High-Gain bidirectional isolated DC-DC converter for PV-BESS systems using a 10 kHz ferrite-core transformer: design, simulation, and experimental validation

• A high-gain bidirectional Dual-Active-Bridge DC-DC converter is developed for PV–BESS integration. • The converter achieves a voltage step-up from 60 V to 600 V with efficiencies above 95.8%. • A medium-frequency transformer (10 kHz) with ferrite cores is designed and implemented. • The transformer design method is simple, replicable, and validated with experimental results. The integration of photovoltaic (PV) and battery energy storage systems (BESS) necessitates advancements in technologies such as electronic converters. These technologies must prioritize high efficiency, low losses, high power density, simple design, and bidirectional voltage gain. The primary objective is to design a ferrite core transformer (MFT) that performs well at medium frequencies (10 kHz) for use in high-voltage gain bidirectional isolated DC-DC converters (DAB type). Compared with conventional frequencies in ferrites (50-100 kHz), using a medium frequency (10 kHz) reduces switching losses and, consequently, achieves a high-efficiency converter. In contrast to other research in the current literature, the methodology for designing the MFT and its application in the bidirectional isolated DC-DC converter is presented in a replicable, straightforward manner. The analysis of winding losses, core design, simulation, construction of the MFT, and switching devices is described in detail. The analytical design results are validated through simulation (Simulink/Matlab) and a laboratory prototype. In both cases, the results are evaluated at 25%, 50%, 75%, and 100% (full load). The converter’s gain voltage is 60V to 600V, a range shared by systems that integrate PV and BESS. Both simulation and experimental results achieve efficiencies greater than 95.83% at full load.