An Inductive Coupled Three-Port Resonant Converter to Achieve Adaptive Power Flow Adjustment for PV Systems

This article proposes a power converter topology to improve the efficiency for standalone photovoltaic (PV) systems. Specifically, a combined three-port LLC structure is designed to optimize the power flow paths, and two multiswitching bridge arms are utilized to merge different portions for cost reduction. Then, by taking the benefit of two inductive coupled resonant tanks in the proposed structure, adaptive load power distribution between the PV and the storage battery is achievable through phase-control, and thus, fulfills single-stage power conversion for both the conditions of battery charging from PV and battery discharging to the load. Also, the battery charging circuit does not need to be bi-directional, since an extra power flow path is added to discharge the battery. Based on detailed theoretical analysis, experimental results verify the effectiveness of the proposed concept.