JP2021136809A - Control device of electric vehicle - Google Patents

Abstract

To provide a control device of an electric vehicle which can detect the internal resistance of a battery which is mounted to the electric vehicle with an influence of polarization being eliminated as much as possible.SOLUTION: A control device (300) of an electric vehicle (1) is constituted so that, when a vehicle speed is equal to or less than a prescribed value α (S1), a torque command of an MG (10) is set to zero, a q-axis current is set to zero, and a d-axis current is supplied (S2), and an internal resistance value of a battery (100) is calculated on the basis of the d-axis current (S3, S4).SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a rotating electric machine for traveling and a control device for an electric vehicle provided with a battery for supplying electric power to the rotating electric machine.

In Japanese Patent No. 3122751 (Patent Document 1), the stopped state of the vehicle is confirmed, the discharge current from the battery in the vehicle acceleration state immediately after that and the battery voltage at this time are detected, and the discharge current and the battery voltage are detected. It is disclosed to calculate the internal resistance of the battery.

Japanese Patent No. 3122751

In Patent Document 1, since the discharge current is always zero when the vehicle is stopped, the discharge current-battery voltage characteristic (IV characteristic) with good reproducibility is always provided without being affected by the battery polarization during the acceleration immediately after that. It is said that it can be obtained and the internal resistance of the battery can be obtained accurately. However, when a large driving force is required when accelerating the vehicle, in other words, when a large amount of electric power is discharged from the battery, the influence of the polarization of the battery becomes large, and the internal resistance of the battery can be detected accurately. There was room for improvement.

An object of the present disclosure is to provide a control device for an electric vehicle capable of detecting the internal resistance of a battery mounted on the electric vehicle by eliminating the influence of polarization as much as possible.

The control device for an electric vehicle of the present disclosure is a control device for an electric vehicle including a rotating electric machine for traveling and a battery for supplying electric power to the rotating electric machine. When the rotation speed of the rotary electric machine is equal to or less than a predetermined value, the control device sets the q-axis current of the rotary electric machine to zero, supplies the d-axis current of the rotary electric machine, and calculates the internal resistance of the battery based on the d-axis current. It is configured as.

According to this configuration, when the rotation speed of the rotary electric machine is equal to or less than a predetermined value, the q-axis current of the rotary electric machine is set to zero, and only the d-axis current of the rotary electric machine is supplied. Since the q-axis current is zero, the torque generated by the rotary electric machine is zero, and the magnitude of the d-axis current can be arbitrarily controlled. Further, since the rotation speed of the rotary electric machine is equal to or less than a predetermined value, it is not easily affected by the regenerative operation of the rotary electric machine. Therefore, the discharge current from the storage battery can be controlled to a current value that is not easily affected by polarization, so that the internal resistance of the battery mounted on the electric vehicle can be detected by eliminating the influence of polarization as much as possible. ..

According to the present disclosure, it is possible to provide a control device for an electric vehicle capable of detecting the internal resistance of a battery mounted on the electric vehicle by eliminating the influence of polarization as much as possible.

It is an overall block diagram of the electric vehicle provided with the control device of the electric vehicle which concerns on this embodiment. It is a figure which showed an example of the detailed structure of the battery 100. It is a flowchart which shows the process executed by the ECU 300.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a diagram showing an overall configuration of an electric vehicle 1 provided with a control device for the electric vehicle according to the present embodiment.

In the present embodiment, the electric vehicle 1 is, for example, an electric vehicle. The electric vehicle 1 includes a motor generator (MG: Motor Generator) 10 which is a rotary electric machine, a power transmission gear 20, a drive wheel 30, a power control unit (PCU: Power Control Unit) 40, and a system main relay (SMR:). It includes a System Main Relay) 50, a battery 100, a monitoring unit 200, and an electronic control unit (ECU) 300 which is an example of a control device.

The MG10 is, for example, an embedded structure permanent magnet synchronous motor (IPM motor), and has a function as an electric motor (motor) and a function as a generator (generator). The output torque of the MG 10 is transmitted to the drive wheels 30 via a power transmission gear 20 including a speed reducer, a differential device, and the like.

