A Novel Initial Mover Position Estimation Method for Planar Switched Reluctance Motors with Bipolar Square-Wave Voltage Injection

The initial position of the mover of a planar switched reluctance motor (PSRM) must be accurately estimated at standstill to produce sufficient and stable starting thrust. If the mover moves during the position estimation, the positioning accuracy of the PSRM will be affected. In this paper, a novel initial translator position estimation method with bipolar square-wave voltage injection is proposed, based on the principle that different initial positions cause different three-phase mover winding inductances. The three-phase bipolar square wave signals, which do not cause the translator to move during the estimation process, are injected into the windings to identify the translator inductances. Then the initial translator position can be accurately estimated based on the three-phase inductance value. Based on the proposed method, initial position detection experiments in the free-running mode were performed. The experimental results show that the estimation precision of the initial translator position is greatly improved compared to the conventional method.