Analysis and design of asymmetric quad-active-bridge converter

Abstract

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.

A High-Power Density DC Converter for Medium-Voltage DC Distribution Networks

“…Voltage Stress ZVS Ability Tracking Performance [9] Medium Poor Poor [13] Low Medium Good [20] High Medium Medium [25] Low Medium Good Proposed Low Good Good…”

“…In [24], the research of modular combined DC converters in flexible DC distribution is carried out. In [25], the modular combined DC converter is improved, and a topology based on four active full-bridge power modules is proposed. Due to its modular structure, high-frequency isolation, and other characteristics, modular combined DC converters have also been widely studied in AC-DC power electronic transformers [26][27][28].…”

Smart transformer universal operation

“…3 (b). It allows achieving minimum leakage inductance and, consequently, enables one more degree of design freedom, when interchangeable external inductors are used to define power transfer characteristics of the given QAB converter [22]. However, interleaved windings results in increased concerns regarding isolation against the partial discharge that could be resolved with vacuum varnishing of the coil, reinforced isolation of the Litz-wire, etc.…”