When braking the electric vehicle 1, the MG 10 is driven by the drive wheels 30, and the MG 10 operates as a generator. As a result, the MG 10 also functions as a braking device that performs regenerative braking that converts the kinetic energy of the electric vehicle 1 into electric power. The regenerative power generated by the regenerative braking force in the MG 10 is stored in the battery 100.

The PCU 40 is a power conversion device that converts power in both directions between the MG 10 and the battery 100. The PCU 40 includes, for example, an inverter and a converter that operate based on a control signal from the ECU 300.

When the battery 100 is discharged, the converter boosts the voltage supplied from the battery 100 and supplies it to the inverter. The inverter converts the DC power supplied from the converter into AC power to drive the MG 10.

On the other hand, when the battery 100 is charged, the inverter converts the AC power generated by the MG 10 into DC power and supplies it to the converter. The converter steps down the voltage supplied from the inverter to a voltage suitable for charging the battery 100 and supplies the voltage to the battery 100.

Further, the PCU 40 suspends charging / discharging by stopping the operation of the inverter and the converter based on the control signal from the ECU 300. The PCU 40 may have a configuration in which the converter is omitted.

The SMR 50 is electrically connected to a power line connecting the battery 100 and the PCU 40. When the SMR 50 is closed (that is, in a conductive state) in response to a control signal from the ECU 300, power can be exchanged between the battery 100 and the PCU 40. On the other hand, when the SMR 50 is opened (that is, in the cutoff state) in response to the control signal from the ECU 300, the electrical connection between the battery 100 and the PCU 40 is cut off.

The battery 100 stores electric power for driving the MG 10. The battery 100 is a DC power source that can be recharged. For example, a plurality of parallel battery blocks formed by connecting a plurality of cells (single batteries) in parallel are connected in series. The cell includes, for example, a secondary battery such as a lithium ion secondary battery. The detailed configuration of the battery 100 will be described later. The electric vehicle 1 is provided with a charging circuit and / or a charger (not shown), and the battery 100 can be charged from an external power source.

The monitoring unit 200 includes a voltage detection unit 210, a current sensor 220, and a temperature detection unit 230. The voltage detection unit 210 detects the voltage VB between the terminals of the plurality of parallel battery blocks. The current sensor 220 detects the current IB input / output to / from the battery 100. The temperature detection unit 230 detects the temperature TB of each of the plurality of cells. Each detection unit outputs the detection result to the ECU 300.

The ECU 300 includes a CPU (Central Processing Unit) 301 and a memory (including, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), and the like) 302. The ECU 300 is based on information such as a signal received from the monitoring unit 200, a signal from various sensors (not shown) (for example, an accelerator opening signal, a vehicle speed signal, etc.), a map stored in the memory 302, a program, and the like. Control each device so that is in the desired state.

<Detailed configuration of battery 100>
FIG. 2 is a diagram showing an example of a detailed configuration of the battery 100 shown in FIG. With reference to FIG. 2, the battery 100 is configured by connecting a plurality of (for example, N) cells in parallel to form a parallel battery block, and connecting a plurality of (for example, M) parallel battery blocks in series. Will be done.

Specifically, the battery 100 includes parallel battery blocks 100-1 to 100-M connected in series, and each of the parallel battery blocks 100-1 to 100-M contains N cells connected in parallel. Consists of including. It is desirable that M is 3 or more.

The voltage detection unit 210 includes voltage sensors 210-1 to 210-M. The voltage sensors 210-1 to 210-M detect the voltage between the terminals of the parallel battery blocks 100-1 to 100-M, respectively. That is, the voltage sensor 210-1 detects the inter-terminal voltage VB1 of the parallel battery block 100-1. Similarly, the voltage sensors 210-2 to 210-M detect the inter-terminal voltages VB2 to VBM of the parallel battery blocks 100-2 to 100-M, respectively. The voltage detection unit 210 transmits the detected inter-terminal voltages VB1 to VBM to the ECU 300. The current sensor 220 detects the current IB flowing through each of the parallel battery blocks 100-1 to 100-M.

In the battery 100 using a parallel battery block in which a plurality of cells are connected in parallel, when one of the cells in the parallel battery block is disconnected, the current is concentrated on the cells that are not disconnected. For this reason, the amount of heat generated by the cells that are not broken increases and the temperature rises, which may lead to deterioration. At the time of discharge, there is a concern that the SOC of the cell that is not broken will decrease at an early stage and the mileage will decrease. Further, at the time of charging, there is a concern that the SOC of the cell that is not broken will rise faster and will be overcharged.

