Analysis and design of asymmetric quad-active-bridge converter

The focus of this paper is on power flow control in the asymmetric quad-active-bridge (QAB) converter and its limitations imposed by uneven values of parasitic elements in the isolation transformer. The QAB converter under study is intended for solid-state transformer applications in asymmetric configuration, where one of the ports is placed at the low voltage side and rated for the threefold power of the medium voltage ports. Significant imbalance between leakage inductance could be observed between them. The steady-state analysis of the asymmetric QAB converter and assessment of power losses using numerical simulation are provided. Experimental waveforms were obtained using a prototype rated for cumulative MV dc link of 2400 V and power of 30 kW