HIGH VOLTAGE INTERLOCK STRATEGY

• US 20110010126A1
• Filed: 07/07/2009
• Published: 01/13/2011
• Est. Priority Date: 07/07/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: XIANG, Joe Youqing, Sankaran, Venkateswa Anand, Degner, Michael W.
• Granted Patent: US 9,026,393 B2
• Time in Patent Office: Days
• US Class Current: 702/117
• CPC Class Codes: B60L 15/025 using field orientation; Vector control; Direct Torque Control [DTC]
• CPC Class Codes: B60L 3/0023 Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train
• CPC Class Codes: B60L 50/50 using propulsion power supplied by batteries or fuel cells
• CPC Class Codes: G01R 31/66 Testing of connections, e.g. of plugs or non-disconnectable joints testing for incorrect line connections G01R31/55
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

A High Voltage Interlock Strategy (HVIS) uses feedback current to detect cable connectivity status for a high-voltage cable configured to connect a power conversion circuit with a remote permanent magnet synchronous machine (PMSM). One or more feedback factors are calculated based on detected feedback current. Various algorithms for calculating a feedback factor, and for determining connectivity status based on calculated feedback factors, can be practiced, according to the PMSM operational mode. Fault detection action can be performed in response to detecting a cable disconnect. The HVIS can be implemented by software, making it a safe, economical solution for cable connectivity detection.

Claims

1. A system for determining a voltage cable connection status, comprising:

a permanent magnet synchronous machine (PMSM);

a power conversion circuit configured to provide power to said PMSM;

a controller coupled to said power conversion circuit and configured to control said power conversion circuit;

a cable configured to electrically connect said power conversion circuit to said PMSM;

at least one sensor configured to detect current conducted by said cable;

a high voltage interlock strategy (HVIS) module configured to determine said cable connectivity status by calculating at least one feedback factor based on said detected current.

2. The system of claim 1, wherein said HVIS module comprises software configured for execution on a general purpose computing device.

3. The system of claim 1, wherein said cable comprises a high-voltage three-phase cable.

4. A method for determining cable connectivity for a cable configured to connect a permanent magnet synchronous machine (PMSM) to a power conversion circuit, comprising:

detecting that a pre-charging contact is closed;

in response to detecting said pre-charging contact is closed, performing a pre-charging mode detection algorithm;

in response to determining that cable connectivity is good as a result of performing said pre-charging mode detection algorithm, performing a zero-current mode detection algorithm when a command current for a PMSM is zero, or a current-generation mode detection algorithm when said command current is not zero.

5. The method of claim 4, further comprising performing a fault-detection action when said cable is determined to be disconnected.

6. The method of claim 5, wherein said fault-detection action comprises initiating discharge of a capacitor.

7. The method of claim 4, wherein said current generation mode detection algorithm comprises a closed loop version configured to be performed during a current regulation loop of said PMSM operation.

8. The method of claim 4, wherein said current generation mode detection algorithm comprises an open loop version configured to be performed during a slow loop of said PMSM operation.

9. A method for determining voltage cable connection status, comprising:

calculating at least one feedback factor based on feedback current;

using said at least one calculated feedback factor to determine cable connectivity for a cable configured to connect a permanent magnet synchronous machine (PMSM) with a power conversion circuit configured to provide current to said PMSM via said cable; and

performing an action in response to a cable connectivity determination.

10. The method of claim 9, wherein said feedback current is detected during a zero-current operational mode of said PMSM.

11. The method of claim 9, wherein said feedback current is detected during a pre-charging operational mode of said PMSM.

12. The method of claim 9, wherein said calculated feedback factor comprises a magnitude of a feedback current vector representing said detected feedback current in a d-q reference frame of a rotor of said PMSM.

13. The method of claim 12, wherein said cable is determined to be connected when said magnitude of said feedback current vector is within a predetermined range of values.

14. The method of claim 9, further comprising providing constant command voltages for a predetermined period prior to calculating said at least one feedback factor.

15. The method of claim 9, wherein said feedback current is detected while said PMSM is not rotating.

16. The method of claim 13, wherein in response to a determination that said cable is connected, said method is repeated after a predetermined time interval.

17. A method for detecting voltage cable connectivity, comprising:

calculating a difference between a command current for a permanent magnet synchronous machine (PMSM) and a feedback current for said PMSM;

calculating an average of a square of said difference between said command current and said feedback current over a predetermined period;

calculating a squared difference magnitude using said calculated average;

calculating a squared command current magnitude using a square of said command current;

comparing said squared difference magnitude and said squared command current magnitude to determine connectivity status of a cable configured to connect said PMSM to a power circuit configured to provide current to said PMSM.

18. The method of claim 17, further comprising performing an action in response to determining said cable is disconnected from one of said power circuit and said PMSM.

19. The method of claim 17, wherein said feedback current detection and said calculations are performed during a current regulation loop of said PMSM control.

20. The method of claim 17, wherein said calculating a difference between a command current for a permanent magnet synchronous machine (PMSM) and a feedback current for said PMSM comprises calculating a difference using a first vector that represents said command current in a d-q reference frame of a rotor of said PMSM and a second vector that represent said feedback current in said d-q reference frame.

21. The method of claim 17, wherein said calculating a square of a command current magnitude comprises calculating a square of a magnitude of a vector that represents said command current in a d-q reference frame of a rotor of said PMSM.

22. A method for determining a voltage cable connection status, comprising:

calculating a feedback current vector magnitude for a current vector representing feedback current;

calculating back electromotive force for a permanent magnet synchronous motor (PMSM);

calculating an estimated feedback current vector using said calculated back electromotive force;

calculating an estimated feedback current vector magnitude using said estimated feedback current vector; and

comparing said feedback current vector magnitude with said estimated feedback current vector magnitude to determine connectivity status of a cable configured to connect said PMSM with a power circuit configured to provide current to said PMSM.

23. The method of claim 22, further comprising performing a fault-detection action in response to determining said cable is not connected to at least one of said PMSM and said power circuit.

24. The method of claim 22, wherein said method is implemented in a slow loop of electric motor control of said PMSM.

25. A computer-readable medium having stored thereon sequences of instructions, the sequences of instructions, when executed by a digital processor, cause the processor to calculate a feedback factor based on feedback current, and to use said feedback factor to detect the connectivity status of a cable configured to connect a permanent magnet synchronous motor (PMSM) with a power circuit configured to provide current to said PMSM.

26. The computer-readable medium of claim 26, wherein the sequences of instructions are configured as processor-based software executed on a general purpose computing device.