Power conversion device

Abstract

A power conversion device (10) includes a connection path (60) that electrically connects a negative electrode side of a first storage battery (21) and a positive electrode side of a second storage battery (22) among the first storage battery and the second storage battery connected in series to a neutral point (O) of a winding (41U, 41V, 41W, 41X, 41Y) of a rotating electric machine (40), and a control section (70) that performs switching control of upper arm switches (QUH, QVH, QWH, QXH, QYH) and lower arm switches (QUL, QVL, QWL, QXL, QYL) of an inverter so that current flows between the first storage battery and the second storage battery via the inverter (30), the winding, and the connection path to perform transmission and reception of energy between the first storage battery and the second storage battery.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a power conversion device. BACKGROUND

[0002] In the past, as shown in Patent Literature 1, a voltage equalization device that equalizes terminal voltages of each battery cell configuring a battery pack is known. In detail, the device includes two switching elements corresponding to two adjacent battery cells and a reactor. A step-up / down converter is formed by the switching elements and the reactor, and by the operation of the converter, energy is transferred and received between the battery cells, thereby equalizing the terminal voltages of the battery cells.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2013-247690 SUMMARY

[0006] In the device described in Patent Literature 1, dedicated switching elements and a reactor for transferring and receiving energy between the battery cells are required. Therefore, the device can be large.

[0007] The main object of the present disclosure is to provide a power conversion device that can be downsized.

[0008] The present disclosure is a power conversion device including: a rotating electric machine having a winding;

[0009] an inverter having a series connection of an upper arm switch and a lower arm switch, wherein the power conversion device includes:

[0010] a connection path electrically connecting a negative electrode side of a first storage battery and a positive electrode side of a second storage battery in the series connection and a neutral point of the winding; and

[0011] a control section that performs switching control of the upper arm switch and the lower arm switch so as to transfer and receive energy between the first storage battery and the second storage battery by causing a current to flow between the first storage battery and the second storage battery via the inverter, the winding, and the connection path.

[0012] In the present disclosure, 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 of the winding through the connection path. Therefore, by performing the switching control of the upper arm switch and the lower arm switch, it is possible to perform the transfer and reception of energy between the first storage battery and the second storage battery by causing the current to flow between the first storage battery and the second storage battery via the inverter, the winding, and the connection path.

[0013] According to the present disclosure described above, it is possible to perform the transfer and reception of energy between the first storage battery and the second storage battery using the winding of the rotating electric machine and the inverter. Therefore, it is possible to achieve the downsizing of the power conversion device. BRIEF DESCRIPTION OF DRAWINGS

[0014] The above objects, other objects, features, and advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0015] Figure 1 is a configuration diagram of the power conversion device of the first embodiment.

[0016] Figure 2 is a flowchart showing the processing steps of the control device.

[0017] Figure 3 is a diagram showing an equivalent circuit.

[0018] Figure 4 is a block diagram showing the processing of the control device at the time of parking.

[0019] Figure 5 is a diagram showing the setting method of the command current.

[0020] Figure 6 is a block diagram showing the processing of the control device at the time of driving the rotating electric machine.

[0021] Figure 7 is a timing chart showing the transition of the modulation factor at the time of transferring electric power from the first storage battery to the second storage battery.

[0022] Figure 8 is a timing chart showing the transition of the modulation factor at the time of transferring electric power from the second storage battery to the first storage battery.

[0023] Figure 9 is a timing chart showing the transition of the phase current and the like at the time of transferring electric power from the first storage battery to the second storage battery.

[0024] Figure 10 is a timing chart showing the transition of the phase current and the like at the time of transferring electric power from the second storage battery to the first storage battery.

[0025] Figure 11 is a configuration diagram of the power conversion device of the second embodiment.

[0026] Figure 12 This is a structural diagram of the power conversion device according to the third embodiment.

[0027] Figure 13 This is a structural diagram of the power conversion device according to the fourth embodiment.

[0028] Figure 14 This is a structural diagram of the power conversion device according to the fifth embodiment.

[0029] Figure 15 It is a flowchart representing the processing steps of the control device.

[0030] Figure 16 It is a timing diagram that shows the transition of phase currents, etc., during charging from an external charger.

[0031] Figure 17 This is a structural diagram of a power conversion device in other embodiments. Detailed Implementation

[0032] <First Implementation>

[0033] Hereinafter, a first embodiment of the power conversion device of this disclosure will be described with reference to the accompanying drawings. The power conversion device of this embodiment is, for example, installed in an electric vehicle or a hybrid vehicle.

[0034] like Figure 1 As shown, the power conversion device 10 includes an inverter 30 and a rotating motor 40. The rotating motor 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 a star configuration as stator windings. Each phase winding 41U, 41V, and 41W is arranged with an electrical angle offset of 120°. The rotating motor 40 is, for example, a permanent magnet synchronous machine. In this embodiment, the rotating motor 40 is an on-board unit and serves as the vehicle's power source.

