D15.5 - A Decoupled Control Methodology for Stable Operation of Current-Fed Quad Active Bridge Converter

Quad-active bridge (QAB) converters are increasingly being used for multi-port isolated dc power conversion. In a current-fed QAB converter, control design becomes challenging due to cross-coupling between ports, necessitating the use of decoupling techniques. In this converter, the presence of a right-half-plane (RHP) zero in the converter’s control-to-output transfer function results in a RHP pole in the decoupled controller, leading to instability. Although RHP-induced instability has been addressed in current-fed triple active bridge converters, those approaches do not directly extend to current-fed QAB converter, where the added fourth control variable introduces additional coupling and design constraints. This paper presents a decoupled control method for current-fed QAB converters that mitigates the RHP pole issue in decoupled controller and achieves stable-loop decoupling. This work contributes to the extension of the control framework for multi-port isolated converters involving current-fed architectures. Its feasibility is demonstrated through both simulation and experimental results.