Robust adaptive control of variable reluctance stepper motors

Robust adaptive nonlinear control of variable reluctance motors is considered. Utilizing a model for the motor that incorporates magnetic saturation, an adaptive controller is designed for the plant that is robust to parametric and dynamic uncertainties in the entire electromechanical system. A robust torque profile is first designed for the motor. Thereafter, a commutation strategy is applied to define desired currents that would produce the desired torque signals. The desired currents then become the tracking objective for the electrical subsystem. Voltage level control inputs are designed using backstepping and the robust control design methodology to track the desired currents. The overall stability of the system is shown using Lyapunov techniques. The tracking error is shown to be globally uniformly bounded. The control design is shown to be applicable to other motor models wherein the flux linkage is modeled as separable products of functions of the rotor position and winding currents. Simulation results are illustrated to show the performance of the controller.