Battery system

Patent metadata

Field	Value
Publication number	US-12148899-B2
Application number	US-202318539633-A
Country	US
Kind code	B2
Filing date	Dec 14, 2023
Priority date	Jun 12, 2020
Publication date	Nov 19, 2024
Grant date	Nov 19, 2024

Abstract

A battery system that avoids an over discharge with a simple sensor element is provided. The battery system comprises: a battery pack including a plurality of battery cells connected in series, a monitoring unit that monitors a condition of the battery pack, and a control unit that controls a discharge of the battery pack. The control unit calculates capacity condition A of the battery pack at a first discharge cutoff voltage based on the total voltage and the total current, estimates capacity condition B of the battery pack at the first discharge cutoff voltage based on the total current and the temperature, determines an occurrence of an over discharge based on the capacity condition A and the capacity condition B, changes the first discharge cutoff voltage to a second discharge cutoff voltage that is higher than the first discharge cutoff voltage, when the occurrence of the over discharge is determined.

First claim

What is claimed is:

1. A process of using a battery system, the battery system comprising:
a battery pack including a plurality of battery cells connected in series,
a monitoring unit configured to monitor a condition of the battery pack, and
a control unit configured to control at least a discharge of the battery pack, and
the monitoring unit includes:
a voltage sensor configured to measure a total voltage of the battery pack,
a current sensor configured to measure a total current of the battery pack, and
a temperature sensor configured to measure a temperature of the battery pack,
the process comprising the control unit:
calculating capacity condition A of the battery pack at a first discharge cutoff voltage based on the total voltage and the total current,
estimating capacity condition B of the battery pack at the first discharge cutoff voltage based on the total current and the temperature,
determining an occurrence of an over discharge based on the capacity condition A and the capacity condition B, and
changing the first discharge cutoff voltage to a second discharge cutoff voltage that is higher than the first discharge cutoff voltage, when the occurrence of the over discharge is determined.

2. The process according to claim 1 , wherein the process further comprises the control unit specifying capacity condition C corresponding to voltage α in an estimated discharge curve of an over discharged cell,
Specifying voltage β corresponding to the capacity condition C in an actually measured discharge curve of the battery pack, and
setting the second discharge cutoff voltage based on the voltage β.

3. The process according to claim 2 , wherein the voltage α is a voltage of 0 V or more.

4. The process according to claim 1 , wherein the monitoring unit includes no voltage sensor configured to measure a voltage of the battery cells individually.

Assignees

• Toyota Motor Co Ltd

Inventors

• Kawakami Masatsugu
• Oguma Yasumasa

Classifications

• H02J7/585

  Sequential battery discharge in systems with a plurality of batteries · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/63

  against overdischarge · CPC title

• G01R31/3835

  involving only voltage measurements · CPC title

• G01R31/3842

  combining voltage and current measurements · CPC title