A novel line-to-line back EMF calculation for sensorless brushless DC motor drives

This paper proposes a novel line-to-line back EMF detection method for sensorless brushless DC (BLDC) motor drives. The actual phase back EMF signal can be indirectly obtained from the line-to-line back EMF. F function constructed based on line-to-line back EMF is calculated for commutation estimation. Compared to the traditional back EMF method, this scheme is simple to implement without the need to sense or reconstruct the motor neutral, and good motor performance is achieved from near zero to high speed. The results of simulation and experiment verify the validity of the proposed method with sufficient accuracy in both steady state and dynamic operation.