Permanent magnet (PM) motors have been widely applicable for electric vehicles due to their excellent power density and efficiency. Yet, due to the relatively constant
airgap magnetic field, the motor always suffers from a limited speed range. So, the achievement of a wide speed range is one of the hot research orientations for PM motors. In recent years,
a type of leakage-flux-controllable (LFC) motor has attracted some interest and attention of researchers, where the magnetic bridge and flux barrier are purposely designed in PM rotor for
forming the controllable leakage flux1. Based on this, the LFC-PM motor possesses the potential advantages of speed regulation2. It is noted that to realize the condition of no leakage
flux in motor drive process, a relatively strong armature field is usually required to be applied at this time, and, correspondingly, the magnetic saturation comes with that. It means that the
torque capability of LFC PM motor is worthy of attention and full of challenge, especially on the drive requirements of low-speed large torque.
In this study, a V-typed leakage-flux-controllable PM (VFLC-PM) motor with multiple functional magnetic flux barrier units is proposed, which can provide relatively high output torque
and a wide speed range. The motor topology and magnetic barrier structure analysis are shown in Fig. 1. The magnetic field distributions under different operating conditions are shown in
Fig. 2. At no load, the flux leakage barrier guides parts of PM flux into the flux leakage path and reduces the air gap effective flux. As the armature current increases, the flux focusing
barrier guides the PM flux to pass through the air gap rather than flux leakage path, and the main flux is enhanced. And then, a response surface method is adopted to optimize the key
parameters related to the magnetic flux barrier units in Fig. 3. After optimization, the torque performances of the motor are significantly improved both at different operating conditions as
shown in Fig. 4. Finally, the torque characteristics of the motor are verified through experiments in Fig. 5. The experimental results are in good agreement with the simulation results,
which verifies the effectiveness of the motor design.
1 T. Kato, T. Matsuura and K. Sasaki, Proc. IEEE Energy Convers. Congr. Expo., 2017, pp. 5803–5810.
2 X. Zhou, X. Zhu and W. Wu, IEEE Trans. Ind. Electron., vol. 68, no. 8, pp. 6516–6526, Aug. 2021.