Analysis of a DC–DC Sepic Converter Using Coupled Inductor and a Multiplier Capacitor in a Photovoltaic System

Abstract

The output voltage of photovoltaic (PV) systems is highly dependent on solar irradiance and ambient temperature, resulting in voltage fluctuations that reduce the effectiveness of battery charging and DC power supply systems. Conventional Single-Ended Primary Inductor Converter (SEPIC) topologies generally require a high duty cycle to achieve a high voltage conversion ratio, leading to increased switching losses and voltage stress on power semiconductor devices. This study proposes a high-gain Sepic converter employing a coupled inductor and a voltage multiplier capacitor to improve voltage gain while maintaining stable converter operation under varying photovoltaic conditions. The proposed converter was designed and evaluated through PSIM simulation using a photovoltaic system integrated with a battery. Performance analysis was carried out using solar irradiance data collected on 13, 14, and 15 April 2026 under both battery-connected and battery-disconnected operating conditions. The simulation results show that the proposed converter successfully increased the photovoltaic output voltage from an input voltage range of 9.20–13.32 V to an output voltage range of 18.42–26.67 V, depending on the operating condition. The coupled inductor effectively increased the voltage conversion ratio through magnetic coupling, while the voltage multiplier capacitor reduced voltage ripple and switching stress. Furthermore, the converter maintained stable output voltage despite variations in solar irradiance ranging from 810.5 W/m² to 1050.8 W/m², demonstrating good adaptability to practical photovoltaic operating conditions. These results indicate that the proposed topology is suitable for photovoltaic battery charging systems and other renewable energy applications requiring efficient high-gain DC–DC power conversion.