System and method for detecting an earth ground fault of an external power supply connected to a vehicle

1. A method for determining a faulty earth connection within a vehicle, the method comprising:

establishing an electrical connection between the vehicle and an external Alternating Current (AC) power source, wherein the electrical connection is a three phase electrical connection configured to receive an input voltage signal on a phase, neutral, and earth connection;

determining whether the input signal received on the phase connection exceeds a predetermined phase threshold when referenced to the earth connection;

determining whether input signal received on the neutral connection exceeds a predetermined neutral threshold when referenced to the earth connection; and

determining that a faulty earth connection exists between the vehicle and the AC power source when the input signal received from the phase connection does not exceed the predetermined phase threshold and the input signal received from the neutral connection does not exceed the predetermined neutral threshold.

2. The method of claim 1 further comprising:

determining that a faulty earth connection exists between the vehicle and the AC power source when the input signal received from the phase connection exceeds the predetermined phase threshold and the input signal received from the neutral connection exceeds the predetermined neutral threshold.

3. The method of claim 1 further comprising:

modifying the input signal received from the phase connections so that only a positive phase semi-cycle signal is evaluated; and

modifying the input signal received from the neutral connections so that only a positive neutral semi-cycle signal is evaluated.

4. The method of claim 3 further comprising:

limiting the voltage level of each of the positive phase and neutral semi-cycle signals; and

adapting the impedances and drive currents for each of the phase and neutral semi-cycle signals.

5. The method of claim 4 further comprising:

filtering the positive phase semi-cycle signals in order to reduce high frequency noise present on the phase connection; and

filtering the positive neutral semi-cycle signals in order to reduce high frequency noise present on the neutral connection.

6. The method of claim 5 further comprising:

transmitting the filtered positive phase semi-cycle signal to a first comparator, the first comparator being configured to determine whether the positive phase semi-cycle signal exceeds a predetermined voltage threshold; and

transmitting the filtered positive neutral semi-cycle signal to a second comparator, the second comparator being configured to determine whether the positive neutral semi-cycle signal exceeds a predetermined voltage threshold.

7. The method of claim 1 further comprising:

generating one or more output signals indicating the existence of a ground fault condition.

8. The method of claim 7 wherein, the one or more output signals are transmitted to a vehicle safety system, and the vehicle safety system activating a visual alert system when the output signals indicate that a ground fault condition exists.

9. The method of claim 7 wherein, the one or more output signals are transmitted to a vehicle safety system, and the vehicle safety system activating an audible alert system when the output signals indicate that a ground fault condition exists.

10. The method of claim 1 further comprising:

determining that a ground fault condition does not exist between the vehicle and the AC power source when the input signal received from the phase connection exceeds the predetermined phase threshold and the input signal received from the neutral connection does not exceed the predetermined neutral threshold.

11. The method of claim 1 further comprising:

generating one or more output signals indicating the existence of a faulty earth connection; and

transmitting the one or more output signals to a vehicle safety system.

12. A system used for determining a faulty earth connection within a vehicle, the system comprising:

an electrical connector used for electrically connecting the vehicle and an external Alternating Current (AC) power source, wherein the electrical connector is a three phase electrical connector configured to receive a corresponding input voltage signal on a phase, neutral, and earth connection; and

a controller configured to:

determine whether the input signal received on the phase connection exceeds a predetermined phase threshold when referenced to the earth connection;

determine whether input signal received on the neutral connection exceeds a predetermined neutral threshold when referenced to the earth connection; and

determine that a ground fault condition exists between the vehicle and the AC power source when the input signal received from the phase connection does not exceed the predetermined phase threshold and the input signal received from the neutral connection does not exceed the predetermined neutral threshold.

13. The system of claim 12 , wherein the controller includes an adaption circuit and a controller circuit.

14. The system of claim 13 , wherein the adaptation circuit is configured to:

modify the input signal received from the phase connections so that only a positive phase semi-cycle signal is evaluated; and

modify the input signal received from the neutral connections so that only a positive neutral semi-cycle signal is evaluated.

15. The system of claim 14 , wherein the adaptation circuit is further configured to:

limit the voltage level of each of the positive phase and neutral semi-cycle signals; and

adapt the impedances and drive currents for each of the phase and neutral semi-cycle signals.

16. The system of claim 15 , wherein the adaptation circuit is further configured to:

filter the positive phase semi-cycle signals in order to reduce high frequency noise present on the phase connection,

filter the positive neutral semi-cycle signals in order to reduce high frequency noise present on the neutral connection.

17. The system of claim 16 , wherein the comparator circuit includes a first and second comparator, the first comparator being configured to determine whether the positive phase semi-cycle signal exceeds the predetermined phase threshold, and the second comparator being configured to determine whether the positive neutral semi-cycle signal exceeds a predetermined neutral threshold.

18. The system of claim 17 , wherein the comparator circuit is further configured to:

generate one or more output signals indicating the existence of a ground fault condition; and

transmit the one or more output signals to a vehicle safety system.