Research of speed-torque characteristics of brushless DC motor based on back electromotive force

Speed-torque characteristics of brushless DC motors with trapezoidal and sinusoidal back electromotive force (EMF) based on two devices conducted drive method are analyzed separately. A back EMF coefficient using the average value during conduction region is used to calculate the speed-torque characteristics with real back EMF. Simulation and experimental results show this method can precisely meet the real speed-torque characteristics.