POWER CONVERSION DEVICE, PROGRAM, AND METHOD FOR CONTROLLING POWER CONVERSION DEVICE

Abstract

To provide a power conversion device that can be miniaturized, and a program.SOLUTION: A power conversion device 10 includes: an inverter 30; a rotary electric machine 40 having coils 41U-41W electrically connected to the inverter 30; a connection path 60 which electrically connects an intermediate terminal B between a first storage battery 21 and a second storage battery 22 with a neutral point O; and a control device 70. The control device 70 calculates the DC component of current that flows between the first storage battery 21 and the second storage battery 22 via the connection path 60, and calculates the AC component of current that flows between the first storage battery 21 and the second storage battery 22 via the connection path 60. The control device 70 performs the switching control of upper and lower arm switches QUH-QWL of the inverter 30 so that the total current of the DC component and the AC component flows through the connection path 60.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device. , P Program and a method for controlling a power conversion device Regarding. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as described in Patent Document 1, for example, a power conversion device is known that includes an inverter connected to a power storage device and a rotating electric machine connected to the inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2010 / 103063 Summary of the Invention [Problem to be solved by the invention]

[0004] Some power storage devices connected to an inverter include a series-connected first power storage unit and a second power storage unit. Here, for example, in order to eliminate a difference in the amount of stored power between the first and second power storage units, it may be necessary to transfer energy between the first and second power storage units. In this case, if a device for transferring energy is added, there is a concern that the power conversion device may become larger.

[0005] It may also be necessary to increase the temperature of the first and second power storage units that are placed in a low-temperature environment. In this case, if a device (e.g., a heater) for increasing the temperature of the first and second power storage units is added, there is a concern that this addition will also increase the size of the power conversion device.

[0006] The present invention relates to a power conversion device that can be made compact. , P Program and a method for controlling a power conversion device The main purpose is to provide. [Means for solving the problem]

[0007] The present invention provides an inverter including a series-connected body of upper and lower arm switches, the series-connected body being connected in parallel to a series-connected body of a first power storage unit and a second power storage unit; a rotating electric machine having a winding electrically connected to the inverter; a connection path electrically connecting the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit to the winding; a DC component calculation unit that calculates a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; an AC component calculation unit that calculates an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; and a control unit that performs switching control of the upper and lower arm switches so that the total current of the DC component and the AC component flows through the connection path.

[0008] In the present invention, the negative electrode side of the first power storage unit and the positive electrode side of the second power storage unit are electrically connected to the windings of the rotating electric machine by the connection paths, so that the inverter can be used to ensure a path for transmitting and receiving energy between the first power storage unit and the second power storage unit.

[0009] Furthermore, in the present invention, switching control of the upper and lower arm switches is performed so that the total current of the DC and AC components of a current flows through the connection path. The DC component contributes to power supply from one of the first and second power storage units to the other. The AC component contributes to heat generation in the first and second power storage units. According to the present invention described above, the inverter can be used to simultaneously exchange energy between the first and second power storage units and raise the temperatures of the first and second power storage units. This makes it possible to reduce the size of the power conversion device. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a configuration diagram of a power conversion device. [Diagram 2] FIG. 4 is a block diagram showing the processing of the control device. [Diagram 3] FIG. [Figure 4]FIG. 4 is a diagram showing the relationship between a determination voltage Vj, a target charging time Lvtgt, and a DC command value Idc. [Diagram 5] FIG. 4 is a diagram showing an AC command value Iac. [Figure 6] 4 is a graph showing the relationship between the temperature deviation ΔT, the target temperature rise time Lttgt, and the amplitude IA of the AC command value Iac. [Figure 7] FIG. 4 is a diagram showing fluctuations in terminal voltage of a discharging battery. [Figure 8] FIG. 4 is a diagram showing fluctuations in terminal voltage of a charging side storage battery. [Figure 9] 5 is a time chart showing changes in the modulation rate and the carrier signal when power is supplied from the first storage battery to the second storage battery. [Figure 10] 5 is a time chart showing changes in the modulation rate and the carrier signal when power is supplied from the second storage battery to the first storage battery. [Figure 11] 5 is a time chart showing calculation results of a neutral point current and the like when voltage equalization control is executed; [Figure 12] 4 is a time chart showing the transition of the gate signal of each switch. [Figure 13] 4 is a flowchart showing a procedure for voltage equalization control and temperature rise control during external charging. [Figure 14] 5 is a flowchart showing a procedure for voltage equalization control and temperature rise control during driving of an electric load. [Figure 15] 10 is a time chart showing changes in a modulation rate and a carrier signal according to another embodiment. [Figure 16] 10 is a time chart showing changes in a modulation rate and a carrier signal according to another embodiment. [Figure 17] 10 is a time chart showing changes in a modulation rate and a carrier signal according to another embodiment. [Figure 18] 10 is a time chart showing changes in a modulation rate and a carrier signal according to another embodiment. [Figure 19] FIG. 13 is a configuration diagram of a power conversion device according to another embodiment. [Figure 20] FIG. 13 is a configuration diagram of a power conversion device according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a power converter according to the present invention will now be described with reference to the drawings. The power converter according to the present embodiment is mounted on a vehicle such as an electric vehicle or a hybrid vehicle.

