双有源桥串联谐振变换器的暂态过程与控制

Transient Process and Control of Dual-bridge Series Resonant Converter

基于移相控制的双有源桥串联谐振变换器(dual-bridge series resonant converter,DBSRC)在传输功率的快速调控过程中,移相角将发生较大的阶跃变化,导致谐振腔出现大幅度长时间的振荡过程,不仅严重恶化了变换器的动态性能,电路元件也会面临严重的过电压和过电流风险。该文首先基于基波分析法推导DBSRC暂态过程的通用计算模型,分析暂态过程中的振荡特性,精确估算暂态过程中的谐振电压峰值、谐振电流峰值以及暂态过渡时间,评估暂态过程中的过电压与过电流程度。基于暂态过程计算模型,提出一种振荡的抑制方法,使变换器在一个开关周期后能够到达新的稳定状态,有效地避免了过电压与过电流的风险,并且大幅改善了闭环控制的动态特性。最后,通过仿真与实验结果验证理论分析和所提出的控制方法。

During the rapid adjustment of transmission power,the dual-bridge series resonant converter(DBSRC)based on phase-shifting control will have a large step change in the phase shift angle,resulting in a large amplitude and long settling time oscillation process in the resonant cavity.Not only the dynamic performance of the converter is seriously deteriorated,but also the circuit components suffer from serious overvoltage and overcurrent.In this paper,a general calculation model of the transient process in DBSRC based on the fundamental harmonic approximation is derived,and the oscillation characteristics in the transient process are analyzed.Then,the resonant voltage peak,the resonant current peak and the transient settling time in the transient process are estimated accurately.Based on the transient process calculation model,this paper proposes a suppression method for the oscillation phenomenon,which can force the converter to reach a new steady state after one switching cycle,thereby effectively avoid the risk of overvoltage and overcurrent and greatly improve the dynamic performance of the closed-loop control.Finally,the theoretical analysis results and the proposed control method are verified by simulations and experiments.