Detection of faults in redundant grounding systems

1. A method of detecting ground loss of an electrical component, the method comprising:

monitoring a ground circuit including a first ground line connected to the electrical component and a second ground line connected to the electrical component, wherein the monitoring includes measuring a current through each of the first ground line and the second ground line, and measuring a voltage through each of the first ground line and the second ground line;

calculating a first resistance of the first ground line and a second resistance of the second ground line based on the measured current and the measured voltage;

estimating a difference between the first resistance and the second resistance, and comparing the estimated difference to a threshold difference, wherein the calculating and estimating the difference is performed at each of a plurality of time points;

based on the estimated difference being greater than the threshold difference, detecting a ground fault, diagnosing the ground fault based on a number of time points for which the ground fault is detected, and outputting an indication of the ground fault, wherein the ground fault is diagnosed as an intermittent fault based on the number of time points being greater than a first threshold number, and the ground fault is diagnosed as a permanent fault based on the number of time points being greater than a second threshold number, the second threshold number being greater than the first threshold number; and

based on detecting the ground fault, performing at least one of derating the electrical component and controlling a vehicle that includes the electrical component.

2. The method of claim 1 , wherein the number of time points is determined based on incrementing a diagnostic counter.

3. The method of claim 1 , wherein the diagnostic counter is incremented for each time point at which the ground fault is detected.

4. The method of claim 1 , wherein diagnosing the ground fault includes determining a level of severity of the ground fault based on at least one of:

a value of the estimated difference, the number of time points at which the ground fault is detected, and a length of a time period during which the ground fault is detected.

5. The method of claim 1 , wherein the indication is output to at least one of a driver, a vehicle control system and an external system.

6. The method of claim 1 , wherein the ground circuit includes a first switch connected between the first ground line and the electrical component and a second switch connected between the second ground line and the electrical component.

7. The method of claim 6 , wherein calculating the first resistance and the second resistance includes:

generating a current through the electrical component;

measuring a first current through the first ground line, a second current through the second ground line and a total current when the first switch and the second switch are closed;

measuring a first voltage of the electrical component when the first switch is closed and the second switch is open;

measuring a second voltage of the electrical component when the first switch is open and the second switch is closed; and

calculating the first resistance and the second resistance based on a difference between the first voltage and the second voltage, the first current, the second current and the total current.

8. The method of claim 7 , wherein the first resistance is calculated based on:

R

G

⁢

1

=

(

V

M

⁢

2

-

⁢

V

M

⁢

1

)

/

(

I

*

(

1

-

I

G

⁢

1

/

I

G

⁢

2

)

)

,

and

the second resistance is calculated based on:

R

G

⁢

2

=

(

V

M

⁢

1

-

⁢

V

M

⁢

2

)

/

(

I

*

(

1

-

I

G

⁢

2

/

I

G

⁢

1

)

)

,

wherein R G1 is the first resistance, R G2 is the second resistance, V M1 is the first voltage, V M2 is the second voltage, I* is the total current, I G1 is the first current and I G2 is the second current.

9. The method of claim 1 , wherein the electrical component is a control module of the vehicle.

10. A system for detecting ground loss of an electrical component, the system comprising:

a ground circuit including a first ground line connected to the electrical component and a second ground line connected to the electrical component; and

a processing device configured to measure a current through each of the first ground line and the second ground line, and measure a voltage through each of the first ground line and the second ground line, the processing device configured to perform:

calculating a first resistance of the first ground line, and a second resistance of the second ground line based on the measured current and the measured voltage;

estimating a difference between the first resistance and the second resistance, and comparing the estimated difference to a threshold difference, wherein the calculating and estimating the difference is performed at each of a plurality of time points;

based on the estimated difference being greater than the threshold difference, detecting a ground fault, diagnosing the ground fault based on a number of time points for which the ground fault is detected, and outputting an indication of the ground fault, wherein the ground fault is diagnosed as an intermittent fault based on the number of time points being greater than a first threshold number, and the ground fault is diagnosed as a permanent fault based on the number of time points being greater than a second threshold number, the second threshold number being greater than the first threshold number; and

based on detecting the ground fault, performing at least one of derating the electrical component and controlling a vehicle that includes the electrical component.

11. The system of claim 10 , wherein the number of time points is determined based on incrementing a diagnostic counter.

12. The system of claim 10 , wherein the diagnostic counter is incremented for each time point at which the ground fault is detected.

13. The system of claim 10 , wherein diagnosing the ground fault includes determining a level of severity of the ground fault based on at least one of:

a value of the estimated difference, the number of time points at which the ground fault is detected, and a length of a time period during which the ground fault is detected.

14. The system of claim 10 , wherein the indication is output to at least one of a driver, a vehicle control system and an external system.

15. The system of claim 10 , wherein the ground circuit includes a first switch connected between the first ground line and the electrical component and a second switch connected between the second ground line and the electrical component, and calculating the first resistance and the second resistance includes:

generating a current through the electrical component;

measuring a first current through the first ground line, a second current through the second ground line and a total current when the first switch and the second switch are closed;

measuring a first voltage of the electrical component when the first switch is closed and the second switch is open;

measuring a second voltage of the electrical component when the first switch is open and the second switch is closed; and

calculating the first resistance and the second resistance based on a difference between the first voltage and the second voltage, the first current, the second current and the total current.

16. The system of claim 15 , wherein the first resistance is calculated based on:

R

G

⁢

1

=

(

V

M

⁢

2

-

⁢

V

M

⁢

1

)

/

(

I

*

(

1

-

I

G

⁢

1

/

I

G

⁢

2

)

)

,

the second resistance is calculated based on:

R

G

⁢

2

=

(

V

M

⁢

1

-

⁢

V

M

⁢

2

)

/

(

I

*

(

1

-

I

G

⁢

2

/

I

G

⁢

1

)

)

,

wherein R G1 is the first resistance, R G2 is the second resistance, V M1 is the first voltage, V M2 is the second voltage, I* is the total current, I G1 is the first current and I G2 is the second current.

17. A vehicle system comprising:

a memory having computer readable instructions; and

a processing device for executing the computer readable instructions, the computer readable instructions controlling the processing device to perform a method including:

monitoring a ground circuit including a first ground line connected to an electrical component and a second ground line connected to the electrical component, wherein the monitoring includes measuring a current through each of the first ground line and the second ground line, and measuring a voltage through each of the first ground line and the second ground line;

calculating a first resistance of the first ground line, and a second resistance of the second ground line based on the measured current and the measured voltage;

estimating a difference between the first resistance and the second resistance, and comparing the estimated difference to a threshold difference, wherein the calculating and estimating the difference is performed at each of a plurality of time points;

based on the estimated difference being greater than the threshold difference, detecting a ground fault, diagnosing the ground fault based on a number of time points for which the ground fault is detected, and outputting an indication of the ground fault, wherein the ground fault is diagnosed as an intermittent fault based on the number of time points being greater than a first threshold number, and the ground fault is diagnosed as a permanent fault based on the number of time points being greater than a second threshold number, the second threshold number being greater than the first threshold number; and

based on detecting the ground fault, performing at least one of derating the electrical component and controlling a vehicle that includes the electrical component.

18. The vehicle system of claim 17 , wherein the number of time points is determined based on incrementing a diagnostic counter, and the diagnostic counter is incremented for each time point at which the ground fault is detected.

19. The vehicle system of claim 17 , wherein the indication is output to at least one of a driver, a vehicle control system and an external system.

20. The vehicle system of claim 17 , wherein the ground circuit includes a first switch connected between the first ground line and the electrical component and a second switch connected between the second ground line and the electrical component.