A Global State Observer-Based Open-Switch Fault Diagnosis for Bidirectional DC–DC Converters in Hybrid Energy Source System

Open-switch fault is one of the most common faults of dc–dc converter. If the fault cannot be diagnosed in time, it will have a serious impact on the normal operation of the system. To solve this problem, this article proposes an open-switch fault diagnosis method for bidirectional dc–dc converter based on global state observer. In this method, the global mathematical model of two bidirectional dc–dc converters in hybrid energy sources system is first derived, and then a global state observer is constructed based on Luenberger observer. The open-switch fault detection and location are achieved through the residuals of battery current and supercapacitor current. Both the simulation and experimental results verify the effectiveness of the proposed open-switch fault diagnosis method.