Abstract:The conventional pulse injection method for low-speed operation of switched reluctance motors utilizes only the information of the non-conducting phase currents, which has the problems of limited conduction intervals and continuation currents affecting the estimation accuracy. In this paper, the low-speed control strategy and the principle of position-sensorless detection are investigated, and a three-phase current slope difference position-sensorless detection scheme with dual current chopper-limited PWM hysteresis loop control is proposed. The proposed scheme adopts dual chopper-limited PWM hysteresis loop control in the conduction zone, which increases the number of current chopping in the conduction zone, improves the performance during low-speed operation, and increases the calculation accuracy of the current slope difference. Compared with the traditional non-conducting phase current comparison method that utilizes only the non-conducting phase information, this scheme adds the on-phase current calculation. After calculating the on-phase current slope difference, the three-phase current slope difference is formed with the two non-conducting phases to estimate the real-time position information of the motor. The related simulation and experimental verification are carried out with a three-phase 12 / 8 structure motor, and the experimental results show that the scheme can effectively solve the problems of fixed on-phase intervals and real-time angle calculation affected by the continuation current that exist in the traditional method.