EVALUATING CAPACITY FADE IN DUAL INSERTION BATTERIES USING POTENTIAL AND TEMPERATURE MEASUREMENTS

• US 20170194669A1
• Filed: 03/17/2016
• Published: 07/06/2017
• Est. Priority Date: 12/31/2015
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Klein, Reinhardt, Christensen, John F., Srouji, Abdul-Kader, Krupadanam, Ashish, MirTabatabaei, Anahita, Ravi, Nikhil
• Granted Patent: US 10,224,579 B2
• Time in Patent Office: Days
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: H01M 10/425 Structural combination with electronic components, e.g. electronic circuits integrated to the outside of the casing printed circuits H05K1/00
• CPC Class Codes: H01M 10/4257 Smart batteries, e.g. electronic circuits inside the housing of the cells or batteries
• CPC Class Codes: H01M 10/443 in response to temperature
• 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 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 10/613 Cooling or keeping cold
• CPC Class Codes: H01M 10/615 Heating or keeping warm
• CPC Class Codes: H01M 10/623 Portable devices, e.g. mobile telephones, cameras or pacemakers
• CPC Class Codes: H01M 10/625 Vehicles
• CPC Class Codes: H01M 10/633 characterised by algorithms, flow charts, software details or the like
• CPC Class Codes: H01M 10/6567 Liquids
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• 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: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/0068 : Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/007184 : in response to battery voltage gradient
• CPC Class Codes: H02J 7/007192 : in response to temperature
• CPC Class Codes: H02J 7/007194 : of the battery
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries

Abstract

Methods and systems are described of managing a battery system. The battery system including at least one battery cell and one or more sensors configured to measure a temperature of the at least one battery cell. The method includes receiving a measurement of the temperature of the at least one battery cell, estimating an open circuit potential of the at least one battery cell, estimating a capacity fade of the at least one battery cell based on the open circuit potential of the at least one battery cell and a ratio of a change in the open circuit potential relative to a change in the temperature of the at least one battery cell, and regulating at least one of charging or discharging of the at least one battery cell based on the estimation of the capacity fade.

Claims

1. A method of managing a battery system, the battery system including at least one battery cell and one or more sensors configured to measure a temperature of the at least one battery cell, the method comprising:

receiving, by a computer-based battery management system from the one or more sensors, a measurement of the temperature of the at least one battery cell;

estimating, by the battery management system, an open circuit potential of the at least one battery cell;

estimating, by the battery management system, a capacity fade of the at least one battery cell based on the open circuit potential of the at least one battery cell and a ratio of a change in the open circuit potential relative to a change in the temperature of the at least one battery cell; and

regulating, by the battery management system, at least one of charging or discharging of the at least one battery cell based on the estimation of the capacity fade.

2. The method of claim 1, wherein the one or more sensors are further configured to measure a voltage and a current of the at least one battery cell, the method further comprising receiving, by the battery management system from the one or more sensors, a measurement of the voltage of the at least one battery cell and a temporally corresponding measurement of the current and the temperature of the at least one battery cell.

3. The method of claim 2, wherein estimating the open circuit potential of the at least one battery cell includes estimating the open circuit potential to be equal to the voltage of the at least one battery cell when the at least one battery cell is in a quasi-equilibrium state, wherein the quasi-equilibrium state occurs when the current is negligible and a rate of change of the voltage over time is below a threshold value.

4. The method of claim 3, wherein the threshold value is less than 3 millivolts per hour.

5. The method of claim 3, further comprising:

deactivating the at least one battery cell to achieve the quasi-equilibrium state; and

responsive to estimating the open circuit potential, reactivating the at least one battery cell.

6. The method of claim 2, wherein estimating the open circuit potential of the at least one battery cell includes fitting a decaying exponential of the voltage over time to extrapolate a value of the open circuit potential.

7. The method of claim 1, wherein estimating the open circuit potential of the at least one battery cell includes estimating a value of the open circuit potential with a mathematical model of the at least one battery cell and parameter estimation algorithms when the at least one battery cell is under load.

8. The method of claim 1, further comprising:

controllably varying, by the battery management system, the temperature of the at least one battery cell;

receiving, by the battery management system from the one or more sensors, a plurality of estimates of the open circuit potential, wherein each estimate of the plurality of estimates is at a temporally corresponding temperature as the temperature of the at least one battery cell is varied; and

storing each estimate of the plurality of estimates of the open circuit potential and the temporally corresponding measurement of the temperature to a non-transitory computer-readable memory.

