A reduced-order observer-based control system designed in the frequency domain for dual-active-bridge converter

A new strategy for controlling single-phase dual-active-bridge converter is proposed in this paper. It is realized by employing dynamic control of the direct and quadrature current components, detached from the transferred current. The direct component Id is determined approximately from the terminal current, whereas, the quadrature one, Iq, is estimated by a reduced-order observer. All the models and equations are derived based on the frequency-domain analysis. Switching frequency is then variable to manipulate Id, while the phase shift between the two bridges is used to handle Iq and the power flow. Since Id and Iq are controlled, active and reactive power in the circuit are completely handled. A 500 W experiment system is built to verify the proposed control algorithm.