[0035] The inverter 30 includes a series connection of upper arm switches QUH, QVH, QWH and lower arm switches QUL, QVL, QWL corresponding to three phases. In this embodiment, voltage-controlled semiconductor switching elements, specifically IGBTs, are used as each of the switches QUH, QVH, QWH, QUL, QVL, QWL. 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 of the diodes DUH, DVH, DWH, DUL, DVL, DWL, serving as freewheeling diodes, is connected in reverse parallel.

[0036] The first end of the U-phase winding 41U 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 conductive member 32U such as a bus bar. The first end of the V-phase winding 41V is connected to the emitter of the V-phase upper arm switch QVH and the collector of the V-phase lower arm switch QVL via the V-phase conductive member 32V such as a bus bar. The first end of the W-phase winding 41W 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 conductive member 32W such as a bus bar. 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 the present embodiment, the number of turns of each of the phase windings 41U, 41V, and 41W is set to be the same. Thus, the inductance of each of the phase windings 41U, 41V, and 41W is set to be the same, for example.

[0037] The collector of each of the upper arm switches QUH, QVH, and QWH is connected to the positive terminal of the battery group 20 via the positive-side bus bar Lp such as a bus bar. The emitter of each of the lower arm switches QUL, QVL, and QWL is connected to the negative terminal of the battery group 20 via the negative-side bus bar Ln such as a bus bar.

[0038] The power conversion device 10 includes a capacitor 31 that connects the positive-side bus bar Lp and the negative-side bus bar Ln. The capacitor 31 can be built in the inverter 30 or can be provided outside the inverter 30.

[0039] The battery group 20 is configured as a series connection body of battery cells as single cells, and the terminal voltage is several hundred V, for example. In the present embodiment, the terminal voltage (e.g., the rated voltage) of each of the battery cells that configures the battery group 20 is set to be the same as each other. As the battery cell, a secondary battery such as a lithium-ion battery can be used, for example. Further, the battery group 20 is provided outside the power conversion device 10, for example.

[0040] In the present embodiment, a series connection body of a plurality of battery cells on the high-potential side among the battery cells that configures the battery group 20 configures the first storage battery 21, and a series connection body of a plurality of battery cells on the low-potential side configures the second storage battery 22. That is, the battery group 20 is divided into two blocks. In the present embodiment, the number of battery cells that configures the first storage battery 21 is the same as the number of battery cells that configures the second storage battery 22. Thus, the terminal voltage (e.g., the rated voltage) of the first storage battery 21 is the same as the terminal voltage (e.g., the rated voltage) of the second storage battery 22.

[0041] In the battery group 20, an intermediate terminal B is connected to the negative terminal of the first storage battery 21 and the positive terminal of the second storage battery 22.

[0042] The power conversion device 10 includes a monitoring unit 50. The monitoring unit 50 monitors the terminal voltage, SOC, SOH, temperature, and the like of each battery cell that constitutes the battery pack 20.

[0043] The power conversion device 10 includes a connection path 60 and a connection switch 61. The connection path 60 electrically connects the middle terminal B of the battery pack 20 and 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 be on, the middle terminal B and the neutral point O are electrically connected. On the other hand, by setting the connection switch 61 to be off, the middle terminal B and the neutral point O are electrically cut off.

[0044] The power conversion device 10 includes a current sensor 62 and a phase current sensor 63. The current sensor 62 detects the current flowing in the connection path 60. The phase current sensor 63 detects the phase current corresponding to at least two phases. The phase current sensor 63, for example, detects the current flowing in at least the conductive members corresponding to two phases among the conductive members 32U to 32W. The detection values of each of the current sensors 62, 63 are input to a control device 70 (corresponding to a control section) included in the power conversion device 10.

[0045] The control device 70 is configured mainly of a microcomputer, and performs switching control of each switch that constitutes the inverter 30 to feedback control the control amount of the rotating electric machine 40 to the command value. The control amount is, for example, torque. In each phase, the upper arm switch and the lower arm switch are alternately turned on.

[0046] The control device 70 turns on and off the connection switch 61, and is capable of communicating with the monitoring unit 50. In addition, the control device 70 realizes various control functions by executing a program stored in a storage device included therein. The various functions can be realized by an electronic circuit as hardware, or by both hardware and software.

[0047] Next, the equalization control performed by the control device 70 will be described. Figure 2 is a flowchart showing the steps of the equalization control process. The process is repeatedly performed by the control device 70 at, for example, a prescribed control cycle.

