A New Method for Automatic Identification of Electric-mechanical Angle Deviation of SPMLSM

The identification of electric-mechanical angle deviation before starting is crucial for surface-mounted permanent magnet linear synchronous motors (SPMLSM). Pre-positioning method and the back electromotive force (back-EMF) method are effective methods to identify electric-mechanical angle deviation. However, both require motor motion to achieve, and the back-EMF method cannot be identified automatically. This paper proposes a method of making the difference between the secondary electrical angle measured by pulse injection before starting and the secondary position measured by the grating ruler to realize automatic identification in static state. Firstly, the working principle of the linear motor system is introduced, and the relationship among each angle of the grating ruler and electric-mechanical angle deviation is analyzed. Secondly, the theory of pulse injection dichotomy and the calculation method are expounded. Finally, the feasibility of the method is confirmed by the SPMLSM experimental platform based on TMS320F28379D.