Real-Time Battery Thermal Management For Electric Vehicles

• US 20150280294A1
• Filed: 04/01/2015
• Published: 10/01/2015
• Est. Priority Date: 04/01/2014
• Status: Active Grant

• Current Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Original Assignee: Board of Regents of the University of Michigan (University of Michigan)
• Inventors: Shin, Kang G., Kim, Eugene
• Granted Patent: US 9,893,394 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60L 1/02 to electric heating circuits
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2240/662 Temperature
• CPC Class Codes: B60L 2240/80 Time limits
• CPC Class Codes: B60L 2260/44 by parameter estimation
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 3/12 Recording operating variables ; Monitoring of operating variables
• CPC Class Codes: B60L 50/51 characterised by AC-motors
• CPC Class Codes: B60L 50/64 Constructional details of batteries specially adapted for electric vehicles
• CPC Class Codes: B60L 50/66 Arrangements of batteries
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/16 responding to battery ageing, e.g. to the number of charging cycles or the state of health [SoH]
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: B60L 58/26 by cooling
• 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 10/625 : Vehicles
• CPC Class Codes: H01M 10/633 : characterised by algorithms, flow charts, software details or the like
• CPC Class Codes: H01M 10/6551 : Surfaces specially adapted for heat dissipation or radiation, e.g. fins or coatings
• 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
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 : Information or communication technologies improving the operation of electric vehicles

Abstract

A method includes estimating, for a given battery cell of a plurality of battery cells, an internal resistance, estimating, for the given battery cell, an open-circuit voltage, determining a target output voltage for the given battery cell, determining a target discharge current for the given battery cell, determining a target internal resistance for the given battery cell based on the estimated open-circuit voltage for the given battery cell, the target output voltage for the given battery cell, and the target discharge current for the given battery cell, determining a target cell temperature for the given battery cell based on the target internal resistance for the given battery cell, and controlling a flow of coolant adjacent to the given battery cell based on the target temperature for the given battery cell.

Claims

1. A real-time thermal management method for a plurality of battery cells in an electric vehicle, comprising:

estimating, for a given battery cell of the plurality of battery cells, an internal resistance based on a measured output voltage of the given battery cell and a measured discharge current of the given battery cell;

estimating, for the given battery cell, an open-circuit voltage based on the estimated internal resistance for the given battery cell;

determining a target output voltage for the given battery cell based on a vehicle power requirement associated with the electric vehicle;

determining a target discharge current for the given battery cell as a function of an estimated state of charge for the given battery cell, a total measured discharge current for the plurality of battery cells, and a total estimated state of charge for the plurality of battery cells;

determining a target internal resistance for the given battery cell based on the estimated open-circuit voltage for the given battery cell, the target output voltage for the given battery cell, and the target discharge current for the given battery cell;

determining a target cell temperature for the given battery cell based on the target internal resistance for the given battery cell; and

controlling a flow of coolant adjacent to the given battery cell based on the target temperature for the given battery cell.

2. The method of claim 1 further comprising estimating the open-circuit voltage for the given battery cell based on the measured voltage for the given battery cell plus the product of the measured discharge current for the given battery cell and the estimated internal resistance for the given battery cell.

3. The method of claim 1 further comprising determining whether the vehicle power requirement divided a product of a total number of battery cells in the plurality of battery cells and a total measured output voltage for the plurality of battery cells is less than a predefined discharge current rate limit for the given cell.

4. The method of claim 3 further comprising setting the target discharge current for the given battery cell equal to a product of a total measured discharge current for the plurality of battery cells and a ratio of the estimated state of charge for the given battery cell and a total estimated state of charge for the plurality of battery cells in response to a determination that the vehicle power requirement divided the product of a total number of battery cells in the plurality of battery cells and the total measured output voltage for the plurality of battery cells is less than a predefined discharge current rate limit for the given battery cell.

5. The method of claim 3 further comprising setting the target discharge current for the given battery cell equal to a total measured discharge current for the plurality of battery cells divided by the total number of battery cells in response to a determination that the vehicle power requirement divided the product of a total number of battery cells in the plurality of battery cells and the total measured output voltage for the plurality of battery cells is not less than a predefined discharge current rate limit for the given battery cell.

6. The method of claim 1 further comprising determining a target ambient temperature associated with the given battery cell as a function of a measured cell temperature of the given battery cell, the target internal resistance for the given battery cell, and the target discharge current for the given battery cell.

7. The method of claim 6 further comprising determining a target temperature for a thermal fin associated with the given battery cell as a function of the measured cell temperature of the given battery cell, the target cell temperature for the given battery cell, and the target ambient temperature for the given battery cell.

8. The method of claim 7 further comprising comparing the target temperature for the thermal fin with a measured temperature of the thermal fin.

9. The method of claim 8 further comprising controlling flow of cool coolant adjacent to the given battery cell in response to a determination that the target temperature for the thermal fin is less than the measured temperature of the thermal fin.

