GROUND FAULT DETECTING CIRCUIT, AND POWER SUPPLY DEVICE

摘要

PROBLEM TO BE SOLVED: To appropriately perform ground fault determination, taking into account possible influence of noise generated by an inverter while a motor operates.SOLUTION: A ground fault detecting circuit causes an oscillation circuit of a microprocessor 11 to generate AC signal and inputs the signal to a positive pole terminal side of a high-voltage battery 1 via a coupling capacitor 14 for input use. The voltage of the positive pole terminal side of the high-voltage battery 1 is divided by a resistor 17 and a resistor 19, and its AC component is inputted as a ground fault detection signal to the microprocessor 11 via a coupling capacitor 15 for detection use. The microprocessor 11 determines a noise level between the high-voltage battery 1 and a motor 7 on the basis of the result of measurement of the ground fault detection signal when no AC signal is generated and the result of measurement of the ground fault detection signal when the AC signal is generated, and detects the ground fault.