JP2021093845A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power conversion device capable of driving a rotary electric machine while controlling the temperature rise of a storage battery. A power conversion device 10 includes a rotary electric machine 40 having each phase winding 41U, 41V, 41W, and an inverter 30. Further, the power conversion device 10 includes a connection path 60 for electrically connecting the negative side of the first storage battery 21 and the positive side of the second storage battery 22 and the neutral points of the phase windings 41U, 41V, 41W. When it is determined that there is a temperature rise request and it is determined that there is a drive request, the first storage battery 21 and the second storage battery 22 are connected to each other via the inverter 30, each phase winding 41U, 41V, 41W and the connection path 60. A control unit 70 for performing switching control of the upper arm switches QUAH to QWH and the lower arm switches QUAL to QWL of each phase is provided so as to drive the rotary electric machine 40 while passing a current between them. [Selection diagram] Fig. 1

Description

The present invention relates to a power converter.

Conventionally, when the temperature of the storage battery is low, the temperature of the storage battery is controlled by using a power conversion device. Patent Document 1 discloses a power conversion device including a storage battery, a capacitor, an inverter connected between the storage battery and the capacitor, and an armature winding connected to each phase of the inverter. Each phase of the inverter is composed of a series connection of an upper arm switch and a lower arm switch which are IGBTs, and one of them, the emitter of the U-phase upper arm switch and the collector of the U-phase lower arm switch, is connected to the connection path. It is connected to the positive electrode of the storage battery via. The temperature of the storage battery can be raised by exchanging and receiving reactive power between the storage battery and the capacitor via this connection path, the inverter, and the armature winding.

Japanese Patent No. 5865736

In the circuit configuration described in Patent Document 1, only the U-phase winding of each phase winding is connected to the positive electrode of the storage battery via the connection path. Therefore, when the temperature rise control is implemented, a larger current flows through this U-phase winding than with other windings that are not connected to the positive electrode of the storage battery. As a result, in the circuit configuration described in Patent Document 1, the rotating electric machine cannot be driven by balancing the current flowing through each phase winding during the temperature rise control. However, since it may be necessary to drive the rotary electric machine before the temperature of the storage battery rises, a technique capable of driving the rotary electric machine while performing temperature rise control is desired.

Therefore, a main object of the present invention is to provide a power conversion device capable of driving a rotary electric machine while controlling the temperature rise of a storage battery.

The present invention comprises a first storage battery and a second storage battery connected in series in a power conversion device including a rotary electric machine having a star-shaped winding and an inverter having a series connection of an upper arm switch and a lower arm switch. In the storage battery, a connection path for electrically connecting the negative side of the first storage battery, the positive side of the second storage battery, and the neutral point of the winding, and a request for temperature rise of the first storage battery and the second storage battery. It is determined that there is a temperature rise determination unit that determines whether or not there is a temperature rise, a drive determination unit that determines whether or not there is a drive request for the rotary electric machine, and that there is a temperature rise request and there is a drive request. In this case, the upper arm switch and the lower arm switch are driven so as to drive the rotary electric machine while passing a current between the first storage battery and the second storage battery via the inverter, the winding, and the connection path. It includes a control unit that performs switching control of the arm switch.

In the present invention, the negative electrode side of the first storage battery, the positive electrode side of the second storage battery, and the neutral point of the winding are electrically connected by a connection path. Therefore, when it is determined that there is a request for temperature rise of the first storage battery and the second storage battery, the switching control of the upper and lower arm switches is performed, so that the first storage battery and the first storage battery are connected via the inverter, the winding, and the connection path. A current can be passed between the first storage battery and the second storage battery to raise the temperature of the first storage battery and the second storage battery. In particular, since the neutral point of the winding is connected to the negative electrode side of the first storage battery and the positive electrode side of the second storage battery, the current does not concentrate on the winding of a certain phase during the temperature rise control, and each phase winding. The current flowing through the wire is kept in balance. As a result, since the current due to the temperature rise control does not interfere with the driving of the rotary electric machine, the rotary electric machine can be driven while controlling the temperature rise of the first storage battery and the second storage battery.

