Fault Characteristics and Riding-Through Methods of Dual Active Bridge Converter Under Short-Circuit of the Load

The fault riding-through (FRT) capability is a key problem in the dc distribution network. In order to achieve the FRT, it is necessary to analyze the worst-case scenario (WCS) of the short-circuit transient process of distribution components. This article analyzes the whole fault characteristic in a dual active bridge (DAB) in the WCS when a short-circuit occurs on the load at different locations that has not been considered in the existing literature. The short-circuit in the WCS can cause various fault current in the whole circuit, introducing a risk of the overcurrent. In order to overcome this problem, FRT-based methods are proposed in this article. One of the methods is to block the power switches for a certain period and restart the circuit, and another is to add a series output inductor with a reasonable inductance. By these methods, the faulty branch can be cut off by the corresponding circuit breaker in time. The results are verified by the simulations on a 50-kW DAB by MATLAB/Simulink, and the experiments on a 3-kW prototype. The results presented in this article provide a theoretical reference for FRT of DABs.