Analysis of Modulation and Optimal Design Methodology for Half-Bridge Matrix-Based Dual-Active-Bridge (MB-DAB) AC-DC Converter

Recent research reveals the merits of single-stage half-bridge Matrix-based (MB) Dual-Active-Bridge (DAB) converter for modular Medium-Voltage AC (MVAC) to Low-Voltage DC (LVDC) conversion. The complete set of modulation modes for this AC-DC converter is yet to be analyzed in the literature. Such holistic investigation is necessary before carrying out a design optimization of the AC-DC converter for given voltage and power specifications. The objective of this paper is to present a comprehensive analysis of the half-bridge MB-DAB converter’s modulation possibilities and optimal design. The exhaustive sets of ZCS and ZVS constrained modulation modes for the half-bridge MB-DAB converter are systematically investigated and the analysis reveals the boundaries of operation and feasible modulation schemes. Suitable simulation results illustrating modulation limits of the AC-DC converter reinforce the theoretical analysis. Additionally, an efficiency (η) - power density (ρ) optimal converter design algorithm is presented, which reveals that an all-SiC half-bridge MB-DAB design with ZVS constrained modulation offers the best η-ρ design. The hardware prototype’s experimental results validate the converter’s operation.