A Parallel Input and Versatile Output Dual Active Bridge Converter
Sohaib Qazi, P. Venugopal, Alan J. Watson, Patrick Wheeler, Thiago Batista Soeiro
Abstract
Due to their easy scalability to high power, simple control mechanism, and effective semiconductor and transformer utilization, H-bridge-derived isolated dc/dc converters have taken a central stage in various power electronics applications such as fast charging stations, dc microgrids, and renewable energy integration. Among the bidirectional variants, the dual active bridge (DAB) converter stands out as a common choice due to its direct power flow control mechanism, inherent soft switching realization, symmetric and modular structure, etc. However, the conventional version of the topology exhibits a significant reduction in efficiency when subjected to wide ranges in voltage gain and output power. This limitation can potentially hinder its application in public dc chargers, where different charging profiles and vehicle voltage classes are frequently expected. This article proposes a new versatile topology derived from the DAB converter that caters to the requirement of a wide output voltage range and improves the efficiency characteristics while mitigating the current and/or voltage stresses on the semiconductor devices. Furthermore, a suitable modulation strategy is developed that optimizes the soft switching action of the converter in accordance with the load demand. The converter operation is explained and validated through a steady-state model, simulations and an 11 kW experimental prototype.