Therefore, it is desired to detect the disconnection of the cell in the parallel battery block at an early stage. If the cell in the parallel battery block is disconnected, the internal resistance of the parallel battery block changes. Therefore, it is desirable to accurately obtain the internal resistance of the parallel battery block. Conventionally, the current-voltage of each parallel battery block 100-1 to 100-M is used by using the current IB flowing through the parallel battery blocks 100-1 to 100-M and the inter-terminal voltage VB1 to VBM while the electric vehicle 1 is running. The characteristics (IV characteristics) were obtained, and the internal resistance of each parallel battery block 100-1 to 100-M was obtained from the inclination of the IV characteristics.

When the internal resistance of the parallel battery block is obtained while the electric vehicle 1 is traveling, the influence of polarization cannot be avoided when the current IB is large, and the calculated internal resistance tends to vary. In the present embodiment, when the rotation speed of the MG 10 is equal to or less than a predetermined value, the torque command of the MG 10 is set to zero, so that the q-axis current of the MG 10 is set to zero. Then, by supplying only the d-axis current to the MG10, the current IB flowing through the parallel battery blocks 100-1 to 100-M is set to a current value that is not easily affected by polarization, and the parallel battery blocks 100-1 to 100-M Calculate the internal resistance. This makes it possible to eliminate the influence of polarization as much as possible and obtain an accurate internal resistance.

FIG. 3 is a flowchart showing a process executed by the ECU 300, which is a control device. This process is repeatedly executed at predetermined intervals, for example, during the activation of the electric vehicle 1.

In step 1 (hereinafter abbreviated as S) 1, it is determined whether or not the accelerator pedal is not depressed (accelerator opening degree = 0) and the vehicle speed of the electric vehicle 1 is equal to or less than a predetermined value α. For example, the predetermined value α is 5 km / h. If the accelerator pedal is depressed or the vehicle speed exceeds the predetermined value α, a negative judgment is made and the process is returned. If the accelerator pedal is not depressed and the vehicle speed is equal to or less than the predetermined value α and a positive judgment is made, the process proceeds to S2. When the vehicle speed is equal to or less than the predetermined value α, the vehicle is almost stopped, and the rotation speed of the MG 10 is equal to or less than the predetermined value.

In S2, the torque command of MG10 is set to zero. Specifically, for example, as is well known, the current supplied to the MG 10 and the current phase are controlled by an inverter to make the q-axis current zero, so that the torque generated by the MG 10 becomes zero, and d. The shaft current is controlled within a predetermined range. The value of the d-axis current is such that the maximum value can eliminate the influence of the polarization of each cell of the parallel battery block when calculating the internal resistance. Further, the minimum value of the d-axis current is a value at which the detection error of the voltage sensors 210-1 to 210-M and the current sensor 220 can be ignored when calculating the internal resistance. These values differ depending on the characteristics of the cell and each sensor, and are set in advance by experiments or the like.

Following S2, in S3, the current IB and the inter-terminal voltage VB-1 to VB-M of each parallel battery block are acquired from the detection signals of the current sensor 220 and the voltage sensor 210-1 to 210-M, and the process goes to S4. move on. Since the q-axis current is zero, the current IB is the d-axis current.

In S4, the IV characteristics of each parallel battery block 100-1 to 100-M are obtained based on the current IB (that is, the d-axis current) and the voltage between terminals VB-1 to VB-M. For example, the IV characteristic of the parallel battery block 100-1 can be obtained by plotting a plurality of relationships between the current IB and the terminal voltage VB-1. Then, as is well known, the internal resistance VR-1 of the parallel ionization block 100-1 is calculated from the obtained slope of the IV characteristic. In this way, after calculating the internal resistance VR-1 to VR-M of each parallel battery block 100-1 to 100-M, the process proceeds to S5.