10. The method of claim 8 further comprising controlling flow of heated coolant adjacent to the given battery cell in response to a determination that the target temperature for the thermal fin is greater than the measured temperature of the thermal fin.

11. A real-time thermal management system for a plurality of battery cells in an electric vehicle, comprising;

a coolant controller that directs coolant adjacent to each of the plurality of battery cells;

an estimation module that;

estimates, for a given battery cell of the plurality of battery cells, an internal resistance based on a measured output voltage of the given battery cell and a measured discharge current of the given battery cell; and

estimates, for the given battery cell, an open-circuit voltage based on the estimated internal resistance for the given battery cell;

a power control module that;

determines a target output voltage for the given battery cell based on a vehicle power requirement associated with the electric vehicle;

determines a target discharge current for the given battery cell as a function of an estimated state of charge for the given battery cell, a total measured discharge current for the plurality of battery cells, and a total estimated state of charge for the plurality of battery cells; and

determines a target internal resistance for the given battery cell based on the estimated open-circuit voltage for the given battery cell, the target output voltage for the given battery cell, and the target discharge current for the given battery cell; and

a cell temperature control module that determines a target cell temperature for the given battery cell based on the target internal resistance for the given battery cell and selectively instructs the coolant controller to direct a flow of coolant adjacent to the given battery cell based on the target temperature for the given battery cell.

12. The system of claim 11 wherein the estimation module estimates the open-circuit voltage for the given battery cell based on the measured voltage for the given battery cell plus the product of the measured discharge current for the given battery cell and the estimated internal resistance for the given battery cell.

13. The system of claim 11 wherein the power control module determines whether the vehicle power requirement divided a product of a total number of battery cells in the plurality of battery cells and a total measured output voltage for the plurality of battery cells is less than a predefined discharge current rate limit for the given cell.

14. The system of claim 13 wherein the power control module sets the target discharge current for the given battery cell equal to a product of a total measured discharge current for the plurality of battery cells and a ratio of the estimated state of charge for the given battery cell and a total estimated state of charge for the plurality of battery cells in response to a determination that the vehicle power requirement divided the product of a total number of battery cells in the plurality of battery cells and the total measured output voltage for the plurality of battery cells is less than a predefined discharge current rate limit for the given battery cell.

15. The system of claim 13 wherein the power control module sets the target discharge current for the given battery cell equal to a total measured discharge current for the plurality of battery cells divided by the total number of battery cells in response to a determination that the vehicle power requirement divided the product of a total number of battery cells in the plurality of battery cells and the total measured output voltage for the plurality of battery cells is not less than a predefined discharge current rate limit for the given battery cell.

16. The system of claim 11 wherein the cell temperature control module determines a target ambient temperature associated with the given battery cell as a function of a measured cell temperature of the given battery cell, the target internal resistance for the given battery cell, and the target discharge current for the given battery cell.

17. The system of claim 16 wherein the cell temperature control module determines a target temperature for a thermal fin associated with the given battery cell as a function of the measured cell temperature of the given battery cell, the target cell temperature for the given battery cell, and the target ambient temperature for the given battery cell.

18. The system of claim 17 wherein the cell temperature control module compares the target temperature for the thermal fin with a measured temperature of the thermal fin.

19. The system of claim 18 wherein the cell temperature control module instructs the coolant controller to direct flow of cool coolant adjacent to the given battery cell in response to a determination that the target temperature for the thermal fin is less than the measured temperature of the thermal fin.

20. The system of claim 18 wherein the cell temperature control module instructs the coolant controller to direct flow of heated coolant adjacent to the given battery cell in response to a determination that the target temperature for the thermal fin is greater than the measured temperature of the thermal fin.

21. A real-time thermal management method for a plurality of battery cells in an electric vehicle, comprising:

receiving, via a plurality of cell sensors, a measured output voltage for a given battery cell of the plurality of battery cells;

receiving, via the plurality of cell sensors, a measured discharge current for the given battery cell;

receiving, via the plurality of cell sensors, a measured cell temperature for the given battery cell;

estimating, based on the measured output voltage and the measured discharge current, a state of charge for the given battery cell;

estimating, based on the measured output voltage and the measured discharge current, an internal resistance for the given battery cell;

estimating an open-circuit voltage for the given battery cell based on the measured output voltage, the measured discharge current, and the estimated internal resistance;

receiving a vehicle power requirement for the electric vehicle;

determining a target output voltage for the given battery cell based on the vehicle power requirement;

determining a target discharge current for the given battery cell as a function of the estimated state of charge for the given battery cell, a total measured discharge current for the plurality of battery cells, and a total state of charge for the plurality of battery cells;

determining a target internal resistance for the given battery cell based on the estimated open-circuit voltage for the given battery cell, the target output voltage for the given battery cell, and target discharge current for the given battery cell;

determining a target cell temperature for the given battery cell based on the target internal resistance for the given battery cell;

comparing, for the given battery cell, the target cell temperature and the measured cell temperature; and

controlling a flow of coolant adjacent to the given battery cell in response to the comparison between the target cell temperature and the measured cell temperature.