Optimizing PV–Battery Hybrid Systems: A Reconfigurable Approach with Module-Level Maximum-Power-Point Tracking and Load Sharing

This paper presents a novel hybrid reconfigurable battery and photovoltaic (PV) system designed to meet the growing demand for efficient renewable energy sources. The system features a modular reconfigurable architecture with compact coupled inductors and a unique modulation strategy, which enhance flexibility and energy utilization. The system ensures that each PV component operates at its maximum power point (MPP) to maximize power generation, while it solves the problems of hard-wired connections, such as local optima and scalability. The battery module seamlessly adapts to fluctuations in PV power output and load demands, while it ensures a stable DC-bus voltage output. Intermediate states between parallel and series connectivity are created through coupled inductors to manage voltage differences between paralleled modules. These inductors offer a small footprint and minimal magnetic material usage. They do not need to manage the high common-mode magnetic flux at high load currents but serve for the balancing currents through high differential-mode inductance. The proposed modulation strategy enables efficient bidirectional energy transfer and allows precise control of power exchange between modules independently of output control. The independent control facilitates charge and load balancing between battery and PV panels with varying voltages. Simulations and experiments demonstrate the system's MPP tracking performance with at least 97% efficiency, an approximate 19% increase in energy output compared to a fixed string of two PVs, and < 1% ripple in the output voltage and current.