figure 3The circuit (b) is a buck-boost chopper circuit capable of bidirectional power transmission between the first battery 21 and the second battery 22. Figure 3 In (b), VBH represents the terminal voltage of the first battery 21, IBH represents the current flowing to the first battery 21, VBL represents the terminal voltage of the second battery 22, and IBL represents the current flowing to the second battery 22. When the charging current of the first battery 21 and the second battery 22 flows, IBH and IBL are negative, and when the discharging current of the first battery 21 and the second battery 22 flows, IBH and IBL are positive. In addition, VR represents the terminal voltage of the winding 41, and IR represents the current flowing to the neutral point O. When the current flows to the neutral point O in the positive direction from the winding 41 toward the intermediate terminal B, IR is negative, and when the current flows to the neutral point O in the opposite direction, IR is positive.

[0040] Reference Figure 3 (b), when the upper arm switch QH is in the on state, the terminal voltage VR of the winding 41 is "VBH". On the other hand, when the lower arm switch QL is in the on state, the terminal voltage VR of the winding 41 is "-VBL". That is, by turning on the upper arm switch QH, the excitation current can flow in the winding 41 in the positive direction, and by turning on the lower arm switch QL, the excitation current can flow in the winding 41 in the negative direction.

[0041] Figure 4 A block diagram of temperature-boosting PWM control is shown.

[0042] In the control device 70, the current deviation calculation unit 71 calculates the current deviation by subtracting the current detected by the current sensor 62 (hereinafter referred to as the detection current IMr) from the command current IM*. Figure 5As shown, the command current IM* is set to a sine wave. In detail, the command current IM* is set in such a way that the positive command current IM* and the negative command current IM* in one cycle Tc of the command current IM* are point-symmetrical with respect to the zero-crossing moment of the command current IM*. Thus, the period from the upward zero-crossing moment of the command current IM* to the downward zero-crossing moment is the same as the period from the downward zero-crossing moment of the command current IM* to the upward zero-crossing moment. In addition, in one cycle Tc of the command current IM*, the area S1 of the first region is equal to the area S2 of the second region. The first region S1 is a region surrounded by the time axis from the upward zero-crossing moment of the command current IM* to the downward zero-crossing moment and the positive command current IM* in one cycle Tc of the command current IM*. The second region is a region surrounded by the time axis from the downward zero-crossing moment of the command current IM* to the upward zero-crossing moment and the negative command current IM* in one cycle Tc. By setting “ S1 = S2 ”, the balance of charge and discharge currents of the first battery 21 and the second battery 22 in one cycle Tc can be made consistent, thereby preventing the difference between the terminal voltages of the first battery 21 and the second battery 22 from increasing due to temperature increase control.

[0043] For example, the frequency fc of the command current IM*, which is the inverse of one cycle Tc of the command current IM*, is preferably set to a frequency on the lower limit side of the human audible range. Specifically, the frequency fc is preferably set to a frequency region where the correction value (dB) in the A characteristic is 0 or less, that is, 1 kHz or less, and more preferably set to a frequency between 30 Hz and 100 Hz (e.g., 50 Hz).

[0044] The feedback control unit 72 calculates the duty ratio Duty as an operation variable for feedback-controlling the calculated current deviation to 0. The duty ratio Duty is a value that determines the ratio (Ton / Tsw) of the on-time Ton in one switching cycle Tsw of each switch QUH to QWL. In addition, the feedback control used in the feedback control unit 72 may be, for example, proportional-integral control.

[0045] The PWM generation unit 73 generates a gate signal for each upper arm switch QUH, QVH, QWH based on the calculated duty ratio Duty. The gate signal is a signal that instructs on control or off control. In the present embodiment, the gate signals for each upper arm switch QUH, QVH, QWH are synchronized.

[0046] The inverter 74 generates gate signals for the lower arm switches QUL, QVL, QWL by inverting the logic of the gate signals for the upper arm switches QUH, QVH, QWH generated by the PWM generator 73. In the present embodiment, the gate signals for the lower arm switches QUL, QVL, QWL are synchronized.

[0047] Figure 6 The figure shows the transition of the switching mode and the like during the temperature increase PWM control. Figure 6 (a) shows the transition of the gate signal of each upper arm switch QUH, QVH, QWH, Figure 6 (b) shows the transition of the gate signal of each lower arm switch QUL, QVL, QWL. Figure 6 (c) shows the transition of the current IR flowing to the neutral point O and the transition of the command current IM*. Figure 6 (d) represents the transition of the current IBH flowing to the first storage battery 21, Figure 6 (e) shows the transition of the current IBL flowing to the second battery 22 .

