A practical method to eliminate the conduction torque ripple in BLDCM using cascade topology

This paper presents a comprehensive research on torque ripples of brushless dc motor drive in conduction region based on the mathematical models.The phenomenon of torque ripples of conduction exists because of diode freewheeling happened under the conventional PWM schemes. Through theoretical and mathematical analysis, a new method for reducing the torque ripple in brushless dc motors with a single current sensor has been proposed by adding the DC-DC converter that regulates the amplitude of the current. So in such drives, torque ripples are theoretically eliminated in conduction region. Effectiveness and feasibility of the proposed control method is verified by experiments. Torque ripples due to diode freewheeling current and conventional high-frequency PWM modulation have vanished. So it is preferable for the drive system of high accuracy-controlling BLDCM.