[0048] In step S10, it is determined whether or not there is a request for equalization of the terminal voltage of each of the first battery 21 and the second battery 22. In the present embodiment, it is determined that there is a request for equalization in a case where it is determined that the absolute value of the difference between the terminal voltage VBH of the first battery 21 and the terminal voltage VBL of the second battery 22 exceeds a prescribed value ΔV. Here, the terminal voltage VBH of the first battery 21 and the terminal voltage VBL of the second battery 22 can be obtained from the monitoring unit 50.

[0049] In the case where it is determined in step S10 that there is no equalization request, the routine proceeds to step Sll, where it is determined whether there is a drive request for the rotating electric machine 40. In the present embodiment, the drive request includes a request to travel the vehicle by the rotational drive of the rotating electric machine 40.

[0050] In the case where it is determined in step Sll that there is no drive request, the routine proceeds to step S12, where the standby mode is set. By setting this mode, the respective switches QUL to QWL of the inverter 30 are turned off. Then, in step S13, the connecting switch 61 is turned off. Thereby, the intermediate terminal B is electrically cut off from the neutral point O.

[0051] In the case where it is determined in step Sll that there is a drive request, the routine proceeds to step S14, where the drive mode of the rotating electric machine 40 is set. Then, in step S15, the connecting switch 61 is turned on. Thereby, the intermediate terminal B is electrically connected to the neutral point O via the connecting path 60. Thereafter, in step S16, the switch control of the respective switches QUL to QWL of the inverter 30 is performed to drive the rotating electric machine 40 to rotate. Thereby, the drive wheels of the vehicle are rotated, so that the vehicle can travel.

[0052] In the case where it is determined in step S10 that there is an equalization request, the routine proceeds to step S17, where the equalization control mode is set. In step S18, the connecting switch 61 is turned on.

[0053] In step S19, the equalization control to equalize the terminal voltages of the first and second storage batteries 21 and 22, respectively, is performed. Hereinafter, this control will be described.

[0054] Figure 3 (a) of FIG. 10 shows an equivalent circuit of the power conversion device 10 used in the equalization control. In Figure 3 In (a) of FIG. 10, the respective phase windings 41U to 41W are shown as the winding 41, the respective upper arm switches QUL, QVL, QWL are shown as the upper arm switch QH, and the respective upper arm diodes DUH, DVH, DWH are shown as the upper arm diode DH. In addition, the respective lower arm switches QUL, QVL, QWL are shown as the lower arm switch QL, and the respective lower arm diodes DUL, DVL, DWL are shown as the lower arm diode DL.

[0055] Figure 3 The equivalent circuit of (a) of FIG. 10 can be shown as Figure 3 the equivalent circuit of (b) of FIG. 10. Figure 3 The circuit of (b) of FIG. 10 is a step-up / down chopper circuit that can perform bidirectional power transmission between the first and second storage batteries 21 and 22. In Figure 3In (b) of FIG. 9, IBH denotes a current flowing to the first battery 21, and IBL denotes a current flowing to the second battery 22. IBH and IBL are negative when the charging current of the first battery 21 and the second battery 22 flows, and are positive when the discharging current of the first battery 21 and the second battery 22 flows. In addition, VR denotes a terminal voltage of the winding 41, and IR denotes a current flowing to the neutral point O. IR is negative when the current flows to the neutral point O in the positive direction from the winding 41 toward the intermediate terminal B, and is positive when the current flows to the neutral point O in the opposite direction.

[0056] Referring to Figure 3 (b) of FIG. 9, when the upper arm switch QH is turned on, the terminal voltage VR of the winding 41 is "VBH". On the other hand, when the lower arm switch QL is turned on, the terminal voltage VR of the winding 41 is "-VBL". That is, by turning on the upper arm switch QH, it is possible to make the field current flow in the winding 41 in the positive direction, and by turning on the lower arm switch QL, it is possible to make the field current flow in the winding 41 in the negative direction.

[0057] Figure 4 A block diagram of the equalization control is shown. Figure 4 is a control block of the equalization control implemented in the parking of the vehicle before the rotary electric machine 40 is driven.

[0058] The control device 70 includes an equalization control section 90. The equalization control section 90 includes an instruction value setting section 91, a neutral point deviation calculation section 92, a neutral point control section 93, a U-phase overlap section 94U to a W-phase overlap section 94W.

[0059] The instruction value setting section 91 sets the neutral point instruction current IM*. In detail, the instruction value setting section 91 calculates a judgment voltage Vj (= VBH - VBL) by subtracting the terminal voltage VBL of the second battery 22 from the terminal voltage VBH of the first battery 21. The instruction value setting section 91 sets the neutral point instruction current IM* to a positive value when the calculated judgment voltage Vj is a positive value, and in detail, as shown in FIG. 10, the higher the judgment voltage Vj, the larger the neutral point instruction current IM* is set. Figure 5

[0060] The instruction value setting section 91 sets the neutral point instruction current IM* to a negative value when the calculated judgment voltage Vj is a negative value, and in detail, the larger the absolute value of the judgment voltage Vj, the larger the absolute value of the neutral point instruction current IM* is set.

