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DE-102025132205-A1 - Vehicle and method for estimating battery deterioration

DE102025132205A1DE 102025132205 A1DE102025132205 A1DE 102025132205A1DE-102025132205-A1

Abstract

A vehicle comprises: a traction motor-generator; a power control unit (PCU) that drives the motor-generator; a main battery that is charged and discharged by the PCU while the vehicle is in use; and a processor. When the vehicle is in use, the processor calculates a cycle degradation measure of the main battery by performing a cycle degradation process using the amount of electrical charge that has flowed through the main battery. When the vehicle is not in use, the processor calculates a calendar degradation measure of the main battery by performing a calendar degradation process using the duration of main battery inactivity. The processor estimates the degree of main battery degradation based on the sum of the cycle and calendar degradation measures. Even when the vehicle is in use, the processor performs the calendar degradation measure process if the amount of electrical charge falls below a reference value.

Inventors

  • Kumiko Noda

Assignees

  • TOYOTA JIDOSHA KABUSHIKI KAISHA

Dates

Publication Date
20260513
Application Date
20250813
Priority Date
20241111

Claims (5)

  1. Vehicle comprising: a traction motor generator (90); a drive unit (80) configured to drive the motor generator (90); a battery (40) configured to be charged and discharged by the drive unit (80) while the vehicle is in motion; and a processor configured to calculate, when the vehicle is in use, a cycle degradation measure of the battery (40) by performing a cycle degradation process using an amount of electrical charge that has passed through the battery (40); and to calculate, when the vehicle is not in use, a calendar degradation measure of the battery (40) by performing a calendar degradation procedure using a period of inactivity of the battery (40), and to estimate a degradation degree of the battery (40) based on a sum of the cycle degradation measure and the calendar degradation measure, where the processor is configured to also perform the calendar degradation process when the amount of electrical charge is less than a reference value when the vehicle is in use.
  2. Vehicle after Claim 1 , wherein the processor is configured to calculate an amount in the cycle degradation process for each temperature of the battery (40) by multiplying a square root of the amount of electrical charge by a cycle degradation rate of the battery (40), and to calculate the cycle degradation extent by summing the calculated amount for all temperatures, and in the calendar degradation process to calculate an amount for each temperature of the battery (40) and each state of charge of the battery (40) by multiplying a square root of the period of inactivity by a calendar degradation rate of the battery (40), and to calculate the calendar degradation extent by summing the calculated amounts for all temperatures and all states of charge.
  3. Vehicle after Claim 2 , wherein the processor is configured to calculate a current battery capacity maintenance rate (40) as the degradation rate by subtracting a square root from the sum of a battery capacity maintenance rate (40) before degradation.
  4. vehicle after one of the Claims 1 until 3 , further comprising: an auxiliary battery (70); a charger configured to charge the auxiliary battery (70) with electrical energy supplied by the battery (40); a power supply connection; and a power supply unit configured to provide electrical energy outside the vehicle via the power supply connection using the electrical energy supplied by the battery (40), the processor being configured to perform the cycle degradation process when the drive unit (80) is operating because the amount of electrical charge is greater than or equal to the reference value, and to perform the calendar degradation process when the charger or the power supply unit is operating because the amount of electrical charge is less than the reference value.
  5. A method for estimating the degradation of a battery (40) mounted in a vehicle, wherein the method comprises estimating a degree of degradation of the battery (40) using a processor, the estimation including: when the vehicle is in use, calculating a cycle degradation extent of the battery (40) by performing a cycle degradation process using an amount of electrical charge that has flowed through the battery (40); when the vehicle is not in use, calculating a calendar degradation extent of the battery (40) by performing a calendar degradation process using a period of inactivity of the battery (40); also when the vehicle is in use, performing the calendar degradation process when the amount of electrical charge is less than a reference value; and estimating the degree of degradation based on a sum of the cycle degradation extent and the calendar degradation extent.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention The present disclosure relates to vehicles and methods for estimating the degradation of a battery. 2. Description of the related prior art The unexamined Japanese patent application disclosure no. 2019-53074 ( JP 2019-53074 A Disclosure discloses a degradation estimation device capable of accurately estimating the degradation of an energy storage element. The degradation estimation device comprises a sensing unit and an estimation unit. The sensing unit acquires time-series data on the state of charge (SOC) of the energy storage element. The estimation unit calculates a cycle degradation value using a coefficient based on the magnitude of the SOC variation in the time-series data acquired by the sensing unit and estimates the degradation of the energy storage element based on the sum of the calculated cycle degradation value and a non-cycle degradation value. The cycle degradation value indicates the degradation of the energy storage element caused by current flow, and the non-cycle degradation value indicates the degradation of the energy storage element not caused by current flow. BRIEF SUMMARY OF THE INVENTION There is a constant need for an accurate estimation of the degradation rate of a battery installed in a vehicle. The inventors have focused on the fact that when estimating the degradation rate of a battery, the accuracy of the estimation decreases under certain conditions due to the distinction between current-flow-induced and non-current-flow-induced degradation. The present disclosure was made to address the above problem, and one objective of the present disclosure is to improve the accuracy of estimating the degree of degradation of a battery installed in a vehicle. A vehicle according to a first aspect of the present disclosure comprises: a traction motor-generator; a drive unit configured to drive the motor-generator; a battery configured to be charged and discharged by the drive unit while the vehicle is in use; and a processor. The processor is configured to calculate, when the vehicle is in use, a cycle degradation amount of the battery by performing a cycle degradation process using the amount of electrical charge that has flowed through the battery, and, when the vehicle is not in use, to calculate a calendar degradation amount of the battery by performing a calendar degradation process using a period of battery inactivity, and to estimate a degree of battery degradation based on the sum of the cycle degradation amount and the calendar degradation amount. The processor is configured to perform the calendar degradation measure process even when the vehicle is in use, if the amount of electrical charge is less than a reference value. A method for estimating the degradation of a battery according to a second aspect of the present disclosure is a method for estimating the degradation of a battery installed in a vehicle. The method comprises the estimation of a battery degradation degree by a processor. The estimation includes: when the vehicle is in use, calculating a cycle degradation degree of the battery by performing a cycle degradation process using the amount of electrical charge that has flowed through the battery; when the vehicle is not in use, calculating a calendar degradation degree of the battery by performing a calendar degradation process using a period of battery inactivity; even when the vehicle is in use, performing the calendar degradation process if the amount of electrical charge is less than a reference value; and estimating the degradation degree based on the sum of the cycle degradation amount and the calendar degradation amount. The present disclosure can improve the accuracy of estimating the degree of degradation of a battery installed in a vehicle. BRIEF DESCRIPTION OF THE DRAWINGS Features, advantages and technical and industrial significance of embodiments of the invention are described below with reference to the accompanying drawings, in which the same symbols denote the same elements and in which: 1 is a block diagram that shows an example of the overall configuration of a vehicle according to a specific embodiment; 2 shows tables that represent a cycle degradation coefficient and a calendar degradation coefficient; 3 is a diagram that illustrates the reason for the occurrence of an error in a cycle degradation value; 4 is a flowchart showing an embodiment of a degradation protection method that corresponds to the embodiment; 5 shows diagrams illustrating simulated driving patterns for determining the cycle degradation coefficient; and 6 shows diagrams illustrating the cycle degradation coefficient and the calendar degradation coefficient. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES An embodiment of the present disclosure is described in detail below with reference to the drawings. Identical or corresponding parts are marked with the same symbols in the drawings, and the description is not repeated. E