Adaptive Position Control Strategy of SRM-Based EMA System for Precision Position Tracking

The electromechanical actuator (EMA) driven by switched reluctance motor (SRM) is promising to be used in the steering vane control system on the landing craft air cushion (LCAC) hovercraft due to its reduced maintenance costs and increased control flexibility. The system parameter uncertainty, the unknown load disturbance, and the large torque ripple of SRM, however, make it challenging to achieve high position control precision. To improve the position control accuracy of the SRM-based EMA system, an adaptive position control strategy is proposed in this article. First, an adaptive fast terminal sliding mode controller (AFTSMC) is designed to address the issues of model parameter estimation and load disturbance rejection, which improves the dynamic response performance of the SRM-based EMA system. Second, a current-limited direct torque controller (CL-DTC) is proposed to track the reference torque calculated by AFTSMC with lower torque ripple and to limit the excessive currents of SRM at the same time, which helps further enhance the position control precision and prevent the SRM-based EMA from overheating. Finally, the proposed position control strategy is tested and compared with three other position controllers based on simulations and experiments. The results demonstrate the effectiveness and superiority of the proposed position control strategy.