[0048] like Figure 6 As shown in (a) and (b), a temperature increase PWM control is implemented to alternately turn on the upper arm switches QUH, QVH, QWH and the lower arm switches QUL, QVL, QWL. This control is Figure 2 The step S10 continues until the temperature increase request disappears. Figure 6 As shown in (d) and (e) of FIG. 1 , a pulsed current flows to the first battery 21 and the second battery 22. During a period when the command current IM* is positive, the first battery 21 is discharged and the second battery 22 is charged. On the other hand, during a period when the command current IM* is negative, the second battery 22 is discharged and the first battery 21 is charged. In addition, the average values ​​IBHave and IBLave of the above-mentioned pulsed current are sinusoidal currents containing a component of the same frequency as the frequency of the command current IM*.

[0049] Figure 7 The simulation results of this embodiment are shown. Figure 7 (a) to (c) and the above Figure 6 (c) to (e) correspond to, Figure 7 (d) shows the transition of the terminal voltage of capacitor 31. Figure 7 As shown in (d), the terminal voltage of capacitor 31 does not change.

[0050] Figure 8 The simulation results of the comparative example of the structure described in the above-mentioned Patent Document 1 are shown. Figure 8 (a), (b) and the above Figure 7 (a) and (d) correspond to each other. In addition, Figure 8 (b) and Figure 7 SK shown in (d) is a symbol for indicating the scale of the time axis.

[0051] like Figure 8As shown in (b), in the comparative example, the terminal voltage of the capacitor varies greatly with the same cycle as the current IR flowing to the neutral point O. In order to reduce this variation, it is necessary to increase the capacitance of the capacitor or reduce the amplitude of the command current IM*, that is, the temperature rise capability.

[0052] According to the present embodiment described in detail above, the following effects can be obtained.

[0053] The intermediate terminal B and the neutral point O are connected through the connection path 60 instead of the switches QUH to QWL of the inverter 30. In this configuration, the control device 70 controls the switching of the inverter 30 so that the pulsating current flows between the first battery 21 and the second battery 22 via the inverter 30, the phase windings 41U, 41V, 41W, and the connection path 60. As a result, the variation of the terminal voltage of the capacitor 31 can be reduced without increasing the frequency fc (=1 / Tc) of the reactive power (pulsating current). Therefore, the noise generated during the temperature increase control of the battery pack 20 can be reduced.

[0054] Furthermore, since the amount of variation in the terminal voltage of the capacitor 31 can be reduced, the capacitance of the capacitor 31 can also be reduced, thereby miniaturizing the capacitor 31 .

[0055] The control device 70 synchronizes the switching control of the upper arm switches QUH, QVH, and QWH of all phases during the temperature rise control, and synchronizes the switching control of the lower arm switches QUL, QVL, and QWL of all phases. As a result, the windings 41U, 41V, and 41W of each phase can be regarded as an equivalent circuit in which the windings are connected in parallel. Therefore, the inductance of the windings during the temperature rise control can be reduced. As a result, the change in the current flowing to the neutral point O in one switching cycle Tsw can be increased, and a larger current can be used for temperature rise control.

[0056] Furthermore, by synchronizing the switching control, it is possible to suppress the rotor of the rotary electric machine 40 from being driven to rotate.

[0057] When determining that there is a request to increase the temperature of the battery pack 20, the control device 70 turns on the connection switch 61, and when determining that there is no request to increase the temperature, the control device 70 turns off the connection switch 61. This can suppress the current from flowing from the neutral point O to the intermediate terminal B when the vehicle is running.

[0058] <Modification 1 of the first embodiment> like Fig. 9 As shown, the temperature increase PWM control may be implemented by performing on-off control on two of the three phases. Fig. 9 An example is shown in which the W-phase upper arm switch QWH and the W-phase lower arm switch QWL are maintained in the OFF control. Fig. 9(a) shows the transition of the gate signal of the U-phase upper arm switch QUH and the V-phase upper arm switch QVH. Fig. 9 (b) shows the transition of the gate signal of the U-phase lower arm switch QUL and the V-phase lower arm switch QVL. Fig. 9 (c) shows the transition of the gate signal of the W-phase upper arm switch QWH and the W-phase lower arm switch QWL. Fig. 9 (d) to (f) and the above Figure 6 (c) to (e) correspond to.