[0061] ​The neutral-point deviation calculation section 92 calculates the neutral-point current deviation ΔIM by subtracting the neutral-point current IMr detected by the current sensor 62 from the neutral-point command current IM*. In the present embodiment, the neutral-point command current IM* is a direct-current signal.

[0062] The neutral-point control section 93 calculates the offset correction amount CF as an operation amount for feedback-controlling the calculated neutral-point current deviation ΔIM to 0. In the present embodiment, proportional-integral control is used as this feedback control. In addition, the feedback control is not limited to proportional-integral control, and may, for example, be proportional-integral-derivative control.

[0063] The U-phase overlap section 94U calculates the U-phase final command voltage "Vu+CF" by adding the U-phase command voltage Vu to the offset correction amount CF. The V-phase overlap section 94V calculates the V-phase final command voltage "Vv+CF" by adding the V-phase command voltage Vv to the offset correction amount CF. The W-phase overlap section 94W calculates the W-phase final command voltage "Vw+CF" by adding the W-phase command voltage Vw to the offset correction amount CF. In the present embodiment, the U-phase command voltage Vu, the V-phase command voltage Vv, and the W-phase command voltage Vw are 0 because the vehicle is in a stop state. Therefore, the U-phase final command voltage, the V-phase final command voltage, and the W-phase final command voltage are the offset correction amount CF. Figure 4

[0064] The control device 70 includes the U-phase modulation section 95U to the W-phase modulation section 95W. The U-phase modulation section 95U calculates the U-phase modulation coefficient Mu by dividing the U-phase final command voltage by the power supply voltage Vdc. Here, the power supply voltage Vdc is the sum of the terminal voltage VBH of the first storage battery 21 and the terminal voltage VBL of the second storage battery 22, which are acquired from the monitoring unit 50. The V-phase modulation section 95V calculates the V-phase modulation coefficient Mv by dividing the V-phase final command voltage by the power supply voltage Vdc. The W-phase modulation section 95W calculates the W-phase modulation coefficient Mw by dividing the W-phase final command voltage by the power supply voltage Vdc.

[0065] The control device 70 performs switching control of the switches QUH to QWL corresponding to the three phases on the basis of the calculated modulation coefficients Mu, Mv, and Mw. Specifically, for example, the control device 70 can perform switching control by PWM control based on a size comparison of the modulation coefficients Mu, Mv, and Mw and a carrier signal (for example, a triangular wave signal).

[0066] The equalization control can be implemented not only in the stop state but also when the rotating electric machine 40 is driven and the vehicle is in a running state. Figure 6 is a control block of the equalization control implemented in this case. In addition, in Figure 6 , the same reference numerals are attached to the same structures as those shown in the previous Figure 4 .​

[0067] In the control device 70, the d-axis deviation calculation section lOOd calculates a d-axis current deviation ΔId by subtracting the d-axis current Idr from the d-axis command current Id*. The q-axis deviation calculation section lOOq calculates a q-axis current deviation ΔIq by subtracting the q-axis current Iqr from the q-axis command current Iq*. Here, the d-axis command current Id* and the q-axis command current Iq* are set based on the command torque of the rotating electric machine 40. In addition, the d-axis current Ird and the q-axis current Iqr are calculated based on the detection value of the phase current sensor 63 and the electric angle of the rotating electric machine 40. Further, the electric angle can be a detection value of a resolver or the like rotating angle sensor, or can be an estimated value estimated by a position sensorless control.

[0068] The d-axis control section lOId calculates a d-axis voltage Vd as an operation amount for feedback-controlling the calculated d-axis current deviation ΔId to 0. The q-axis control section lOIQ calculates a q-axis voltage Vq as an operation amount for feedback-controlling the calculated q-axis current deviation ΔIq to 0. In the present embodiment, proportional integral control is used as the feedback control of each control section lOId, lOIQ. Further, as the feedback control, proportional integral control is not limited to proportional integral control, and for example, proportional integral derivative control can also be used.

[0069] The three-phase conversion section 102 calculates U-phase command voltages Vu to W-phase command voltages Vw in a three-phase fixed coordinate system based on the d-axis voltage Vd, the q-axis voltage Vq, and the above-mentioned electric angle. Each phase command voltage Vu to Vw is a signal (specifically, a sinusoidal signal) in which phases are each shifted by 120 degrees in electric angle.