The block diagram of the power conversion apparatus which concerns on 1st Embodiment. The flowchart which shows the procedure of the temperature rise control process. The figure which shows the equivalent circuit. Functional block diagram of the control device. The figure which shows the waveform of the neutral point command current. A time chart showing the transition of the modulation rate. The figure which shows the transition of each phase current and the like. The figure which shows the transition of each phase current at the time of temperature rise control in the circuit configuration described in Patent Document 1 as a comparative example. The functional block diagram of the control device which concerns on 2nd Embodiment. The functional block diagram of the control device which concerns on the modification of 2nd Embodiment. The flowchart which shows the procedure of the temperature rise control process which concerns on 3rd Embodiment. The figure which shows the current operating point in Idr = 0 control. The block diagram of the power conversion apparatus which concerns on 4th Embodiment.

<First Embodiment>
Hereinafter, the first embodiment in which the power conversion device according to the present invention is embodied will be described with reference to the drawings. The power conversion device of this embodiment is mounted on, for example, an electric vehicle or a hybrid vehicle.

As shown in FIG. 1, the power conversion device 10 includes an inverter 30 and a rotary electric machine 40. The rotary electric machine 40 is a three-phase synchronous machine, and includes U, V, and W phase windings 41U, 41V, and 41W connected in a star shape as stator windings. The phase windings 41U, 41V, and 41W are arranged so as to be offset by 120 ° in terms of electrical angle. The rotary electric machine 40 is, for example, a permanent magnet synchronous machine. In the present embodiment, the rotary electric machine 40 is an in-vehicle main engine and serves as a traveling power source for the vehicle.

The inverter 30 includes a series connection body of U, V, W phase upper arm switches QUAH, QVH, QWH and U, V, W phase lower arm switches QUAL, QVL, QWL for three phases. In the present embodiment, voltage-controlled semiconductor switching elements are used as the switches QUAH, QVH, QWH, QUAL, QVL, and QWL, and specifically, IGBTs are used. Therefore, the high-potential side terminals of the switches QUAH, QVH, QWH, QUAL, QVL, and QWL are collectors, and the low-potential side terminals are emitters. The diodes DUH, DVH, DWH, DUL, DVL, and DWL as freewheel diodes are connected in antiparallel to each switch QUAH, QVH, QWH, QUAL, QVL, and QWL.

The emitter of the U-phase upper arm switch QUAH and the collector of the U-phase lower arm switch QUA are connected to the first end of the U-phase winding 41U via a U-phase conductive member 32U such as a bus bar. The emitter of the V-phase upper arm switch QVH and the collector of the V-phase lower arm switch QVL are connected to the first end of the V-phase winding 41V via a V-phase conductive member 32V such as a bus bar. The emitter of the W-phase upper arm switch QWH and the collector of the W-phase lower arm switch QWL are connected to the first end of the W-phase winding 41W via a W-phase conductive member 32W such as a bus bar. The second ends of the U, V, W phase windings 41U, 41V, 41W are connected to each other at the neutral point O. In this embodiment, the number of turns of each phase winding 41U, 41V, 41W is set to be the same. As a result, the inductances of the phase windings 41U, 41V, and 41W are set to be the same, for example.

The collectors of the upper arm switches QUAH, QVH, and QWH and the positive electrode terminal of the assembled battery 20 are connected by a positive electrode side bus Lp such as a bus bar. The emitters of the lower arm switches QL, QVL, and QWL and the negative electrode terminal of the assembled battery 20 are connected by a negative electrode side bus Ln such as a bus bar.

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

The assembled battery 20 is configured as a series connection of battery cells as a single battery, and has a terminal voltage of, for example, several hundred volts. In the present embodiment, the terminal voltage (for example, rated voltage) of each battery cell constituting the assembled battery 20 is set to be the same as each other. As the battery cell, for example, a secondary battery such as a lithium ion battery can be used. The assembled battery 20 is provided outside, for example, the power conversion device 10.

Among the battery cells constituting the assembled battery 20, the series connection of a plurality of battery cells on the high potential side constitutes the first storage battery 21, and the series connection of the plurality of battery cells on the low potential side constitutes the second storage battery 22. It is configured. That is, the assembled battery 20 is divided into two blocks. In the present embodiment, the number of battery cells constituting the first storage battery 21 and the number of battery cells constituting the second storage battery 22 are the same. Therefore, the terminal voltage of the first storage battery 21 (for example, the rated voltage) and the terminal voltage of the second storage battery 22 (for example, the rated voltage) are the same.

In the assembled battery 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.

The power conversion device 10 includes a monitoring unit 50. The monitoring unit 50 monitors the terminal voltage, temperature, and the like of each battery cell constituting the assembled battery 20.

