Analysis of a Sinusoidal Rotor Segments Axial Flux Interior Permanent Magnet Synchronous Motor with 120-degree Phase Belt Toroidal Windings

Axial flux permanent magnet (AFPM) motors are widely applied in many applications due to their performance advantages. A novel AFPM which owns a special winding form (120-degree phase belt toroidal windings) and a distinct rotor structure (sinusoidal rotor segments) is proposed in this paper to further improve the torque density of this kind of machine. First, the structure and working principle of the 120-degree phase belt toroidal windings sinusoidal rotor segments AFPM interior synchronous motor (120D-TWSRSAFPMISM) are clarified. Then, the design formula and crucial parameters of the motor are presented. Subsequently, the cogging torque is optimized by dividing the magnet grouping. Finally, the characteristics of the 120D-TWSRSAFPMISM are analyzed and compared with those of the traditional toroidal windings sinusoidal rotor segments AFPMISM (T-TWSRSAFPMISM) and another T-TW motor without the sinusoidal rotor segments (T-TWAFPMISM) by finite element method (FEM). The results show that the 120D-TW can significantly increase the back electromotive force (EMF) compared with the T-TW, and the sinusoidal rotor segments can increase the air-gap flux density compared with the traditional interior rotor. Therefore, the 120D-TW and sinusoidal rotor segments are combined in the AFPM motor. This combination can further increase the torque density compared with the contrast motors.