System and method for contactor status check for electrified vehicle
A power distribution system includes a contactor between a traction battery and a high-voltage bus. The system includes a controller configured to generate a contactor status to determine if the contactor is operating as commanded. The controller identifies a contactor as closed responsive to a rate of change of a voltage difference between a traction battery voltage and a high-voltage bus voltage over each of a predetermined number of time intervals being within a predetermined range.
1. A vehicle comprising:
a traction battery;
a contactor configured to selectively electrically couple a terminal of the traction battery to a terminal of a high-voltage bus; and
a controller programmed to command the contactor to open at an end of an ignition cycle and, responsive to a rate of change of a voltage difference between the traction battery and the high-voltage bus for each of a first predetermined number of consecutive time intervals being within a predetermined range, cause a display to show a status indicator to indicate the contactor is welded closed during a subsequent ignition cycle, and, responsive to the rate of change for each of a second predetermined number of consecutive time intervals falling outside the predetermined range, enter a shutdown mode without causing the display to show the status indicator for the subsequent ignition cycle.
2. The vehicle of claim 1 , wherein values defining the predetermined range are based on values of a resistance and a capacitance that are coupled to the high-voltage bus through which the high-voltage bus is passively discharged when the contactor is opened.
3. The vehicle of claim 1 , wherein the first predetermined number of consecutive time intervals and the second predetermined number of consecutive time intervals each define a duration that is less than a time for a voltage of the high-voltage bus voltage to decay from a voltage of the traction battery to below a predetermined low-voltage threshold.
4. The vehicle of claim 1 , wherein the controller is further programmed to store a diagnostic code responsive to the rate of change for each of the first predetermined number of consecutive time intervals being within the predetermined range.
5. The vehicle of claim 1 , wherein the controller is further programmed to evaluate the rate of change between consecutive voltage measurements.
6. The vehicle of claim 1 , wherein the second predetermined number of consecutive time intervals is less than the first predetermined number of consecutive time intervals.
7. The vehicle of claim 1 , wherein the controller is further programmed to, responsive to a voltage of the high-voltage bus falling below a predetermined low-voltage threshold, enter the shutdown mode without causing the display to show the status indicator for the subsequent ignition cycle.
8. A power distribution system for a vehicle comprising:
a contactor configured to selectively electrically couple a terminal of a traction battery to a corresponding terminal of a high-voltage bus; and
a controller programmed to command the contactor to transition from closed to open and, responsive to a rate of change of a difference between an average of a first set of voltage differences between a traction battery voltage and a high-voltage bus voltage and an average of a second set of voltage differences between the traction battery voltage and the high-voltage bus voltage being within a predetermined range over each of a predetermined number of time intervals, cause a display in the vehicle to show a status indicator indicative of the contactor being welded closed.
9. The power distribution system of claim 8 , wherein the first set of voltage differences are consecutive measurements over a first time interval and the second set of voltage differences are consecutive measurements over a second time interval.
10. The power distribution system of claim 9 , wherein the second time interval immediately follows the first time interval.
11. The power distribution system of claim 9 , wherein the first time interval and the second time interval each includes a same number of voltage measurements.
12. The power distribution system of claim 8 , wherein values defining the predetermined range are based on values of a resistance and a capacitance that are coupled to the high-voltage bus through which the high-voltage bus is passively discharged when the contactor is opened.
13. The power distribution system of claim 8 , wherein the predetermined number of time intervals defines a duration that is less than a time for the high-voltage bus voltage to decay to less than a predetermined low-voltage threshold.
14. The power distribution system of claim 8 , wherein the controller is further programmed to, responsive to the rate of change over each of a second predetermined number of time intervals falling outside of the predetermined range, cause the controller to enter a low-power mode without causing the display to show the status indicator.
15. The power distribution system of claim 14 , wherein the second predetermined number of time intervals is different than the predetermined number of time intervals.
16. A method comprising:
commanding, by a controller, a contactor disposed between a terminal of a traction battery and a terminal of a high-voltage bus to transition from closed to open; and
outputting, by the controller, to a display a status indicator indicative of a welded contactor responsive to a rate of change of a voltage difference between a traction battery and a high-voltage bus over each of a predetermined number of consecutive time intervals being within a predetermined range that varies according to values of a resistance and a capacitance that are coupled to the high-voltage bus through which the high-voltage bus passively discharges when the contactor is opened.
17. The method of claim 16 further comprising entering a controller shutdown mode without outputting the status indicator responsive to the rate of change of the voltage difference over each of a second predetermined number of consecutive time intervals falling outside of the predetermined range.
18. The method of claim 17 , wherein the second predetermined number of consecutive time intervals is different than the predetermined number of consecutive time intervals.
19. The method of claim 16 , wherein the predetermined number of consecutive time intervals defines a duration that is less than a time for the high-voltage bus voltage to decay below a low-voltage threshold.