The power conversion device 10 includes a connection path 60 and a connection switch 61. The connection path 60 electrically connects the intermediate terminal B of the assembled battery 20 and the neutral point O. 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 cut off.

The power conversion device 10 includes a phase current sensor 62 and a neutral point current sensor 63. The phase current sensor 62 detects the phase currents Iu, Iv, and Iw flowing through the conductive members 32U to 32W. Further, the neutral point current sensor 63 detects the current flowing through the neutral point O. The detected values of the phase current sensor 62 and the neutral point current sensor 63 are input to the control device 70 included in the power conversion device 10. In the present embodiment, the control device 70 corresponds to the control unit.

The control device 70 is mainly composed of a microcomputer, and performs switching control of each switch constituting the inverter 30 in order to feedback control the control amount of the rotary electric machine 40 to the command value thereof. The control amount is, for example, torque. In each phase, the upper and lower arm switches are turned on alternately.

The control device 70 turns on / off the connection switch 61, and is capable of communicating with the monitoring unit 50. Incidentally, the control device 70 realizes various control functions by executing a program stored in the storage device provided by the control device 70. Various functions may be realized by an electronic circuit which is hardware, or may be realized by both hardware and software.

Subsequently, the temperature rise control executed by the control device 70 will be described. FIG. 2 is a flowchart showing the procedure of the temperature rise control process. This process is repeatedly executed by the control device 70, for example, at a predetermined control cycle.

In step S10, it is determined whether or not there is a request for temperature rise of the first storage battery 21 and the second storage battery 22. In the present embodiment, when it is determined that the temperature T of the assembled battery 20 is equal to or lower than the target temperature T *, it is determined that there is a temperature rise request. Here, the temperature T of the assembled battery 20 may be obtained from the monitoring unit 50. As the temperature T of the assembled battery 20, the temperature of the first storage battery 21, the temperature of the second storage battery 22, and the average temperature of the first storage battery 21 and the second storage battery 22 may be used. Further, in the present embodiment, step S10 corresponds to the temperature rise determination unit.

If it is determined in step S10 that there is no temperature rise request, the process proceeds to step S11 to determine whether or not there is a drive request for the rotary electric machine 40. This drive request includes a request for driving the vehicle by driving the rotary electric machine 40. In this embodiment, step S11 corresponds to the drive determination unit.

If it is determined in step S11 that there is no drive request for the rotary electric machine 40, the process proceeds to step S12 to set the standby mode. In the standby mode, the switches QUAH to QWL of the inverter 30 are turned off. Then, in step S13, the connection switch 61 is turned off. As a result, the intermediate terminal B and the neutral point O are electrically cut off.

If it is determined in step S11 that there is a drive request for the rotary electric machine 40, the process proceeds to step S14 to set the drive mode. Then, in step S15, the connection switch 61 is turned off. As a result, the intermediate terminal B and the neutral point O are electrically cut off via the connection path 60. After that, in step S16, drive PWM control is performed. In the drive PWM control, switching control of each switch QUAH to QWL of the inverter 30 is performed in order to drive the rotary electric machine 40. As a result, the drive wheels of the vehicle rotate, and the vehicle can be driven.

If it is determined in step S10 that there is a temperature rise request, the process proceeds to step S17 to determine whether or not there is a drive request for the rotary electric machine 40.

If it is determined in step S17 that there is no drive request for the rotary electric machine 40, the process proceeds to step S18 to set the temperature rise control mode. Then, in step S19, the connection switch 61 is turned on. As a result, the intermediate terminal B and the neutral point O are electrically conducted via the connection path 60. In step S20, a temperature rise PWM control is performed to raise the temperature of the first storage battery 21 and the second storage battery 22. In the temperature rise PWM control, the switching control of each switch QUAH to QWL is performed, so that the first storage battery 21 and the second storage battery 22 are connected to each other via the inverter 30, each phase winding 41U, 41V, 41W and the connection path 60. A current is passed between the two, and the temperature of the first storage battery 21 and the second storage battery 22 is raised.

If it is determined in step S17 that there is a drive request for the rotary electric machine 40, the process proceeds to step S21 to set the temperature rise control / drive mode. Then, in step S22, the connection switch 61 is turned on. In step S23, temperature rise / drive PWM control is performed.

The switching frequency f2 in steps S20 and S23 is set higher than the switching frequency f1 in step S16. Further, the switching frequency f2 is set to a frequency deviating from the human audible range. Specifically, the switching frequency f2 is set to, for example, a frequency of 16 kHz or higher.

