Isolated Totem-Pole PFC Integrated Buck Converter for Low-Voltage Energy Storage Applications

High efficiency, low total harmonic distortion (THD), and near-unity power factor are essential for low voltage battery charging systems to satisfy modern power quality requirements. In this study, an isolated totem-pole power factor correction (PFC) integrated buck converter has been designed and analyzed for low-voltage battery charging applications. The proposed topology combines a bridgeless totem-pole PFC front end with an isolated buck DC-DC stage to provide galvanic isolation, regulates constant-current/constant-voltage output, and improves power quality. A closed-loop control scheme employing PI controllers regulated both input and output parameters under steady-state and dynamic operating conditions. The system has been designed for an input range of 180−260 V AC and delivers 31.6 W to the load. Simulation results showed that the converter achieved a power factor above 0.99801 and THD below 4.90%, complying with IEEE Standard 519. The converter demonstrates stable operation under input voltage and load variations, making it suitable for low-to-medium power applications such as UPS, LED lighting, security camera systems, and portable electronics.