[0070] The U-phase command voltages Vu to W-phase command voltages Vw calculated by the three-phase conversion section 102 are added to the offset correction amount CF in the U-phase overlap section 94U to the W-phase overlap section 94W. Thereby, U-phase final command voltages to W-phase final command voltages are calculated.

[0071] Here, Figure 7 The transition of each phase modulation factor Mu to Mw when the neutral point command current IM* is positive is shown. In this case, current is supplied from the first battery 21 to the second battery 22, and the terminal voltages of each battery 21, 22 are equalized.

[0072] Figure 8 The transition of each phase modulation factor Mu to Mw when the neutral point command current IM* is negative is shown. In this case, current is supplied from the second battery 22 to the first battery 21, and the terminal voltages of each battery 21, 22 are equalized.

[0073] Figure 9 Each waveform when the neutral point command current IM* is set to a positive value is shown.Figure 9 (a) represents the transitions of the phase currents Iu, Iv, and Iw. Figure 9 (b) represents the transition of the neutral point current IMr. Figure 9 (c) represents the change in the current IBH flowing through the first battery 21. Figure 9 (d) represents the change in current IBL flowing through the second battery 22. On the other hand, Figure 10 The waveform is shown when the neutral point command current IM* is set to a negative value. Figure 10 (a) to (d) and the previous Figure 9 The correspondence between (a) and (d). For example Figure 9 (b) and Figure 10 As shown in (b), DC current flows through connection path 60.

[0074] Based on the implementation method described above, the following effects can be obtained.

[0075] Intermediate terminal B and neutral point O are electrically connected via connection path 60. Therefore, when an equalization request is detected, by controlling the switching of each switch QUH to QWL, current can flow between the first battery 21 and the second battery 22 via the inverter 30, windings 41U to 41W, and connection path 60, thereby equalizing the terminal voltages of the first battery 21 and the second battery 22. In this way, the existing windings 41U to 41W and inverter 30 can be used to equalize the terminal voltages of the first battery 21 and the second battery 22. Therefore, it is not necessary to add a dedicated reactor for equalization, thereby enabling miniaturization of the power conversion device 10.

[0076] If an equalization request is detected, the connection switch 61 located on the connection path 60 is turned on. Conversely, if no equalization request is detected, the connection switch 61 is turned off. Thus, in the absence of an equalization request, current flow between the neutral point O and the intermediate terminal B can be suppressed.

[0077] If an equalization request is detected during the driving of the rotary motor 40, the switching control of switches QUH to QWL is performed to equalize the terminal voltages of the first battery 21 and the second battery 22 while driving the rotary motor 40. This ensures both drive control and equalization control of the rotary motor 40.

[0078] The switching control of the upper arm switches QUH, QVH, QWH of all phases is synchronized in the equalization control, and in addition, the switching control of the lower arm switches QUL, QVL, QWL of all phases is synchronized. Due to this, each phase winding 41U, 41V, 41W can be regarded as an equivalent circuit in which the windings are connected in parallel. Therefore, the inductance of the windings at the time of equalization control can be reduced. Due to this, the amount of change in the current flowing to the neutral point O can be made large in one switching period of each switch QUH to QWL, and equalization control using a large current can be performed, for example, in parking.

[0079] <Second Embodiment>

[0080] Hereinafter, with reference to the drawings, the second embodiment will be described focusing on the points different from the first embodiment. In the present embodiment, as shown in Figure 11 , the electric compressor 110 and the DC-DC converter 111, which are high voltage loads, are connected in parallel to the second battery 22. In addition, in Figure 11 , the same symbols are attached to the same structures as those shown in the previous Figure 1 .

[0081] The electric compressor 110 is provided for air conditioning in the vehicle cabin, and is driven to circulate refrigerant of a refrigeration cycle. The DC-DC converter 111 is driven to step down the output voltage of the second battery 22 and supply it to the low voltage battery 120. The low voltage battery 120 is, for example, a lead battery with a rated voltage of 12 V.

[0082] In the present embodiment, in a case where it is determined that at least one of the electric compressor 110 and the DC-DC converter 111 is driven, the control device 70 determines that there is an equalization request. The control device 70, in a case where it is determined that there is an equalization request, equalizes the terminal voltages of the second battery 22 and the first battery 21 by performing switching control of each switch QUH to QWL to cause current to flow from the first battery 21 to the second battery 22 via the inverter 30 and the connection path 60.

[0083] According to the above-described present embodiment, even in a case where power is taken out from the second battery 22 by driving at least one of the electric compressor 110 and the DC-DC converter 111, the SOC of each of the first battery 21 and the second battery 22 can be suppressed from greatly deviating.

