Torque-Ripple Mitigation for BLDC using Integrated Converter Connected Three-Level T Type NPC-MLI

Abstract

Owing to the small inductance, traditional modulated six-switch two-level voltage source inverter (VSI) connected brushless DC motor (BLDCM) drive engenders serious stator current ripple, which roots to high torque and speed ripple, hence motor leads to poor speed-torque characteristic, and momentous vibration. This paper examines the torque-ripple reduction method and proposes a SEPIC boost integrated DC to DC converter connected three-phase three-level T type neutral point clamped (NPC) multilevel Inverter (MLI). The control strategy is proposed in the commutation interval to match the equal transition of motor upcoming and ongoing phase current through integrated SEPIC converter to reduce the torque ripple. According to the speed and load torque, the converter is effectively preserving the required DC-link voltage to the inverter. The T type NPC-MLI is helps further torque ripple mitigation through improving the current waveform. The detailed analysis for the torque ripple conviction and entanglement to suppress is deliberated. Simulations and experimentation results are validated to confirm that the proposed topology and its control strategy can reduce the torque ripple significantly. The proposed converter fed BLDCM drive performance is compared with various reported topologies and shown their pros.