| With the development of aeronautical and space technologies, deep-sea exploration and automotive industries, high power density motors gradually become research focuses. Currently, increasing the number of pole pairs are adopted to increase the torque density of the motor. However, these practices will increase the eddy effect, thereby increasing the total loss.Soft composite material makes it possible that manufacture PMSM with complicated flux. This paper proposes a novel structure that is based on SMC and combines axial flux and radial flux, and further introduces the structure, how it works, design theory and steps in detail.Aiming at this structure, detailed structure parameters are listed, and related FEA are performed, such as load state and unload state. The design theory is then proved to be feasible. Subsequently the impacts that gap length, slot depth, slot width, slenderness ratio on back EMF and its harmonics are analyzed. It indicates that increasing the slot width and slot depth will aggrandize the third harmonic due to the wide slot opening. However, if slot width and depth are decreased, the current density will increase significantly to achieve the same torque, resulting in high temperature rise in coils. Meanwhile, the slot leakage reactance will increase. For this structure, increasing gap length will help reduce the third harmonic in back EMF. In order to demonstrate the novel motor’s advantage over traditional PMSM in improving torque density, a comparison motor is designed. The result shows that the torque density of hybrid flux PMSM is higher than that of traditional PMSM with the same volume, electrical load, and bigger gap density.Then loss calculation is performed on the motor, the efficiency of the hybrid flux PMSM achieves 88.6% under rated state. Subsequently the impacts that load current, gap length, slot width, slot depth and the angles that current lags and leads EMF have on total motor loss and losses of different parts are analyzed. The result shows that gap length exerts more influence on losses, as it effects gap flux density obviously. Rotors adopting different materials as SMC and S10 C are analyzed in terms of rotor loss. The comparison shows that rotors made of SMC will help reduce rotor loss dramatically without influence other properties.3-D Finite element thermal calculation is performed on hybrid flux PMSM, the result shows that the temperature of different parts is not very high when the steady state is reached, in spite of low thermal conductivity of SMC. Additional cooling capabilities in the stator iron are not necessary. |