[0084] <Third Embodiment>

[0085] Hereinafter, with reference to the drawings, the third embodiment will be described focusing on the points different from the second embodiment. In the present embodiment, as shown in Figure 12As shown, the electric compressor 110 is connected in parallel to the first battery 21, and the DC-DC converter 111 is connected in parallel to the second battery 22. Further, in Figure 12 In the present embodiment, for convenience, the same reference signs are attached to the same structures as those shown in the first embodiment. Figure 11 In the present embodiment, for convenience, the same reference signs are attached to the same structures as those shown in the first embodiment.

[0086] In the case where it is determined that at least one of the electric compressor 110 and the DC-DC converter 111 is driven, the control device 70 determines that there is a request for equalization. The control device 70, in the case where it is determined that there is a request for equalization, performs switching control of the switches QUH to QWL so that a current for equalizing the terminal voltages of the second battery 22 and the first battery 21 respectively flows between the first battery 21 and the second battery 22 via the inverter 30 and the connection path 60.

[0087] For example, in the case where it is determined that the electric power taken out from the first battery 21 by driving of the electric compressor 110 is greater than the electric power taken out from the second battery 22 by driving of the DC-DC converter 111, the control device 70 performs switching control of the switches QUH to QWL so that a current flows from the second battery 22 to the first battery 21 via the inverter 30 and the connection path 60. Further, for example, in the case where it is determined that the electric power taken out from the second battery 22 by driving of the DC-DC converter 111 is greater than the electric power taken out from the first battery 21 by driving of the electric compressor 110, the control device 70 performs switching control of the switches QUH to QWL so that a current flows from the first battery 21 to the second battery 22 via the inverter 30 and the connection path 60.

[0088] According to the present embodiment described above, even in the case where the electric power taken out, the driving timing, or the operation rate of the electric compressor 110 and the DC-DC converter 111 are different, it is possible to suppress the SOC of the first battery 21 and the second battery 22 from greatly deviating.

[0089] <Fourth Embodiment>

[0090] Hereinafter, the fourth embodiment will be described with reference to the drawings, focusing on the points different from the second embodiment. In the present embodiment, as shown in FIG. 10, the electric compressor 110 and the DC-DC converter 111 are connected in parallel to the first battery 21. Further, in Figure 13 In the present embodiment, for convenience, the same reference signs are attached to the same structures as those shown in the first embodiment. Figure 13 In the present embodiment, for convenience, the same reference signs are attached to the same structures as those shown in the first embodiment. Figure 11 In the present embodiment, for convenience, the same reference signs are attached to the same structures as those shown in the first embodiment.

[0091] According to the present embodiment described above, the same effects as those of the second embodiment can be obtained.

[0092] Fifth Embodiment

[0093] Hereinafter, the fifth embodiment will be described with reference to the drawings, using Figure 14 The fifth embodiment will be described with focus on the points different from the first embodiment. Also, in the following description, the same structures as those shown in the first embodiment are labeled with the same symbols for convenience. Figure 14 Figure 1

[0094] In the present embodiment, the rated voltage of each of the first storage battery 21 and the second storage battery 22 is 400 V. Therefore, the rated voltage of the battery pack 20 is 800 V.

[0095] The second storage battery 22 (corresponding to "target battery") is connectable to a first charger 121 provided outside the vehicle, and the series connection body of the first storage battery 21 and the second storage battery 22 is connectable to a second charger 122 provided outside the vehicle. The charging voltage of the second charger 122 is set higher than the charging voltage of the first charger 121. The first charger 121 corresponds to quick charging, and the second charger 122 corresponds to super quick charging.

[0096] The positive electrode side of the first charger 121 is connectable to the intermediate terminal B via a first switch SW1. The negative electrode sides of the first charger 121 and the second charger 122 are connectable to the negative electrode side of the second storage battery 22 via a second switch SW2. The positive electrode side of the second charger 122 is connectable to the positive electrode side of the first storage battery 21 via a third switch SW3. In the present embodiment, the first switch SW1 to the third switch SW3 are turned on or off by the control device 70.

[0097] The steps of the equalization control processing according to the present embodiment will be described using Figure 15 The processing is repeatedly executed by the control device 70 at, for example, a prescribed control cycle.

[0098] In step S30, it is determined whether or not there is an implementation request for quick charging of the second storage battery 22 by the first charger 121.

[0099] When it is determined affirmative in step S30, it is determined that there is an equalization request, and the processing proceeds to step S31. In step S31, the first switch SW1 and the second switch SW2 are turned on, and the third switch SW3 is turned off. Also, the connection switch 61 is turned on.

[0100] ​​In step S32, switching control of each of the switches Q UH to Q WL corresponding to the three phases is performed so that current flows from the second storage battery 22 to the first storage battery 21 via the inverter 30 and the connection path 60. Thereby, even in the absence of the second charger 122, the battery pack 20 can be properly charged by the first charger 121 while equalizing the terminal voltages of the first storage battery 21 and the second storage battery 22. Figure 16 The transition of each waveform at the time of performing the process of step S32 is shown. Figure 16 (a) to (d) of FIG. 6 correspond to the previous Figure 9 (a) to (d) of FIG. 6.

