Mitigation of propagation of thermal runaway in a multi-cell battery pack

• US 7,433,794 B1
• Filed: 07/18/2007
• Issued: 10/07/2008
• Est. Priority Date: 07/18/2007
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Kohn, Scott Ira, Lyons, David Frederick, Straubel, Jeffrey Brian, Cole, Philip David, Berdichevsky, Eugene Michael, Hermann, Weston Arthur, Mendez, Noel Jason, Hebert, Arthur Joseph, Kelty, Kurt Russell
• Primary Examiner(s): Barlow, Jr.; John E.
• Assistant Examiner(s): Washburn; Douglas N
• Application Number:
  US11/779,654
• Time in Patent Office: 447 Days
• Field of Search: 320/127, 320/150, 320/151, 320/152, 320/153, 702/63, 702/130, 702/132
• US Class Current: 702/130
• 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 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 50/64 Constructional details of batteries specially adapted for electric vehicles
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: B60L 58/26 by cooling
• CPC Class Codes: H01M 10/486 for measuring temperature
• CPC Class Codes: H01M 10/613 Cooling or keeping cold
• CPC Class Codes: H01M 10/625 Vehicles
• CPC Class Codes: H01M 10/643 Cylindrical cells
• CPC Class Codes: H01M 10/6556 Solid parts with flow channel passages or pipes for heat exchange closed pipes H01M10/6552
• CPC Class Codes: H01M 10/6563 with forced flow, e.g. by blowers
• CPC Class Codes: H01M 10/663 the system being an air-conditioner or an engine
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/00302 Overcharge protection
• CPC Class Codes: H02J 7/00306 Overdischarge protection
• CPC Class Codes: H02J 7/00308 Overvoltage protection
• CPC Class Codes: H02J 7/00309 Overheat or overtemperature protection
• 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

A method of mitigating propagation of a thermal event in an energy storage system having a plurality of cells is disclosed. The method includes the steps of identifying the heat sources within the energy storage system and plurality of cells. The method then controls a temperature of the energy storage system and plurality of cells and also detects predetermined conditions within the energy storage system. The method then performs a predetermined action based on when one of the predetermined conditions is detected. A plurality of sensors and switches along with associated hardware or software will be used to control the temperature of the energy storage system upon detection of predetermined conditions involving overheating, over current, over voltage of the like.

Claims

1. A method of mitigating propagation of a thermal event in an energy storage system having a plurality of cells, said method including the steps of:

identifying a heat source within the energy storage system and plurality of cells;

controlling a temperature of the energy storage system and plurality of cells;

detecting predetermined conditions of the energy storage system; and

performing a predetermined action when one of said predetermined conditions is detected.

2. The method of claim 1 wherein said step of identifying includes determining if a high rate of discharge is occurring in one of said cells or if a short circuit has occurred within the energy storage system.

3. The method of claim 1 wherein said step of identifying includes determining if one of the cells has a high voltage, has suffered internal damage and is producing excess heat, or a high resistance connection is detected between cells or in the energy storage system.

4. The method of claim 1 wherein said step of identifying includes determining if an electrical arc is occurring within the energy storage system, if an ambient temperature is higher than a predetermined level, or other predetermined heat sources are effecting the energy storage system.

5. The method of claim 1 wherein said step of controlling includes using thermal mass in predetermined locations and in predetermined quantities to thermally balance the energy storage system.

6. The method of claim 5 wherein said thermal mass includes an electrically insulated and thermally conductive material arranged around at least a portion of the cells, a cooling tube adjacent to the cells, said cooling tube having a coolant therein, and collector plates arranged at each end of the cells.

7. The method of claim 6 wherein said collector plates are made of metal and reflect radiant heat inside the energy storage system.

8. The method of claim 1 wherein said controlling step includes using cylindrical shaped cells arranged in a predetermined shaped array, said array have the cells with a predetermined transverse and axial spacing therebetween and with respect to corners and edges of the energy storage system.

9. The method of claim 7 wherein said controlling step includes arranging insulators adjacent to said collector plates to form a heat barrier between sheets of cells in the energy storage system, said insulator is made of a fire resistant material.