Hereinafter, the temperature rise control / drive mode temperature rise control will be described. FIG. 3A shows an equivalent circuit of the power conversion device 10 used for temperature rise control. In FIG. 3A, each phase winding 41U to 41W is shown as a winding 41, each upper arm switch QUAH, QVH, QWH is shown as an upper arm switch QH, and each upper arm diode DUH, DVH, DWH is shown as an upper arm. It is shown as a diode DH. Further, each lower arm switch QL, 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.

The equivalent circuit of FIG. 3 (a) can be shown as the equivalent circuit of FIG. 3 (b). The circuit of FIG. 3B is a buck-boost chopper circuit capable of bidirectional power transmission between the first storage battery 21 and the second storage battery 22. In FIG. 3B, IBH indicates the current flowing through the first storage battery 21, VBH indicates the terminal voltage of the first storage battery 21, IBL indicates the current flowing through the second storage battery 22, and VBL indicates the current flowing through the second storage battery 22. Indicates the terminal voltage. IBH and IBL are negative when the charging currents of the first and second storage batteries 21 and 22 flow, and IBH and IBL are positive when the discharge currents of the first and second storage batteries 21 and 22 flow. Further, VR indicates the terminal voltage of the winding 41, and IMr indicates the current flowing through the neutral point O. The case where the neutral point current IMr flows from the winding 41 to the intermediate terminal B via the connection path 60 is positive, and the neutral point current flows from the intermediate terminal B to the winding 41 via the connection path 60. The case where the point current IMr flows is negative.

With reference to FIG. 3B, when the upper arm switch QH is turned on, the terminal voltage VR 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". That is, when the upper arm switch QH is turned on, an exciting current can be passed through the winding 41 in the positive direction of the neutral point current IMr, and when the lower arm switch QL is turned on, the winding 41 is in the middle. An exciting current can be passed in the negative direction of the neutral current IMr.

FIG. 4 shows a block diagram of temperature rise control in the temperature rise control / drive mode. FIG. 4 is a control block diagram of temperature rise control performed while the vehicle is running after the rotary electric machine 40 is driven.

In the control device 70, the d and q-axis command current setting unit 80 sets the d-axis command current Id * and the q-axis command current Iq * based on the torque command value Trq * of the rotary electric machine 40. The d-axis deviation calculation unit 81d 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 81q 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 current Idr and the q-axis current Iqr are calculated based on the detected value of the phase current sensor 62 and the electric angle of the rotary electric machine 40. The electric angle may be a detected value of a rotation angle sensor such as a resolver, or may be an estimated value estimated by position sensorless control.

The d-axis control unit 82d calculates the d-axis voltage Vd as an operation amount for feedback-controlling the d-axis current deviation ΔId calculated by the d-axis deviation calculation unit 81d to 0. The q-axis control unit 82q calculates the q-axis voltage Vq as an operation amount for feedback-controlling the q-axis current deviation ΔIq calculated by the q-axis deviation calculation unit 81q to 0. In this embodiment, proportional integration control is used as feedback control of the control units 82d and 82q. The feedback control is not limited to the proportional integral control, and may be, for example, the proportional integral differential control.

The three-phase conversion unit 83 calculates the U to W phase command voltages Vu to Vw in the three-phase fixed coordinate system based on the d-axis voltage Vd, the q-axis voltage Vq, and the electric angle. The U to W phase command voltages Vu to Vw when it is determined that there is a drive request are sinusoidal signals having the same amplitude and being out of phase by 120 degrees in electrical angle. In the process of step S20, the U to W phase command voltages Vu to Vw when it is determined that there is no drive request is 0.

The control device 70 includes a temperature rise control unit 90. The temperature rise control unit 90 includes a command value setting unit 91, a neutral point deviation calculation unit 92, a neutral point control unit 93, and U to W phase superimposition units 94U to 94W.

The command value setting unit 91 sets the neutral point command current IM *. In the present embodiment, the waveform of the neutral point command current IM * is set as a sine wave as shown in FIG. Specifically, the amplitude of the neutral point command current IM * is Ia, and the period is Tc. Then, with respect to the timing when the value of the neutral point command current IM * changes from a value other than 0 to 0 (hereinafter, zero cross timing), the positive neutral point command current IM * and the negative neutral point command current IM * Set the neutral point command current IM * so that and is point-symmetrical. As a result, in FIG. 5, the period from the first zero cross timing C1 to the second zero cross timing C2 of the neutral point command current IM * becomes equal to the period from the second zero cross timing C2 to the third zero cross timing C3.

