A Method for Magnetic Polarity Detection of Sinusoidal Doubly Salient Electromagnetic Machine in Initial Position Estimation

Detecting magnetic polarity is an indispensable step for estimating the initial position by pulsating high frequency (HF) voltage injecting strategy, so the improvement of the process of detecting the magnetic polarity will do help to shorten the time consumed for the initial position detection. To simplify magnetic polarity detection process, a strategy of magnetic polarity detection applied to sinusoidal doubly salient electromagnetic machine (SDSEM) is proposed. Based on the mutual inductance characteristic of SDSEM existing in the coupling between armature winding and exciting winding, the expression of the HF response current on exciting winding is derived, of which the amplitude of the sinusoidal function is used to judge the polarity. In proposed strategy, there is no additional positive or negative voltage pulse injection compared to the existing methods, simplifies the magnetic polarity detection process successfully, and the algorithm is brief. Finally, the validity of the theoretical analysis of the proposed strategy is verified by simulation.