[0012] As shown in Fig. 1, the power conversion device 10 includes an inverter 30 and a rotating electric machine 40. The rotating electric machine 40 is a three-phase synchronous machine, and includes U-, V-, and W-phase windings 41U, 41V, and 41W that are star-connected as stator windings. The phase windings 41U, 41V, and 41W are arranged with an electrical angle of 120° between them. The rotating electric machine 40 is, for example, a permanent magnet synchronous machine. In this embodiment, the rotating electric machine 40 is an in-vehicle main engine, and serves as a power source for running the vehicle.

[0013] The inverter 30 includes three phases of series-connected upper arm switches QUH, QVH, and QWH and lower arm switches QUL, QVL, and QWL. In this embodiment, a voltage-controlled semiconductor switching element, specifically an IGBT, is used as each switch QUH, QVH, QWH, QUL, QVL, and QWL. Therefore, the high-potential terminal of each switch QUH, QVH, QWH, QUL, QVL, and QWL is a collector, and the low-potential terminal is an emitter. Diodes DUH, DVH, DWH, DUL, DVL, and DWL are connected in inverse parallel to each switch QUH, QVH, QWH, QUL, QVL, and QWL as freewheel diodes.

[0014] A 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 a U-phase conductive member 32U such as a bus bar. A 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 a V-phase conductive member 32V such as a bus bar. A 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 a W-phase conductive member 32W such as a bus bar. Second ends of the U-, V-, and W-phase windings 41U, 41V, and 41W are connected to each other at a neutral point O. In this embodiment, the number of turns of each phase winding 41U, 41V, and 41W is set to be the same. As a result, for example, the inductance of each phase winding 41U, 41V, and 41W is set to be the same.

[0015] The collectors of the upper arm switches QUH, QVH, and QWH are connected to the positive terminal of the battery pack 20 by a positive bus Lp such as a bus bar. The emitters of the lower arm switches QUL, QVL, and QWL are connected to the negative terminal of the battery pack 20 by a negative bus Ln such as a bus bar.

[0016] The power conversion device 10 includes a capacitor 31 that connects the positive bus Lp and the negative bus Ln. The capacitor 31 may be built in the inverter 30 or may be provided outside the inverter 30.

[0017] The battery pack 20 is configured as a series connection of battery cells, which are single batteries. In this embodiment, the terminal voltages (e.g., rated voltages) of the battery cells constituting the battery pack 20 are set to be the same as each other. As the battery cells, for example, secondary batteries such as lithium ion batteries can be used. The battery pack 20 is provided, for example, outside the power conversion device 10.

[0018] In this embodiment, among the battery cells constituting the battery pack 20, a series connection of multiple battery cells on the high potential side constitutes the first storage battery 21 (corresponding to the "first power storage section"), and a series connection of multiple battery cells on the low potential side constitutes the second storage battery 22 (corresponding to the "second power storage section"). That is, the battery pack 20 is divided into two blocks. In this 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. In this embodiment, the rated voltage of each of the first storage battery 21 and the second storage battery 22 is 400V. Therefore, the rated voltage of the battery pack 20 is 800V.

[0019] In the battery pack 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.

[0020] 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. The monitoring information of the monitoring unit 50 is input to a control device 70 (corresponding to a "control unit") included in the power conversion device 10.

[0021] 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 and the neutral point O of the battery pack 20. The connection switch 61 is provided on the connection path 60. In this embodiment, a relay is used as the connection switch 61. When the connection switch 61 is turned on, the intermediate terminal B and the neutral point O are electrically connected. On the other hand, when the connection switch 61 is turned off, the intermediate terminal B and the neutral point O are electrically disconnected.

[0022] The power conversion device 10 includes an electric load 100. The electric load 100 includes a DC-DC converter, an air conditioning inverter, an air conditioning heater, and an on-board charger. The DC-DC converter is driven to step down the output voltage of the second storage battery 22 and supply it to a low-voltage storage battery (not shown). The low-voltage storage battery is, for example, a lead storage battery with a rated voltage of 12V.

[0023] The air conditioning inverter drives an electric compressor that circulates the refrigerant in the refrigeration cycle. The air conditioning heater is driven to heat the vehicle cabin. The vehicle-mounted charger converts AC voltage output from an AC power source installed in a house or the like into DC voltage and supplies it to the second storage battery 22, and is also called an on-board charger (OBC).

[0024] The second storage battery 22 can be connected to a charger 200 provided outside the vehicle. The charger 200 supports quick charging (for example, 400V quick charging). The charger 200 includes a first switch SW1, a second switch SW2, and a rectifier 201. The positive electrode side of the charger 200 can be connected to the intermediate terminal B via the first switch SW1. The negative electrode side of the charger 200 can be connected to the negative electrode side of the second storage battery 22 via the second switch SW2. When the second storage battery 22 is charged from the charger 200, the switches SW1 and SW2 are switched on. The rectifier 201 converts a three-phase AC voltage supplied from a three-phase system power supply 210 into a DC voltage and supplies the DC voltage to the second storage battery 22. This charges the second storage battery 22.

[0025] In addition, the first and second switches SW1 and SW2 are actually driven by an external control device separate from the control device 70. However, since being driven by an external control device is not essential, in this embodiment, the first and second switches SW1 and SW2 are driven by the control device 70.

