Battery system and method of controlling battery system

Patent metadata

Field	Value
Publication number	US-2021276451-A1
Application number	US-202117183558-A
Country	US
Kind code	A1
Filing date	Feb 24, 2021
Priority date	Mar 3, 2020
Publication date	Sep 9, 2021
Grant date	—

Abstract

A battery system includes a nickel-metal hydride battery and an ECU that controls charging and discharging of the nickel-metal hydride battery. The ECU calculates a discharge electricity amount showing an integrated value of a current discharged from the nickel-metal hydride battery, and further calculates ΔSOC of the nickel-metal hydride battery in a prescribed time period. The ECU calculates a charge reserve capacity of the nickel-metal hydride battery based on a temperature of the nickel-metal hydride battery, the discharge electricity amount, and the ΔSOC.

First claim

What is claimed is:

1 . A battery system comprising:
a nickel-metal hydride battery; and a controller that controls charging and discharging of the nickel-metal hydride battery, wherein the controller
calculates a discharge electricity amount showing an integrated value of a current discharged from the nickel-metal hydride battery,
calculates an SOC variation range of the nickel-metal hydride battery in a prescribed time period, and
calculates a charge reserve capacity of the nickel-metal hydride battery based on a temperature of the nickel-metal hydride battery, the discharge electricity amount, and the SOC variation range.

2 . The battery system according to claim 1 , wherein
the controller performs control to suppress a decrease in the charge reserve capacity when the charge reserve capacity decreases below a threshold value.

3 . The battery system according to claim 2 , wherein
the controller controls charging and discharging of the nickel-metal hydride battery to reduce the SOC variation range to be smaller when the charge reserve capacity decreases below the threshold value than when the charge reserve capacity dose not decrease below the threshold value.

4 . The battery system according to claim 3 , wherein
the controller raises a control lower limit of an SOC of the nickel-metal hydride battery to reduce the SOC variation range to be smaller when the charge reserve capacity decreases below the threshold value than when the charge reserve capacity dose not decrease below the threshold value.

5 . The battery system according to claim 1 , wherein
the controller
calculates a first amount of increase in discharge reserve capacity using a previously obtained correlation among the temperature, time, and an amount of increase in a discharge reserve capacity of the nickel-metal hydride battery, the first amount of increase in discharge reserve capacity showing the amount of increase resulting from the temperature and the time,
calculates a second amount of increase in discharge reserve capacity using a previously obtained correlation of the amount of increase with the temperature, the discharge electricity amount, and the SOC variation range, the second amount of increase in discharge reserve capacity showing the amount of increase resulting from the temperature, the discharge electricity amount, and the SOC variation range,
corrects an amount of decrease in the discharge reserve capacity with a previously obtained coefficient to calculate the amount of decrease corrected by a negative electrode SOC of the nickel-metal hydride battery, the amount of decrease in the discharge reserve capacity being calculated from the temperature and time using a previously obtained correlation among the temperature, the time, and the amount of decrease in the discharge reserve capacity, the previously obtained coefficient being higher in value as the negative electrode SOC of the nickel-metal hydride battery is higher,
calculates the discharge reserve capacity of the nickel-metal hydride battery by subtracting the corrected amount of decrease in the discharge reserve capacity from a total amount of increase in discharge reserve capacity, the total amount of increase in discharge reserve capacity being obtained by adding the second amount of increase in discharge reserve capacity to the first amount of increase in discharge reserve capacity,
calculates a negative electrode capacity of the nickel-metal hydride battery by subtracting an amount of decrease in the negative electrode capacity from an initial negative electrode capacity in an initial state of the nickel-metal hydride battery, the amount of decrease in the negative electrode capacity being calculated using a previously obtained correlation between the total amount of increase in discharge reserve capacity and the amount of decrease in the negative electrode capacity of the nickel-metal hydride battery,
calculates a positive electrode capacity of the nickel-metal hydride battery by subtracting an amount of decrease in the positive electrode capacity from an initial positive electrode capacity in the initial state of the nickel-metal hydride battery, the amount of decrease in the positive electrode capacity being calculated using a previously obtained correlation between the discharge electricity amount and the amount of decrease in the positive electrode capacity of the nickel-metal hydride battery, and
calculates the charge reserve capacity by subtracting the positive electrode capacity and the discharge reserve capacity from the negative electrode capacity.

6 . A method of controlling a battery system including a nickel-metal hydride battery, the method comprising:
calculating a discharge electricity amount showing an integrated value of a current discharged from the nickel-metal hydride battery; calculating an SOC variation range of the nickel-metal hydride battery in a prescribed time period; and calculating a charge reserve capacity of the nickel-metal hydride battery based on a temperature of the nickel-metal hydride battery, the discharge electricity amount, and the SOC variation range.

7 . The method of controlling a battery system according to claim 6 , further comprising performing control to suppress a decrease in the charge reserve capacity when the charge reserve capacity decreases below a threshold value.

8 . The method of controlling a battery system according to claim 7 , wherein the performing control includes controlling charging and discharging of the nickel-metal hydride battery to reduce the SOC variation range to be smaller when the charge reserve capacity decreases below the threshold value than when the charge reserve capacity dose not decrease below the threshold value.

9 . The method of controlling a battery system according to claim 8 , wherein the performing control includes raising a control lower limit of an SOC of the nickel-metal hydride battery to reduce the SOC variation range to be smaller when the charge reserve capacity decreases below the threshold value than when the charge reserve capacity dose not decrease below the threshold value.

10 . The method of controlling a battery system according to claim 6 , wherein
the calculating the charge reserve capacity includes:
calculating a first amount of increase in discharge reserve capacity using a previously obtained correlation among the temperature, time, and an amount of increase in a discharge reserve capacity of the nickel-metal hydride battery, the first amount of increase in discharge reserve capacity showing the amount of increase resulting from the temperature and the time;
calculating a second amount of increase in discharge reserve capacity using a previously obtained correlation of the amount of increase with the temperature, the discharge electricity amount, and the SOC variation range, the second amount of increase in discharge reserve capacity showing the amount of increase resulting from the temperature, the discharge electricity amount, and the SOC variation range;
correcting an amount of decrease in the discharge reserve capacity with a previously obtained coefficient to calculate the amount of decrease corrected by a negative electrode SOC of the nickel-metal hydride battery, the amount of decrease in the discharge reserve capacity being calculated from the temperature and time using a previously obtained correlation among the temperature, the time, and the amount of decrease in the discharge reserve capacity, the previously obtained coefficient being higher in value as the negative electrode SOC of the nickel-metal hydride battery is higher;
calculating the discharge reserve capacity of the nickel-metal hydride battery by subtracting th

Assignees

• Toyota Motor Co Ltd
• Primearth Ev Energy Co Ltd

Inventors

• Irie Takayuki
• Satoh Jun
• Matsumoto Junichi
• KOBA Daisuke
• Murota Yosuke
• Nakano Kazuki
• Muraki Suguru

Classifications

• H02J7/977

  of the battery · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H01M10/48

  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

• G01R31/3842

  combining voltage and current measurements · CPC title

• H01M10/486

  for measuring temperature · CPC title