[0059] In addition, if Fig.10 As shown, the temperature increase PWM control may be implemented by performing on-off control on one of the three phases. Fig.10 An example is shown in which only the U-phase upper arm switch QUH and the U-phase lower arm switch QUL are controlled to be on and off. Fig.10 (a) and (b) show the transition of the gate signals of the U-phase upper arm switch QUH and the U-phase lower arm switch QUL. Fig.10 (c) shows the transition of the gate signals of the V-phase upper arm switch QVH, the V-phase lower arm switch QVL, the W-phase upper arm switch QWH, and the W-phase lower arm switch QWL. Fig.10 (d) to (f) and the above Fig. 9 (d) to (f) correspond to.

[0060] Even in Fig. 9 or Fig.10 The switching control shown may increase the equivalent inductance of the winding 41 to reduce the current ripple when the pulsating current is small, thereby reducing the iron loss compared to switching control of all phases.

[0061] <Modification 2 of the first embodiment> replace Figure 4 The structure can also be Fig.11 In the control device 70, the hysteresis control unit 75 generates a current command based on the command current IM* and the detection current IMr. Fig.12 1 and 1. The gate signals of the upper arm switches QUH, QVH, and QWH shown in (b) of FIG. 1 are shown in FIG. 1. Specifically, the hysteresis control unit 75 generates the gate signals of the upper arm switches QUH, QVH, and QWH based on the current deviation between the command current IM* and the detection current IMr. The inverter 74 generates the gate signals of the upper arm switches QUH, QVH, and QWH by inverting the logic of the gate signals of the upper arm switches QUH, QVH, and QWH generated by the hysteresis control unit 75. Fig.12 The gate signals of the lower arm switches QUL, QVL, and QWL shown in (c) are as follows. Fig.12 As shown in (a), the detection current IMr is controlled within a range having a width of ±ΔI with respect to the command current IM*.

[0062] <Second Embodiment> Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

[0063] In the present embodiment, the control device 70 corrects the command current IM* so that the terminal voltage of the first battery 21 and the terminal voltage of the second battery 22 are balanced. Specifically, the control device 70 calculates the terminal voltage VHr of the first battery 21 and the terminal voltage VLr of the second battery 22 based on the information sent from the monitoring unit 50. Then, when it is determined that the terminal voltage VHr of the first battery 21 is higher than the terminal voltage VLr of the second battery 22, the control device 70 calculates the terminal voltage VHr of the first battery 21 and the terminal voltage VLr of the second battery 22. Fig.13 As shown in FIG. 1 , the control device 70 calculates the corrected command current by adding the DC component Idc (>0) to the command current IM*. As a result, in the corrected command current of one cycle Tc, the area S1 of the first region is larger than the area S2 of the second region. As a result, in one cycle Tc, the discharge current of the first storage battery 21 exceeds the discharge current of the second storage battery 22, so that the terminal voltage of the first storage battery 21 and the terminal voltage of the second storage battery 22 are balanced.

[0064] On the other hand, when it is determined that the terminal voltage VHr of the first battery 21 is lower than the terminal voltage VLr of the second battery 22, Fig.14 As shown in FIG. 1 , the control device 70 calculates the corrected command current by subtracting the DC component Idc from the command current IM*. As a result, in the corrected command current of one cycle Tc, the area S1 of the first region is smaller than the area S2 of the second region. As a result, in one cycle Tc, the discharge current of the second storage battery 22 exceeds the discharge current of the first storage battery 21, so that the terminal voltage of the first storage battery 21 and the terminal voltage of the second storage battery 22 are balanced.

[0065] According to the present embodiment described above, the terminal voltage of the first storage battery 21 and the terminal voltage of the second storage battery 22 can be balanced while performing the temperature increase control.

[0066] <Modification of Second Embodiment> The DC component Idc may be variably set based on the voltage difference between the terminal voltage VHr of the first battery 21 and the terminal voltage VLr of the second battery 22. Specifically, for example, when the terminal voltage VHr of the first battery 21 is higher than the terminal voltage VLr of the second battery 22, the DC component Idc may be set larger as "VHr-VLr" increases. Also, when the terminal voltage VHr of the first battery 21 is lower than the terminal voltage VLr of the second battery 22, the DC component Idc may be set larger as "VLr-VHr" increases.

[0067] In the correction process of command current IM*, instead of the terminal voltage of each battery, for example, the lowest voltage among the terminal voltages of the battery cells constituting each battery or the average value of the terminal voltages of the battery cells constituting each battery may be used.

[0068] <Third embodiment> Hereinafter, the third embodiment will be described with reference to the accompanying drawings, centering on the differences from the first embodiment. In this embodiment, the control device 70 sets the switching frequency fsw (=1 / Tsw) when the drive of the rotating electric machine 40 is stopped to a frequency higher than the switching frequency of the upper arm switch QUH to the lower arm switch QWL when the rotating electric machine 40 is driven to rotate and the vehicle is traveling, and to a frequency in the inaudible range of humans.