[0026] The power conversion device 10 includes a current sensor 62 and a phase current sensor 63. The current sensor 62 detects a current flowing through the connection path 60. The phase current sensor 63 detects phase currents for at least two phases. The phase current sensor 63 detects, for example, currents flowing through conductive members for at least two phases among the conductive members 32U to 32W. The detection values ​​of the current sensors 62, 63 are input to the control device 70.

[0027] The control device 70 is mainly composed of a microcomputer 70a, and the microcomputer 70a has a CPU. The functions provided by the microcomputer 70a can be provided by software recorded in a substantial memory device and a computer that executes the software, by software alone, by hardware alone, or by a combination of these. For example, when the microcomputer 70a is provided by an electronic circuit that is hardware, it can be provided by a digital circuit including a large number of logic circuits, or by an analog circuit. For example, the microcomputer 70a executes a program stored in a non-transitory tangible storage medium as a storage unit provided in the microcomputer 70a. The program includes, for example, programs for voltage equalization control and temperature rise control, which will be described later. By executing the program, a method corresponding to the program is executed. The storage unit is, for example, a non-volatile memory. The program stored in the storage unit can be updated, for example, via a network such as the Internet.

[0028] The control device 70 performs switching control of each switch constituting the inverter 30 so as to feedback control the control amount of the rotating electric machine 40 to the command value. In this embodiment, the control amount is torque. In each phase, the upper arm switch and the lower arm switch are alternately turned on.

[0029] The control device 70 turns the connection switch 61 on or off, and is capable of communicating with the monitoring unit 50 .

[0030] FIG. 2 shows a block diagram of the process executed by the control device 70. As shown in FIG.

[0031] The d-axis deviation calculation unit 71d calculates the d-axis current deviation ΔId by subtracting the d-axis current Idr from the d-axis command current Id*. The q-axis deviation calculation unit 71q calculates the 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 a command value of a controlled variable of the rotating electric machine 40 (hereinafter, command torque). In addition, the d-axis current Idr and the q-axis current Iqr are calculated based on a detection value of the phase current sensor 63 and an electrical angle of the rotating electric machine 40. Note that the electrical angle may be a detection value of a rotation angle sensor such as a resolver, or may be an estimated value estimated by position sensorless control.

[0032] The d-axis control unit 72d 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 unit 72q calculates a q-axis voltage Vq as an operation amount for feedback controlling the calculated q-axis current deviation ΔIq to 0. In this embodiment, proportional integral control is used as the feedback control of each of the control units 72d and 72q. Note that the feedback control is not limited to proportional integral control, and may be, for example, proportional integral derivative control.

[0033] The three-phase conversion unit 73 calculates U- to W-phase command voltages Vu-Vw in a three-phase fixed coordinate system based on the d-axis voltage Vd, the q-axis voltage Vq, and the electrical angle. The phase command voltages Vu-Vw are signals (specifically, for example, sinusoidal signals) with a phase difference of 120 degrees in electrical angle.

[0034] The U-phase superimposing unit 74U calculates a U-phase final command voltage "Vu+CF" by adding an offset correction amount CF to the U-phase command voltage Vu. The V-phase superimposing unit 74V calculates a V-phase final command voltage "Vv+CF" by adding an offset correction amount CF to the V-phase command voltage Vv. The W-phase superimposing unit 74W calculates a W-phase final command voltage "Vw+CF" by adding an offset correction amount CF to the W-phase command voltage Vw. The method of calculating the offset correction amount CF will be described in detail later.

[0035] When the control device 70 acquires a vehicle travel request signal, it determines that there is a request to drive the rotating electric machine 40, and performs switching control to rotate and drive the rotor of the rotating electric machine 40. In this case, as described above, the phase command voltages Vu to Vw are signals with a phase difference of 120 electrical degrees. On the other hand, when the vehicle is stopped, the command torque is set to 0, and the phase command voltages Vu, Vv, and Vw are also 0. Therefore, the final command voltage of each phase becomes the offset correction amount CF.

[0036] The U-phase modulation unit 75U calculates the U-phase modulation factor Mu by dividing the U-phase final command voltage "Vu+CF" 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 acquired from the monitoring unit 50. The V-phase modulation unit 75V calculates the V-phase modulation factor Mv by dividing the V-phase final command voltage "Vv+CF" by the power supply voltage Vdc. The W-phase modulation unit 75W calculates the W-phase modulation factor Mw by dividing the W-phase final command voltage "Vw+CF" by the power supply voltage Vdc.

[0037] The U, V, W phase modulation factors Mu, Mv, Mw are input to the non-inverting input terminals of the U, V, W phase comparators 76U, 76V, 76W. The U, V, W phase carrier signals Sgu, Sgv, Sgw generated by the U, V, W phase carrier generators 77U, 77V, 77W are input to the inverting input terminals of the U, V, W phase comparators 76U, 76V, 76W. In this embodiment, each of the carrier signals Sgu, Sgv, Sgw is a triangular wave signal whose increasing speed and decreasing speed are equal. The amplitude of each of the carrier signals Sgu, Sgv, Sgw is 1. Each of the carrier signals Sgu, Sgv, Sgw takes a value in the range from -1 to 1 with 0 as the center. In this embodiment, each of the carrier signals Sgu, Sgv, Sgw is a common carrier signal.

