Patent ID: 8207698

Claim:
An electric drive system having a three-wire high-voltage cable extending between a drive system inverter and a three-phase permanent-magnet synchronous motor, the system comprising: a current transformer including a voltage source inverter, the voltage source inverter having a DC bus capacitor and being configured to generate a high-frequency common-mode pulse-width-modulated voltage and apply the high-frequency common-mode pulse-width-modulated voltage between the drive system inverter and the motor when the drive system inverter is in an idle state, the high-frequency common-mode pulse-width-modulated voltage providing a high-frequency common-mode current through the cable, the current transformer being positioned to detect the high-frequency common-mode current through the cable to obtain a common-mode current signal; and a controller configured to determine a condition of the electric drive system in response to the common-mode current signal when the drive system inverter is in the idle state and to generate a discharge signal to discharge the DC bus capacitor when the controller detects an inadequate electrical connection between the drive system inverter and the motor.