10. The method of claim 6 wherein at least a portion of said cooling tube is made of a low melting temperature material to allow a coolant to flood or saturate a cell in thermal runaway.

11. The method of claim 1 wherein said step of controlling includes venting fumes and heat from the energy storage system via a valve or membrane and using self extinguishing materials in the energy storage system.

12. The method of claim 1 wherein said step of detecting includes monitoring inertia of the electric storage system, roll over of the electric storage system or immersion of the energy storage system in a fluid.

13. The method of claim 1 wherein said step of detecting includes monitoring humidity of the energy storage system or if smoke, organic vapor, gas or mist is present in the energy storage system.

14. The method of claim 1 wherein the step of detecting includes monitoring temperatures, voltage of individual bricks, current in the energy storage system and fuses arranged at predetermined positions within the energy storage system.

15. The method of claim 1 wherein said step of performing an action includes balancing and monitoring voltage in the cells, opening contactors of the energy storage system if an over voltage, under voltage, over temperature, under temperature or over current condition occurs.

16. The method of claim 1 wherein said step of performing an action includes operating a HVAC pump to distribute heat in the energy storage system and sending errors to a vehicle management system or a server.

17. The method of claim 1 further including a step of incorporating a positive thermal coefficient fuse and current interrupt device into the cell.

18. An apparatus for mitigating the propagation of a thermal event in an energy storage system for use in a vehicle, said apparatus including:

a vehicle management system located on an onboard computer of the vehicle;

a battery safety monitor in communication with said vehicle management system;

a plurality of battery monitor boards associated with a sheet of a predetermined number of cells of the energy storage system, said battery monitor boards in communication with said vehicle management system and said battery safety monitor;

a power electronics module in communication with said battery safety monitor; and

a heating ventilation and air conditioning unit in communication with said battery safety monitor and said vehicle management system.

19. The apparatus of claim 18 further including an electronically insulating and thermally conductive material arranged around said cells and a cooling tube adjacent to every cell to control a temperature of said cells.

20. The apparatus of claim 19 wherein said cooling tube is filled with a coolant and said cells are arranged between collector plates, said collector plates provide a thermal sink for the energy storage system.

21. The apparatus of claim 20 wherein said heating and air conditioning unit is in fluid communication with said cooling tube to provide active cooling or heating to said cells.

22. The apparatus of claim 18 wherein said cells have a cylindrical shape and are arranged in a predetermined shaped array with predetermined axial and transverse spacing therebetween to provide passive heating and cooling to said cells.

23. The apparatus of claim 18 further including an insulator arranged adjacent to at least one end of said cells.

24. The apparatus of claim 18 further including a valve or other bidirectional transfer device arranged on a surface of an enclosure of an energy storage system to provide a venting pathway for heat and fumes during a thermal event.

25. The apparatus of claim 18 further including self extinguishable materials within the energy storage system.

26. The apparatus of claim 18 further including a plurality of sensors in communication with said battery safety monitor.

27. The apparatus of claim 26 wherein said sensors monitor immersion, humidity, smoke, organic vapors, current, and temperature sensitive compounds within and adjacent to the energy storage system.

28. The apparatus of claim 18 further including an inertia switch and rollover switch.

29. The apparatus of claim 18 further including a thermistor arranged on each sheet and in communication with said battery monitoring board.

30. The apparatus of claim 18 further including a plurality of fuses arranged throughout the energy storage system to protect against over current conditions and the associated heat.

31. The apparatus of claim 18 wherein said battery monitoring boards communicate with each other to balance voltage of said cells.

32. The apparatus of claim 18 further including contactors, said contactors are opened when an over voltage, under voltage, over temperature, under temperature or over current is detected.

33. The apparatus of claim 18 wherein said cells having a positive thermal coefficient fuse and a current interrupt device.

34. The apparatus of claim 18 wherein an error message is sent to said vehicle management system and an external server to notify of problems with the energy storage system.

35. The apparatus of claim 18 wherein said heating ventilation and air conditioning unit operates during non normal driving conditions to provide extra cooling to the energy storage system.