[0038] The control device 70 generates gate signals for the U-phase upper and lower arm switches QUH, QUL based on the PWM signal output from the U-phase comparison unit 76U, and supplies the generated gate signals to the gates of the U-phase upper and lower arm switches QUH, QUL. This allows switching control of the U-phase upper and lower arm switches QUH, QUL. Similarly, the control device 70 controls the switching of the V-phase upper and lower arm switches QVH, QVL based on the PWM signal output from the V-phase comparison unit 76V, and controls the switching of the W-phase upper and lower arm switches QWH, QWL based on the PWM signal output from the W-phase comparison unit 76W.

[0039] The offset correction amount CF is a parameter required for voltage equalization control of the storage batteries 21, 22 and temperature rise control of the storage batteries 21, 22. Fig. 3(a) shows an equivalent circuit of the power conversion device 10 used in the voltage equalization control and temperature rise control. In Fig. 3(a), each phase winding 41U to 41W is shown as a winding 41, each upper arm switch QUH, QVH, QWH is shown as an upper arm switch QH, and each upper arm diode DUH, DVH, DWH is shown as an upper arm diode DH. In addition, each lower arm switch QUL, QVL, QWL is shown as a lower arm switch QL, and each lower arm diode DUL, DVL, DWL is shown as a lower arm diode DL.

[0040] The equivalent circuit of Fig. 3(a) can be shown as an equivalent circuit of Fig. 3(b). The circuit of Fig. 3(b) is a buck-boost chopper circuit capable of bidirectional power transmission between the first storage battery 21 and the second storage battery 22. Referring to Fig. 3(b), when the upper arm switch QH is turned on, the terminal voltage of the winding 41 becomes "VBH". On the other hand, when the lower arm switch QL is turned on, the terminal voltage VR of the winding 41 becomes "-VBL". In other words, when the upper arm switch QH is turned on, an excitation current flows in a specific direction in the winding 41, and when the lower arm switch QL is turned on, an excitation current flows in a direction opposite to the specific direction in the winding 41.

[0041] The control device 70 includes a DC component calculation unit 80 as a component for voltage equalization control. The DC component calculation unit 80 calculates a judgment voltage Vj (=VBH-VBL) by subtracting the terminal voltage VBL of the second storage battery 22 from the terminal voltage VBH of the first storage battery 21. When the calculated judgment voltage Vj is a positive value, the DC component calculation unit 80 sets the DC command value Idc to a positive value, and more specifically, as shown in FIG. 4, the higher the judgment voltage Vj is, the larger the DC command value Idc becomes, continuously or stepwise. When the calculated judgment voltage Vj is a negative value, the DC component calculation unit 80 sets the DC command value Idc to a negative value, and more specifically, as the absolute value of the judgment voltage Vj is larger, the DC component calculation unit 80 increases the absolute value of the DC command value Idc continuously or stepwise.

[0042] When the second storage battery 22 is being charged by the charger 200, the DC component calculation unit 80 increases the absolute value of the DC command value Idc as the target charging time Lvtgt becomes shorter. The target charging time Lvtgt is a target time from when charging of the second storage battery 22 by the charger 200 is started to when charging of the second storage battery 22 is completed. The target charging time Lvtgt is also a target time from when equalization of the terminal voltages of the first storage battery 21 and the second storage battery 22 is started to when it is completed. According to the calculation method of the DC command value Idc shown in FIG. 4, both charging and voltage equalization can be completed within the target charging time Lvtgt. In the DC component calculation unit 80, as a parameter indicating the amount of charge stored in each of the storage batteries 21, 22, the battery capacity [Ah] or the SOC may be used instead of the terminal voltage.

[0043] The control device 70 includes an AC component calculation unit 81 as a component for temperature rise control. The AC component calculation unit 81 sets an AC command value Iac based on the temperature of the battery pack 20 (hereinafter, battery temperature Td), the target temperature Ttgt of the battery pack 20, and the target temperature rise time Lttgt acquired from the monitoring unit 50. In this embodiment, the waveform of the AC command value Iac is set as a sine wave as shown in FIG. 5. More specifically, the amplitude of the AC command value Iac is IA, and the period is Tc. The AC command value Iac is set so that the positive AC command value Iac and the negative AC command value Iac are point-symmetric with respect to the timing at which the value of the AC command value Iac changes from a value other than 0 to 0 (hereinafter, zero cross timing). As a result, the period from the first zero cross timing C1 to the second zero cross timing C2 of the AC command value Iac becomes equal to the period from the second zero cross timing C2 to the third zero cross timing C3.

[0044] In addition, in one period Tc of the AC command value Iac, the area S1 of the first region and the area S2 of the second region are equal. The area S1 of the first region is an area surrounded by the positive AC command value Iac and the time axis from the first zero cross timing C1 to the second zero cross timing C2 of the AC command value Iac in one period Tc of the AC command value Iac. The area S2 of the second region is an area surrounded by the time axis from the second zero cross timing C2 to the third zero cross timing C3 of the AC command value Iac in one period Tc and the negative neutral point command current IM*. In this embodiment, the frequency fc (=1 / Tc) of the AC command value Iac is lower than the frequencies of the modulation factors Mu, Mv, and Mw.

