A New PM-Assisted Synchronous Reluctance Motor With Three-Dimensional Trench Air Gap

This paper proposes a new 3-D motor with a trench-shaped air gap. The proposed motor has high torque without rare-earth magnets compared to conventional 2-D single air gap motors due to its multiple air gap and ferrite permanent-magnet-assisted segment rotor poles. First, the practical design is described of the winding and side stator core composition, which increase the air-gap area. Second, the reduction method of eddy-current loss in the side stator core is described. Finally, it is confirmed by finite-element analysis and some experimental data that the motor efficiency is improved without reducing torque output.