Model-Free Optimization of Isolated DC-DC Triple Active Bridge Converters for ZVS and Reduced RMS Current Operation

Isolated multi-port converters (IMPCs) find applications across several domains. The triple active bridge converter (TAB) is an IMPC that interconnects three dc ports via a three-terminal high-frequency transformer. TAB operation allows zero voltage switching (ZVS) without requiring additional snubber circuits. However, specific loading conditions may lead to loss of ZVS and increased rms currents. Remarking the benefits of ZVS include enhanced efficiency, improved reliability, and reduced EMI noises, the paper proposes a model-free online optimization employing multi-dimensional ripple correlation search (MD-RCC) to ensure ZVS optimization while concurrently reducing rms currents. The MD-RCC features the advantages of being online and model-free, thus endowing the proposed solution robustness against parameter uncertainties or variations due to changes in operating conditions.