[0045] The DC component calculation unit 80 calculates the temperature deviation ΔT by subtracting the battery temperature Td from the target temperature Ttgt. As the temperature deviation ΔT is larger, the DC component calculation unit 80 increases the amplitude IA of the AC command value Iac continuously or stepwise as shown in FIG. 6. Also, the DC component calculation unit 80 increases the amplitude IA of the AC command value Iac continuously or stepwise as the target temperature rise time Lttgt is shorter. The target temperature rise time Lttgt is a target time from when the temperature rise control is started to when the temperature rise control is completed. Completion of the temperature rise control means, for example, that the battery temperature Td has reached the target temperature Ttgt.

[0046] The adder 82 calculates the neutral point command current IM* by adding the AC command value Iac to the DC command value Idc. The neutral point deviation calculator 83 calculates the neutral point current deviation ΔIM by subtracting the neutral point current IMr, which is the current detected by the current sensor 62, from the neutral point command current IM*.

[0047] The neutral point control unit 84 calculates an offset correction amount CF as an operation amount for feedback controlling the calculated neutral point current deviation ΔIM to 0. In this embodiment, proportional-integral control is used as this feedback control. Note that the feedback control is not limited to proportional-integral control, and may be, for example, proportional-integral-derivative control.

[0048] In this embodiment, the amplitude IA of the AC command value Iac is set by the DC component calculation unit 80 so that the terminal voltage of the discharging battery, of the first storage battery 21 and the second storage battery 22, in the voltage equalization control is equal to or lower than the allowable upper limit voltage VlimH and equal to or higher than the allowable lower limit voltage VlimL, as shown in FIG. 7. The allowable upper limit voltage VlimH and the allowable lower limit voltage VlimL of the storage battery are determined as values ​​that do not reduce the reliability of the storage battery. In FIG. 7, OCVd indicates the open circuit voltage of the discharging battery, and CCVMd indicates the time average value of the terminal voltage of the discharging battery. CCVHd indicates the maximum terminal voltage of the discharging battery, and CCVLd indicates the minimum terminal voltage of the discharging battery. Here, there are the relationships "CCVMd=OCVd-I1d×R1d", "CCVHd=CCVMd+IA×R2d", and "CCVLd=CCVMd-IA×R2d". I1d indicates a DC current flowing through the discharging battery, R1d indicates a DC resistance of the discharging battery, IA indicates the amplitude of the AC command value Iac described above, and R2d indicates an AC resistance of the discharging battery.

[0049] In addition, the amplitude IA of the AC command value Iac is set by the DC component calculation unit 80 so that the terminal voltage of the charging side battery, of the first storage battery 21 and the second storage battery 22, becomes equal to or lower than the allowable upper limit voltage VlimH and equal to or higher than the allowable lower limit voltage VlimL in the voltage equalization control, as shown in FIG. 8. In FIG. 8, OCVc indicates the open circuit voltage of the charging side battery, and CCVMc indicates the time average value of the terminal voltage of the charging side battery. CCVHc indicates the maximum terminal voltage of the charging side battery, and CCVLc indicates the minimum terminal voltage of the charging side battery. Here, there are the relationships "CCVMc=OCVc+I1c×R1c", "CCVHc=CCVMc+IA×R2c", and "CCVLc=CCVMc-IA×R2c". I1c indicates the DC current flowing through the charging side battery, R1c indicates the DC resistance of the charging side battery, and R2c indicates the AC resistance of the charging side battery.

[0050] Incidentally, for example, the DC component calculation unit 80 may set the amplitude IA of the AC command value Iac based on the map information that defines the amplitude IA such that the terminal voltages of the respective storage batteries 21 and 22 are equal to or lower than the allowable upper limit voltage VlimH and equal to or higher than the allowable lower limit voltage VlimL of the storage battery. Also, for example, the DC component calculation unit 80 calculates CCVHd, CCVLd, CCVHc, and CCVLc each time based on the information acquired from the monitoring unit 50, and adjusts the amplitude IA each time so that "CCVHd, CCVHc > VlimH" or "CCVLd, CCVLc < VlimL" does not occur. Thereby, it is possible to prevent the reliability of the first storage battery 21 and the second storage battery 22 from deteriorating.

[0051] FIG. 9 shows the transitions of the respective carrier signals Sgu, Sgv, Sgw and the respective modulation ratios Mu, Mv, Mw when power is supplied from the first storage battery 21 to the second storage battery 22 by voltage equalization control during vehicle parking and the AC command value Iac is set to 0. FIG. 10 shows the transitions of the respective carrier signals Sgu, Sgv, Sgw and the respective modulation ratios Mu, Mv, Mw when power is supplied from the second storage battery 22 to the first storage battery 21 by voltage equalization control during vehicle parking and the AC command value Iac is set to 0.

[0052] According to the examples shown in FIGS. 9 and 10, the upper arm switches QUH, QVH, QWH of each phase are turned on or off synchronously, and the lower arm switches QUL, QVL, QWL of each phase are turned on or off synchronously. Note that FIG. 11 shows the calculation results of the respective phase currents Iur, Ivr, Iwr, the neutral point current IMr, the current IBH flowing through the first storage battery 21, and the current IBL flowing through the second storage battery 22 when voltage equalization control is performed. LK shown in FIG. 11 indicates the scale of the vertical axis.

