A SURVEY OF ADVANCED CONTROL METHODS FOR PERMANENT MAGNET STEPPER MOTORS

Permanent Magnet (PM) stepper motors have been widely used in industry due to their low material costs and robustness against the environment. Furthermore, it is relatively easy to implement a control system compared to other type motors. It has been recently reported that advanced control methods show improved tracking performance over the conventional microstepping control. In this paper, we make a survey of advanced control methods for PM stepper motors. First, we introduce basic principles of open-loop control of PM stepper motors, including microstepping. Then we explain various advanced feedback control techniques based on Lyapunov stability. Second, we briefly summarize how PM stepper motors can be modelled as a linear parameter varying system and its tracking performance optimization based on H-2 sense is made with nonlinear torque modulation. Third, we show the equivalency of field orient control and field weakening control to microstepping with nonlinear torque modulation. Then we introduce Proximate In-Phase Current Estimator for PM stepper motors and Phase-Compensated Microstepping for PM stepper motors. Their performances are illustrated by experiments on PM stepper motors.