Hybrid control of ISOP-DAB converters based on double-loop decoupling

Abstract

In medium and high voltage DC microgrids, the input series output parallel dual active bridge (ISOP-DAB) converter, as one of the key devices, has received more and more attention from experts and researchers. This is due to the power imbalance and poor dynamic performance of each module of ISOP-DAB converters. Based on the double-loop decoupling strategy, this paper proposes a hybrid control strategy of a super twisting sliding mode considering backflow power optimization. First, the power model and ZVS characteristics of the DAB converter in two modes under extended phase-shift modulation are analyzed, and a reduced-order model of the DAB converter is established on the basis of the transmitted power model. Second, an output voltage loop super twisting sliding mode controller and a backflow power optimization module are designed based on the established mathematical model. Finally, simulation results show that the ISOP-DAB system has good dynamic performance in load switching and input voltage mutation, can ensure the input voltage of each sub-module, and can effectively reduce the backflow power.