[0053] Fig. 12 shows the transition of the gate signals of the switches QUH to QWL when "Idc=0" and temperature rise control is being performed while the vehicle is stopped. In Fig. 12, Tsw indicates one switching period of each switch QUH to QWL, and one switching period Tsw is the same as the period of each carrier signal Sgu, Sgv, Sgw. In the example shown in Fig. 12, one period Tc of the AC command value Iac is divisible by one switching period Tsw.

[0054] When "Idc=0" and temperature rise control is being performed, over N periods "N×Tc" (N is a positive integer) of the AC command value Iac, the sum of the on-times TonH of the upper arm switches of each phase and the sum of the on-times TonL of the lower arm switches of each phase are equal or approximately equal.

[0055] On the other hand, when voltage equalization control is performed to supply power from the first storage battery 21 to the second storage battery 22 in addition to the temperature rise control, the sum of the on-times TonH of the upper arm switches of each phase becomes longer than the sum of the on-times TonL of the lower arm switches of each phase during N periods “N×Tc” of the AC command value Iac.

[0056] On the other hand, when voltage equalization control is performed to supply power from the second storage battery 22 to the first storage battery 21 in addition to the temperature rise control, the sum of the on-times TonL of the lower arm switches of each phase becomes longer than the sum of the on-times TonH of the upper arm switches of each phase during N periods “N×Tc” of the AC command value Iac.

[0057] Next, a procedure of the voltage equalization control and the temperature rise control executed by the control device 70 while the charger 200 is charging the second storage battery 22 will be described with reference to Fig. 13. The process shown in Fig. 13 is executed while the vehicle is stopped.

[0058] In step S10, it is determined whether or not a charge command has been issued from the charger 200 to the second storage battery 22.

[0059] If it is determined in step S10 that a charge command has been issued, the process proceeds to step S11, where it is determined whether or not there is a request to increase the temperature of the battery pack 20. For example, if the battery temperature Td is lower than the target temperature Ttgt, it may be determined that there is a request to increase the temperature.

[0060] If it is determined in step S11 that there is no temperature increase request, the process proceeds to step S12, where the amplitude IA is set to 0 in the AC component calculation unit 81. That is, the AC command value Iac is set to 0.

[0061] In step S13, it is determined 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. For example, when it is determined that the absolute value of the difference between the terminal voltage VBH of the first storage battery 21 and the terminal voltage VBL of the second storage battery 22 exceeds a predetermined value ΔV, it may be determined that there is a request for equalization.

[0062] If it is determined in step S13 that there is no equalization request, the process proceeds to step S14, where the DC component calculation unit 80 sets the DC command value Idc to 0. In the following step S15, the adder 82 calculates the neutral point command current IM* by adding the AC command value Iac and the DC command value Idc calculated in steps S12 and S14. Since it is determined that there is no temperature rise request or equalization request, the neutral point command current IM* becomes 0. Therefore, the connection switch 61 is turned off, and temperature rise control and voltage equalization control are not performed.

[0063] On the other hand, if it is determined in step S13 that there is an equalization request, the process proceeds to step S16, where the DC command value Idc is calculated in the DC component calculation unit 80. In this case, in the following step S15, "IM*=Idc" is satisfied. Then, the connection switch 61 is switched on, and the voltage equalization control out of the temperature rise control and the voltage equalization control is performed.

[0064] If it is determined in step S11 that there is a temperature increase request, the process proceeds to step S17, where the AC component calculation unit 81 calculates the amplitude IA (≠0) of the AC command value Iac based on the battery temperature Td, the target temperature Ttgt, and the target temperature increase time Lttgt.

[0065] In step S18, it is determined 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. Whether or not there is a request for equalization may be determined in the same manner as in step S13.

[0066] If it is determined in step S18 that there is no equalization request, the process proceeds to step S14, where the DC command value Idc is set to 0 in the DC component calculation unit 80. In this case, in the following step S15, "IM* = Iac" is obtained. Then, the connection switch 61 is switched on, and the temperature rise control of the temperature rise control and the voltage equalization control is performed.

[0067] On the other hand, if it is determined in step S18 that there is an equalization request, the process proceeds to step S16, where the DC command value Idc is calculated in the DC component calculation unit 80. In this case, in the following step S15, "IM*=Idc+Iac" is satisfied. Then, the connection switch 61 is switched on to perform both the temperature rise control and the voltage equalization control.

[0068] Next, a procedure of the voltage equalization control and the temperature rise control executed by the control device 70 while the electric load 100 is being driven will be described with reference to Fig. 14. The process shown in Fig. 14 is executed while the vehicle is stopped or running.

[0069] In step S20, it is determined whether the electric load 100 is being driven.

[0070] If it is determined in step S20 that the load is being driven, the process proceeds to step S21. The processes in steps S21 to S26 are the same as those in steps S11 to S16 in Fig. 13. However, in step S26, for example, the DC command value Idc may be calculated based on the power consumption of the electric load 100 instead of the target charging time Lvtgt. In more detail, the greater the power consumption, the greater the absolute value of the DC command value Idc may be.

