An Improved Three-Port Resonant PV Converter for Wide Range Operation Based on Adjustable Inductor Coupling Assisted Resonance

This article proposes a simple scheme to improve efficiencies for standalone three-port photovoltaic (PV) systems. Specifically, the new scheme skillfully couples a resonant inductor with an existing filtering inductor of battery management, and thus, achieves an effect that focuses on adjusting the resonant states for isolated power conversion (such as LLC) without affecting other functions or adding extra costs. This leads to a wide voltage gain range between the PV port and the load port, even when only a single-stage resonant power conversion with a narrow switching frequency range is utilized. Also, the adjustability of resonance is achieved simply through phase-shift regulation between the <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> bridges, which does not add much complexity to overall system control. Additionally, due to the abovementioned advantages, a larger magnetizing inductance for the transformer is allowed in comparison to regular LLC converters. Based on a detailed theoretical analysis, experimental results verify the effectiveness of the proposed concept.