Optimal Lead Angle Calculation for Brushless DC Motor

Recently, the brushless dc (BLDC) motor is receiving more interest due to the high reliability and low drive cost. The trend in the industry is to replace conventional DC motor with BLDC motor based on electric motor technology. However, BLDC motor needs more complicated motor drive technology comparing with DC motor drive. One of the complicated points is current lagging problem in high speed since the inductive reactance of the windings results in a significant time constant at high frequency. To solve the problem, lead angle injection has been utilized. But, there is no common rule in lead angle decision. In this paper, a lead angle adjustment method for BLDC motor is presented. The method is based on the results of current dynamics analysis during current commutation interval. Experimental results are shown to validate the proposed method.