Trajectory-Prediction-Based Fast Bidirectional Power Transient Control for Series Resonant Dual-Active-Bridge Converter

This paper proposed a trajectory prediction control strategy for series resonant dual-active-bridge converter (SR-DAB), achieving extremely fast bidirectional power transient performance when voltages of both DC buses are approximately constant. State-trajectory analysis of LC series resonant tank is here further developed to describe the SR-DAB, which is featured of constant switching frequency, phase-shift operation method, and capability of handling bidirectional power flow. State trajectories of the converter reveal the fastest transient process between different steady states, leading to an intuitive open-loop power transient control strategy. This strategy is implemented by a 2-layer digital controller structure. Simulation and experimental results on a 4-kW prototype converter validated that, through this method, both amount and direction of the average transmission power of SR-DAB can be modified swiftly and smoothly within one switching period in large power range. Besides, impact and oscillation caused by the power transient of resonant tank can also be significantly reduced.