Methodology for charging batteries safely

• US 10,534,028 B2
• Filed: 11/22/2016
• Issued: 01/14/2020
• Est. Priority Date: 06/08/2010
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Inc.
• Inventors: Stewart, Sarah G., Dangler, Christopher, Kishiyama, Clay H., Hermann, Weston A., Kohn, Scott I., Kelty, Kurt R.
• Primary Examiner(s): Ngon, Ricky
• Application Number:
  US15/359,210
• Publication Number:
  US 20170074918A1
• Time in Patent Office: 1,148 Days
• Field of Search: 702 63
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: G01R 31/52 Testing for short-circuits, leakage current or ground faults
• CPC Class Codes: H01M 10/0525 Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• CPC Class Codes: H01M 10/482 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 2220/20 Batteries in motive systems, e.g. vehicle, ship, plane
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0016 using shunting, discharge or bypass circuits
• CPC Class Codes: H02J 7/0025 Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0029 with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00302 Overcharge 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

An apparatus and method for identifying a presence of a short circuit in a battery pack. A fault-detection apparatus for a charging system that rapidly charges a collection of interconnected lithium ion battery cells, the safety system includes a data-acquisition system for receiving a set of data parameters from the collection while the charging system is actively charging the collection; a monitoring system evaluating the set of data parameters to identify a set of anomalous conditions; and a controller comparing the set of anomalous conditions against a set of predetermined profiles indicative of an internal short in one or more cells of the collection, the controller establishing an internal-short state for the collection when the comparing has a predetermined relationship to the set of predetermined profiles.

Claims

1. A fault-detection apparatus for a charging system that charges a collection of interconnected battery cells, the fault-detection apparatus comprising:

at least one communication bus;

a data-acquisition system coupled to the at least one communication bus for receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters including a change in charging voltage over time (dV/dt), wherein the set of data parameters are measured during a charge cycle that begins with deltaT<

(deltaT)max, where deltaT is a difference in temperature between battery cells of the collection and an ambient temperature, and (deltaT)max is a maximum acceptable difference in temperature relating to charging;

a monitoring system coupled to the at least one communication bus for evaluating the set of data parameters;

a controller coupled to the at least one communication bus for determining that a short exists in the collection when dV/dt is less than zero during a constant current charging interval, the controller configured to;

set an internal-short notification in response to determining that a short exists in the collection; and

modify a charging behavior of the charging system in response to setting the internal-short notification.

2. The fault-detection apparatus of claim 1, wherein:

the set of data parameters further includes a change in charging voltage versus a change in charge capacity (dV/dQ); and

the controller further determining that a short exists in the collection when dV/dQ is less than zero during the constant current charging interval.

3. The fault-detection apparatus of claim 2, wherein the controller further determining that a short is no longer active when dV/dQ increases by a threshold.

4. The fault-detection apparatus of claim 1, wherein the set of data parameters are measured during a charge cycle that further begins when the collection of interconnected battery cells is in a partially discharged state.

5. The fault-detection apparatus of claim 1, wherein the controller verifies that a charge current has not decreased or been interrupted and that no additional load has been introduced before determining that the short exists.

6. The fault-detection apparatus of claim 1, wherein the controller further determines a false short upon one or more of:

a step change in charging voltage from one constant current level to another constant current level;

a step change in charging voltage from one constant power level to another constant power level;

a reduction in charge rate due to grid power or charger power limits in the presence of a high voltage vehicle load;

or

an external heating of the collection causing a reduction in impedance of the collection.

7. A fault-detection apparatus for a charging system that charges a collection of interconnected battery cells, the fault-detection apparatus comprising:

at least one communication bus;

a data-acquisition system coupled to the at least one communication bus for receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters including change in charging voltage versus a change in charge capacity (dV/dQ), wherein the set of data parameters are measured during a charge cycle that begins with deltaT<

(deltaT)max, where deltaT is a difference in temperature between battery cells of the collection and an ambient temperature, and (deltaT)max is a maximum acceptable difference in temperature relating to charging;

a monitoring system coupled to the at least one communication bus for evaluating the set of data parameters;

a controller coupled to the at least one communication bus for determining that a short exists in the collection when dV/dQ is less than zero during a constant current charging interval, the controller configured to;

set an internal-short notification in response to determining that a short exists in the collection; and

modify a charging behavior of the charging system in response to setting the internal-short notification.

