Variation Regularity of Key Performance Indexes Against the Slot Number of Tooth-Coil PMSMs

Tooth-coil permanent magnet synchronous machines (TC-PMSMs) are commonly used in wind power generation and wheel-hub propulsion applications. These machines operate at low speeds and have a large number of poles and slots, providing various pole/slot combinations as options. Typically, these combinations have similar performances, making it challenging to choose the best one from different perspectives. This study focuses on 32-pole TC-PMSMs with different slot numbers to understand how key electromagnetic and thermal performance indicators vary with slot numbers. Using the finite element method, parameters such as torque density, cogging torque, inductance, flux-weakening capability, losses, and temperature rise are evaluated and compared. Prototypes of the wheel-hub TC-PMSM are manufactured and tested on a back-to-back test rig, to validate the analysis results. The findings and conclusions derived from this research can assist in determining the optimal slot number or narrowing down the selection range of competitive pole/slot combinations during the scheme comparison stage.