Further, in one cycle Tc of the neutral point command current IM *, the area S1 of the first region and the area S2 of the second region become equal. The area S1 of the first region is positively neutral with the time axis from the first zero cross timing C1 to the second zero cross timing C2 of the neutral point command current IM * in one cycle Tc of the neutral point command current IM *. This is the area surrounded by the point command current IM *. The area S2 of the second region is surrounded by the time axis from the second zero cross timing C2 to the third zero cross timing C3 of the neutral point command current IM * and the negative neutral point command current IM * in one cycle Tc. Area.

By setting the area S1 of the first region and the area S2 of the second region to be equal to each other, the balance of charge / discharge currents of the first storage battery 21 and the second storage battery 22 in one cycle Tc can be matched. Therefore, it is possible to prevent the difference between the terminal voltage VBH of the first storage battery 21 and the terminal voltage VBL of the second storage battery 22 from becoming large due to the temperature rise control.

Returning to the description of FIG. 4, the neutral point deviation calculation unit 92 subtracts the neutral point current IMr, which is the current detected by the neutral point current sensor 63, from the neutral point command current IM *. Calculate the neutral current deviation ΔIM.

The neutral point control unit 93 calculates an 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. The feedback control is not limited to the proportional integral control, and may be, for example, the proportional integral differential control.

The U-phase superimposition unit 94U calculates the U-phase final command voltage “Vu + CF” by adding the offset correction amount CF to the U-phase command voltage Vu. The V-phase superimposition unit 94V calculates the V-phase final command voltage “Vv + CF” by adding the offset correction amount CF to the V-phase command voltage Vv. The W phase superimposition unit 94W calculates the W phase final command voltage “Vw + CF” by adding the offset correction amount CF to the W phase command voltage Vw.

The control device 70 includes U to W phase modulation units 95U to 95W. The U-phase modulation unit 95U calculates the U-phase modulation factor Mu by dividing the U-phase final command voltage by the power supply voltage Vdc. Here, the power supply voltage Vdc is the total value 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 95V calculates the V-phase modulation rate Mv by dividing the V-phase final command voltage by the power supply voltage Vdc. The W-phase modulation unit 95W calculates the W-phase modulation factor Mw by dividing the W-phase final command voltage by the power supply voltage Vdc.

The control device 70 performs switching control of each switch QUAH to QWL based on the calculated modulation factors Mu, Mv, and Mw. Specifically, for example, the control device 70 may perform switching control by PWM control based on a magnitude comparison between each modulation factor Mu, Mv, Mw and a carrier signal (for example, a triangular wave signal).

FIG. 6 shows the transition of each modulation factor Mu, Mv, Mw when the neutral point command current IM * is set to a sine wave. In the present embodiment, the frequency of the neutral point command current IM * is lower than the frequencies of the respective modulation factors Mu, Mv, and Mw.

FIG. 7 shows each waveform in the temperature rise control. FIG. 7 (a) shows the transition of each phase current Iu, Iv, Iw, FIG. 7 (b) shows the transition of the neutral point current IMr, and FIG. 7 (c) shows the terminal voltage VBH of the first storage battery 21. The transition is shown, and FIG. 7D shows the transition of the terminal voltage VBL of the second storage battery 22.

As shown in FIG. 7A, each phase current Iu, Iv, Iw is controlled to have a waveform corresponding to each modulation factor Mu, Mv, Mw. As a result, as shown in FIG. 7B, the neutral point current IMr is controlled to a sine wave having the same period as the neutral point command current IM * by the temperature rise control. When the neutral point current IMr is positive, the first storage battery 21 is discharged and the second storage battery 22 is charged. When the neutral point current IMr is negative, the second storage battery 22 is discharged and the first storage battery 21 is charged. Therefore, as shown in FIGS. 7C and 7D, the transitions of the terminal voltage VBH of the first storage battery 21 and the terminal voltage VBL of the second storage battery 22 are in opposite phases to each other.

FIG. 8 shows, as a comparative example, the transition of each phase current Iu, Iv, Iw when the temperature rise control is performed with the circuit configuration described in Patent Document 1. FIG. 8A shows the transition of the U-phase current Iu, FIG. 8B shows the transition of the V-phase current Iv, and FIG. 8C shows the transition of the W-phase current Iw.