8. The fault-detection apparatus of claim 7, wherein the controller further determining that a short is no longer active when dV/dQ increases by a threshold.

9. The fault-detection apparatus of claim 7, wherein the set of data parameters are measured during a charge cycle that further begins when the collection of interconnected battery cells is in a partially discharged state.

10. The fault-detection apparatus of claim 7, wherein the controller verifies that a charge current has not decreased or been interrupted and that no additional load has been introduced before determining that the short exists.

11. The fault-detection apparatus of claim 7, wherein the controller further determines a false short upon one or more of:

a step change in charging voltage from one constant current level to another constant current level;

a step change in charging voltage from one constant power level to another constant power level;

a reduction in charge rate due to grid power or charger power limits in the presence of a high voltage vehicle load;

or

an external heating of the collection causing a reduction in impedance of the collection.

12. A fault-detection apparatus for a charging system that charges a collection of interconnected battery cells, the fault-detection apparatus comprising:

at least one communication bus;

a data-acquisition system coupled to the at least one communication bus for receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters including change in charging current over time (dI/dt), wherein the set of data parameters are measured during a charge cycle that begins with deltaT<

(deltaT)max, where deltaT is a difference in temperature between battery cells of the collection and an ambient temperature, and (deltaT)max is a maximum acceptable difference in temperature relating to charging;

a monitoring system coupled to the at least one communication bus for evaluating the set of data parameters;

a controller coupled to the at least one communication bus for determining that a short exists in the collection when dI/dt is greater than zero during a constant voltage charging interval, the controller configured to;

set an internal-short notification in response to determining that a short exists in the collection; and

modify a charging behavior of the charging system in response to setting the internal-short notification.

13. The fault-detection apparatus of claim 12, wherein:

the set of data parameters further includes a change in charging current versus change in charge capacity (dI/dQ); and

the controller further determining that a short exists in the collection when dI/dQ is greater than zero during the constant voltage charging interval.

14. The fault-detection apparatus of claim 12, wherein the set of data parameters are measured during a charge cycle that further begins when the collection of interconnected battery cells is in a partially discharged state.

15. The fault-detection apparatus of claim 12, wherein the controller verifies that a charge current has not decreased or been interrupted and that no additional load has been introduced before determining that the short exists.

16. The fault-detection apparatus of claim 12, wherein the controller further determines a false short upon one or more of:

a step change in charging voltage from one constant current level to another constant current level;

a step change in charging voltage from one constant power level to another constant power level;

a reduction in charge rate due to grid power or charger power limits in the presence of a high voltage vehicle load;

or

an external heating of the collection causing a reduction in impedance of the collection.

17. A fault-detection apparatus for a charging system that charges a collection of interconnected battery cells, the fault-detection apparatus comprising:

at least one communication bus;

a data-acquisition system coupled to the at least one communication bus for receiving a set of data parameters from the collection while the charging system is actively charging the collection, the set of data parameters including change in charging current versus a change in charge capacity (dI/dQ), wherein the set of data parameters are measured during a charge cycle that begins with deltaT<

(deltaT)max, where deltaT is a difference in temperature between battery cells of the collection and an ambient temperature, and (deltaT)max is a maximum acceptable difference in temperature relating to charging;

a monitoring system coupled to the at least one communication bus for evaluating the set of data parameters;

a controller coupled to the at least one communication bus for determining that a short exists in the collection when dI/dQ is greater than zero during a constant voltage charging interval, the controller configured to;

set an internal-short notification in response to determining that a short exists in the collection; and

modify a charging behavior of the charging system in response to setting the internal-short notification.

18. The fault-detection apparatus of claim 17, wherein the controller further determining that a short is no longer active when dV/dQ increases by a threshold.

19. The fault-detection apparatus of claim 17, wherein the set of data parameters are measured during a charge cycle that further begins when the collection of interconnected battery cells is in a partially discharged state.

20. The fault-detection apparatus of claim 17, wherein the controller verifies that a charge current has not decreased or been interrupted and that no additional load has been introduced before determining that the short exists.

21. The fault-detection apparatus of claim 17, wherein the controller further determines a false short upon one or more of:

a step change from one constant current level to another constant current level;

a step change from one constant power level to another constant power level;

a reduction in charge rate due to grid power or charger power limits in the presence of a high voltage vehicle load;

or

an external heating of the collection causing a reduction in impedance of the collection.