| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground detecting device for a vehicle which enables the simplification of a circuit configuration, and high-precision detection of the level of the reduction of insulation resistance form a vehicle body. SOLUTION: This is a ground detector 30 for an electric vehicle which has a high-voltage DC power source 31 electrically insulated from a vehicle body B, and a three-phase AC motor 33 to be driven by a DC voltage from the power source 31. The ground detector 30 has a microcomputer 1 which supplies a ground detecting signal composed of rectangular waves to the DC source 31 via a detecting resistor 3 and a coupling capacitor 4, detects the voltage amplitude value of a ground detecting point A being the junction between the detecting resistor 3 and the coupling capacitor 4, converts the detected voltage amplitude value into an insulation resistance value on the basis of the relation between a preset voltage amplitude value and the insulation resistance value, and detects the level of deterioration of the insulation resistance of the DC source 31 by comparing the converted insulation resistance value with a preset ground determining threshold. |
