Comparative Analysis of SEPIC and Buck Converter-Fed PMBLDC Motor Drive for Power Factor Correction and Speed Regulation

Abstract

This paper presents a comparative analysis of SEPIC (Single-Ended Primary-Inductor Converter) and Buck converter-fed Permanent Magnet Brushless DC (PMBLDC) motor drives, focusing on efficiency, voltage regulation, ripple performance, and application suitability. A voltage follower approach in discontinuous conduction mode (DCM) is employed for speed regulation. The Buck converter excels in step-down applications with high efficiency, whereas the SEPIC converter offers bidirectional voltage conversion (step-up/step-down) with continuous input current, enhancing power quality. MATLAB/Simulink simulations validate the performance of both converters under varying load conditions. Results demonstrate that the SEPIC converter provides superior voltage regulation and reduced input current ripple, making it ideal for applications with fluctuating input voltages, such as renewable energy systems and battery-powered devices. In contrast, the Buck converter is more efficient for stable step-down requirements in low-voltage motor drives. The study provides key insights for selecting the optimal converter topology based on design constraints and operational requirements.