Analysis of Inductance According to the Applied Current in Spoke-Type PMSM and Suggestion of Driving Mode

The spoke-type permanent magnet synchronous motor (PMSM) is a motor built using nonrare earth elements, which feature low flux density. It has a flux concentrated structure of permanent magnet arrangement to improve power density. Further, the torque in the spoke-type PMSM is composed of a magnetic torque component from the permanent magnets and a reluctance torque arising from the inductance difference between the d - and q -axis. This paper analyzed the d - and q -axes inductances that affect the reluctance torque depending on the magnitude of the applied current and the current phase angle of the spoke-type PMSM at base speed. We also derived the variation of the d - and q - axis inductances, which is shown at the operation speed region. Accordingly, the variation of the current phase angle for generating the maximum output power is analyzed. Based on the above results, we predicted the variation in the driving mode of the spoke-type PMSM, and subsequently verified the prediction experimentally.