JP-2026075920-A - Electric vehicles

Abstract

[Problem] To provide an electric vehicle that can detect the progression of deterioration of energy storage cells installed in the electric vehicle at an early stage. [Solution] The electric vehicle 1 comprises a battery 45a mounted on the electric vehicle 1 and a control unit 20. The control unit 20 acquires battery characteristic information Ei of the battery 45a at predetermined intervals Δt, and estimates the internal pressure Pbi and positive electrode potential Vbi of the battery 45a based on the battery characteristic information Ei. If the internal pressure Pbi exceeds a first threshold Th1, the control unit 20 counts the integrated internal pressure value Npi, and if the positive electrode potential Vbi exceeds a second threshold Th2, the control unit 20 counts the integrated potential value Nvi. The control unit 20 calculates a degradation index Exi, which is the value obtained by multiplying the integrated internal pressure value Npi by the integrated potential value Nvi, and determines that the battery 45a has deteriorated if the degradation index Exi exceeds a third threshold Th3. [Selection Diagram] Figure 2

Inventors

• 太田 創之

Assignees

• トヨタ自動車株式会社

Dates

Publication Date

20260511

Application Date

20241023

Claims (4)

1. The battery installed in the electric vehicle, It includes a control unit, The control unit acquires battery characteristic information of the battery at predetermined intervals, estimates the internal pressure and positive electrode potential of the battery based on the battery characteristic information, counts the integrated internal pressure value if the internal pressure exceeds a first threshold, and counts the integrated potential value if the positive electrode potential exceeds a second threshold. The control unit calculates a degradation index, which is the value obtained by multiplying the integrated internal pressure by the integrated potential, and determines that the battery has deteriorated if the degradation index exceeds a third threshold, in an electric vehicle.
2. The battery installed in the electric vehicle, It includes a control unit, The control unit acquires battery characteristic information of the battery at predetermined intervals in association with the mileage of the electric vehicle, estimates the internal pressure and positive electrode potential of the battery based on the battery characteristic information, counts the integrated internal pressure value if the internal pressure exceeds a first threshold, and counts the integrated potential value if the positive electrode potential exceeds a second threshold. The control unit calculates a degradation index which is the value obtained by multiplying the integrated internal pressure value by the integrated potential value, An electric vehicle wherein the control unit calculates the rate of deterioration, which is the increase in the deterioration index per unit of driving distance, based on the deterioration index, and determines that the battery has deteriorated when the deterioration index exceeds a fourth threshold.
3. The electric vehicle according to claim 1 or 2, wherein the battery characteristic information includes information on the battery voltage, information on the battery current, and information on the battery temperature.
4. The aforementioned battery is one of the energy storage cells that make up the battery pack, The aforementioned internal pressure is the pressure inside the cell case of the energy storage cell, The electric vehicle according to claim 1 or claim 2, wherein the positive electrode potential is the potential at the positive electrode terminal of the energy storage cell.

Description

This disclosure relates to electric vehicles. Japanese Patent Publication No. 2023-12835 (Patent Document 1) discloses a system for estimating the degradation index of each of the multiple energy storage cells forming a battery pack installed in an electric vehicle. More specifically, the ECU of the electric vehicle acquires the positive electrode potential and the internal pressure within the cell case of the energy storage cell at regular time intervals. The ECU estimates the degradation index of the energy storage cell by accumulating the time spent in a state where both the acquired positive electrode potential and the acquired internal pressure exceed a certain threshold. The ECU determines that an energy storage cell whose degradation index exceeds a certain threshold is an energy storage cell that has exceeded an acceptable level of degradation. Japanese Patent Publication No. 2023-12835 This is a schematic diagram of an electric vehicle according to an embodiment of the present disclosure.This is a control flow diagram of an electric vehicle according to an embodiment of the present disclosure.This figure shows the relationship between the integrated internal pressure and integrated potential according to the embodiment of this disclosure.This figure shows the control flow of an electric vehicle according to an embodiment of this disclosure.This figure shows the relationship between mileage and deterioration index according to the embodiments of this disclosure. Embodiments of this disclosure will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and their descriptions will not be repeated. <Overall configuration of electric vehicles> Figure 1 is a diagram showing a schematic configuration of an electric vehicle according to an embodiment of the present disclosure. The electric vehicle 1 is, for example, an electric car. The electric vehicle 1 comprises a motor generator (MG) 11 (a rotating electric machine), drive wheels 12, a power control unit (PCU) 13, a system main relay (SMR) 14, an ECU 20, a battery pack 40, and a monitoring unit 50. The ECU 20 is communicated with the PCU 13, the SMR 14, and the monitoring unit 50. MG11 is, for example, an embedded permanent magnet synchronous motor (IPM motor) that has both motor and generator functions. The output torque of MG11 is transmitted to the drive wheels 12 via a power transmission system that includes a reduction gear and a differential gear. During braking of the electric vehicle 1, the MG 11 is driven by the drive wheels 12, and the MG 11 operates as a generator. As a result, the MG 11 also functions as a braking device that performs regenerative braking, converting the kinetic energy of the electric vehicle 1 into electrical energy. The regenerative power generated by the regenerative braking force in the MG 11 is stored in the battery pack 40. The PCU 13 is a power conversion device that converts power bidirectionally between the MG 11 and the battery pack 40. The PCU 13 includes, for example, an inverter and a converter that operate based on a control signal from the ECU 20. When the battery pack 40 is discharged, the converter boosts the voltage supplied from the battery pack 40 and supplies it to the inverter. The inverter converts the DC power supplied from the converter into AC power to drive the MG 11. Note that the PCU 13 may also be configured without the converter. The SMR14 is electrically connected to the power line connecting the battery pack 40 and the PCU 13. When the SMR14 is closed (ON) (i.e., conducting) in response to a control signal from the ECU 20, power can be exchanged between the battery pack 40 and the PCU 13. Conversely, when the SMR14 is open (OFF) (i.e., disconnected) in response to a control signal from the ECU 20, the electrical connection between the battery pack 40 and the PCU 13 is interrupted. The ECU 20 includes a processor 21, a memory 22, and a storage 23. The processor 21 is a computing device such as a CPU (Central Processing Unit) or MPU (Micro-Processing Unit). The memory 22 is volatile memory (working memory) such as RAM (Random Access Memory). The storage 23 is rewritable non-volatile memory such as flash memory. The storage 23 stores a system program including an OS (Operating System) and a control program including computer-readable code necessary for control calculations. The processor 21 performs various processes by reading the system program and control program, loading them into the memory 22, and executing them. The ECU 20 may be divided into multiple ECUs according to function. Note that the ECU 20 is an example of a "control unit" in this disclosure. The battery pack 40 is mounted on the electric vehicle 1. The battery pack 40 has a plurality of energy storage cells 45. The plurality of energy storage cells 45 are electrically connected in series. Each of the plurality of energy storage ce