A Fault-Tolerant Strategy for Three-Phase Dual Active Bridge Converter

Due to several advantages, three-phase Dual Active Bridge (DAB) converter is widely used in numerous applications nowadays. On the other hand, this converter is very vulnerable to Transistor Open-Circuit Fault (TOCF). Therefore, a fault-tolerant (FT) scheme has been proposed in this paper to solve the problem. First, normal and faulty conditions are investigated, and according to the results, a fault-diagnosis (FD) approach is introduced. Using the outcomes of FD unit, a new post-fault strategy is proposed for the converter. The FD method is based on the DC component of transformer phase currents, and the basis of FT technique is shedding the faulty phase. Some benefits of the proposed scheme are preventing the shut-down of the system, no overvoltage or overcurrent, no additional power components, and insensitivity to operational conditions. Simulation results are also provided to confirm the analyses, and evaluate the performance of the proposed scheme.