Ripple Reduction in BLDC Motor Based on Cascaded DC-DC Converter

Abstract

This paper proposes a novel converter topology to reduce the commutation torque ripple in brushless DC (BLDC) motor drives. The proposed topology is composed of a three-level neutral-point-clamped (NPC) inverter, two modified SEPIC (single-ended primary inductor converter) DC-DC converters, and a commutation voltage selection circuit. The torque ripple appears due to stator winding inductance during phase commutation, which prevents the use of BLDC motor in high performance applications due to undesirable vibration and acoustic noise. The three-level NPC inverter is used to reduce the torque ripple during conduction period. To weaken the torque ripple during the commutation period, two modified SEPIC converters are used to adjust the DC bus voltage to the desired value depending upon the BLDC motor rotational speed. A metal oxide semiconductor field effect transistor (MOSFET)-based commutation voltage selection circuit is used to apply the regulated DC bus voltage during the commutation period. Finally, experimental results show that torque ripple can be significantly reduced by the proposed modified SEPIC DC-DC converters with three-level NPC inverter and commutation voltage selection circuit.