A Double Flux Magnetic Field Modulation Motor with Ventilation Slot and Uneven Air Gap

Magnetic field-modulated motors have the strengths of low speed, high torque, and high power density. However, the dual flux magnetic field modulation motor (DFMM) structure is complex and not conducive to heat dissipation. To reduce losses and reduce the risk of permanent magnets (PMs) demagnetization, this paper proposes a DFMM with ventilation slot and uneven air gaps. The three symmetry slots of the outer stator are not connected to the winding for ventilation, which can effectively dissipate heat during motor operation. The proposed DFMM adopts a single-layer winding, which can reduce the complexity of wiring. The inner rotor permanent magnet adopts Halbach structure and uneven air gap structure to reduce the risk of PMs demagnetization. Finally, the temperature field of the motor was calculated using finite element method. It was found that the output torque of the proposed DFMM increased by 16.92N m and the loss decreased by 19.52W. The proposed DFMM can increase the output torque and reduce the risk of PMs demagnetization.