[0101] In the case where the determination in step S30 is negative, the process proceeds to step S33, where it is determined whether or not there is a request for implementation of super-fast charging of the battery pack 20 by the second charger 122.

[0102] In the case where the determination in step S33 is affirmative, the process proceeds to step S34, where the second switch SW2 and the third switch SW3 are turned on, and the first switch SW1 is turned off. In addition, the connection switch 61 is turned on. Thereby, the battery pack 20 is charged by the second charger 122.

[0103] In addition, in the case where the determination in step S33 is negative, the first switch SW1 to the third switch SW3 and the connection switch 61 are turned off.

[0104] According to the present embodiment described above, in a system corresponding to super-fast charging of 800 V, the battery pack 20 can be charged using fast charging of 400 V by implementing equalization control.

[0105] In addition, in the present embodiment, for example, the electric compressor 110 and the DC-DC converter 111 can be connected in parallel with the second storage battery 22. In this case, in a system corresponding to super-fast charging of 800 V, a high-voltage electric load corresponding to 400 V can be used. That is, in a system corresponding to super-fast charging of 800 V, the input voltage of the high-voltage electric load can be halved.

[0106] <Other Embodiments>

[0107] In addition, each of the above embodiments can be implemented with the following modifications.

[0108] • In the fifth embodiment, the structure shown in FIG. 6 can be used. Figure 14 In the structure shown in FIG. 6, the charge object of the first charger 121 can not be the second storage battery 22 but the first storage battery 21.

[0109] • As the rotating electric machine and the inverter, a rotating electric machine and an inverter other than three phases, such as five phases or seven phases, can be used.Figure 17 indicates a power conversion device at the time of five phases. In Figure 17 In the above embodiment, the same reference numerals are assigned to the same structures as those shown in the previous Figure 1

[0110] In the above embodiment, the same reference numerals are assigned to the same structures as those shown in the previous Figure 17 In the above embodiment, the same reference numerals are assigned to the same structures as those shown in the previous

[0111] • The setting position of the current sensor that detects the current flowing to the neutral point O is not limited to that shown in Figure 1 For example, the current sensor can be provided to each of the conductive members 32U, 32V, 32W of the Figure 1 In this case, in the equalization control, it is sufficient to set the sum of the currents detected by the current sensors of the conductive members 32U, 32V, 32W as the neutral point current IMr.

[0112] • The control device 70 can synchronize the switching control of the upper arm switches QUH, QVH, QWH of all the phases in the equalization control, and in addition, can synchronize the switching control of the lower arm switches QUL, QVL, QWL of all the phases.

[0113] • As the connection switch 61, a relay is not necessarily used. For example, as the connection switch 61, a pair of N-channel MOSFETs whose sources are connected to each other, or an IGBT can be used.

[0114] • The connection switch 61 is not necessarily provided. In this case, the intermediate terminal B and the neutral point O are always electrically connected.

[0115] • As the upper arm switches and the lower arm switches that constitute the inverter, IGBTs are not necessarily used, and for example, N-channel MOSFETs can be used.

[0116] • The first storage battery and the second storage battery can not constitute a battery pack.

[0117] • In each of the above embodiments, the energy is transmitted and received between the first storage battery 21 and the second storage battery 22 for the purpose of equalizing the terminal voltages of the first storage battery 21 and the second storage battery 22, but this is not necessarily the case, and the energy can be transmitted and received between the first storage battery 21 and the second storage battery 22 without the purpose of equalizing the terminal voltages.

[0118] ​In this case, for example, in the first embodiment, the determination of whether or not there is a request to transfer or receive energy from one of the first storage battery 21 and the second storage battery 22 to the other is performed instead of the determination of whether or not there is a request for equalization of the terminal voltages of the first storage battery 21 and the second storage battery 22. In a case where it is determined that there is the request, the command value setting portion 91, for example, can calculate an energy target value to be transferred or received from one of the first storage battery 21 and the second storage battery 22 to the other, and set the neutral-point command current IM* based on the calculated energy target value. Specifically, for example, the command value setting portion 91 calculates a positive energy target value in a case where energy is transferred or received from the first storage battery 21 to the second storage battery 22, and the larger the positive energy target value, the larger the neutral-point command current IM* is set. On the other hand, the command value setting portion 91 calculates a negative energy target value in a case where energy is transferred or received from the second storage battery 22 to the first storage battery 21, and the larger the absolute value of the negative energy target value, the larger the absolute value of the neutral-point command current IM* is set.

