Fuzzy back-EMF observer for improving performance of sensorless brushless DC motor drive

In this paper, a sensorless brushless DC (BLDC) motor drive using the fuzzy back-EMF observer is proposed to improve the performance of conventional sensorless drive methods. Most existing sensorless methods of the BLDC motor have low performance at transients or low speed range and occasionally require additional circuit. To cope with this problem, the estimation of a back-EMF using the fuzzy logic is suitable for high performance because the back-EMF of the BLDC motor has a trapezoidal shape. The proposed algorithm using fuzzy back-EMF observer can achieve robust control for the change of an external condition and continuously estimate speed of the rotor at transients as well as steady state. The robustness of the proposed algorithm is proved through the simulation and is compared with other sensorless drive methods.