A Three-Port LLC Resonant Converter for Photovoltaic-Battery Hybrid System

Photovoltaic (PV) systems with integrated energy storage units traditionally have been complex and required multiple DC-DC converters. In this paper, a novel multiport isolated LLC resonant converter and a modified maximum power point tracking (MMPPT) control method are introduced to reduce complexity. The proposed topology is designed to operate under a wide input voltage range and contains an integrated bidirectional pulse width modulation (PWM) converter and a LLC resonant converter. Frequency modulation control is implemented for regulating the output voltage of the whole system while the PWM converter is controlled by the MMPPT which generates the battery current reference and PI controller. MATLAB/Simulink was used to demonstrate the feasibility of the topology.