Fault Diagnosis and Tolerant Method of Open-Circuit Fault for Triple Active-Bridge DC-DC Converter

Abstract

Triple active-bridge (TAB) DC-DC converter is widely used in bidirectional DC distributed system. The open-circuit fault (OCF) of TAB may threaten the system safety operation and should be eliminated in time. This article proposed an OCF diagnosis and tolerant method for TAB three-port dc-dc converter consisting of one DC bus and two energy storage systems. Firstly, normal mode and OCF mode of TAB is analyzed. Base on the analysis, the average value of the midpoint voltage of each bridge arm can be used as an OCF diagnosis indicator. Then the overcurrent and the DC bias of transformer winding current are eliminated by blocking the gate-driving signal of the faulty bridge arm. Finally, fault-tolerant operation is achieved by regulating the phase shift angle. If the OCF occurs on the energy storage side, the energy storage cut off. If the OCF occurs on the DC bus side, the DC bus side can still absorb power. The OCF can be diagnosed quickly and accurately according to the experimental results. The impact of OCF can be reduced, which promotes the reliability of TAB converters.