Prediction of loss-of-synchronism for a five-phase stepping motor

Proposed in this paper is a method of predicting loss-of-synchronism caused by excessive torque-load for a five-phase stepping motor, which is being operated within the maximum self-startup frequency. This is achieved using a signal available in the motor-driver and does not require an additional angle sensor, retaining the open-loop nature of the motor. Experimental results are shown to verify its performance under medium and high rotation-speed regions, while an improvement may be required for low-speed region.