Soft switching and soft starting of TCHB converter-based dual active bridge converter by using SPS and EPS control techniques

Renewable energy has significant potential for future electric networks, and direct current (DC) technology offers a viable solution to address related challenges. Efficient DC-DC converters are essential for achieving high voltage step-up ratios. This work presents a novel bidirectional soft-switching DC-DC converter that integrates a two-level converter on the low-voltage side and a transistor-clamped h-bridge (TCHB) multilevel converter on the high-voltage side. A phase-shift control method is employed to manage bi-directional power flow in a resonant converter operating at higher frequencies. The proposed method ensures soft-switching for all power devices across the entire power spectrum, enabling smooth transitions between power directions. Current stress measurements indicate significant reductions: from 19 A to 2 A in single-phase shift (SPS) and from 16 A to 1.6 A in extended phase shift (EPS). The performance of the same converter is validated through MATLAB/Simulink simulations and real-time experiments using an OPAL-RT simulator, demonstrating improved efficiency and reduced switching stress.