Design of High Torque Density Multi-Core Concentrated Flux-Type Synchronous Motors Considering Vibration Characteristics

This paper proposes a novel structure for the concentrated flux-type synchronous motor (CFSM) in order to improve the torque density, as well as the vibration characteristics. First, the conventional surface-mounted permanent magnet synchronous motor as prototype for the electric booster in the brake system is investigated through tests. Then, the relationship between the vibration characteristics and the number of poles and slots is analyzed. Based on the analysis results, a pole–slot combination for an improved CFSM is determined to enhance the vibration characteristics. Furthermore, a novel structure for the improved motor that employs three different core shapes in the rotor is proposed to increase the torque density. As a result, the improved motor with excellent vibration characteristics as well as a high torque density is designed. Finally, experiments are conducted to verify the effectiveness and the feasibility of the proposed method.