Sensorless Commutation of BLDC Motor without Low Pass Filter and Phase Shifter

 In this paper, a novel sensorless commutation method for BLDC motors is presented to simultaneously eliminate phase shifter and low-pass filter. An analytical model of the motor is presented and ripples resulted from the current commutation are investigated in detail. By detecting the zero crossing points of the unfiltered voltages of the motor terminals referred to the ground and DC link, the commutation signals can be generated using a set of proposed logical equations. The extracted commutation points are phase delay-free, because the low-pass filters are eliminated. Therefore, the proposed method can be used in a wide range of speed. Moreover, the method is cost-effective because it does not need any phase shifter. Simulation and real-time implementation results show the effectiveness of the proposed method.