GROUND FAULT DETECTION CIRCUIT FOR VEHICLE HAVING HIGH VOLTAGE POWER SOURCE SYSTEM

摘要

PROBLEM TO BE SOLVED: To provide a ground fault detection circuit for a vehicle having a high voltage power source system that is able to appropriately achieve detection frequency and detection accuracy of ground fault of a high voltage power source system.SOLUTION: A ground fault detection circuit 10 that detects ground fault of a high voltage power source system electrically insulated from a vehicle body comprises: a coupling capacitor Cs connected to the high voltage power source system and configured to insulate a DC component; a resistance element Rs connected to the coupling capacitor Cs in series; an oscillation circuit 12 connected to the resistance element Rs in series and configured to apply AC voltage of predetermined frequency to the resistance element Rs; detecting means 11, 13 that detect ground fault of the high voltage power source system on the basis of voltage at a connection point P between the coupling capacitor Cs and the resistance element Rs; and varying means 11 that changes the predetermined frequency fc of AC voltage output from the oscillation circuit 20 according to the state of connection between a battery 20 included in the high voltage power source system and other electric apparatus included in the high voltage power source system.SELECTED DRAWING: Figure 1