The U-phase winding is connected to the positive electrode of the storage battery via a connection path. In the temperature rise control, since the current is passed through the connection path, the amplitude of the U-phase current Iu is larger than the amplitude of the V and W-phase currents Iv and Iw. Therefore, the current flowing through each phase winding is not balanced.

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

The neutral point O and the intermediate terminal B are electrically connected by the connection path 60. Therefore, when it is determined that there is a request for temperature rise of the first storage battery 21 and the second storage battery 22, the temperature rise control is performed via the inverter 30, each phase winding 41U to 41W, and the connection path 60. A current can be passed between the first storage battery 21 and the second storage battery 22 to raise the temperature of the first storage battery 21 and the second storage battery 22. In particular, since the neutral point O is connected to the intermediate terminal B, the current does not concentrate on the windings of a certain phase during the temperature rise control, and the currents flowing through the windings 41U to 41W of each phase can be balanced. it can. As a result, since the current due to the temperature rise control does not interfere with the driving of the rotary electric machine 40, the rotary electric machine 40 can be driven while controlling the temperature rise of the first storage battery 21 and the second storage battery 22.

When it is determined that there is a temperature rise request, the connection switch 61 provided in the connection path 60 is turned on. On the other hand, when it is determined that there is no temperature rise request, the connection switch 61 is turned off. As a result, it is possible to suppress the flow of current between the neutral point O and the intermediate terminal B when there is no request for temperature rise.

The switching frequency f2 in the temperature rise control / drive PWM control and the temperature rise PWM control is set to a frequency higher than the switching frequency f1 in the drive PWM control and deviating from the human audible range. This makes it possible to reduce noise during temperature rise control.

<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment. In FIG. 9, the same components as those shown in FIG. 4 above are designated by the same reference numerals for convenience.

The temperature rise control unit 90 includes a temperature deviation calculation unit 96. The temperature deviation calculation unit 96 calculates the temperature deviation ΔT as the required amount of temperature rise by subtracting the temperature T of the assembled battery 20 detected by the monitoring unit 50 from the target temperature T *. The command value setting unit 91 sets the neutral point command current IM * based on the temperature deviation ΔT which is an input value. Specifically, as shown in FIG. 10A, the command value setting unit 91 increases the amplitude Ia of the neutral point command current IM * as the temperature deviation ΔT increases. Here, the correlation between the temperature deviation ΔT and the amplitude Ia of the neutral point current IMr may be designed in advance, for example. The upper limit of the amplitude Ia of the neutral point current IMr may be set within the allowable current range of the first storage battery 21 and the second storage battery 22.

Further, the command value setting unit 91 sets the neutral point command current IM * based on the torque command value Trq * which is an input value. Specifically, as shown in FIG. 10B, the command value setting unit 91 reduces the amplitude Ia of the neutral point command current IM * as the torque command value Trq * of the rotary electric machine 40 increases. Here, the correlation between the torque Trq of the rotary electric machine 40 and the amplitude Ia of the neutral point current IMr may be designed in advance, for example.

Further, the command value setting unit 91 sets the neutral point command current IM * based on the rotation speed N set for the rotary electric machine 40 which is an input value. Specifically, as shown in FIG. 10C, the command value setting unit 91 reduces the amplitude Ia of the neutral point command current IM * as the rotation speed N of the rotary electric machine 40 increases. Here, the correlation between the rotation speed N of the rotary electric machine 40 and the amplitude Ia of the neutral point current IMr may be designed in advance, for example.

The rotation speed N may be calculated based on, for example, a detection value of a rotation angle sensor such as a resolver. Further, the amplitude Ia may be calculated based on, for example, the temperature deviation ΔT, the torque command value Trq *, and the map information in which the rotation speed N and the amplitude Ia are related.

<Third Embodiment>
Hereinafter, the third embodiment will be described with reference to the drawings, focusing on the differences from the first embodiment.

As the amount of temperature rise required increases, the current flowing through the rotary electric machine 40 increases, so that the rotary electric machine 40 tends to be in a magnetically saturated state, and the inductance of the rotary electric machine 40 fluctuates greatly. As a result, the torque may fluctuate greatly while the rotary electric machine 40 is being driven.

Therefore, in the present embodiment, in order to suppress the fluctuation of the torque, Idr = 0 control is performed when the required amount of temperature rise is larger than the set value. Hereinafter, the temperature rise control in this embodiment will be described.

