Improved design of IPMSM for sensorless drive with absolute rotor position estimation capability

In this paper, two designs of Interior Permanent Magnet Synchronous Machine (IPMSM) for sensorless drive with absolute rotor position estimation capability are proposed. A conventional IPMSM design prepared for the same purpose had a demerit that for absolute position estimation, saying that the rotor should initially stroke for 100° in the worst case. In order to reduce the initial stroke of the rotor, two new IPMSM designs featuring asymmetric winding and asymmetric rotor geometry are proposed and constructed as prototype motors. With the prototype motors, initial stroke of the rotor has been reduced to 30°. Moreover, basic characteristics of the motor such as torque ripples and harmonics of EMF have been also conspicuously improved. The overall performances of the proposed designs have been evaluated by rigorous finite element analysis and experimental test.