9. The method of claim 8, further comprising determining at least one state of the at least one battery cell corresponding to each estimate of the plurality of estimates of the open circuit potential and the temporally corresponding temperature of the at least one battery cell, the at least one state being selected from a group consisting of a state of charge and a state of health, and wherein estimating the capacity fade of the at least one battery cell includes

determining a change in the open circuit potential relative to a change in temperature for each of a plurality of states of charge, and

estimating a total capacity of the at least one battery cell based on the change in the open circuit potential relative to the change in temperature for each of the plurality of states of charge.

10. The method of claim 9, further comprising determining a current state of charge of the at least one battery cell by

accessing a table stored in the non-transitory computer-readable memory, the table defining an experimentally determined ratio of the change in open circuit potential relative to the change in the temperature for each of a plurality of state of charge values;

controllably varying the temperature of the at least one battery cell at the current state of charge;

measuring the open circuit potential and the temporally corresponding temperature at each of a plurality of temperatures;

determining a current ratio of the change in open circuit potential relative to the change in temperature; and

identifying, using the table, the state of charge value of the plurality of state of charge values corresponding to the current ratio of the change in open circuit potential relative to the change in the temperature.

11. The method of claim 8, wherein varying the temperature of the at least one battery cell includes changing, by the battery management system, a flow rate of coolant.

12. The method of claim 8, wherein varying the temperature of the at least one battery cell includes actively heating, by the battery management system, the at least one battery cell via a fluid medium.

13. The method of claim 8, wherein varying the temperature of the at least one battery cell includes changing, by the battery management system, a flow direction of coolant.

14. A battery system comprising:

at least one battery cell;

one or more sensors configured to measure a temperature of the at least one battery cell; and

a battery management system including an electronic processor configured to

receive a measurement of the temperature of the at least one battery cell from the one or more sensors,

estimate an open circuit potential of the at least one battery cell,

estimate a capacity fade of the at least one battery cell based on the open circuit potential of the at least one battery cell and a ratio of a change in the open circuit potential relative to a change in the temperature of the at least one battery cell, and

regulate at least one of charging or discharging of the at least one battery cell based on the capacity fade.

15. The system of claim 14, wherein the one or more sensors are further configured to measure a voltage and a current of the at least one battery cell, the electronic processor of the battery management system further configured to receive a measurement of the voltage of the at least one battery cell and a temporally corresponding measurement of the current and the temperature of the at least one battery cell from the one or more sensors.

16. The system of claim 15, wherein, to estimate the open circuit potential of the at least one battery cell, includes the electronic processor configured to estimate the open circuit potential to be equal to the voltage of the at least one battery cell when the at least one battery cell is in a quasi-equilibrium state, wherein the quasi-equilibrium state occurs when the current is negligible and a rate of change of the voltage over time is below a threshold value.

17. The system of claim 16, wherein the electronic processor is further configured to

deactivate the at least one battery cell to achieve the quasi-equilibrium state, and

responsive to estimating the open circuit potential of the at least one battery cell, reactivate the at least one battery cell.

18. The system of claim 14, wherein, to estimate the open circuit potential of the at least one battery cell, includes the electronic processor configured to estimate a value of the open circuit potential with a mathematical model of the at least one battery cell and parameter estimation algorithms when the at least one battery cell is under load.

19. The system of claim 14, wherein the electronic processor is further configured to

controllably vary the temperature of the at least one battery cell,

receive a plurality of estimates of the open circuit potential from the one or more sensors, wherein each estimate of the plurality of estimates of the open circuit potential is at a different temporally corresponding temperature as the temperature of the at least one battery cell is varied, and

store the plurality of estimates of the open circuit potential from the one or more sensors in a computer-readable memory.

20. The system of claim 19, wherein the electronic processor is further configured to determine at least one of a state of the at least one battery cell corresponding to each estimate of the open circuit potential and the temporally corresponding temperature of the at least one battery cell, the at least one state being selected from a group consisting of a state of charge and a state of health, and wherein, to estimate the capacity fade of the at least one battery cell, includes the electronic processor configured to

determine a change in the open circuit potential relative to a change in temperature for each of a plurality of states of charge, and

estimate a total capacity of the at least one battery cell based on the change in the open circuit potential relative to the change in the temperature for each of the plurality of states of charge.