High-voltage safety monitoring device for electric automobile

The invention relates to a monitoring device of a high voltage system which is used for an electric automobile or a hybrid electric vehicle, comprising a battery management module which supplies a weak signal at one end of the high voltage system, and receives a return signal passing the voltage system at the other end, and judges whether the high voltage system occurs short circuit or open circuit failures according to amplitude of the return signal. One end of a positive end relay is connected to a positive end of the high voltage system, the other end is connected to a positive end of an inverter; one end of a negative end relay is connected to a negative end of the high voltage system, and the other end is connected to a negative end of the inverter. A precharge circuit formed by connecting a precharge relay and a precharge resistor in series is parallely connected with the positive end relay. The high voltage security monitoring device provided by the invention can avoid the circuit failure happened in a switching on process of the high voltage system and electrical impact of electrical equipments, and realize the safe switching on of the high voltage system through comparing the relation between the voltages of two ends of the high voltage system and the voltages of two ends of a battery.