Torque ripple reduction in BLDC motor with 120 degree conduction inverter

Reduction of torque ripple in Brushless DC motors (BLDC) due to phase current commutation is the main focus of this work. The causes for the development of torque ripple are described in detail with necessary equations. It is found that by injecting additional voltage at the time of commutation, torque ripple can be minimized. From the derived equations for phase currents, the magnitude and duration for which the additional voltage that has to be injected is established. A new topology is proposed to supply additional voltage at the time of commutation and thereby reducing the torque ripple at the time of commutation. It is observed that, with the new topology for the same input power, the percentage torque ripple has reduced from 13.71 to 6.5. Furthermore, the new topology gives the benefit of an increased steady state speed and negligible speed ripple.