INSULATION RESISTANCE DETECTION SYSTEM FOR ELECTRIC VEHICLE AND INSULATION RESISTANCE DETECTION METHOD THEREOF

An insulation resistance detection system for an electric vehicle is used to detect a positive insulation resistance between a positive electrode of a battery of the electric vehicle and an equipment grounding point, and detect a negative insulation resistance between a negative electrode of the battery and the equipment grounding point. The insulation resistance detection system includes a negative detection circuit, a positive detection circuit, and a control unit. The control unit controls the negative detection circuit to be charged to generate a first capacitor voltage, and controls the positive detection circuit to be charged to generate a second capacitor voltage. The control unit determines whether the negative insulation resistance is abnormal according to the first capacitor voltage and a battery voltage of the battery, and determines whether the positive insulation resistance is abnormal according to the second capacitor voltage and the battery voltage.