A Study on the Maximum Flux Linkage and the Goodness Factor for the Spoke-Type PMSM

In this paper, we propose a goodness factor that shows how the output density of a Spoke-type permanent-magnet synchronous motor (PMSM) is improved than that of the conventional surface permanent-magnet synchronous motor (SPMSM). The application of the goodness factor, which is defined as the ratio of the total flux between different motor configurations, enables a comparison of the total flux between the SPMSM and spoke-type PMSM. A performance comparison analysis between the two motor configurations with the same rotor diameter, air gap length, stack length, permanent-magnet usage, and materials was performed using the proposed goodness factor. In order to improve the performance prediction accuracy, furthermore, the effect of both the bridge leakage and the axial leakage was included during the analysis process of the spoke-type PMSM. Finally, in order to verify the proposed method, SPMSM and Spoke-type PMSM with the same outer diameter size and permanent-magnet usage were fabricated and evaluated.