FIG. 11 is a flowchart showing the procedure of the temperature rise control process. In FIG. 11, the same components as those shown in FIG. 2 above are designated by the same reference numerals for convenience.

If it is determined in step S17 that there is a drive request for the rotary electric machine 40, the process proceeds to step S24 to determine whether the temperature rise request amount is greater than or less than the set value. Here, the temperature deviation ΔT described in the second embodiment may be used as the required amount of temperature rise. If the required amount of temperature rise is equal to or less than the set value, the process proceeds to step S21. On the other hand, when the required amount of temperature rise is larger than the set value, the process proceeds to step S25 to set the temperature rise control / limit drive mode. In this embodiment, step S24 corresponds to the temperature rise request amount determination unit.

In the following step S26, the connection switch 61 is turned on. In step S27, in addition to the temperature rise / drive PWM control, Idr = 0 control is performed.

FIG. 12 shows the current operating points of the rotary electric machine 40 determined by the d, q-axis currents Idr and Iqr in the temperature rise control / drive mode and the temperature rise control / limit drive mode. The horizontal axis of FIG. 12 is the d-axis current Idr, and the vertical axis is the q-axis current Iqr. Ltc indicates an equitorque line composed of a combination of d, q-axis currents Idr, and Iqr when the torques are the same. The equal torque line is determined based on the torque command value Trq *. Lmtpa indicates a maximum efficiency line consisting of a combination of d, q-axis currents Idr, and Iqr corresponding to minimum current and maximum torque control (MTPA).

The first operating point OP1 is a current operating point in the temperature rise control / drive mode when Idr = 0 control is not performed. In the temperature rise control / drive mode, the d and q-axis currents Idr and Iqr are not limited, and for example, the current operating point is controlled on the maximum efficiency line Lmtpa. On the other hand, the second operating point OP2 is a current operating point in the temperature rise control / limited drive mode. In the temperature rise control / limited drive mode, the current operating point is controlled on the equal torque line Ltc with the d-axis current Idr set to 0. That is, the torque of the rotary electric machine 40 is controlled by the torque command value Trq *, and the d-axis current Idr is controlled to 0.

By controlling Idr = 0 in the temperature rise control / limited drive mode, only the q-axis current Iqr is used for torque control among the d, q-axis currents Idr and Iqr used for torque control. As a result, the second operating point OP2 shifts on the Iqr axis. Therefore, since the d-axis current Idr does not contribute to the torque, the torque fluctuation due to the change in the inductance of the rotary electric machine 40 can be suppressed.

The d-axis current Idr of the second operating point OP2 is set to 0, but the present invention is not limited to this. The absolute value of the d-axis current Idr for the field weakening of the second operating point OP2 is the first, provided that the second operating point OP2 is positioned on the equal torque line passing through the first operating point OP1. It may be smaller than the absolute value of the d-axis current Idr of the operating point OP1 and larger than 0. Even in this case, the torque fluctuation due to the change in the inductance of the rotary electric machine 40 can be suppressed.

<Fourth Embodiment>
In the first embodiment, the rotary electric machine 40 and the inverter 30 may be other than three phases such as five-phase or seven-phase. FIG. 13 shows the power conversion device 10 in the case of five phases. In FIG. 13, the same components as those shown in FIG. 1 above are designated by the same reference numerals for convenience.

In FIG. 13, in the inverter 30, the X-phase upper and lower arm switches QXH and QXL and the diodes DXH and DXL are added, and the Y-phase upper and lower arm switches QYH and QYL and the diodes DYH and DYL are added. Further, in the rotary electric machine 40, an X-phase winding 41X and a Y-phase winding 41Y are added. Further, in the power conversion device 10, an X-phase conductive member 32X and a Y-phase conductive member 32Y are added.

<Other Embodiments>
Each of the above embodiments may be modified as follows.

-The method of setting the neutral point command current IM * is not limited to that shown in FIG. For example, while satisfying the relationship that the positive neutral point command current IM * and the negative neutral point command current IM * are point symmetric with respect to the zero cross timing of the neutral point command current IM * in one cycle Tc, for example. The positive neutral point command current IM * and the negative neutral point command current IM * may be set to trapezoidal waves or rectangular waves, respectively.

