volume | PIER Journals

Abstract

In order to decouple traditional levitation windings and armature windings, a new self-decoupling magnetic levitation generator (SDMLG) is proposed for wind turbines. This new generator adopts double-stator structure. The armature windings are in the outer stator, and the levitation windings are in the inner stator. The rotor is made of a distributed hollow structure, so that it can effectively decouple the levitation subsystem and armature subsystem. The new structure and operating principle of the generator are presented in this paper. Then the expressions of levitation forces are deduced by analyzing magnetic flux distributions and winding flux linkages. Finite-element analysis method (FEA) is used as the tool for analyzing the performance of the new generator. And the results verify that the levitation windings and armature windings are effectively decoupled.

1. Zurcher, F., T. Nussbaumer, and J. W. Kolar, "Motor torque and magnetic levitation force generation in bearingless brushless multipole motors," IEEE Transactions on Mechatronics, Vol. 17, No. 6, 1088-1097, 2012.
doi:10.1109/TMECH.2011.2159511 Google Scholar

2. Asama, J., D. Kanehara, and T. Oiwa, "Levitation performance of a two-axis actively regulated consequent-pole bearingless motor," IEEE Transactions on Energy Conversion, Vol. 28, No. 4, 894-901, 2013.
doi:10.1109/TEC.2013.2283724 Google Scholar

3. Nishida, K., T. Ahmed, and M. Nakaoka, "A cost-effective high-efficiency power conditioner with simple MPPT control algorithm for wind-power grid integration," IEEE Transactions on Industry Applications, Vol. 47, No. 2, 893-900, 2011.
doi:10.1109/TIA.2010.2103294 Google Scholar

4. Chinchilla, M., S. Arnaltes, and J. C. Burgos, "Control of permanent-magnet generators applied to variable-speed wind-energy systems connected to the grid," IEEE Transactions on Energy Conversion, Vol. 21, No. 1, 130-135, 2006.
doi:10.1109/TEC.2005.853735 Google Scholar

5. Wai, R. J., C. Y. Lin, and Y. R. Chang, "Novel maximum power extraction algorithm for PMSG wind generation system," IET Electric Power Applications, Vol. 1, No. 2, 275-283, 2007.
doi:10.1049/iet-epa:20050514 Google Scholar

6. Fan, Y. H., Y. T. Lee, Ch.Wang, et al. "Passive magnetic bearing design for a small wind generator system," Applied Mechanics and Materials, Vol. 145, 174-178, 2012. Google Scholar

7. Patel, N. and M. N. Uddin, "Design and performance analysis of a magnetically levitated vertical axis wind turbine based axial flux PM generator," 7th International Conference on Electrical and Computer Engineering, ICECE 2012, 741-745, 2012.
doi:10.1109/ICECE.2012.6471657 Google Scholar

8. Shrestha, G., H. Polinder, D.-J. Bang, et al. "Structural flexibility: A solution for weight reduction of large direct-drive wind-turbine generators," IEEE Transactions on Energy Conversion, Vol. 25, No. 3, 732-740, 2010.
doi:10.1109/TEC.2010.2048713 Google Scholar

9. Zhang, G. M., L. Mei, and D. M. Wang, "A direct-drive wind power generator along horizontal axis with five-degree of freedom magnetic levitation,", 201110083824.6, Patent, China, Apr. 2, 2011. Google Scholar

10. Sun, X. D., L. Chen, and Z. B. Yang, "Overview of bearingless permanent-magnet synchronous motors," IEEE Transactions on Industrial Electronics, Vol. 60, No. 12, 5528-5538, 2013.
doi:10.1109/TIE.2012.2232253 Google Scholar

11. Okada, Y., T. Shimonishi, S.-J. Kim, et al. "Development of hybrid type self-bearing slice motor for small and high speed rotary machines," 2001 Conference Record-IAS Annual Meeting (IEEE Industry Applications Society), Vol. 3, 2005-2012, 2001. Google Scholar

12. Cao, X. and Z. Q. Deng, "A full-period generating mode for bearingless switched reluctance generators," IEEE Transactions on Applied Superconductivity, Vol. 20, No. 3, 1072-1076, 2010.
doi:10.1109/TASC.2010.2041206 Google Scholar

13. Wang, J., S. Kim, and N. Kim, "A study on the bearingless switched reluctance rotation motor with improved motor performance," Journal of Mechanical Science and Technology, Vol. 27, No. 5, 1407-1414, 2013.
doi:10.1007/s12206-013-0321-6 Google Scholar

14. Asama, J., Y. Hamaski, T. Oiwa, et al. "Proposal and analysis of a novel single-drive bearingless motor," IEEE Transactions on Industrial Electronics, Vol. 60, No. 1, 129-138, 2013.
doi:10.1109/TIE.2012.2183840 Google Scholar

15. Chiba, A. and J. Asama, "Influence of rotor skew in induction type bearingless motor," IEEE Transactions on Magnetics, Vol. 48, No. 11, 4646-4649, 2012.
doi:10.1109/TMAG.2012.2198872 Google Scholar

16. Zhu, Z. Q. and D. Howe, "Influence of design parameters on cogging torque in permanent magnet machines," IEEE Transactions on Energy Conversion, Vol. 15, No. 4, 407-412, 2006.
doi:10.1109/60.900501 Google Scholar

17. Wang, H., Y. Wang, X. Liu, et al. "Design of novel bearingless switched reluctance motor," IET Electric Power Applications, Vol. 6, No. 2, 73-81, 2012.
doi:10.1049/iet-epa.2010.0229 Google Scholar

18. Peng, W., F. G. Zhang, and J. W. Ahn, "Design and control of novel bearingless SRM with double stator," 2012 IEEE International Symposium on Industrial Electronics, 1928-1933, 2012.
doi:10.1109/ISIE.2012.6237387 Google Scholar

19. Hu, Y. F., Z. D. Zhou, and Z. F. Jiang, The Basic Theory and Application of Magnetic Bearings, Machinery Industry Publishers, Beijing, 2006.

20. Young, W. C., Roark’s Formulas for Stress and Strain, 6th Edition, McGraw-Hill, Singapore, 1989.

Dr. Yanjun Yu

Prof. Huangqiu Zhu

Dr. Si Zeng