Harmonics and torque ripple reduction of Brushless DC motor (BLDCM) using Cascaded H-Bridge multilevel inverter

Abstract

Brushless DC motors are widely used in variable speed drive application. The torque produced by the Brushless DC (BLDC) motors with trapezoidal back Electromotive force (BEMF) is constant under ideal condition. However in practice the torque ripple appears on the delivered output torque. Smoothness of variable speed drive operation is critical due to this torque ripple. The brushless DC motors uses power electronic switches for the commutation purpose, it creates the Harmonics in armature current. This paper proposes Cascaded H-Bridge Multilevel Inverter with current controller used to reduce the torque ripple and the harmonics. This has been simulated with the help of PSIM simulation software and the amount of torque ripple and total harmonic distortion (THD) are calculated.