Anew forced commutation current Discharge scheme for torque ripple Waning in bldc motors and Development performance enhanced Controllers

Abstract

This research work has mainly focussed on the torque ripple modelling and minimization techniques for the Permanent Magnet Brushless DC motor (BLDCPM) to achieve high-performance and reliable machine drive for practical industrial and consumer applications. Torque ripple is generated at the output of the Brushless Direct Current Motor (BLDCM) due to the factors such as current ripple, non-sinusoidal Back Electromotive Force (EMF) and cogging torque. The vibrations caused by the torque ripple are transmitted through the mechanical system and then interacted with the motor housing to cause acoustic emissions. These acoustic emissions limit the applications available to the BLDC. Since, the part of the cogging torque component is based on the manufacturing error; the motor design alone cannot eliminate the entire torque ripples. However, the torque ripples and acoustic emissions can be reduced via the control of the output torque. newlineThe control of the BLDC motor is similar to the DC motors during the non-commutation interval. However, three phases are involved in the electromechanical energy conversion during the commutation interval, making the control of BLDCM similar to three phase AC motor during the commutation interval. BLDCM is difficult to achieve smooth torque ripple with fast response, which typically depends on the variation of slew rate line current in the commutation period. Current hysteresis control is acceptable to maintain the incoming phase current and outgoing phase current at the same rate throughout the commutation period. It also decreases the commutation torque ripple with successful commutation newline