Patent ID: 8164344

Claim:
An electric vehicle incorporating a ground fault detecting system, which includes a load, a first ungrounded power supply having a voltage for supplying electric power to the load, a converter having input and output terminals connected between the load and the first ungrounded power supply, and a second ungrounded power supply having a voltage lower than the voltage of the first ungrounded power supply and which is connected to other input and output terminals of the converter, the ground fault detecting system comprising: a first ground fault detector for detecting a ground fault of the first ungrounded power supply based on a change in a circuit impedance before and after a first switch is opened and closed, the first ground fault detector having a first insulation resistor inserted between the first ungrounded power supply and a grounded region, the first insulation resistor being connected to an end of a first detection resistor through the first switch, the first detection resistor having another end connected to the grounded region or an AC signal source which generates an AC signal; a second ground fault detector for detecting a ground fault of the second ungrounded power supply based on a change in a circuit impedance before and after a second switch is opened and closed, the second ground fault detector having a second insulation resistor inserted between the second ungrounded power supply and the grounded region, the second insulation resistor being connected to an end of a second detection resistor through the second switch, the second detection resistor having another end connected to the grounded region or the AC signal source; and a switch controller for performing an exclusive switch control process for inhibiting the second switch from being closed when the first switch is closed and inhibiting the first switch from being closed when the second switch is closed.