[0069] Fig.15 2 shows the steps of the temperature increase control process of this embodiment. This process is repeatedly executed by the control device 70 in a predetermined control cycle, for example. Fig.15 For convenience, Figure 2 The same processes as shown are denoted by the same symbols.

[0070] After the processing of step S18 is completed, the process proceeds to step S20 to perform temperature increase PWM control. Here, the switching frequency fsw of each switch QUH to QWL is set to be higher than the switching frequency set in the processing of step S16. Specifically, the switching frequency fsw is set to a frequency of 16 kHz or more, for example, a frequency in the inaudible range of humans (20 kHz or more).

[0071] Temperature rise control is implemented during parking. Such a situation is a situation in which the sensitivity of human hearing to the noise generated by the switching control of the inverter 30 becomes high. Therefore, by setting the switching frequency fsw to a frequency of 16 kHz or higher that is difficult for humans to hear and not a frequency in the inaudible range, or setting it to a frequency in the inaudible range, the NVH characteristics of the power conversion device 10 during temperature rise control can be improved. In addition, since frequencies above 16 kHz are too high, heating of each switch QUH~QWL due to switching losses may occur. However, during temperature rise control, since the surrounding environment of the vehicle is a low temperature environment, the temperature of each switch QUH~QWL is less likely to exceed its allowable upper limit value.

[0072] <Fourth embodiment> In the first embodiment, the rotating electric machine and the inverter may be five-phase, seven-phase, or other than three-phase rotating electric machines and inverters. Fig.16 Indicates a five-phase power conversion device. Fig.16For convenience, Figure 1 The same structures as shown are marked with the same symbols.

[0073] exist Fig.16 In the embodiment, an X-phase upper arm switch QXH, an X-phase lower arm switch QXL, and diodes DXH and DXL are added to the inverter 30, and a Y-phase upper arm switch QYH, a Y-phase lower arm switch QYL, and diodes DYH and DYL are added. In addition, an X-phase winding 41X and a Y-phase winding 41Y are added to the rotating electric machine 40. In addition, an X-phase conductive member 32X and a Y-phase conductive member 32Y are added to the power conversion device 10.

[0074] <Fifth embodiment> Hereinafter, with reference to the drawings, a fifth embodiment will be described focusing on differences from the first embodiment.

[0075] Fig.17 FIG. 2 is a diagram showing a configuration of a power conversion device in this embodiment. Fig.17 For convenience, Figure 1 The same structures as shown are marked with the same symbols.

[0076] In the above Figure 1 In the structure of the first embodiment shown, the power conversion device 10 includes a connection path 60, a connection switch 61, and a current sensor 62. In this embodiment, instead of these structures, the power conversion device 10 includes a connection path 90, a connection switch 91, and a current sensor 92. The emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL are connected to the intermediate terminal B of the battery pack 20 via the connection path 90. The connection switch 91 and the current sensor 92 are provided on the connection path 90.

[0077] In this embodiment, the control device 70 also performs the above Figure 2 Here, the connection switch 61 in steps S13, S15, and S18 is replaced by a connection switch 91. The equivalent circuit of the power conversion device 10 used in the temperature increase PWM control of this embodiment is the same as that of the above-mentioned Figure 3 The circuits shown are the same. In the temperature increase control process of this embodiment, the method of switching control in the temperature increase PWM control of step S19 is changed. This control will be described below.

[0078] Fig.18 FIG. 2 shows a block diagram of the temperature increase PWM control in this embodiment. Fig.18 In the embodiment, the configurations of the current deviation calculation unit 71 and the feedback control unit 72 and the method of setting the command current IM* are the same as those of the first embodiment, and thus their description is omitted.

[0079] The PWM generation unit 73 generates gate signals for the V-phase upper arm switch QVH and the W-phase upper arm switch QWH based on the duty ratio Duty calculated by the feedback control unit 72. The inverter 74 generates gate signals for the V-phase lower arm switch QVL and the W-phase lower arm switch QWL by inverting the logic of the gate signals for the V-phase upper arm switch QVH and the W-phase upper arm switch QWH. In the present embodiment, the U-phase upper arm switch QUH and the U-phase lower arm switch QUL are controlled to be disconnected. In addition, the switching control of the V-phase upper arm switch QVH and the W-phase upper arm switch QWH is synchronized, and the switching control of the V-phase lower arm switch QVL and the W-phase lower arm switch QWL is synchronized.

