A Cascade Control Approach for Motion Systems Driven By Nonlinear Reluctance Actuator

This paper introduces a cascade control strategy designed to improve tracking performance in motion systems driven by a reluctance actuator (RA). The proposed approach features an inner current control loop that compensates for the RA’s nonlinear behavior across varying operating conditions. An outer position control loop, incorporating a PID controller augmented by an extended high-gain observer (EHGO), is employed to accurately track the reference position while addressing unknown system dynamics. The effectiveness of the current control design is validated through both simulation and experimental studies. Results confirm that the proposed controller successfully linearizes the RA response across different load conditions and air gaps, producing a dynamic behavior comparable to that of a spring-mass-damper system. Furthermore, the position control significantly enhances reference tracking accuracy and minimizes tracking errors. Simulations also demonstrate the controller’s robustness against system uncertainties and measurement noise.