Patent ID: 8334670

Claim:
Method to control an electric motor control circuit including an electric energy storage device electrically connected via a positive DC electric power bus and a negative DC electric power bus to an inverter circuit, the inverter circuit electrically connected via an alternating current circuit to an electric machine, the method comprising: controlling the inverter circuit to control electric current flow between the alternating current circuit and the electric machine; continuously monitoring AC electric current flow through a capacitive shunt circuit electrically connected between the positive DC electric power bus and the negative DC electric power bus, the capacitive shunt circuit including a node electrically coupled to a chassis ground; detecting a fault associated with one of the alternating current circuit and the electric machine when the AC electric current flow through the capacitive shunt circuit exceeds a predetermined threshold; and controlling the inverter circuit to interrupt the flow of electric current between the alternating current circuit and the electric machine in response to a detected fault.