[0080] Fig.19 The figure shows the transition of the current IR and the like in this embodiment. Fig.19 (a) shows the transition of the current IR flowing to the connection path 90, Fig.19 (b) shows the transition of the current IBH flowing to the first storage battery 21, Fig.19 (c) shows the transition of the current IBL flowing to the second battery 22 . Fig.19 (d) shows the transition of the gate signal of the U-phase upper arm switch QUH and the U-phase lower arm switch QUL. Fig.19 (e) shows the transition of the gate signal of the V-phase upper arm switch QVH and the W-phase upper arm switch QWH. Fig.19 (f) shows the transition of the gate signals of the V-phase lower arm switch QVL and the W-phase lower arm switch QWL.

[0081] In this embodiment, if Fig.19 As shown in (d), the U-phase upper arm switch QUH and the U-phase lower arm switch QUL are turned off. Fig.19 As shown in (e) and (f), the V-phase upper arm switch QVH, the W-phase upper arm switch QWH and the V-phase lower arm switch QVL, the W-phase lower arm switch QWL are alternately turned on. Fig.19 As shown in (b) and (c), a pulse current flows to the first battery 21 and the second battery 22. Fig.19 As shown in (a), the current IR is controlled to be the command current IM*.

[0082] Fig. 20 The simulation results of this embodiment are shown. Fig. 20 (a) to (c) and the above Fig.19 (a) to (c) correspond to, Fig. 20 (d) shows the transition of the terminal voltage of capacitor 31. Fig. 20 As shown in (d), the terminal voltage of capacitor 31 does not change. Fig. 20SK shown in (d) is a symbol used to indicate the ratio of the time axis, which is the same as the above Figure 8 The SK shown in (b) corresponds to .

[0083] According to the present embodiment described in detail above, the following effects can be obtained.

[0084] The intermediate terminal B of the battery pack 20 is connected to the emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL via the connection path 90. In this structure, the control device 70 performs switching control of each switch QUH to QWL so that the pulsating current flows between the first battery 21 and the second battery 22 via the V-phase upper arm switch QVH, the V-phase lower arm switch QVL, the W-phase upper arm switch QWH, the W-phase lower arm switch QWL, the respective phase windings 41U, 41V, 41W, and the connection path 90. Thus, the same effect as that of the first embodiment can be obtained.

[0085] The control device 70 synchronizes the switching control of the V-phase upper arm switch QVH and the W-phase upper arm switch QWH during the temperature rise control, and synchronizes the switching control of the V-phase lower arm switch QVL and the W-phase lower arm switch QWL. As a result, the V-phase winding 41V and the W-phase winding 41W can be regarded as an equivalent circuit in which the windings are connected in parallel. Therefore, the inductance of the winding during the temperature rise control can be reduced.

[0086] <Modification 1 of the Fifth Embodiment> replace Fig.18 The structure can also be Fig.21 The structure shown in the figure performs switching control. In the control device 70, the hysteresis control unit 75 generates the gate signals of the V-phase upper arm switch QVH and the W-phase upper arm switch QWH based on the command current IM* and the detection current IMr. The inverter 74 generates the gate signals of the V-phase lower arm switch QVL and the W-phase lower arm switch QWL by inverting the logic of the gate signals of the V-phase upper arm switch QVH and the W-phase upper arm switch QWH generated by the hysteresis control unit 75.

[0087] <Variation 2 of the Fifth Embodiment> The control device 70 may perform temperature increase PWM control for performing on-off control on only one phase. Fig. 22 An example is shown in which the W-phase upper arm switch QWH and the W-phase lower arm switch QWL are controlled to be on and off. Fig. 22 (a) to (c) and the above Fig.19 (a) to (c) correspond to. Fig. 22 (d) represents the transition of the gate signals of the U-phase upper arm switch QUH, the U-phase lower arm switch QUL, the V-phase upper arm switch QVH, and the V-phase lower arm switch QVL. Fig. 22 (e) shows the transition of the gate signal of the W-phase upper arm switch QWH. Fig. 22 (f) represents the transition of the gate signal of the W-phase lower arm switch QWL.

[0088] In this embodiment, if Fig. 22 As shown in (d), the U-phase upper arm switch QUH, the U-phase lower arm switch QUL, the V-phase upper arm switch QVH, and the V-phase lower arm switch QVL are turned off. Fig. 22 As shown in (e) and (f), the W-phase upper arm switch QWH and the W-phase lower arm switch QWL are alternately controlled to be turned on.

[0089] according to Fig. 22 The switching control shown reduces the current ripple by increasing the equivalent inductance of the winding 41 when the pulsating current is small, and can reduce the iron loss compared to performing the switching control of the V phase and the W phase.