In S5, the ratio of the internal resistances of adjacent parallel battery blocks is calculated. For example, the ratio Rr-1 of the internal resistance VR-1 of the parallel battery block 100-1 to the internal resistance VR-2 of the parallel battery block 100-2 is calculated as Rr-1 = VR-1 / VR-2. Similarly, the ratio Rr-2 (= VR-2 / VR-3) of the internal resistance VR-2 of the parallel battery block 100-2 and the internal resistance VR-3 of the parallel battery block 100-3 is calculated. In this way, in each of the parallel battery blocks 100-1 to 100-M, the ratio (resistivity ratio) of the internal resistances of the adjacent parallel battery blocks Rr-1 to Rr- (M-1) is calculated.

In the following S6, it is determined whether or not the values of the resistivity ratios Rr-1 to Rr- (M-1) calculated in S5 are within a predetermined range. For example, it is determined whether or not "predetermined value A <resistivity ratio <predetermined value B" is satisfied. When all of the resistance ratios Rr-1 to Rr- (M-1) are within a predetermined range, a positive judgment is made and a return is made. If at least one of the resistivity ratios Rr-1 to Rr- (M-1) is out of the predetermined range, a negative determination is made and the process proceeds to S7. When the cells in the parallel battery block are disconnected, the internal resistance of the parallel battery block becomes larger than when the cells are not disconnected. Therefore, the resistivity ratio of the parallel battery block in which the cell is disconnected and the parallel ionization block in which the cell is not disconnected greatly changes with respect to the resistivity ratio between the parallel battery blocks in which the cell is not disconnected. Therefore, the resistivity ratio between the parallel battery blocks in which the cell is not broken is within the predetermined range, but the resistivity ratio between the parallel battery block in which the cell is broken and the parallel ionization block in which the cell is not broken is out of the predetermined range. .. The predetermined range (predetermined value A, predetermined value B) may be set in advance by an experiment or the like.

In S7, the warning light provided on the instrument panel of the electric vehicle 1 is turned on to notify the occurrence of an abnormality, and the diagnosis code is stored in the memory 302. The diagnosis code may be information indicating an abnormality (cell disconnection abnormality) of the battery 100, and may include information indicating a resistance ratio Rr-1 to Rr- (M-1) that is out of the predetermined range. .. It may also include information indicating a parallel battery block in which an abnormality has occurred (including a broken cell). For example, when the cell in the parallel battery block 100-2 is disconnected, the resistance ratio Rr-1 and the resistance ratio Rr-2 are out of the predetermined range, and it can be identified that the parallel battery block 100-2 is abnormal. As described above, when the resistance ratio with the parallel battery blocks on both sides is out of the predetermined range, it can be identified that an abnormality (cell disconnection) has occurred in the parallel battery block. When the processing of S7 is completed, it is returned.

In the present embodiment, when the vehicle speed of the electric vehicle 1 is equal to or less than a predetermined value α and the rotation speed of the MG 10 is equal to or less than a predetermined value, the torque command of the MG 10 is set to zero. Since the torque command of the MG 10 becomes zero, the inverter is controlled so that the q-axis current becomes zero, the torque generated by the MG 10 becomes zero, and the d-axis current is controlled within a predetermined range. Since the q-axis current is zero, the magnitude of the d-axis current can be arbitrarily controlled, and since the rotation speed of the MG 10 is equal to or less than a predetermined value, it is not easily affected by the regenerative operation of the MG 10. Therefore, the discharge current (d-axis current) from the battery 100 (parallel battery blocks 100-1 to 100-M) can be controlled to a current value that is not easily affected by polarization, so that the parallel row battery blocks 100-1 to 100 The internal resistance of −M can be calculated by eliminating the influence of polarization as much as possible.

In the above embodiment, the disconnection of the cell (cell) is determined based on the ratio (resistivity ratio) Rr-1 to Rr- (M-1) of the internal resistances of the adjacent parallel battery blocks. The determination of disconnection does not have to be based on the resistance ratio. For example, the deviation of the internal resistance of the adjacent parallel battery blocks may be obtained, and if the deviation is equal to or greater than a predetermined value, it may be determined that the cell is broken.

