A Novel Twelve-Step Sensorless Drive Scheme for a Brushless DC Motor

This paper presents a novel twelve-step sensorless drive scheme for a three-phase brushless DC motor, which combines the traditional six-step 120deg and 180deg conduction modes and has varied active angular period. The proposed scheme is implemented on a single FPGA-chip. Several experiments for various active angle periods from 124deg to 168.75deg are undertaken. The experimental results show that the torque constant is larger for the larger active angular period