A Dual Active Bridge Converter with an Extended High-Efficiency Range by DC Blocking Capacitor Voltage Control

Journal article (2018)

Authors

Z. Qin DC systems, Energy conversion & Storage - EEMCS
Yanfeng Shen Aalborg University
P.C. Loh The Chinese University of Hong Kong
Huai Wang Aalborg University
Frede Blaabjerg Aalborg University
Research Group
DC systems, Energy conversion & Storage (EEMCS) (TU Delft)
Copyright: © 2018 Z. Qin, Yanfeng Shen, Poh Chiang Loh, Huai Wang, Frede Blaabjerg
DOI: https://doi.org/10.1109/TPEL.2017.2746518
Modulation High efficiency Dual active bridge Circulating power Soft switching
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Published Date

2018

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Department

Electrical Sustainable Energy

Research Group

DC systems, Energy conversion & Storage

Abstract

A Dual Active Bridge (DAB) converter can achieve a wide high-efficiency range when its input and output voltages are equal, assuming a 1:1 turns ratio for its isolation transformer. If its input or output voltage is doubled, efficiency of the DAB will drop significantly, because of the introduction of hard switching and high circulating power. Thus, a new modulation scheme has been proposed, whose main idea is to introduce a voltage offset across the dc blocking capacitor connected in series with the transformer. Operational principle of the proposed modulation has been introduced, before analyzing its soft-switching area and circulating power mathematically. The final modulation scheme is not difficult to implement, but can help the DAB achieve soft switching, low circulating power, and thereby high efficiency, even with its input or output voltage doubled.
These features have been verified by experimental results obtained with a 1.2 kW prototype.