In the above embodiment, the example in which the electric vehicle 1 is an electric vehicle has been described, but the electric vehicle may be a hybrid vehicle. In a hybrid vehicle that uses an internal combustion engine and a rotary electric machine (motor generator) as a running drive source, if the hybrid vehicle is provided with a running mode in which the rotary electric machine is stopped while running using the internal combustion engine, even during running. , The rotation speed of the rotary electric machine becomes less than or equal to the predetermined value. During such traveling, the q-axis current may be set to zero by setting the torque command to the rotary electric machine to zero, and the d-axis current may be controlled to calculate the internal resistance of the parallel battery block.

By exemplifying the embodiments in the present disclosure, the following aspects can be exemplified.
1) A control device for an electric vehicle including a rotary electric machine for traveling and a battery for supplying electric power to the rotary electric machine. The control device is a rotary electric machine when the rotation speed of the rotary electric machine is equal to or less than a predetermined value. By setting the torque command to zero, the q-axis current of the rotating electric machine is set to zero, the d-axis current of the rotating electric machine is supplied, and the internal resistance value of the battery is calculated based on the d-axis current. Control device for electric vehicles.

2) A control device for an electric vehicle including a rotary electric machine for traveling and a battery for supplying electric power to the rotary electric machine. The control device is q of the rotary electric machine when the vehicle speed of the electric vehicle is equal to or less than a predetermined value. A control device for an electric vehicle, which is configured to set the shaft current to zero, supply the d-axis current of a rotating electric machine, and calculate the internal resistance value of the battery based on the d-axis current. By setting the torque command of the rotary electric machine to zero, the q-axis current of the rotary electric machine may be set to zero and the d-axis current of the rotary electric machine may be supplied.

3) A control device for an electric vehicle equipped with a rotary electric machine for traveling and a battery for supplying electric power to the rotary electric machine. The control device is such that the vehicle speed of the electric vehicle is equal to or less than a predetermined value and the accelerator pedal is depressed. When not, the control of the electric vehicle is configured to set the q-axis current of the rotating electric machine to zero, supply the d-axis current of the rotating electric machine, and calculate the internal resistance value of the battery based on the d-axis current. Device. By setting the torque command of the rotary electric machine to zero, the q-axis current of the rotary electric machine may be set to zero and the d-axis current of the rotary electric machine may be supplied.

4) In any of the above 1 to 3, the battery is configured by connecting a plurality of parallel battery blocks including a plurality of cells (single batteries) connected in parallel in series.

5) In 4 above, the internal resistance (VR-1 to VR-) of each parallel battery block is based on the current flowing through the parallel battery blocks (IB) and the voltage between the terminals of each parallel battery block (VB-1 to VB-M). M) is calculated.

6) In 5 above, the internal resistance (VR-1 to VR-M) of each parallel battery block is obtained based on the slope of the IV characteristic of each parallel battery block.

7) In 5 or 6 above, the ratio (resistivity ratio (Rr-1 to Rr- (M-1))) of the internal resistances (VR-1 to VR-M) of adjacent parallel battery blocks is obtained, and at least one resistance is obtained. When the ratio (Rr-1 to Rr- (M-1) is out of the predetermined range, it is determined to be abnormal. The abnormality may be a disconnection of the cell (cell) in the parallel battery block.

8) In 5 or 6 above, when the deviation of the internal resistance (VR-1 to VR-M) of the adjacent parallel battery blocks is equal to or greater than a predetermined value, the cells (cells) constituting the parallel battery blocks are disconnected. Judge.

9) In 5 or 6 above, the disconnection of the cells (cells) constituting the parallel battery block is determined by comparing the internal resistances (VR-1 to VR-M) of the adjacent parallel battery blocks.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the description of the embodiment described above, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 Electric vehicle, 10 MG (rotary electric machine), 20 power transmission gear, 30 drive wheels, 40 PCU, 50 SMR, 100 battery, 200 monitoring unit, 210 voltage detector, 220 current sensor, 230 temperature detector, 300 ECU ( Control unit), 301 CPU, 302 memory.

Claims (1)

Rotating electric machine for running and
A control device for an electric vehicle provided with a battery for supplying electric power to the rotary electric machine.
When the rotation speed of the rotary electric machine is equal to or less than a predetermined value, the control device sets the q-axis current of the rotary electric machine to zero and supplies the d-axis current of the rotary electric machine, and the battery is based on the d-axis current. An electric vehicle control device that is configured to calculate the internal resistance of an electric vehicle.

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