Method and means for contactor monitoring in electric vehicle supply equipment

1. A method for contactor monitoring and control in electric vehicle supply equipment, the method comprising:

a) updating contactor error counts based on a detected condition of a contactor comprising:

i) updating an open error count; and

ii) updating a close error count;

b) determining a detected state of the contactor by comparing the open error count and the close error count to maximum and minimum values; and

c) performing at least one of: (i) controlling the state of the contactor based on the determined contactor state; or (ii) providing a visual indicator based on the determined contactor state.

2. The method of claim 1 , wherein updating contactor error counts comprises:

a) detecting contactor input line voltages and comparing each of the contactor input line voltages to a threshold; and

b) detecting a combined contactor input line voltage and contactor combined output line voltage and comparing the contactor input line voltage with contactor output line voltage to a delta value.

3. The method of claim 1 further comprising detecting a condition of the contactor by comparing voltages at outputs of the contactor to a threshold value.

4. The method of claim 3 , wherein detecting the condition comprises determining an open condition is satisfied when the voltages at the outputs of the contactor are both less than the threshold value.

5. The method of claim 3 , wherein detecting the condition comprises determining a close condition is satisfied when either of the voltages at the outputs of the contactor are greater than the threshold value and the absolute value of a difference between an input voltage less an output voltage of the contactor is less than a delta value.

6. The method of claim 3 , wherein detecting the condition comprises determining an unknown condition is satisfied when either of the voltages at the outputs of the contactor are greater than the threshold value and the absolute value of a difference of an input voltage less an output voltage of the contactor is not less than a delta value.

7. The method of claim 1 , wherein updating contactor error counts comprises:

a) decrementing the open error count when the detected condition of the contactor is open and the open error count is greater than zero; and

b) incrementing the close error count when the detected condition of the contactor is open and the close error count is less than a maximum value.

8. The method of claim 1 , wherein updating contactor error counts comprises:

a) decrementing the close error count when the detected condition of the contactor is close and the close error count is greater than zero; and

b) incrementing the open error count when the detected condition of the contactor is close and the open error count is less than a maximum value.

9. The method of claim 1 , wherein updating contactor error counts comprises:

a) incrementing the open error count when the detected condition of the contactor is unknown and the open error count is less than a maximum; and

b) incrementing the close error count when the detected condition of the contactor is unknown and the close error count is less than a maximum.

10. The method of claim 1 , wherein controlling the state of the contactor comprises reclosing the contactor when in a charging state and when a contactor open event is received and a contactor control relay is closed.

11. The method of claim 1 , wherein performing comprises providing a visual indicator of a fault when in a charging state and when a contactor open event is received and a contactor control relay is open.

12. The method of claim 1 , wherein performing comprises providing a visual indicator of a fault when in a charging state and when a contactor unknown event is received and a reclose count is not less than a maximum.

13. The method of claim 1 , wherein performing comprises providing a visual indicator of a fault when in a charging state and when a contactor unknown event is received and a reclose count is not less than a maximum value.

14. The method of claim 1 , wherein performing comprises controlling the state of the contactor by reclosing the contactor when in a charging state and when a contactor unknown event is received and a reclose count is less than a maximum value.

15. The method of claim 1 , wherein performing comprises providing a visual indicator of a fault and sending an opening to the contactor when not in a charging state and when one of: (a) a contactor closed event; or (b) a contactor unknown event is received.

16. The method of claim 1 , further comprising communicating the detected state of the contactor to a main state machine, and wherein performing comprises using the main state machine to perform the at least one of: (i) controlling the state of the contactor based on the determined contactor state; or (ii) providing a visual indicator based on the determined contactor state.

17. A method for contactor monitoring and control in electric vehicle supply equipment, the method comprising:

a) updating contactor error counts based on a detected condition of a contactor comprising:

i) updating an open error count; and

ii) updating a close error count;

b) determining a detected state of the contactor by comparing the open error count and the close error count to maximum and minimum values;

c) performing at least one of: (i) controlling the state of the contactor based on the determined contactor state; or (ii) providing a visual indicator based on the determined contactor state and

d) wherein determining a detected state of the contactor comprises determining the detected state is one of (i) closed when the open error count is greater than or equal to a maximum value and the close error count is equal to a minimum value; (ii) unknown when the open error count is greater than or equal to a maximum value and the close error count is greater than or equal to a maximum value; or (iii) open when the open error count is equal to a minimum value and the close error count is greater than or equal to a maximum value.

18. The method of claim 17 , further comprising: (a) communicating a contactor close event to a controller main state machine if the detected state of the contactor is closed; (b) communicating a contactor unknown event to a controller main state machine if the detected state of the contactor is unknown; or (c) communicating a contactor open event to a controller main state machine if the detected state of the contactor is open.

19. The method of claim 17 , wherein updating contactor error counts comprises:

a) detecting contactor input line voltages and comparing each of the contactor input line voltages to a threshold; and

b) detecting a combined contactor input line voltage and contactor combined output line voltage and comparing the contactor input line voltage with contactor output line voltage to a delta value.

20. The method of claim 17 further comprising detecting a condition of the contactor by comparing voltages at outputs of the contactor to a threshold value, and wherein detecting the condition comprises determining one of: (a) an open condition is satisfied when the voltages at the outputs of the contactor are both less than the threshold value; (b) a close condition is satisfied when either of the voltages at the outputs of the contactor are greater than the threshold value and the absolute value of a difference between an input voltage less an output voltage of the contactor is less than a delta value; or (c) an unknown condition is satisfied when either of the voltages at the outputs of the contactor are greater than the threshold value and the absolute value of a difference of an input voltage less an output voltage of the contactor is not less than a delta value.