Detecting approach and device of motor controller pre-fill line breakdown

The invention discloses a detecting approach and a device of motor controller pre-fill line breakdown, and the approach is applied to a motor controller pre-fill circuit. The motor controller pre-fill circuit comprises a closed loop circuit composed of a direct current power supply, a first main relay, a motor controller and a second main relay which are sequentially connected, and the first main relay is in parallel connection with a pre-fill relay and a resistor which are connected in series. The approach includes real-time monitoring a first voltage of the two ends of the motor controller and the grand total time of circuit connection after the second main relay and the pre-fill relay are connected and communicated, real-time grand total first connecting time is acquired as the first voltage is equal to a second voltage of two ends of the direct current power supply, the second relay and the pre-fill relay are controlled and disconnected, and a disconnecting signal is emitted as the first connecting time is less than the shortest pre-filled charging time. The invention further discloses a motor controller pre-fill line breakdown detecting device.