[0090] <Variation 3 of the Fifth Embodiment> The control device 70 can also be Fig.15 In this case, the control device 70 performs the temperature increase control in the above steps. Fig.15 After the processing of step S18 is completed, the process proceeds to step S20 to perform temperature increase PWM control. In this embodiment, the switching frequency fsw of the V-phase upper arm switch QVH, the V-phase lower arm switch QVL, the W-phase upper arm switch QWH, and the W-phase lower arm switch QWL is set to be higher than the switching frequency set in the processing of step S16. As a result, the same effect as the third embodiment can be obtained.

[0091] <Variation 4 of the Fifth Embodiment> As described in the second embodiment, the control device 70 may correct the command current IM* so as to balance the terminal voltage of the first battery 21 and the terminal voltage of the second battery 22. This can achieve the same effects as those of the second embodiment.

[0092] <Variation 5 of the Fifth Embodiment> The upper arm switch and the lower arm switch connected to the intermediate terminal B of the battery pack 20 are not limited to the U-phase upper arm switch QUH and the U-phase lower arm switch QUL, and may be, for example, the V-phase upper arm switch QVH and the V-phase lower arm switch QVL. In this case, in the temperature rise control, the V-phase upper arm switch QVH and the V-phase lower arm switch QVL are controlled to be disconnected. In addition, the U-phase upper arm switch QUH and the W-phase upper arm switch QWH and the U-phase lower arm switch QUL and the W-phase lower arm switch QWL are alternately controlled to be connected.

[0093] In addition, the upper arm switch and the lower arm switch connected to the intermediate terminal B may be, for example, a W-phase upper arm switch QWH and a W-phase lower arm switch QWL. In this case, in the temperature rise control, the W-phase upper arm switch QWH and the W-phase lower arm switch QWL are controlled to be turned off. In addition, the U-phase upper arm switch QUH and the V-phase upper arm switch QVH and the U-phase lower arm switch QUL and the V-phase lower arm switch QVL are alternately controlled to be turned on.

[0094] <Sixth embodiment> Hereinafter, the sixth embodiment will be described with reference to the accompanying drawings, centering on the differences from the fifth embodiment. In this embodiment, the upper arm switch and the lower arm switch connected to the intermediate terminal B of the battery pack 20 are not limited to one phase. It is sufficient as long as the upper arm switches and the lower arm switches of not all the U phases, V phases, and W phases are connected to the intermediate terminal B.

[0095] Fig.23 The structure diagram of the power conversion device when the U-phase upper arm switch QUH, the U-phase lower arm switch QUL and the W-phase upper arm switch QWH, the W-phase lower arm switch QWL are connected to the intermediate terminal B of the battery pack 20 is shown. In this embodiment, the intermediate terminal B of the battery pack 20 is connected to the emitter of the U-phase upper arm switch QUH and the collector of the U-phase lower arm switch QUL via the U-phase connection path 90U. In addition, the intermediate terminal B of the battery pack 20 is connected to the emitter of the W-phase upper arm switch QWH and the collector of the W-phase lower arm switch QWL via the W-phase connection path 90W.

[0096] In this embodiment, when temperature increase PWM control is implemented, U-phase upper arm switch QUH, U-phase lower arm switch QUL, W-phase upper arm switch QWH, and W-phase lower arm switch QWL are controlled to be turned off, and V-phase upper arm switch QVH and V-phase lower arm switch QVL are controlled to be turned on alternately.

[0097] According to the present embodiment described above, the same effects as those of the fifth embodiment can be obtained.

[0098] <Seventh embodiment> In the fifth embodiment, as described in the fourth embodiment, the rotating electrical machine and the inverter may be a rotating electrical machine and an inverter other than a three-phase machine such as a five-phase machine or a seven-phase machine. Fig.24 Indicates a five-phase power conversion device. Fig.24 For convenience, Fig.17 The same structures as shown are marked with the same symbols.

[0099] <Other embodiments> In addition, each of the above-mentioned embodiments may be implemented with the following modifications.

[0100] The installation location of the current sensor for detecting the current flowing to the neutral point O is not limited to Figure 1 For example, the current sensor can also be set at Figure 1 In this case, during the temperature increase control, the total value of the currents detected by the current sensors provided in the respective conductive members 32U, 32V, 32W may be set as the detection current IMr.

[0101] ·The setting method of command current IM* is not limited to Figure 5 It is also possible that in one cycle Tc, the positive command current IM* and the negative command current IM* satisfy a point-symmetric relationship with respect to the zero-crossing moment of the command current IM*, and for example, the positive command current IM* and the negative command current IM* are respectively set to a trapezoidal wave or a rectangular wave.

