Sensorless Control for Low-Speed Brushless DC Motor Based on the Fuzzy Logic Back-EMF Observer

Most of back-electromotive force (EMF) and flux linkage-based rotor position detection methods need moreaccuracy and they are not able to operate at low as well as high speed. To cope with this problem, sensorless brushlessDC (BLDC) motor drive using the fuzzy back-EMF observer is proposed to improve the performance of conventionalsensorless drive methods in low speed range. In this paper, at first through a back-EMF observer based on fuzzy logic,the estimated back-EMF is obtained. Then, rotor speed can be easily estimated, and the accurate rotor position angle iscalculated by an integrator. At last through a PI (Proportional-Integral) speed controller the reference electromagnettorque is obtained, and the switching pulses are produced by current controller. The proposed algorithm using fuzzyback-EMF observer can achieve robust control for the change of an external condition and continuously estimate lowspeed range of the rotor at transients as well as steady state. The torque ripple can be also reduced by using this methodto reduce the current ripple. The validity of the proposed method is verified through the MATLAB simulation and results.

کلیدواژه ها:

Sensorless control ، Low speed ، Fuzzy logic ، back-EMF observer