Open-Circuit Diagnosis Method for T-Type Three-Level Inverter Based on Extracted IMF Energy Feature

To address the challenges associated with pinpointing single and double-switch open-circuit (OC) faults in conventional fault diagnosis strategies for T-type three-level (T ^{2}3 L) inverters, a method for fault diagnosing based on energy feature extraction of intrinsic mode function (IMF) of voltage is proposed in this article. First, to mitigate modal aliasing and noise interference, the output voltage signal of the inverter is decomposed using the complete ensemble empirical mode decomposition (CEEMD) to extract IMF components. Subsequently, the short-term energy value of the selected IMF components is calculated by segmenting the decomposition results. By establishing a criterion for extracting fault features, the local variations in IMF short-term energy values at different fault locations are distinguished. Based on this criterion, a fault feature vector is constructed, enabling a diagnostic method for OC faults relying on the IMF components' short-term energy values. The experimental results show that the fault diagnosis method proposed in this article can reliably achieve the diagnosis of single and double-switch OC faults in the T-type inverter. The proposed method does not require complex modeling and has strong robustness and high accuracy compared to other types of diagnostic methods.