Direct Charge Control for a Dual-Bridge Series Resonant Converter in the Half-Cycle Discontinuous Conduction Mode

The half-cycle discontinuous conduction mode (HC-DCM) of a dual-bridge series resonant converter (DBSRC) has the advantages of small transient oscillations and zero-current-switching because the inductor current can return to and remain zero in every half-switching cycle. However, due to the inductor current’s segmented and nonlinear characteristics, the modeling and control of DBSRC in HC-DCM is challenging. To address the challenge, this article proposes a charge quantity model (CQM) for DBSRC. The proposed model represents a simple first-order linear model that uses the charge flowing through the resonant inductor as control variable. In addition, based on CQM, a direct charge control (DCC) method is developed, which simplifies the analysis and design process of a closed-loop system. During the control process, changes in the charge quantity inevitably cause an undesirable transient process. Therefore, to suppress the transient process, a transient process compensation (TPC) method is introduced, which can reduce overshoot and shorten the settling time, thereby improving the dynamic performance of closed-loop control. Finally, the effectiveness of the proposed method is verified through simulation and experiments. Compared with the existing studies, the CQM constructed in this article has lower complexity and the proposed DCC with TPC method can achieve better dynamic performance.