The challenges in the implementation and voltage ripple analysis of quasi-three-phase dual active bridge converter

This paper developed novel analytical approach based on multifrequency average technique (MAT) and Simscape based direct modelling (SBDM) to address the following implementation challenges of the Quasi-Three-Phase Dual Active Bridge (QTPDAB) Converter (a) The necessity to ensure that the Initial Arbitrary Pulse Shift (IAPS) does not influence both output voltage’s zeroth component and the transformer currents’ first component amplitude of the converter (b) The need to address transformer currents’ imbalance caused by the output capacitor bank (OCB) to align with the real-world consequence as against the ideal balanced three-phase” being assumed in most papers, (c) The SBDM identifies that the most predominant QTPDAB output voltage ripple occurred at six times switching frequency (6fs) compared with 2fs for the single-phase (or series connection of DABs without IAPS). The investigation proved the fundamental justification of combining three DABs into a QTPDAB topology. It derived a more accurate and convenient formula useful for DAB design engineers for estimating the required inductance and phase shift to meet a specific output voltage. Four cases are investigated leading to the conclusion that better output voltage quality (OVQ) and reduced filter capacitor volume could be obtained from the QTPDAB with IAPSs than the single-phase DAB (or their series connection without IAPS). Finally, it was determined that an additional common capacitor was necessary to be connected with the OCB to offer an improved OVQ.