HIGH-VOLTAGE BUS DISCHARGE WITH LOGARITHMIC SELF-PROTECTION

• US 20090268354A1
• Filed: 04/24/2008
• Published: 10/29/2009
• Est. Priority Date: 04/24/2008
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: KAPLAN, Daniel J.
• Granted Patent: US 8,039,993 B2
• Time in Patent Office: Days
• US Class Current: 361/15
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/70 Interactions with external data bases, e.g. traffic centres
• 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: H02H 3/14 responsive to occurrence of voltage on parts normally at earth potential monitoring earth connection H02H5/105
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 90/16 Information or communication technologies improving the operation of electric vehicles

Abstract

Systems and methods for discharging a high-voltage bus coupled to a discharge circuit are provided. A method comprises obtaining a first voltage level of the high-voltage bus. The method further comprises determining a first discharge time based on the first voltage level and activating the discharge circuit. The method further comprises obtaining a second voltage level of the high-voltage bus after the first discharge time, comparing the first voltage level and the second voltage level, and deactivating the discharge circuit if a difference between the first voltage level and the second voltage level is less than a threshold value.

Claims

1. A method for controlling a discharge circuit coupled to a high-voltage bus, wherein the discharge circuit is activated such that current flows from the high-voltage bus through the discharge circuit, the method comprising:

determining a first discharge time based on a first voltage level of the high-voltage bus;

obtaining a second voltage level of the high-voltage bus after the first discharge time; and

deactivating the discharge circuit if a difference between the first voltage level and the second voltage level is less than a threshold value.

2. The method of claim 1, further comprising:

if the difference between the first voltage level and the second voltage level is less than the threshold value;

waiting for a recovery time thereafter; and

reactivating the discharge circuit in response to a signal indicating the high-voltage bus should be discharged.

3. The method of claim 2, wherein the recovery time is based on an average power handling capacity of the discharge circuit.

4. The method of claim 1, further comprising:

determining a second discharge time based on the second voltage level;

obtaining a third voltage level of the high-voltage bus after the second discharge time; and

deactivating the discharge circuit if a difference between the second voltage level and the third voltage level is less than the threshold value.

5. The method of claim 1, further comprising:

for a plurality of possible voltage levels of the high-voltage bus;

calculating a plurality of discharge times for each of the plurality of possible voltage levels; and

storing the plurality of discharge times in a lookup table associated with each of the plurality of possible voltage levels.

6. The method of claim 5, wherein determining the first discharge time further comprises obtaining the first discharge time from the lookup table based on the first voltage level.

7. The method of claim 1, wherein the first discharge time is governed by

8. The method of claim 1, wherein the threshold value is based on a smallest measurable change in a voltage level of the high-voltage bus.

9. A method for discharging a high-voltage bus coupled to a discharge circuit, the method comprising:

obtaining a first voltage level of the high-voltage bus;

determining a first discharge time based on the first voltage level;

activating the discharge circuit;

obtaining a second voltage level of the high-voltage bus after the first discharge time;

comparing the first voltage level and the second voltage level; and

deactivating the discharge circuit if a difference between the first voltage level and the second voltage level is less than a threshold value.

10. The method of claim 9, further comprising if the difference between the first voltage level and the second voltage level is less than the threshold value, reactivating the discharge circuit after a recovery time in response to a signal indicating the high-voltage bus should be discharged.

11. The method of claim 9, further comprising:

determining a second discharge time based on the second voltage level;

obtaining a third voltage level of the high-voltage bus after the second discharge time; and

deactivating the discharge circuit if a difference between the second voltage level and the third voltage level is less than the threshold value.

12. The method of claim 9, further comprising:

for a plurality of possible voltage levels of the high-voltage bus;

calculating a plurality of discharge times for each of the plurality of possible voltage levels; and

storing the plurality of discharge times in a lookup table associated with each of the plurality of possible voltage levels; and

obtaining the first discharge time from the lookup table based on the first voltage level.

13. The method of claim 9, wherein the first discharge time is governed by

14. The method of claim 13, wherein V_δ

is governed by

15. The method of claim 9, wherein the threshold value is based on a smallest measurable change in a voltage level of the high-voltage bus.

16. A vehicle protection system for a high-voltage capacitor bank coupled to a high-voltage bus, the vehicle protection system comprising:

a discharge circuit coupled to the high-voltage bus; and

a discharge controller coupled to the high-voltage bus and the discharge circuit, the discharge controller being configured to;

activate the discharge circuit;

determine a first discharge time based on a first voltage level of the high-voltage bus;

obtain a second voltage level of the high-voltage bus after the first discharge time; and

deactivate the discharge circuit if a difference between the first voltage level and the second voltage level of the high-voltage bus is less than a threshold value.

17. The vehicle protection system of claim 16, the discharge controller further comprising an analog to digital converter, wherein the threshold value is a smallest change in a voltage level measurable by the analog to digital converter.

18. The vehicle protection system of claim 16, wherein the discharge circuit comprises:

a switch coupled to the high-voltage bus and the discharge controller; and

a pulse resistor coupled to the switch and a ground.

19. The vehicle protection system of claim 18, wherein the discharge controller is configured to deactivate the switch for a recovery time based on an average power handling capacity of the pulse resistor if the difference between the first voltage level and the second voltage level is less than the threshold value.

20. The vehicle protection system of claim 16, further comprising a lookup table coupled to the discharge controller, the lookup table containing a plurality of discharge times associated with a plurality of possible voltage levels of the high-voltage bus, the discharge controller being configured to obtain the first discharge time from the lookup table based on the first voltage level.