Open-circuit Fault Diagnosis Strategy For Modular Multilevel Converter Semiconductor Power Switches

The modular multilevel converter (MMC) is one of the most commonly used power electronic converters in medium and high-power applications. However, reliability is one of the most critical challenges because of the many power switching devices applied in the MMC. Also, many voltage sensors in the converter topology have increased cost and hardware complexity. In this paper, a method for detecting IGBTs open-circuit fault is proposed. In the proposed method, each converter arm is divided into sets. Each set includes two sub-modules and a voltage sensor. These voltage sensors are responsible for monitoring their set. By comparing the output voltage of each set, in normal operation mode and after the open-circuit fault, the fault is detected with great speed and accuracy. Finally, the performance of the proposed method in various scenarios is examined by the simulation results in MATLAB/Simulink.