DETECTION OF OVER-CURRENT IN A BATTERY PACK

• US 20140088809A1
• Filed: 11/25/2013
• Published: 03/27/2014
• Est. Priority Date: 01/05/2012
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Hermann, Weston A., Kohn, Scott I.
• Granted Patent: US 9,257,729 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• 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 58/13 Maintaining the SoC within a determined range
• CPC Class Codes: B60L 58/14 Preventing excessive discharging
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/18 of two or more battery modules
• CPC Class Codes: B60L 58/22 Balancing the charge of battery modules
• CPC Class Codes: B60L 58/26 by cooling
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/60 Heating or cooling; Temperature control
• 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: Y10S 903/907 Electricity storage, e.g. battery, capacitor

Abstract

A controller identifies a condition of a hazardous internal short by comparing patterns of series element voltages to the last known balance condition of the series elements. If the loaded or resting voltage of one or more contiguous series elements uniformly drop from the previously known condition by an amount consistent with an over-current condition, an over-current internal short circuit fault is registered. The desired response is to prevent the affected series elements from heating to a hazardous temperature by summoning the maximum heat rejection capability of the system until the short ceases and the affected elements cool, the cooling function is no longer able to operate due to low voltage, or the affected series string has drained all of its energy through the short. Also includes are responses that allow the battery pack to continue to power the cooling system even though it may enter an over-discharged state.

Claims

1. A microprocessor-implemented response system for an over-current internal short in an battery pack, comprising:

an evaluator monitoring an over-current internal short flag indicative of a possible over-current internal short within a plurality of electrically-serially-coupled battery elements storing energy for the battery pack; and

a remediation system, coupled to said battery elements and responsive to said possible over-current internal short flag when said evaluator detects a likelihood of said possible over-current internal short, to decrease risks associated with said possible over-current internal short when operated.

2. The response system of claim 1 further comprising a cooling system thermally coupled to said battery elements wherein said remediation system operates said cooling system until said over-current internal short flag no longer indicates said possible over-current internal short.

3. The response system of claim 1 further comprising a cooling system thermally coupled to said battery elements, operable using energy from the battery pack or an auxiliary power source, and wherein said remediation system operates said cooling system until said cooling system has insufficient energy to operate.

4. The response system of claim 3 wherein said cooling system includes a protection mechanism to disable said cooling system when available energy falls below an under-energy threshold wherein said remediation system overrides said protection mechanism and enables operation of said cooling system below said under-energy threshold.

5. The response system of claim 1 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, the response system including a cooling system removing heat from said set of battery elements, and wherein said remediation system operates said cooling system until said set of battery elements are below a SOC (state of charge) where further heating is no longer considered to be a risk.

6. The response system of claim 1 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, the response system including a cooling system removing heat from said set of battery elements, and wherein said remediation system operates said cooling system until all useable energy stored in said set of battery elements is dissipated.

7. The response system of claim 1 wherein the battery pack is installed in an electric vehicle as a traction battery and wherein said remediation system initiates a discontinuation of drive energy to the electric vehicle from the battery pack responsive to said possible over-current internal short flag.

8. The response system of claim 1 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, wherein said set of battery elements includes a series-coupled current protection device that interrupts an over-current flowing in the over-current internal short, and wherein said remediation system triggers said series-coupled current protection device responsive to said possible over-current internal short flag to interrupt said over-current.

9. A computer-implemented method for responding to an over-current internal short in an battery pack, the method comprising the steps of:

a) monitoring, using a microprocessor, an over-current internal short flag indicative of a possible over-current internal short within a plurality of electrically-coupled battery elements storing energy for the battery pack; and

thereafter

b) activating a remediation system coupled to said plurality of battery elements, with said remediation system responsive to said possible over-current internal short flag when said evaluator detects a likelihood of said possible over-current internal short, said activation of said remediation system decreasing risks associated with said possible over-current internal short when operated.

10. The responding method of claim 9 wherein the battery pack includes a cooling system removing heat from the plurality of battery elements and wherein said remediation system activating step b) includes operating said cooling system until said over-current internal short flag no longer indicates said possible over-current internal short.

11. The responding method of claim 9 wherein the battery pack includes a cooling system, operable using energy from the battery pack, said cooling system removing heat from said plurality of battery elements and wherein said remediation system activating step b) includes operating said cooling system until said cooling system has insufficient energy from the battery pack to operate.

12. The responding method of claim 11 wherein said cooling system includes a protection mechanism to disable said cooling system when available energy from the battery pack falls below a under-energy threshold wherein said remediation system activating step b) includes overriding said protection mechanism and enabling operation of said cooling system below said under-energy threshold.

13. The responding method of claim 9 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, wherein the battery pack includes a cooling system, operable using energy from the battery pack, removing heat from said set of battery elements, and wherein said remediation system activating step b) includes operating said cooling system until said set of battery elements are below a SOC (state of charge) where further heating is no longer a risk.

14. The responding method of claim 9 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, wherein the battery pack includes a cooling system removing heat from said set of battery elements, and wherein said remediation system activating step b) includes operating said cooling system until all useable energy stored in said set of battery elements is dissipated.

15. The responding method of claim 9 wherein the battery pack is installed in an electric vehicle as a traction battery and wherein said remediation system activating step b) includes initiating a discontinuation of drive energy to the electric vehicle from the battery pack responsive to said possible over-current internal short flag.

16. The responding method of claim 9 wherein the over-current internal short in the battery pack spans a set of said plurality of battery elements, wherein said set of battery elements includes a series-coupled current protection device that interrupts a current flowing in the over-current internal short, and wherein said remediation system activating step b) includes triggering said series-coupled current protection device responsive to said possible over-current internal short flag to interrupt said current.