Optimal Hybrid Fault Tolerant Control With Voltage Balancing for IPOS DAB Converters

ABSTRACTThe input parallel output series connected dual active bridge (DAB) converter is a typical galvanically isolated converter for a wide output voltage range in many applications, such as charging piles for electric vehicles or solar energy storage systems. Open circuit fault (OCF) is an operation accident of power switches that occurs in DAB converters, and the faulty DAB module is degraded to a semi‐DAB converter. In this work, by analyzing three operation modes and the impact of the current stress/power ratio, an optimal hybrid fault‐tolerant control strategy is proposed. In this control method, DAB converters are operated under zero voltage switching/zero current switching under minimum inductor current stress without DC bias current. The proposed OCF fault‐tolerant control strategy helps the DAB converter maintain stable operation under OCF occurrences. A voltage balancing method considering OCF and feedback‐loop competition is also designed to balance the output voltages of faulty and non‐faulty. Prototype experimental results verify the correctness and effectiveness of the proposed control strategy.