A Generalized Time-Domain Modeling of Dual-Bridge Series Resonant Converters for Control Performance Improvement

Abstract

Dual-bridge series resonant converters (DBSRCs) are promising solutions to interface energy storage modules with DC-bus flexibly. To compensate for the defect that the fundamental harmonic approximation (FHA) model has high accuracy only near the resonant frequency point, a generalized time-domain model (the G-TDA model) is proposed for DBSRCs, which can accurately describe operating characteristics and transmission power of DBSRCs. In addition, the evolving time-domain models of other symmetric phase-shift modulations are derived from the G-TDA model. Compared with the FHA model, the G-TDA model can predict the resonant current behavior and zero-voltage-switching (ZVS) conditions with higher accuracy. Then, the relationship between backflow power and resonant current is discussed, the backflow power optimization performance is closely related to the prediction accuracy of the resonant current behavior. Besides, dead time effects are analyzed when switching devices achieve/lose ZVS, which is closely related to ZVS conditions. Finally, comparative experiments of optimization methods based on the FHA model and the G-TDA model are carried out, better control performance of the backflow power optimization and the dead time compensation can be achieved due to the higher accuracy of the G-TDA model, such as zero-backflow power optimization, all switching devices ZVS, and efficiency improvement of DBSRCs.