[0071] According to the present embodiment described above in detail, both the voltage equalization control and the temperature rise control can be performed simultaneously by utilizing the rotating electric machine 40 and the inverter 30. This allows the power conversion device 10 to be made smaller in size.

[0072] <Other embodiments> The above embodiment may be modified as follows.

[0073] 1, the power supply source for charger 200 is not limited to three-phase system power supply 210, but may be a single-phase system power supply. Also, the charger is not limited to an AC charger, but may be a DC charger (for example, a DC quick charger).

[0074] As shown in FIG. 15, the phases of the U-, V-, and W-phase carrier signals Sgu, Sgv, and Sgw may be shifted by 120° each.

[0075] As shown in Fig. 16, the voltage equalization control and the temperature rise control may be performed by switching control of the upper and lower arm switches of only one of the three phases. Fig. 16 shows an example in which only the U phase is used.

[0076] Also, as shown in Figures 17 and 18, voltage equalization control and temperature rise control may be performed by switching control of upper and lower arm switches for only two of the three phases. Figures 17 and 18 show an example in which only the U and V phases are used. Note that the U and V phase carrier signals Sgu and Sgv shown in Figure 17 are out of phase with each other by 180°, and the U and V phase carrier signals Sgu and Sgv shown in Figure 18 have a phase difference of 0.

[0077] In FIG. 1, the electric load 100 and the charger 200 may be connected to the first storage battery 21 instead of the second storage battery 22.

[0078] The method of setting the AC command value Iac is not limited to that shown in Fig. 5. For example, the positive AC command value Iac and the negative AC command value Iac may be set to a trapezoidal wave or a square wave, while satisfying a point-symmetric relationship between the positive AC command value Iac and the negative AC command value Iac with respect to the zero-cross timing of the AC command value Iac in one cycle Tc.

[0079] Furthermore, the method of setting the AC command value Iac is not limited to the one that satisfies the point-symmetric relationship. For example, the AC command value Iac may be set so that, in one cycle Tc, the period from the first zero cross timing C1 to the second zero cross timing C2 of the AC command value Iac is different from the period from the second zero cross timing C2 to the third zero cross timing C3 of the AC command value Iac, and the area S1 of the first region is equal to the area S2 of the second region.

[0080] The power conversion device 10 may be one shown in Fig. 19. This power conversion device 10 includes a connection path 90, a connection switch 91, and a current sensor 92, instead of the connection path 60, the connection switch 61, and the current sensor 62. A first end of the connection path 90 is connected to an emitter of an upper arm switch and a collector of a lower arm switch of a part of the three phases. In the example shown in Fig. 19, the first end of the connection path 90 is connected to the U phase. A second end of the connection path 90 is connected to the intermediate terminal B of the battery pack 20. The connection switch 91 and the current sensor 92 are provided on the connection path 90.

[0081] The control device 70 performs the voltage equalization control and temperature rise control described above. Here, the connection switch 61 is replaced with a connection switch 91. In the voltage equalization control and temperature rise control, the U-phase upper and lower arm switches QUH and QUL are maintained off, and switching control of the V- and W-phase upper and lower arm switches QVH, QVL, QWH, and QWL is performed.

[0082] The rotating electric machine and the inverter may be of a type other than three phase, such as a five-phase or seven-phase type. Fig. 20 shows a power conversion device in the case of a five-phase type. In Fig. 20, X-phase upper and lower arm switches QXH, QXL and diodes DXH, DXL are added to the inverter 30, and Y-phase upper and lower arm switches QYH, QYL and diodes DYH, DYL are added. Furthermore, an X-phase winding 41X and a Y-phase winding 41Y are added to the rotating electric machine 40. Furthermore, an X-phase conductive member 32X and a Y-phase conductive member 32Y are added to the power conversion device 10.

[0083] The connection switch 61 is not limited to a relay. For example, a pair of N-channel MOSFETs with their sources connected to each other, or an IGBT may be used as the connection switch 61.

[0084] The connection switch 61 is not essential. In this case, the intermediate terminal B and the neutral point O are electrically connected at all times.

[0085] The upper and lower arm switches constituting the inverter are not limited to IGBTs, and may be, for example, N-channel MOSFETs.

[0086] In FIG. 1, instead of the storage battery, for example, an electric double layer capacitor may be used.

[0087] The moving body on which the power conversion device is mounted is not limited to a vehicle, but may be, for example, an aircraft or a ship. For example, if the moving body is an aircraft, a rotating electric machine installed in the aircraft serves as the flight power source of the aircraft, and if the moving body is a ship, a rotating electric machine installed in the ship serves as the navigation power source of the ship. Furthermore, the mounting of the power conversion device is not limited to a moving body. [Explanation of symbols]

[0088] 10...power conversion device, 21, 22...first and second storage batteries, 30...inverter, 40...rotating electric machine, 60...connection path, 70...control device.