Further, the method of setting the neutral point command current IM * is not limited to the one satisfying the above-mentioned point symmetry relationship. For example, in one cycle Tc, the period from the first zero cross timing C1 to the second zero cross timing C2 of the neutral point command current IM * and the second zero cross timing C2 to the third zero cross timing C3 of the neutral point command current IM *. The neutral point command current IM * may be set so that the period up to is different and the area S1 of the first region and the area S2 of the second region are equal to each other. Even in this case, the balance of charge / discharge currents of the first storage battery 21 and the second storage battery 22 in one cycle Tc can be matched.

The upper and lower arm switches constituting the inverter 30 are not limited to IGBTs, and may be, for example, N-channel MOSFETs. In this case, the high potential side terminal serves as a drain and the low potential side terminal serves as a source.

-The connection switch 61 is not limited to a relay. As the connection switch 61, for example, a pair of N-channel MOSFETs in which sources are connected to each other or an IGBT may be used.

The controls and methods thereof described in the present disclosure are provided by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. It may be realized. Alternatively, the controls and methods thereof described in the present disclosure may be implemented by a dedicated computer provided by configuring the processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and method thereof described in the present disclosure may be a combination of a processor and memory programmed to perform one or more functions and a processor composed of one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as an instruction executed by the computer.

10 ... Power converter, 21 ... 1st storage battery, 22 ... 2nd storage battery, 30 ... Inverter, U, V, W phase upper arm switch ... QUAH, QVH, QWH, U, V, W phase lower arm switch ... QL, QVL, QWL, 40 ... Rotating electric machine, U, V, W phase winding ... 41U, 41V, 41W, 61 ... Connection switch, 70 ... Control device.

Claims (10)

A rotary electric machine (40) having a star-shaped winding (41U, 41V, 41W, 41X, 41Y) and a rotating electric machine (40).
In a power converter (10) including an inverter (30) having a series connection of an upper arm switch (QUH, QVH, QWH, QXH, QYH) and a lower arm switch (QUL, QVL, QWL, QXL, QYL). ,
In the first storage battery (21) and the second storage battery (22) connected in series, the negative electrode side of the first storage battery, the positive electrode side of the second storage battery, and the neutral point (O) of the winding are electrically connected. The connection path (60) to be connected and
A temperature rise determination unit (70) for determining whether or not there is a request for temperature rise of the first storage battery and the second storage battery, and
A drive determination unit (70) for determining whether or not there is a drive request for the rotary electric machine, and
When it is determined that there is a temperature rise request and there is a drive request, a current is passed between the first storage battery and the second storage battery via the inverter, the winding, and the connection path. A power conversion device including a control unit (70) that performs switching control of the upper arm switch and the lower arm switch so as to drive the rotary electric machine. A connection switch (61) provided in the connection path is provided.
When it is determined that there is a temperature rise request, the control unit performs the switching control with the connection switch turned on, and when it is determined that there is no temperature rise request, the control unit is requested to turn off the connection switch. Item 1. The power conversion device according to item 1. In one cycle of the command value of the current flowing through the connection path, the control unit makes the area of the region specified by the positive command value equal to the area of the region specified by the negative command value. The power conversion device according to claim 1 or 2, wherein the command value is set in 1 and the switching control is performed in order to control the current flowing in the connection path to the command value. 3. The control unit sets the command value so that the positive command value and the negative command value are point-symmetrical with respect to the zero cross timing of the command value in one cycle of the command value. The power converter described in. The power conversion device according to claim 4, wherein the control unit sets the amplitude of the command value to be larger as the temperature rise request of the first storage battery and the second storage battery is higher. The power conversion device according to claim 5, wherein the control unit sets the amplitude of the command value to be smaller as the torque of the rotary electric machine is larger. The power conversion device according to claim 5 or 6, wherein the control unit sets the amplitude of the command value to be smaller as the rotation speed of the rotary electric machine is higher. The claim that the control unit performs the switching control based on the final command voltage that reflects the correction amount set based on the temperature rise request in the command voltage of the winding set based on the drive request. The power conversion device according to any one of 1 to 7. The control unit sets the switching frequency of the switching control when it is determined that there is a temperature rise request to a frequency higher than the switching frequency when it is determined that there is no temperature rise request. The power conversion device according to any one of 8 to 8. The first storage battery and the second storage battery are provided with a temperature rise request amount determination unit (70) for determining whether or not the temperature rise request amount is larger than a set value.
When the control unit determines that the temperature rise request amount is larger than the set value, the d-axis flowing through the winding is more than when it is determined that the temperature rise request amount is equal to or less than the set value. The power conversion device according to any one of claims 1 to 9, wherein the switching control is performed so as to reduce the absolute value of the current.

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