A high-efficiency non-isolated bidirectional converter for power exchange between PV array and battery

Abstract

This paper proposes a high-efficiency non-isolated bidirectional DC-DC converter for power exchange between a photovoltaic (PV) array and a battery energy storage system. The proposed topology is designed to achieve an extended voltage conversion range while maintaining a simple circuit structure, continuous input current, and reduced semiconductor voltage stress. Compared with the conventional bidirectional buck–boost converter, the proposed converter provides an asymmetric voltage conversion ratio, achieving a voltage gain of $$\:\frac{\text{D}}{2}$$ in buck mode and $$\:\frac{2}{1-\text{D}}$$ in boost mode. Synchronous rectification is employed to reduce conduction losses and improve overall conversion efficiency. The operating principles and steady-state characteristics of the converter are analyzed in detail and validated through simulation and experimental investigations. Furthermore, the converter is integrated into a PV-battery power management system, where continuous input current improves compatibility with photovoltaic sources and reduces input filtering requirements. To ensure stable bidirectional power transfer and effective energy management, a sliding mode control (SMC) strategy is implemented, providing fast dynamic response, robust operation, and accurate maximum power point tracking (MPPT) under varying environmental conditions. Experimental results obtained from a laboratory-scale prototype verify the feasibility of the proposed design and demonstrate peak efficiencies of 98.3% in buck mode and 98.4% in boost mode. The combination of extended voltage gain, low device stress, high efficiency, and simple implementation makes the proposed converter a promising solution for PV-battery energy storage systems and other renewable energy applications.