Full-Bridge Push-Pull Forward Dual Active Bridge DC-DC Converter

Abstract:
This work introduces a full-bridge push-pull forward dual active bridge DC-DC converter designed exemplarily for on-board charging applications. The topology is derived from the conventional dual active bridge structure, which has a full-bridge configuration on the primary side. The key distinction lies on the secondary side, where a push-pull forward configuration is used instead of a full-bridge. This modification reduces the number of power MOSFETs, effectively minimizing the overall cost and complexity of the system. A combined phase-shift and frequency modulation scheme is utilized, which minimizes the overall losses in the converter and ensures soft-switching of all the power MOSFETs. Detailed insights into the converter topology, the modulation scheme, and its soft-switching range analysis are presented. To highlight the differences with the dual active bridge converter, analytical comparisons are also presented. The operation of the converter is illustrated using a hardware prototype, with a rated input voltage of 800 V, rated output voltage of 400 V, and rated power of 11 kW. The experimental results confirm the validity of the analytical descriptions.