Reactive Power Flow Analysis in a DAB DC-DC Converter with EPS Modulation

The single-phase shift (SPS) modulated DAB dc-dc converter has significant reactive power circulation which degrades its overall performance. In SPS modulation, the power transfer is achieved by generating two phase-shifted square waves across the high-frequency transformer (HFT) leakage inductor terminals. On the other hand, the use of extended phase shift (EPS) modulation provides a degree of freedom in minimizing the reactive power circulation by generating quasi square wave by one of the H-bridges while generating square wave by the other H-bridge. Such control changes the phasor alignments, and hence, minimizes the reactive power flow. In this paper, this phasor-based approach for the implementation of EPS is discussed and the analysis has been presented to showcase the capability of EPS modulation to provide efficient performance by minimizing reactive power flow. The results obtained from simulations performed in MATLAB/Simulink environment are presented and discussed in detail. Also, the converter efficiency under various operating conditions are presented.