Claims

1. an inverter (30) having a series-connected body of upper and lower arm switches (QUH to QYL), the series-connected body being connected in parallel to a series-connected body of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; a DC component calculation unit (80) that calculates a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; an AC component calculation unit (81) that calculates an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control unit (70) that performs switching control of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path, When N is a positive integer, the control unit when a current is caused to flow from the first power storage unit to the second power storage unit via the connection path, the switching control is performed such that a total value of an on-time of the upper arm switches is longer than a total value of an on-time of the lower arm switches in N periods of the AC component; A power conversion device that performs the switching control when current flows from the second storage unit to the first storage unit via the connection path so that the total on-time of the lower arm switches is longer than the total on-time of the upper arm switches in N periods of the AC component.

2. 2. The power conversion device according to claim 1, wherein the DC component calculation unit increases the absolute value of the DC component as the difference between the storage amounts of the first and second power storage units increases or as the target time for power supply from one of the first and second power storage units to the other increases.

3. 3. The power conversion device according to claim 1, wherein the AC component calculation unit increases the amplitude of the AC component as a target time from when a current starts to flow through the connection path by the switching control to when a temperature increase of the first power storage unit and the second power storage unit is completed is shorter.

4. An inverter (30) having a series connection of upper and lower arm switches (QUH to QYL), the series connection being connected in parallel to a series connection of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; a DC component calculation unit (80) that calculates a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; an AC component calculation unit (81) that calculates an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control unit (70) that performs switching control of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path, The AC component calculation unit sets the amplitude of the AC component so that the terminal voltages of the first storage unit and the second storage unit when current flows through the connection path due to the switching control do not fall outside a range specified by an allowable upper and lower voltage limits.

5. An inverter (30) having a series connection of upper and lower arm switches (QUH to QYL), the series connection being connected in parallel to a series connection of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; a DC component calculation unit (80) that calculates a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; an AC component calculation unit (81) that calculates an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control unit (70) that performs switching control of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path, The control unit is a power conversion device that, when there is a request to drive the rotating electric machine, causes the total current to flow through the connection path and performs the switching control to rotate and drive a rotor of the rotating electric machine.

6. The power conversion device according to any one of claims 1 to 5, wherein the connection path electrically connects a negative electrode side of the first storage unit and a positive electrode side of the second storage unit to a neutral point of the winding.

7. an inverter (30) having a series-connected body of upper and lower arm switches (QUH to QYL), the series-connected body being connected in parallel to a series-connected body of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A program applied to a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; When N is a positive integer, in the control process, when a current is caused to flow from the first power storage unit to the second power storage unit via the connection path, the switching control is performed such that a total value of an on-time of the upper arm switches is longer than a total value of an on-time of the lower arm switches in N periods of the AC component; A program that performs the switching control so that, when current flows from the second storage unit to the first storage unit via the connection path, a total value of on-time of the lower arm switches is longer than a total value of on-time of the upper arm switches in N periods of the AC component.

8. An inverter (30) having a series connection of upper and lower arm switches (QUH to QYL), the series connection being connected in parallel to a series connection of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A program applied to a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; A program that, in the process of calculating the AC component, sets the amplitude of the AC component so that the terminal voltages of the first storage unit and the second storage unit when a current flows through the connection path due to the switching control do not fall outside a range defined by an allowable upper and lower limit voltages.

9. An inverter (30) having a series connection of upper and lower arm switches (QUH to QYL), the series connection being connected in parallel to a series connection of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A program applied to a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; a program for performing the switching control to cause the total current to flow through the connection path and to rotate a rotor of the rotating electric machine when there is a request to drive the rotating electric machine in the control processing.

10. An inverter (30) having a series-connected body of upper and lower arm switches (QUH to QYL), the series-connected body being connected in parallel to a series-connected body of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A control method for a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; When N is a positive integer, in the control process, when a current is caused to flow from the first power storage unit to the second power storage unit via the connection path, the switching control is performed such that a total value of an on-time of the upper arm switches is longer than a total value of an on-time of the lower arm switches in N periods of the AC component; A control method for a power conversion device, wherein, when current is flowed from the second storage unit to the first storage unit via the connection path, the switching control is performed such that a total value of on-time of the lower arm switches is longer than a total value of on-time of the upper arm switches in N periods of the AC component.

11. An inverter (30) having a series-connected body of upper and lower arm switches (QUH to QYL), the series-connected body being connected in parallel to a series-connected body of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A control method for a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; A control method for a power conversion device, in a process of calculating the AC component, the amplitude of the AC component is set so that the terminal voltages of the first storage unit and the second storage unit when a current flows through the connection path due to the switching control do not fall outside a range defined by an allowable upper and lower limit voltages.

12. An inverter (30) having a series connection of upper and lower arm switches (QUH to QYL), the series connection being connected in parallel to a series connection of a first storage unit (21) and a second storage unit (22); a rotating electric machine (40) having windings (41U to 41Y) electrically connected to the inverter; a connection path (60, 90) electrically connecting the negative electrode side of the first storage unit and the positive electrode side of the second storage unit to the winding; A control method for a power conversion device (10) including a computer (70a), The computer includes: calculating a DC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; calculating an AC component of a current flowing between the first power storage unit and the second power storage unit via the connection path; a control process for controlling switching of the upper and lower arm switches so that a total current of the DC component and the AC component flows through the connection path; a control method for a power conversion device, wherein, when there is a request to drive the rotating electric machine in the control process, the total current is caused to flow through the connection path, and the switching control is performed to rotate and drive a rotor of the rotating electric machine.

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