[0102] In addition, the method of setting the command current IM* is not limited to satisfying the above-mentioned point symmetric relationship. For example, in one cycle Tc, the command current IM* may be set so that the period from the upward zero-crossing moment to the downward zero-crossing moment of the command current IM* is different from the period from the downward zero-crossing moment to the upward zero-crossing moment of the command current IM* and the area S1 of the first region and the area S2 of the second region are equal. Even in this case, the balance of the charge and discharge currents of the first storage battery 21 and the second storage battery 22 in one cycle Tc can be made consistent.

[0103] The first battery 21 and the second battery 22 may have different numbers of battery cells. In this case, the terminal voltage of the first battery 21 is different from the terminal voltage of the second battery 22, and the intermediate terminal B is provided at a position that does not divide the battery cells constituting the battery pack 20 equally.

[0104] In the first embodiment, the control device 70 may not synchronize the switching control of the upper arm switches QUH, QVH, QWH of all phases, and may not synchronize the switching control of the lower arm switches QUL, QVL, QWL of all phases during the temperature increase control.

[0105] The connection switch 61 is not limited to a relay. For example, a pair of N-channel MOSFETs or IGBTs whose sources are connected to each other may be used as the connection switch 61.

[0106] In the first to fourth embodiments, the connection switch 61 is not essential. In this case, the intermediate terminal B and the neutral point O are always electrically connected.

[0107] The upper arm switch and the lower arm switch constituting the inverter are not limited to IGBTs, and may be, for example, N-channel MOSFETs. In this case, the high potential side terminal is the drain, and the low potential side terminal is the source.

[0108] The first storage battery and the second storage battery may not constitute a battery pack.

[0109] The control unit and the method of the control unit described in the present disclosure may also be implemented by a special-purpose computer, which is provided by constituting a processor and a memory, and the above-mentioned processor is programmed to execute one or more functions embodied by a computer program. Alternatively, the control unit and the method of the control unit described in the present disclosure may be implemented by a special-purpose computer, which is provided by constituting a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control unit and the method of the control unit described in the present disclosure may be implemented by one or more special-purpose computers, which are constituted by a combination of a processor and a memory programmed to execute one or more functions and a processor constituted by one or more hardware logic circuits. In addition, the computer program may also be stored in a computer-readable non-transitional tangible storage medium as an instruction executed by a computer.

[0110] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and methods, further including only one element, more than one or less than one other combinations and methods also belong to the scope and scope of thought of the present disclosure.

Claims

1. A power conversion device, the power conversion device being electrically connectable to a multi-phase winding (41U, 41V, 41W, 41X, 41Y) of a rotating electrical machine (40), a first storage battery (21), a second storage battery (22), and a capacitor (31), wherein the negative electrode side of the first storage battery and the positive electrode side of the second storage battery are electrically connectable to the neutral point (O) of the winding of each phase via a connection path (60), characterized in that: include: An inverter (30) having a series connection of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL) corresponding to the number of phases, A control unit (70) synchronizes the switching control of the upper arm switches of all phases and synchronizes the switching control of the lower arm switches of all phases so that current flows between the first battery and the second battery via the inverter, the winding and the connection path.

2. The power conversion device according to claim 1, characterized in that: The winding is a three-phase winding. The inverter includes a series connection of the upper arm switches and the lower arm switches corresponding to three phases.

3. The power conversion device according to claim 1, characterized in that: The winding is a five-phase winding. The inverter includes a series connection of the upper arm switches and the lower arm switches corresponding to five phases.

4. The power conversion device according to claim 1, characterized in that: The winding is a seven-phase winding. The inverter includes a series connection of the upper arm switches and the lower arm switches corresponding to seven phases.

5. The power conversion device according to any one of claims 1 to 4, characterized in that: The high potential side terminal of the upper arm switch of each phase can be electrically connected to the positive electrode side of the first battery. The low potential side terminal of the lower arm switch of each phase can be electrically connected to the negative electrode side of the second battery. In each phase, the low potential side terminal of the upper arm switch and the high potential side terminal of the lower arm switch can be electrically connected to the end on the opposite side to the neutral point side of both ends of the winding.

6. The power conversion device according to any one of claims 1 to 4, characterized in that: The control unit sets the command value in such a manner that a region specified by a positive command value and a region specified by a negative command value appear in one cycle of the command value of the current flowing through the connection path, and performs the control processing to control the current flowing in the connection path to the set command value.

7. The power conversion device according to any one of claims 1 to 4, characterized in that: The control unit sets a command value of the current flowing through the connection path to a sine wave shape, and performs the control process so as to control the current flowing through the connection path to the set command value.

