Control of a two-phase linear stepping motor with three-phase voltage source inverter

This paper presents a current control scheme for the micro-stepping of two-phase linear stepping motor drive using three-phase voltage source inverter. The purpose of this scheme is for cost reduction since all the control loops are executed digitally and standard three-phase voltage source inverter is used. Because the operating frequency is quite high, the cross-coupling between motor phase currents are removed to preserve the dynamical characteristics of the current controller as frequency varies. A space vector PWM for a two-phase motor is also presented. The scheme is based on the principle of harmonic injection for three-phase motors. Because the inverter leg voltages are imbalanced when driving a two-phase motor, the dead-time effect of the inverter power switches must be compensated for or significant current error may occur. Good static and dynamic performances were obtained in the experimental verifications.