Nonlinear control based on singular perturbation theory for position tracking of permanent magnet stepper motors

In this paper, a nonlinear position control controller based on singular perturbation theory is proposed. Since the dynamics of a PMSM involves slow and fast models, singular perturbation theory can be applied. Applied conditions and stability proofs are studied. The proposed control design procedure is simplified and robust to variations in the inductance. High-bandwidth control effort for the current tracking is not required, but position and velocity measurements are necessary in the proposed method. The simulation results validate the performance of the proposed method.