[0119] The control portion and the method thereof according to the present disclosure can also be realized by a special-purpose computer provided by a processor programmed to execute one or more functions embodied by a computer program, or a special-purpose computer provided by a processor composed of one or more special-purpose hardware logic circuits. Alternatively, the control portion and the method thereof according to the present disclosure can be realized by a special-purpose computer composed of a processor programmed to execute one or more functions and a memory, and a processor composed of one or more hardware logic circuits. In addition, the computer program can be stored in a computer-readable non-transitory tangible storage medium as instructions to be executed by a computer.

[0120] Although the present disclosure is described based on the embodiments, it should be understood that the present disclosure is not limited to the above-described embodiments, structures. The present disclosure also includes various modifications, modifications within the equivalent scope. In addition, various combinations, modes, further including only one element, one or more or one or less other combinations, modes also belong to the scope, the idea of the present disclosure.

Claims

1. An electric power conversion device including: a rotary electric machine having a winding; an inverter having a series connection of an upper arm switch and a lower arm switch, characterized by comprising: a connection path electrically connecting a negative electrode side of a first battery and a positive electrode side of a second battery, which are connected in series, and a neutral point of the winding; a control portion that performs switching control of the upper arm switch and the lower arm switch so as to perform transmission and reception of energy between the first battery and the second battery by causing current to flow between the first battery and the second battery via the inverter, the winding, and the connection path; and a request judgment portion that judges whether or not there is a request for transmission and reception of energy between the first battery and the second battery, a positive electrode terminal of either one of the first battery and the second battery, which is an object battery, being connectable to a positive electrode side of a first charger outside, and a negative electrode terminal of the object battery being connectable to a negative electrode side of the first charger, a positive electrode terminal of the first battery being connectable to a positive electrode side of a second charger outside, and a negative electrode terminal of the second battery being connectable to a negative electrode side of the second charger, a charging voltage of the second charger being set higher than a charging voltage of the first charger, the request judgment portion judging that there is the request in a case where the object battery is charged by the first charger, the control portion performing the switching control so as to supply energy from the object battery to the first battery and a battery other than the object battery among the second battery in a case where it is judged that there is the request.

2. An electric power conversion device including: a rotary electric machine having a winding; an inverter having a series connection of an upper arm switch and a lower arm switch, characterized by comprising: a connection path electrically connecting a negative electrode side of a first battery and a positive electrode side of a second battery, which are connected in series, and a neutral point of the winding; a control portion that performs switching control of the upper arm switch and the lower arm switch so as to perform transmission and reception of energy between the first battery and the second battery by causing current to flow between the first battery and the second battery via the inverter, the winding, and the connection path; a request judgment portion that judges whether or not there is a request for transmission and reception of energy between the first battery and the second battery; and a connection switch provided to the connection path. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The control section performs the switching control with the connection switch set to the on state to perform transfer and reception of energy between the first and second storage batteries by causing current to flow between the first and second storage batteries via the winding and the connection path, in a case where it is determined that the request exists, and turns off the connection switch in a case where it is determined that the request does not exist.

3. The power conversion device according to claim 2, wherein either of the first and second storage batteries, which is an object battery, is chargeable by a first charger outside, a series connection body of the first and second storage batteries is chargeable by a second charger outside, a charging voltage of the second charger is set to be higher than a charging voltage of the first charger.

4. The power conversion device according to claim 3, wherein the request determination section determines that the request exists in a case where the object battery is charged by the first charger.

5. The power conversion device according to any one of claims 1 to 4, wherein the power conversion device includes an electric load connected in parallel to at least one of the first and second storage batteries.

6. The power conversion device according to claim 5, wherein the request determination section determines that the request exists when the electric load is driven.

7. The power conversion device according to any one of claims 1 to 6, wherein the control section performs the switching control to perform transfer and reception of energy between the first and second storage batteries while driving the rotary electric machine, in a case where it is determined that the request exists in the driving of the rotary electric machine.

8. The power conversion device according to any one of claims 1 to 7, wherein the control section synchronizes switching control of the upper arm switches and the lower arm switches of all phases to perform transfer and reception of energy between the first and second storage batteries by causing current to flow between the first and second storage batteries via the inverter, the winding, and the connection path.

9. The power conversion device according to any one of claims 1 to 8, wherein the request determination section determines whether or not there is a request for equalization of terminal voltages of the first and second storage batteries, the control section performs the switching control to equalize the terminal voltages of the first and second storage batteries by causing current to flow between the first and second storage batteries via the inverter, the winding, and the connection path, in a case where it is determined that the request for equalization exists.

10. The power conversion device according to any one of claims 1 to 9, wherein the control section performs the switching control in a manner that causes direct current to flow through the connection path, so that transfer and reception of energy between the first and second storage batteries are performed.

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