Vehicle AC ground fault detection system

A vehicle ground fault detection system for detecting a ground fault in a vehicle electrical circuit, the system comprising:

• an AC step-up voltage circuit including an AC transformer having a primary coil and a secondary coil for increasing a voltage supplied to the AC transformer;
• a microprocessor for determining a fault detection within the AC step-up voltage circuit;
• a fault detection circuit for detecting a short circuit between a secondary ground of the transformer and a battery ground, the fault detection circuit comprising:
• a resistance element having a predetermined resistance value, the resistance element connected to a supply voltage;
• an electrical switching circuit connected to the resistance element for and the secondary ground;
• and
• a fault detection sense line connected between the resistance element and the electrical switching circuit;
• wherein the electrical switching circuit selectively couples the supply voltage via the resistance element to the secondary ground, andthe microprocessor monitors the fault detection sense line for determining an occurrence of the ground fault prior to a start-up of the AC step-up power transformation.

A method for detecting a ground fault in a vehicle AC electrical system that includes an AC step-up transformer having a primary coil and a secondary coil with a secondary ground and a fault detection circuit that includes a supply voltage input line connected to a resistive element, an electrical switching circuit is connected between the resistive element and the secondary ground, and a fault detection sense line, the method for detecting the ground fault comprising the steps of:

• selectively coupling the resistive element to the secondary ground via the electrical switching circuit;
• monitoring the fault detection sense line;
• and
• determining a ground fault within the vehicle AC electrical system prior to an AC voltage step-up transformation in response to the monitoring of the fault detection sense line.