Adaptive variable structure torque ripple cancellation for permanent magnet stepper motors

Torque ripple compensation for permanent magnet stepper motors is considered in this paper. The control design methodology is based on our earlier work on adaptive variable structure control [1]. A current-level controller is derived for a detailed model of the motor which achieves asymptotic tracking of a reference trajectory while compensating for uncertainties in the mechanical dynamics of the motor. The proposed robust nonlinear controller requires the use of only one adaptation parameter. The control design methodology is of variable structure type with a smooth control action. Simulation results for position and for constant velocity tracking show the efficacy of the proposed control design.