Torque enhancement and vibration reduction design of spoke-type permanent magnet machine with slotted rotor

Purpose This paper aims to investigate how to achieve a balance between high torque density and low vibration noise for the spoke-type permanent magnet (STPM) machine with a slotted rotor. Design/methodology/approach First, an analytical model (AM) of the radial electromagnetic force (REF) and electromagnetic torque for the STPM machine with a slotted rotor is proposed, and the influence of rotor slotting on the REF and electromagnetic torque is analyzed in combination with the finite element method. Then, the multi-physics model is established to analyze the electromagnetic torque and vibration noise with different rotor slotting structures to identify the optimal slotting configuration. Finally, the vibration noise is further optimized to achieve a balance between electromagnetic torque and vibration noise. Findings An appropriate rotor slotting structure can effectively enhance torque density and optimize electromagnetic noise. The optimized machine has higher torque density and lower vibration noise. Finally, two STPM prototypes with initial and optimized machines are manufactured and tested to verify the accuracy of the simulation results. Originality/value In this paper, the spatial order generation principle for REF density in the STPM machine with different rotor structures is revealed and analyzed. In addition, the electromagnetic torque and vibration noise of the STPM machine with different key parameters are analyzed and optimized to improve torque and reduce vibration noise.