Design and Analysis of AC to DC SEPIC Converter for Low Power Applications

This paper presents the design, modeling, and performance analysis of an AC-DC converter employing a Single-Ended Primary Inductor Converter (SEPIC) topology for low-power applications, specifically LED drivers. The proposed converter operates in discontinuous conduction mode (DCM) to achieve inherent power factor correction (PFC) and reduced total harmonic distortion (THD) in the input current, ensuring compliance with IEC 61000-3-2 Class C power quality standards. The converter is designed for a nominal power rating of 15 W, with an input voltage of 230V RMS AC and a regulated output of 15V DC at 1A, making it suitable for high-efficiency LED driver applications. The system is optimized through meticulous selection of passive and active components, including inductors, capacitors, and semiconductor devices (MOSFETs and diodes with minimal switching and conduction losses). The topology operates at a switching frequency of 20 kHz to ensure an optimal tradeoff between efficiency and component size. Analytical modeling and simulations validate the performance of the proposed converter, demonstrating a low output voltage ripple of 1%, input current ripple of 2%, and a source-side current THD of less than 2%. The results confirm that the proposed SEPIC-based PFC converter offers an efficient, compact, and low-THD solution for LED driver applications, contributing to improved power quality and reduced harmonic injection into the grid.