A hybrid synchronous and phase-shifted control strategy for DC transformer

A hybrid synchronous and phase-shifted control strategy is proposed for DC transformer (DCT) in this paper. This configuration of DCT is composed of multiple series resonant dual active bridges (SRDABs). It employs the open-loop synchronous control strategy on some SRDABs and the closed-loop phase-shifted control strategy on the others. It achieves zero current switching (ZCS) for SRDABs controlled by the synchronous strategy. The transmission power and output voltage of DCT can be regulated by SRDABs which are controlled by the phase-shifted control strategy. It achieves high efficiency and flexible controllability for SRDABs-DCT. Simulations on a four-cell 400kW3kV/750V SRDABs-DCT verify the effectiveness of the proposed control strategy.