Method for estimating internal resistance of secondary battery and anomaly detection system of secondary battery

Patent metadata

Field	Value
Publication number	US-11906594-B2
Application number	US-202017612323-A
Country	US
Kind code	B2
Filing date	May 15, 2020
Priority date	May 24, 2019
Publication date	Feb 20, 2024
Grant date	Feb 20, 2024

Abstract

An electric automobile incorporating a secondary battery has a disadvantage such as a difficulty in knowing the remaining capacity accurately and in predicting the time when the remaining capacity becomes zero because of deterioration of the secondary battery. The internal resistance is estimated with high accuracy even when the secondary battery deteriorates. Data used for learning or estimation is a data group (also referred to as data with regenerative charging) that is limited to data acquired within a certain time range around the end of regenerative charging. Such data within the limited range is extracted, used for learning, and subjected to the estimation. Thus, a value of the internal resistance can be output with high accuracy, specifically, with a mean error rate of 1% or less.

First claim

The invention claimed is:

1. A method for estimating internal resistance of a secondary battery in an electric vehicle,
wherein a vehicle comprises a secondary battery, a learned neural network portion for estimating internal resistance of the secondary battery, a regenerative brake for performing regenerative charging on the secondary battery, and a charging circuit for the regenerative charging of the secondary battery,
wherein the method comprises:
performing regenerative charging of the secondary battery when a brake of the vehicle runs;
measuring data of the secondary battery while the electric vehicle is stopped with regenerative charging not running;
inputting the data of the secondary battery to the learned neural network portion; and
outputting estimated internal resistance of the secondary battery from the learned neural network portion, and

wherein the data of the secondary battery is data limited within a first time range around an end of the regenerative charging.

2. The method for estimating internal resistance of a secondary battery in an vehicle according to claim 1 , wherein the first time range comprises a point of time before the end of regenerative charging and a point of resting time later than the end of regenerative charging.

3. The method for estimating internal resistance of a secondary battery in an vehicle according to claim 1 , wherein each of learning data to prepare the learned neural network portion and the data of the secondary battery includes one or more selected from a temperature, a voltage, a power, a current and a voltage.

4. A method for detecting an anomaly of a secondary battery in an electric vehicle,
wherein a vehicle comprises a secondary battery, a learned neural network portion for estimating internal resistance of the secondary battery, a regenerative brake for performing regenerative charging on the secondary battery, and a charging circuit for the regenerative charging of the secondary battery,
wherein the method comprises:
performing regenerative charging of the secondary battery when a brake of the vehicle runs;
measuring data of the secondary battery while the electric vehicle is stopped with regenerative charging not running;
inputting the data of the secondary battery to the learned neural network portion;
outputting estimated internal resistance of the secondary battery from the learned neural network portion; and
comparing a value of the estimated internal resistance with a reference value stored in advance as a range of a normal internal resistance in a memory.

Assignees

• Semiconductor Energy Lab

Inventors

• Saito Jo
• Mikami Mayumi

Classifications

• B60L58/16

  responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH] · CPC title

• B60L58/15

  Preventing overcharging · CPC title

• G01R31/396

  Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery · CPC title

• H01M10/48 Primary

  Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) · CPC title

• H02J7/80

  including monitoring or indicating arrangements · CPC title