State Observer-Based Open-Circuit Fault Diagnosis and Localization Research of DAB Converter

Open-circuit fault (OCF) diagnosis of switching devices is an important aspect of research for ensuring reliable operation of power electronic systems, in order to timely identify the switching device OCF, this article proposes a method for diagnosing open circuit faults in switching devices of dual active bridge (DAB) DC-DC converters based on state observers. Firstly, the mathematical model of DAB converter is established and the state observer is designed based on the mathematical model. The inductor current is detected in real time by an observer and the observation error is calculated in real time. When an OCF occurs in a switching device, the mathematical model of the system will change, at which time the observation error will diverge and exceed the threshold value, the system sends out a fault signal, followed by the localization of the faulty switching device based on the midpoint voltage of the bridge arm of the DAB converter. And the accuracy of the proposed switch device fault diagnosis and positioning method is verified through simulation in MATLAB/SIMULINK.