Light Load Efficiency Improvements in Dual Active Bridge Converters via Dead time Control

Abstract

Many converters suffer from poor efficiency at light loads even though much of their lifetime is spent at lightly loaded conditions. During normal operation, the dual active bridge (DAB) family of converters loses soft switching at low power levels, leading to poor light-load efficiency. In this paper a control approach for DAB converter is investigated that enhances their light-load efficiency via dead time control. A model is developed that captures the relationship between output power and dead time, and is used to formulate a control approach for light-load operation. Experimental results from a prototype converter validate the proposed approach.

Impact on ZVS Operation by Splitting Inductance to Both Sides of Transformer for 1-MHz GaN Based DAB Converter

“…A Gallium Nitride (GaN)-based DAB converter was characterized by analyzing the resonant transition in time domain as well as considering the nonlinearity of GaN transistors' junction capacitance. In [13] and [14], the ZVS performance of a 1 MHz DAB converter was investigated. In [15], the resonant transition of ZVS operation was characterized in frequency domain by using harmonic decomposition of the DAB converter's switching-node waveforms.…”

“…This method is not affected by a sequence change in the modulation pattern and thereby reduces the analysis complexity. In [14] and [15], the transformer's magnetizing inductance was considered in characterizing the resonant transition. With the above characterization methods, the ZVS range of the DAB converter with single-phase-shift-modulation (SPSM), where a phase shift is added between the two full bridges (FBs) to control the power flow, was found to be narrow [3]; however, the ZVS range is able to be extended by using advanced modulation strategies.…”