A study on the speed control of a BLAC motor by feedforward compensation of the back‐EMF using a fuzzy algorithm

Abstract

Back electromotive force (back‐EMF) feedforward compensation is used to improve the control performance of a brushless AC (BLAC) motor. The back‐EMF has a speed component, and the response is slow when the back‐EMF is compensated for by the speed. The back‐EMF feedforward compensation does not operate exactly when the speed fluctuation is severe. To solve these problems, the back‐EMF is compensated by the speed of the motor operation, which is calculated by the proposed method. The speed and the delta speed are the input membership functions of the fuzzy system. The weighting used to estimate the speed is defined as the output membership function of the fuzzy system. The speed is estimated exactly using 15 rules of the fuzzy system, and the back‐EMF feedforward compensation operates using the estimated speed. The membership function and the fuzzy rules are adjusted using simulation. The root‐mean‐square (RMS) value of the error between the real speed and the reference speed is measured. It is confirmed that the performance is excellent when the back‐EMF is compensated by the speed, which is estimated by the proposed algorithm. © 2018 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.