Permanent-magnetmotorsare widely usedin-wheel motors of electric vehiclesand hybrid vehicles. Based on a movable stator design, this paper presents a new type permanent-magnet motor, whose torque can be adjusted in order to meetdifferent driving requirements. The stator geometryis varied by means of changing movable stator positions.Accordingly, the air-gap lengthin permanent-magnet motorsis changed so that torque can be adjusted. To derive an analytical model, Fourier series expansions are employed to formulate air-gap geometry variation. The analytical modelis validated by finite element numerical results.Concerning motor torque variation capability achieved in this study, the ratio of the largest vs. the smallest torque is 2.3.
2. Ishizaki, A., T. Tanaka, K. Takasaki, and S. Nishikata, "Theory and optimum design of PM vernier motor," Seventh International Conference on Electrical Machines and Drives, (Conf. Publ. No. 412), 208-212, 1995.
3. Toba, A. and A. T. Lipo, "Novel dual-excitation permanent magnet vernier machine," Industry Applications Conference, Vol. 4, 2539-2544, 1999.
4. Tasaki, Y., Y. Kashitani, R. Hosoya, and S. Shimomura, "Design of the vernier machine with permanent magnets on both stator and rotor side," Power Electronics and Motion Control Conference, Vol. 1, 302-309, 2012.
5. Ho, S. L., S. Niu, and W. N. Fu, "Design of the vernier machine with permanent magnets on both stator and rotor side," IEEE Transactions on Magnetics, Vol. 47, No. 10, 3280-3283, 2011.
6. VuXuan, H., D. Lahaye, S. O. Ani, H. Polinder, and J. A. Ferreira, "Effect of design parameters on electromagnetic torque of PM machines with concentrated windings using nonlinear dynamic FEM," IEEE International Electric Machine & Drives Conference, 383-388, 2011.
7. Sanada, M., K. Ito, and S. Morimoto, "Equivalent air gap shortening by three-dimensional gap structure for torque improvement of electric machines," Electrical Machines and Systems Conference, 1-6, 2009.
8. Zhang, Y., L. Jing C. Li, G. Tu, and J. Jiang, "Semi-analytical method for air gap main magnetic field computation of direct drive permanent magnet torque motors," Electrical Machines and Systems Conference, 1-4, 2011.
9. Kano, Y. and N. Matsui, "A design approach for direct-drive permanent-magnet motors," IEEE Transactions on Industry Application, Vol. 44, No. 2, 1-4, 2008.
10. Chau, K. T., D. Zhang, J. Z. Jiang, C. Liu, and Y. Zhang, "Design of a magnetic-geared outer-rotor permanent-magnet brushless motor for electric vehicles," IEEE Transactions on Magnetics, Vol. 43, No. 6, 2504-2506, 2007.
11. Chen, G. H. and K. J. Tseng, "Design of a permanent-magnet direct-driven wheel motor drive for electric vehicle," Power Electronics Specialists Conference, Vol. 2, 1933-1939, 1996.
12. Zhao, W., M. Cheng, and R. Cao, "Electromagnetic analysis of a modular flux-switching permanent-magnet motor using finite-element method," Progress In Electromagnetics Research B, Vol. 43, 239-253, 2012.
13. Boughrara, K., T. Lubin, R. Ibtiouen, and M. N. Benallal, "Analytical calculation of parallel double excitation and spoke-type permanent-magnet motors; simplified versus exact model," Progress In Electromagnetics Research B, Vol. 47, 145-178, 2013.
14. Mahmoudi, A., N. A. Rahim, and H. W. Ping, "Genetic algorithm and finite element analysis for optimum design of slotted torus axial-flux permanent-magnet brushless DC motor," Progress In Electromagnetics Research B, Vol. 33, 383-407, 2011.
15. Gao, J., L. Zhang, and X. Wang, AC Machine Systems, Springer-Verlag, Berlin, 2009.
16. Fitzgerald, A. E., C. Kingsley, Jr., and S. D. Umans, Electric Machinery, McGraw-Hill, Singapore, 1983.
17. Islam, M. S., S. Mir, and T. Sebastain, "Issues in reducing the cogging torque of mass-produced permanent-magnet brushless DC motor," IEEE Transactions on Industry Applications, Vol. 40, No. 3, 813-820, 2004.