Device and method for broken wire detection for step motor

The invention discloses a device and a method for broken wire detection for a step motor. The device comprises a control part and a drive part; the drive part is provided with an input port for receiving an input signal of the control part, a connection port electrically connected with the step motor, and a detecting port which is electrically connected with the control part and used for detecting signal output; and the drive part is used for detecting a signal of the step motor and feeding back the signal to the control part. When the feedback signal read by the detecting port is of a high electric level, the judgment result is that no broken wire fault exists and a warning signal is not output; and when the feedback signal read by the detecting port is of a low electric level, the judgment result is that a broken wire fault exists and the warning signal is output. When the step motor or an electronic expansion valve has the broken wire fault, a drive pulse is not output by the circuit any longer, so that the reliability of the step motor or the electronic expansion valve is reinforced.