Systems and methods for diagnosing battery voltage mis-reporting

• US 8,044,786 B2
• Filed: 06/19/2008
• Issued: 10/25/2011
• Est. Priority Date: 06/19/2008
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Motors Incorporated (Tesla Inc.)
• Inventors: Berdichevsky, Eugene Michael, Dunlay, James Jay, Cole, Philip David
• Primary Examiner(s): Nguyen; Tai T
• Application Number:
  US12/142,514
• Publication Number:
  US 20090315698A1
• Time in Patent Office: 1,223 Days
• Field of Search: 340/455, 340/456, 340/569, 340/686.6, 340/636.1, 340/636.6, 340/514, 320/116, 320/118, 320/119, 320/120, 320/126, 320/149, 320/162
• US Class Current: 340/455
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 58/12 responding to state of charge [SoC]
• CPC Class Codes: B60L 58/18 of two or more battery modules
• CPC Class Codes: G01R 31/3648 comprising digital calculation means, e.g. for performing an algorithm
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Systems and methods for diagnosing battery voltage misreporting is described. According to various embodiments, battery voltage may be monitored with respect to a state of charge and/or time. Based on this monitored information, battery charge state data may be generated by computing time derivatives of the monitored battery voltage across a voltage range. This battery charge state data may be compared with an expected set of charge state data if substantial differences exist, an error may be generated. Other embodiments are described and claimed.

Claims

1. A method for diagnosing a battery voltage misreporting, the method comprising:

monitoring a voltage of a battery;

calculating a time derivative curve of the monitored battery voltage across a range of battery voltages;

monitoring a second voltage corresponding to a second battery;

calculating a second time derivative curve of the second monitored battery voltage across said range of battery voltages;

setting said second time derivative curve as an expected set of data

comparing the time derivative curve to the expected set of data; and

generating an error message if the time derivative curve differs from the expected set of data by a predetermined amount.

2. The method of claim 1, wherein the monitoring step is performed during charging of the battery.

3. The method of claim 1, wherein the expected set of data is based on an idealized battery.

4. The method of claim 1, further comprising the step of determining an amount corresponding to a shift between the time derivative curve and the second time derivative curve along a dV/dt axis, wherein said step of generating said error message further comprises comparing the amount of said shift to said predetermined amount.

5. The method of claim 1, further comprising the step of determining an amount corresponding to a shift between the time derivative curve and the second time derivative curve along a voltage axis, wherein said step of generating said error message further comprises comparing the amount of said shift to said predetermined amount.

6. The method of claim 1, further comprising the steps of integrating the time derivative curve to determine a first scalar value, wherein said comparing step further comprises comparing the first scalar value with a second scalar value based on said expected set of data.

7. The method of claim 1, wherein the monitoring step is performed during discharge of the battery.

8. The method of claim 1, wherein the expected set of data is based on a reference battery.

9. The method of claim 1, further comprising the steps of:

monitoring at least one other voltage corresponding to at least one additional battery;

calculating at least one other time derivative curve across said range of battery voltages, wherein said at least one other time derivative curve corresponds to said at least one additional battery; and

basing said expected set of data on said at least one other time derivative curve.

10. The method of claim 9, wherein said at least one other time derivative curve is comprised of a plurality of other time derivative curves, and wherein said expected set of data is based on an average of said plurality of other time derivative curves.

11. The method of claim 1, further comprising the step of modifying operation of a charging system coupled to said battery in response to said error message.

12. The method of claim 1, further comprising the step of terminating operation of a charging system coupled to said battery in response to said error message.

13. A system for diagnosing battery voltage misreporting, the apparatus comprising:

a battery measurement circuit to measure the voltage of a battery to create battery voltage data;

one or more additional battery measurement circuits to measure voltages across one or more additional batteries to create additional voltage data;

a calculation module to receive the battery voltage data and to calculate time derivatives from the battery voltage data across a range of battery voltages;

at least one additional calculation module to receive the additional battery voltage data and to calculate time derivatives of the measured voltages across a voltage range to generate an expected set of time derivatives; and

a diagnostic module to compare the calculated time derivatives to said expected set of time derivatives, the diagnostic module to generate an error message if the calculated time derivatives are substantially different than the expected set of time derivatives.

14. The system of claim 13, wherein the battery is a lithium-ion battery.

15. The system of claim 13, further comprising a charging system to receive the error message and to limit charging of the battery.

16. The system of claim 15, wherein the charging system substantially disallows charging of the battery.

17. The system of claim 13, further comprising a vehicle management system to receive the error message and to adjust the voltages indicated by the battery measurement circuit.

18. A system for diagnosing battery voltage misreporting, the apparatus comprising:

a battery measurement circuit to measure the voltage of a battery to create battery voltage data;

a calculation module to receive the battery voltage data and to calculate a time derivative curve from the battery voltage data across a range of battery voltages; and

a diagnostic module to compare the time derivative curve to an expected set of data, wherein the diagnostic module generates an error message if the time derivative curve is different from the expected set of data by more than a predetermined amount, wherein the calculation module further integrates said time derivative curve to determine a first scalar value, wherein the diagnostic module compares the first scalar value to a second scalar value based on the expected set of data and generates the error message if the first scalar value is different from the second scalar value by more than the predetermined amount.

19. The system of claim 18, wherein the expected set of data is based on an idealized battery.

20. The system of claim 18, wherein the expected set of data is based on a reference battery.

21. The system of claim 18, further comprising a charging system coupled to the diagnostic system, wherein said charging system terminates battery charging when the diagnostic module generates the error message.

22. The system of claim 18, further comprising a charging system coupled to the diagnostic system, wherein said charging system modifies battery charging when the diagnostic module generates the error message.

23. The system of claim 18, further comprising a vehicle management system coupled to the diagnostic system, wherein said vehicle management system modifies voltages reported by the battery measurement circuit when the diagnostic module generates the error message.