This paper describes the reduction in torque ripple due to phase commutation of brushless dc motors. The torque ripple at low speeds is reduced by dual switching mode with 120° switching. In this paper an adaptive hysteresis current controller is proposed to eliminate harmonics and to compensate reactive power of VSI fed BLDC drive. An algorithm based on reference frame theory (d-q-0) is used to determine suitable current reference signals. The result of simulation study presented in the paper along with PI controller is found satisfactory to reduce the commutation torque ripple and to eliminate harmonics in the utility current. These results are compared with the conventional sensored BLDC motor drive which is controlled by outer speed loop using PI controller. The above studies have been carried out through detailed digital dynamic simulation using the MATLAB/Simulink.

1. S.S.Bharatkar, Raju yanamashetti “Reduction of commutation torque ripple in permanent magnet motors,” IEEE Power and Energy (PE Con 08), December 1-3, 2008, Johor Baharu, Malaysia.
2. R. Carlson, M. Lajoie-Mazenc, and J.C.D.S. Fagundes, “Analysis of torque ripple due to phase commutation in brushless DC machines,” IEEE Trans. Ind. Appl., vol.28, no.3, pp. 632-638, May/Jun. 1992.
3. H. Tan, “Controllability analysis of torque ripple due to phase commutation in brushless DC motors,” in Proc. 5th int. conf. Elect. Mach. And Syst., Aug. 18-20, 2001, vol.2, pp. 1317-1322.
4. Y. Murai, Y. Kawase, K. Ohashi, K. Nagatake and K. Okuyama, “Torque ripple improvement for brushless DC miniature motors,” IEEE Trans. Ind. Appl., vol.25, no.3, pp. 441-450, May/Jun. 1989.
5. Y. Sozer and D.A. Torrey, “Adaptive torque ripple control of permanent magnet brushless DC motors,” Proc. 13th Annu. Appl. Power Ele¬ctron. Conf. and Expo., Feb. 15-19, 1998, vol.1, pp. 86- 92.
6. S.J. Kang and S.K. Sul, “Direct torque control of brushless DC motor with non-ideal trapezoidal back-EMF,” IEEE Trans. Power Electron., vol.10, no.6, pp.796-802, Nov.1995.
7. T.S. Kim, S.C. Ahn, and D.S. Hyun, “A new current control algorithm for torque ripple reduction of BLDC motors,” Proc. 27th Annu. Conf. IEEE Ind. Electron. Soc., Nov.29-Dec.2, 2001, vol.2, pp.1521-1526.
8. Z.Q. Zhu, Y. Liu, and D. Howe, “Comparison of performance of brushless DC drives under direct torque control and PWM current control,” Korean IEE Int. Elect. Mach. nergy Convers. Syst., vol. 5-B, no.4, pp.337-342, 2005
9. Y. Liu, Z.Q. Zhu, and D. Howe, “Instantaneous torque estimation in sensor less direct torque controlled brushless DC motors,” IEEE Trans. Ind. Appl., vol.42, no.5, pp.1275-1283, Sept./Oct.2006.
10. Y. Liu, Z.Q. Zhu, and D. Howe, “Commutation torque ripple minimization in direct torque controlled PM brushless DC drives,” IEEE Trans. Ind. Appl., vol.43, no.4, pp. 1012 -1021, July/Aug.2007.
11. Chang, W.J., Sun, C.C. and Fun, C.C., “Discrete Output Fuzzy Controller Design for Achieving Common Controllability Gramian,” Asian Journal of Control, Vol. 2, No. 4, pp. 284-289 (2000).
12. Kim, K., Joh, J., Langari, R. and Kwon, W., “LMI-Based Design of T-S Fuzzy Controllers Using Fuzzy Estimator,” Proc. of the 38th Conference on Decision & Control Phoenix, Arizona, USA, pp. 4343-4348 (1999).
13. Bogumila Mrozek, Zbigniew Mrozek, “Modelling And Fuzzy Control Of Dc Drive “14-th European Simulation Multiconference ESM 2000, May 23-26, Ghent, pp186-190.
14. Wang, L., "Adaptive Furry System and Conlrol Design and Stability Analysis", Prentice Hall. Engle wood Cliffs, N.J. 1994
15. Paul C. Krause, "Analysis of Electric Machinery", McGraw- Hill Book Company, 1987

BLDC motor current commutation current ripple current controller