Phase Compensated Microstepping for Permanent Magnet Stepper Motors

This paper presents a phase-compensated microstepping (PCMS) for permanent-magnet stepper motors in order to overcome the steady-state position error (SSPE) limitation of conventional microstepping without position feedback. An additional phase to compensate for the SSPE is injected into the desired currents for PCMS. Proportional-integral (PI) current feedback with feedforward is proposed in order to guarantee the desired currents for PCMS. Given a desired position error and a desired velocity, the additional phase is calculated in order to ensure the desired position error. In the proposed method, the structure of the PI current feedback with feedforward is not modified, and the additional phase can be obtained by a linear interpolation with an offline generated lookup table. Therefore, it can be easily applied to existing industrial applications without any costs for additional hardwares. The experimental results validate the effectiveness of the proposed method