Fault-Tolerant Multiport Quadruple Active Bridge Converter for Resilient Interconnection of Bipolar DC Systems

In this article, a fault-tolerant quadruple-transformer quadruple-active-bridge (QT-QAB) converter is proposed for resilient interconnection of bipolar DC systems. During normal operation, the proposed QT-QAB can achieve power balancing at both high-voltage (HV) and low-voltage (LV) bipolar systems. In the event of a monopolar short-circuit fault, the QT-QAB can isolate the faulty pole on the LV side. As a result, the HV bipolar DC system and the LV healthy pole can maintain uninterrupted power supply during the LV short-circuit fault. The circuit parameter design and control strategy are analyzed with consideration of ZVS soft switching, bipolar balancing, and fault isolation capability. The proposed topology is compared with traditional QAB, DAB and HFB-QAB topologies in terms of current stress, efficiency, and cost. Based on comparative simulations and experimental results, the bipolar balancing and fault-tolerant operation capabilities of QT-QAB are validated.