A Universal Method for Suppressing Transient DC-Bias in Triple-Active-Bridge Converters Based on Superposition Analysis

Triple-active-bridge (TAB) converter has attracted considerable attention due to its commendable electrical isolation, high energy density, and bidirectional energy transmission capa-bilities. Nevertheless, dynamic variations in the TAB converter can disrupt the volt-second balance, leading to the generation of dc-bias current, which may result in increased current stresses, causing magnetic saturation of the converter and posing a risk of damage to power electronics components. Addressing the analytical complexity stemming from the three- winding transformer in the TAB converter, this work conducts an analysis of the equivalent model based on superposition theorem, effectively reducing control complexity. Additionally, a universal modulation strategy is proposed to eliminate dc-bias current. The strength of this method lies in its versatility across various modulation techniques and its effectiveness in addressing diverse dynamic scenarios, encompassing load changes, fluctuations in power magnitude, power reversal, and start-up processes, among others. Finally, a TAB experimental prototype is constructed to validate the feasibility of the proposed method.