INTERNAL RESISTANCE ESTIMATION METHOD FOR SECONDARY BATTERY, OUTPUT CONTROL METHOD FOR SECONDARY BATTERY, AND VEHICLE

• US 20160375790A1
• Filed: 06/23/2016
• Published: 12/29/2016
• Est. Priority Date: 06/25/2015
• Status: Active Grant

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: KOMIYAMA, Keita
• Granted Patent: US 10,046,664 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/052 Li-accumulators
• CPC Class Codes: H01M 10/06 Lead-acid accumulators semi-lead accumulators H01M10/20
• CPC Class Codes: H01M 10/345 Gastight metal hydride accumulators
• CPC Class Codes: H01M 10/48 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 Class Codes: H01M 10/484 for measuring electrolyte level, electrolyte density or electrolyte conductivity
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 2010/4278 Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: Y02E 60/10 Energy storage using batteries
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

An internal resistance estimation method for a secondary battery includes: acquiring an initial internal resistance value and temperature course information including a battery temperature and time information about time at which the battery temperature has been recorded; estimating an increased amount of the internal resistance value after a lapse of a predetermined time from the predetermined reference time on the basis of the temperature course information; estimating a reduced amount of the internal resistance value of the secondary battery resulting from a relative change between a range of use of a state of charge of the positive electrode and a range of use of a state of charge of the negative electrode on the basis of the temperature course information; and calculating an internal resistance variation in the lapse of the predetermined time on the basis of the increased amount and the reduced amount.

Claims

1. An internal resistance estimation method for a secondary battery, the secondary battery including a positive electrode and a negative electrode, the internal resistance estimation method comprising:

acquiring an initial internal resistance value of the secondary battery and temperature course information, the secondary battery being an evaluation object, the temperature course information including a battery temperature of the secondary battery in use and time information about time at which the battery temperature has been recorded, and the initial internal resistance value being an internal resistance value of the secondary battery at predetermined reference time;

estimating an increased amount of the internal resistance value of the secondary battery after a lapse of a predetermined time from the predetermined reference time, on the basis of the temperature course information;

estimating a reduced amount of the internal resistance value of the secondary battery resulting from a relative change between a range of use of a state of charge of the positive electrode and a range of use of a state of charge of the negative electrode, in the lapse of the predetermined time from the predetermined reference time, on the basis of the temperature course information;

calculating an internal resistance variation in the lapse of the predetermined time from the predetermined reference time, on the basis of the increased amount and the reduced amount; and

obtaining an estimated internal resistance value of the secondary battery after the lapse of the predetermined time from the predetermined reference time, on the basis of the initial internal resistance value and the internal resistance variation.

2. The internal resistance estimation method according to claim 1, further comprising

preparing first data including a relationship between a temperature of a standard secondary battery and a resistance increase coefficient, the standard secondary battery having the same specifications as the secondary battery, and the resistance increase coefficient being an amount of increase in the internal resistance of the standard secondary battery per predetermined unit time, wherein

the estimating the increased amount of the internal resistance value includes

calculating an integrated value of a holding time during which the secondary battery is held at each predetermined temperature, on the basis of the temperature course information, and

calculating the increased amount of the internal resistance value of the secondary battery in the lapse of the predetermined time from the predetermined reference time, by using the integrated value of the holding time at each predetermined temperature and the resistance increase coefficient at each predetermined temperature.

3. The internal resistance estimation method according to claim 2, wherein

the calculating the increased amount of the internal resistance value includes

calculating the internal resistance value of the secondary battery after the lapse of the predetermined time from the reference time by using an integrated amount of the holding time at each temperature and the resistance increase coefficient at each temperature, and

obtaining the increased amount of the internal resistance value on the basis of the internal resistance value of the secondary battery after the lapse of the predetermined time from the reference time, and the initial internal resistance value.

4. The internal resistance estimation method according to claim 2, wherein

the first data includes information regarding a relationship between the state of charge of the secondary battery and the resistance increase coefficient.

5. The internal resistance estimation method according to claim 1, wherein

the temperature course information is acquired during any one of or a combination of two or more of the following periods (1) to (4):

(1) during use of the battery;

(2) during nonuse of the battery, and during a selected period from an end of use of the battery;

(3) when a temperature difference between a maximum air temperature and a minimum air temperature of a day is larger than or equal to 10°

C.; and

(4) when variations in average temperature of a month are larger than or equal to 5°

C.

6. The internal resistance estimation method according to claim 2, further comprising

preparing second data including a relationship among the temperature of the standard secondary battery, a state of charge of the standard secondary battery and a resistance value of a positive electrode of the standard secondary battery, the standard secondary battery having the same specifications as the secondary battery;

and

acquiring positive electrode potential history information including a potential of the positive electrode of the secondary battery during use of the secondary battery and time information about time at which the potential of the positive electrode of the secondary battery is recorded, wherein

the estimating the reduced amount of the internal resistance value includes

calculating a displacement of the potential of the positive electrode of the secondary battery in the lapse of the predetermined time by subtracting a potential of the positive electrode of the secondary battery at the reference time from a potential of the positive electrode of the secondary battery after the lapse of the predetermined time from the reference time,

when the displacement of the potential of the positive electrode of the secondary battery is a positive value, calculating a shift amount of a lower limit value of a state of charge of the secondary battery in the lapse of the predetermined time on the basis of the displacement of the potential of the positive electrode of the secondary battery, and

obtaining a difference, as the reduced amount of the internal resistance value, by subtracting a resistance value of the positive electrode of the secondary battery when the state of charge of the secondary battery has increased, from a resistance value of the positive electrode of the secondary battery at the reference time, on the basis of the second data.

7. The internal resistance estimation method according to claim 2, further comprising

preparing second data including a relationship among the temperature of the standard secondary battery, a state of charge of the standard secondary battery and a resistance value of a positive electrode of the standard secondary battery, the standard secondary battery having the same specification as the secondary battery;

and

acquiring positive electrode potential history information including a potential of the positive electrode of the secondary battery during use of the secondary battery and time information about time at which the potential of the positive electrode of the secondary battery is recorded, wherein

the estimating the reduced amount of the internal resistance value includes

calculating a shift amount of a lower limit value of the state of charge of the secondary battery in the lapse of the predetermined time by subtracting a state of charge of the secondary battery at the reference time in a state where the potential of the positive electrode of the secondary battery is at a lower limit, from a state of charge of the secondary battery after the lapse of the predetermined time in a state where the potential of the positive electrode of the secondary battery is at the lower limit; and

obtaining a difference, as the reduced amount of the internal resistance value, by subtracting a resistance value of the positive electrode of the secondary battery when the state of charge of the secondary battery has increased by the shift amount from a resistance value of the positive electrode of the secondary battery at the reference time, on the basis of the second data.

8. An output control method for a secondary battery, comprising:

where an internal resistance variation of the secondary battery after a lapse of a predetermined time from the predetermined reference time, calculated by the internal resistance estimation method according to claim 1, is Δ

R, decreasing an output of the secondary battery when Δ

R>

0;

keeping the output of the secondary battery when Δ

R=0; and

increasing the output of the secondary battery when Δ

R<

0.

9. A vehicle comprising:

a secondary battery that serves as a power supply for propelling the vehicle; and

an output control circuit that executes output control over the secondary battery by the use of the output control method according to claim 8.