8. A power conversion device, the power conversion device being electrically connectable to a multi-phase winding (41U, 41V, 41W, 41X, 41Y) of a rotating electrical machine (40), a first storage battery (21), a second storage battery (22), and a capacitor (31), wherein the negative electrode side of the first storage battery and the positive electrode side of the second storage battery are electrically connectable to the neutral point (O) of the winding of each phase via a connection path (60), characterized in that: include: An inverter (30) having a series connection of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL) corresponding to the number of phases, a control unit (70) that synchronizes the switching control of the upper arm switches of all phases and synchronizes the switching control of the lower arm switches of all phases so that current flows between the first battery and the second battery via the inverter, the winding and the connection path, The control unit sets the command value in such a manner that an area of ​​a region specified by a positive command value and an area of ​​a region specified by a negative command value in one cycle of the command value of the current flowing through the connection path are equal, and performs the control processing to control the current flowing in the connection path to the set command value.

9. The power conversion device according to claim 8, characterized in that: The control unit sets the command value so that the positive command value and the negative command value in one cycle of the command value are point-symmetrical with respect to a zero-crossing timing of the command value.

10. The power conversion device according to claim 8 or 9, characterized in that: A voltage information detection unit (50) is included, wherein the voltage information detection unit detects voltage information of the first storage battery and the second storage battery. The control unit corrects the command value based on the detected voltage information so that the terminal voltage of the first storage battery and the terminal voltage of the second storage battery are balanced.

11. The power conversion device according to any one of claims 1, 2, 3, 4, 8 and 9, characterized in that: A connection switch (61) is provided in the connection path, and when set to an on state, the negative electrode side of the first battery and the positive electrode side of the second battery are electrically connected to the neutral point, and when set to an off state, the negative electrode side of the first battery and the positive electrode side of the second battery are electrically disconnected from the neutral point.

12. The power conversion device according to claim 11, characterized in that: The control unit turns on the connection switch when it is determined that there is a request to increase the temperatures of the first and second batteries, and turns off the connection switch when it is determined that there is no request to increase the temperatures.

13. The power conversion device according to claim 12, characterized in that: The control unit performs switch control of the upper arm switch and the lower arm switch so as to open the connection switch and drive the rotating electric machine to rotate when it is determined that there is no temperature increase request and when it is determined that there is a drive request for the rotating electric machine.

14. The power conversion device according to claim 12, characterized in that: The control unit turns the connection switch to an OFF state and turns the upper arm switch and the lower arm switch to an OFF state when it is determined that there is no temperature increase request and when it is determined that there is no drive request for the rotating electric machine.

15. The power conversion device according to any one of claims 1, 2, 3, 4, 8 and 9, characterized in that: The control unit sets a switching frequency of the switch control when driving of the rotating electric machine is stopped to a frequency higher than switching frequencies of the upper arm switch and the lower arm switch when driving the rotating electric machine.

16. The power conversion device according to any one of claims 1, 2, 3, 4, 8 and 9, characterized in that: The control unit performs the control process when the rotating electric machine is not driven.

17. A recording medium having a computer-readable program for a power conversion device, wherein the power conversion device can be electrically connected to a multi-phase winding (41U, 41V, 41W, 41X, 41Y) of a rotating electrical machine (40), a first storage battery (21), a second storage battery (22), and a capacitor (31), wherein the negative electrode side of the first storage battery and the positive electrode side of the second storage battery can be electrically connected to the neutral point (O) of the winding of each phase through a connection path (60), characterized in that: The power conversion device comprises: An inverter (30) having a series connection of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL) corresponding to the number of phases, A control unit (70) synchronizes the switching control of the upper arm switches of all phases and synchronizes the switching control of the lower arm switches of all phases so that current flows between the first battery and the second battery via the inverter, the winding and the connection path.

18. A control method for a power conversion device, applicable to the power conversion device, capable of being electrically connected to a multi-phase winding (41U, 41V, 41W, 41X, 41Y) of a rotating electrical machine (40), a first storage battery (21), a second storage battery (22) and a capacitor (31), wherein the negative electrode side of the first storage battery and the positive electrode side of the second storage battery are electrically connected to the neutral point (O) of the winding of each phase through a connection path (60), characterized in that: The power conversion device includes an inverter (30) having a series connection of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL) corresponding to the number of phases. The control method of the power conversion device includes a control step, in which the switching control of the upper arm switches of all phases is synchronized, and the switching control of the lower arm switches of all phases is synchronized so that current flows between the first battery and the second battery via the inverter, the winding and the connection path.

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