Design of Bidirectional DC-DC Converter for Photovoltaic Charging System

This paper proposes a bidirectional DC-DC converter designed for photovoltaic charging systems. The converter aims to efficiently charge batteries while maintaining stable DC voltage and current output. It can convert DC power from solar panels to charge the battery and deliver DC power from the battery to the connected DC bus. The control method for the converter utilizes PI control to achieve a constant output current and voltage. In addition, PI control ensures smooth operation and protects the battery from overcharging or deep discharge. The simulations were conducted using MATLAB/Simulink software, optimizing the converter’s topology, parameters, and controls according to the requirements of the PV charging system.Simulations validate the converter’s performance under various conditions, including input power fluctuations caused by changes in sunlight intensity, varying input voltage, and load power demand. When varying irradiation, the system has small error, range 0.02%-0.05% and also has good efficiency 95.22% at high irradiation. Then, the system’s efficiency increases from 90.65% to a peak of 96.50% at a load power of 175 W, then slightly decreases to 95.08% at a load power of 200 W. Thatresults demonstrate that the bidirectional DC-DC converter effectively operates in charging and discharging modes, maintaining a stable 24V voltage in the DC bus and providing optimal charging performance for the battery.