Micro-stepping control of a two-phase linear stepping motor with three-phase VSI inverter for high-speed applications

This paper presents a synchronous frame current control scheme for micro-stepping a two-phase linear stepping motor drive using a three-phase voltage-source inverter. Because of the wide operating frequency, the frequency-dependent voltages are decoupled from the controller to reduce the current-following errors and preserve the dynamic characteristics as the frequency varies. A motor cogging force compensation scheme performed in the synchronous frame is proposed to reduce the positioning error and velocity ripple caused by the cogging force. A space-vector pulse width modulation scheme is used for motor voltage modulation. This scheme is based on the harmonic injection principle originally derived for three-phase motor drives. Good static and dynamic performance is obtained in the experimental verifications.