I. Introduction
PID control has the advantages of simple structure, high reliability and easy to engineering achieves, so it is still widely used. Traditional speed control system for brushless DC motor is usually used PID control. Despite it is simple, easy to regulate the parameters and has a certain control precision, the PID control algorithm do has limitations. Today controlled objects are increasingly complicated; the traditional PID can no longer meet the requirements of rapid, stability and robustness for speed control system of brushless DC motor. Three PID control parameters of proportion, integral and differential, while coordinating with each other, are nonetheless checking on, which is not a simple linear combination. The desired control effect will be obtained as long as the best relationship is found between the changing non-linear relationships.