Simulation and Experiment of Sensorless Direct Torque Control of Hybrid Stepping Motor Based on DSP

In this paper, direct torque control (DTC) of hybrid stepping motor was investigated. Because of the structural characteristics, stepping motor is usually used for open-looped control. But, only the average torque of stepping motor is controlled by traditional control strategy, which causes intense ripple of torque and speed. Therefore, the torque must be controlled instantaneously to improve the performance of stepping motor. At first, open-looped control of stepping motor is analyzed. In order to get excellent performance, the curves of acceleration and deceleration of stepping motor must be calculated beforehand. Secondly, DTC of AC motor is introduced into the control of hybrid stepping motor. The effects of stator voltage space vectors on stator flux linkage and torque are also analyzed in details. Finally, a sensorless direct torque control system of hybrid stepping motor based on DSP-TMS320F240 is built up. The simulations and experiments validated the feasibility of the proposed system