The presence of a DC bias in the ac stage currents of a multi-active-bridge converter (MAB) deteriorates converter efficiency. The DC biases in the MAB cells are dynamically coupled, but existing strategies do not clearly tackle this cross-coupling. This paper proposes a simplified dynamic model of the DC bias in MAB and a dynamic feedforward control scheme to eliminate the same. In order to simplify transient behavior and facilitate control design, an approximated dynamic model, capturing the higher order dynamics, is proposed. The proposed controller design is outlined for a generic MAB and validated in simulation and experiment on a 50V , 200W quad-active-bridge (QAB).
