Sensorless drive of permanent magnet brushless DC motor with 180 degree commutation

The three-phase wye connected permanent magnet brushless dc motor is conventionally driven by 120 degree commutation. Two phases are conducting current and the other one is always floating without any torque produced in each conduction interval. Rather than the conventional 120 degree drive, all three phases of 180 degree commutation are expected to conduct current in all sectors, which results in more power delivered from inverter side to the motor side for the same power supply voltage. In this paper, a recently proposed sensorless algorithm is highlighted with well performance in low speed operation. Based on dSPACE, comparison of different dynamic conditions between 120 and 180 degree commutation is presented and analyzed comprehensively. Extensive experiment tests show excellent results on dynamic performance of 180 degree commutation, which matches the simulation results from Simulink/Matlab. 180 degree commutation is verified to work properly with the ability to deliver more power when compared with conventional 120 degree commutation.