Battery Diagnostic System for Estimating Capacity Degradation of Batteries

Patent metadata

Field	Value
Publication number	US-2020284846-A1
Application number	US-201916295078-A
Country	US
Kind code	A1
Filing date	Mar 7, 2019
Priority date	Mar 7, 2019
Publication date	Sep 10, 2020
Grant date	—

Abstract

A battery diagnostic system stores capacity degradation models for batteries of a specific type mapped to sets of battery cycle models formed by voltages and/or currents measured at different capacities. Each capacity degradation model is mapped to a set of battery cycle models associated with different battery capacities. The system, upon accepting measurements indicative of a battery cycle and a current capacity of the test battery, compares the battery cycle of the test battery with the battery cycle models of different capacity degradation models associated with a value of the battery capacity closest to the current capacity of the test battery to select a battery cycle model closest to the battery cycle of the test battery and the degradation capacity model mapped to the selected battery cycle model. The system estimates future degradation of the capacity of the test battery based on the retrieved capacity degradation model.

First claim

Claimed is:

1 . A battery diagnostic system, comprising:
a memory configured to store a set of capacity degradation models for batteries of a specific type, each capacity degradation model defines degradation of a battery capacity as a function of time, mapped to sets of battery cycle models formed by values of one or combination of voltages and currents measured for the batteries of the specific type at different capacities during one or combination of a charging cycle and a discharging cycle, such that each capacity degradation model is mapped to a set of battery cycle models associated with different battery capacities; an input interface configured to accept measurements indicative of a battery cycle of a test battery and a current capacity of the test battery; a processor configured to
compare the battery cycle of the test battery with the battery cycle models of different capacity degradation models associated with a value of the battery capacity closest to the current capacity of the test battery to select at least one battery cycle model closest to the battery cycle of the test battery;
retrieve from the memory the degradation capacity model mapped to the selected battery cycle model; and
estimate future degradation of the capacity of the test battery based on the retrieved capacity degradation model; and
an output interface configured to output the estimated future degradation of the capacity of the test battery.

2 . The battery diagnostic system of claim 1 , wherein the battery capacity indicates a capacity of the battery to deliver an amount of charge for a period of time.

3 . The battery diagnostic system of claim 1 , wherein the future degradation of the capacity includes a section of the retrieved capacity degradation model starting at the current capacity of the test battery.

4 . The battery diagnostic system of claim 1 , wherein the input interface receives measurements of a discharge current of the battery, and wherein the processor determines the current capacity as being proportional to an integral of the measurements of the discharge current over a period of time with a constant of proportionality defined by the specific type of the battery.

5 . The battery diagnostic system of claim 1 , wherein the battery cycle models are formed from measurements of tail voltage of the batteries, and wherein the input interface accepts measurements of the tail voltage of the test battery.

6 . The battery diagnostic system of claim 1 , wherein the processor is configured to
select a subset of the battery cycle models closest to the battery cycle of the test battery; retrieve a subset of capacity degradation models corresponding to the selected subset of battery cycle models; and estimate the future degradation of the capacity of the battery based on a combination of the retrieved subset of capacity degradation models.

7 . The battery diagnostic system of claim 6 , wherein the combination is a weighted combination of the retrieved subset of capacity degradation models with weights corresponding to distances between the battery cycle of the test battery and the selected battery cycle models.

8 . The battery diagnostic system of claim 1 , wherein the measurements of the test battery are determined under the same conditions as measurements for determining the set of capacity degradation models and the sets of battery cycle models.

9 . A battery diagnostic method, wherein the method uses a processor coupled to a memory storing a set of capacity degradation models for batteries of a specific type, each capacity degradation model defines degradation of a battery capacity as a function of time, mapped to sets of battery cycle models formed by values of one or combination of voltages and currents measured for the batteries of the specific type at different capacities during one or combination of a charging cycle and a discharging cycle, such that each capacity degradation model is mapped to a set of battery cycle models associated with different battery capacities, wherein the processor is coupled with stored instructions implementing the method, wherein the instructions, when executed by the processor carry out at least some steps of the method, comprising:
accepting measurements indicative of a battery cycle of a test battery and a current capacity of the test battery; comparing the battery cycle of the test battery with the battery cycle models of different capacity degradation models associated with a value of the battery capacity closest to the current capacity of the test battery to select at least one battery cycle model closest to the battery cycle of the test battery; retrieving from the memory the degradation capacity model mapped to the selected battery cycle model; estimating future degradation of the capacity of the test battery based on the retrieved capacity degradation model; and outputting the estimated future degradation of the capacity of the test battery.

10 . The battery diagnostic method of claim 9 , wherein the battery capacity indicates a capacity of the battery to deliver an amount of charge for a period of time, and wherein the future degradation of the capacity includes a section of the retrieved capacity degradation model starting at the current capacity of the test battery.

11 . The battery diagnostic system of claim 9 , further comprising:
receiving measurements of a discharge current of the test battery; and determining the current capacity as being proportional to an integral of the measurements of the discharge current over a period of time with a constant of proportionality defined by the specific type of the test battery.

12 . The battery diagnostic method of claim 9 , wherein the battery cycle models are formed from measurements of tail voltage of the batteries, and wherein the input interface accepts measurements of the tail voltage of the test battery.

13 . The battery diagnostic system of claim 9 , further comprising:
selecting a subset of the battery cycle models closest to the battery cycle of the test battery; retrieving a subset of capacity degradation models corresponding to the selected subset of battery cycle models; and estimating the future degradation of the capacity of the battery based on a combination of the retrieved subset of capacity degradation models.

14 . The battery diagnostic method of claim 13 , wherein the combination is a weighted combination of the retrieved subset of capacity degradation models with weights corresponding to distances between the battery cycle of the test battery and the selected battery cycle models.

15 . A non-transitory computer readable storage medium embodied thereon a program executable by a processor for performing a method, wherein the medium stores a set of capacity degradation models for batteries of a specific type, each capacity degradation model defines degradation of a battery capacity as a function of time, mapped to sets of battery cycle models formed by values of one or combination of voltages and currents measured for the batteries of the specific type at different capacities during one or combination of a charging cycle and a discharging cycle, such that each capacity degradation model is mapped to a set of battery cycle models associated with different battery capacities, the method comprising:
accepting measurements indicative of a battery cycle of a test battery and a current capacity of the test battery; comparing the battery cycle of the test battery with the battery cycle models of different capacity degradation models associated with a value of the battery capacity close

Assignees

• Mitsubishi Electric Res Laboratories Inc

Inventors

• Pajovic Milutin
• Orlik Philip

Classifications

• Y02E60/10

  Energy storage using batteries · CPC title

• G06F30/20

  Design optimisation, verification or simulation (optimisation, verification or simulation of circuit designs G06F30/30) · CPC title

• G06N20/00

  Machine learning · CPC title

• G01R31/367

  Software therefor, e.g. for battery testing using modelling or look-up tables · CPC title

• G06N5/04

  Inference or reasoning models · CPC title