Inverter Open Circuit Fault Diagnosis Method Based on Residual Performance Evaluation via Hypothesis Test
Tianyu Sun, Chaobo Chen, Jiawei Dai, Song Gao, Binbin Zhang, Hongpeng Zhang · 2024
In the analytical model-based fault diagnosis system, in order to manifest the fault information contained in the residual signal and realize the fault diagnosis under the condition of given fault detection rate, a residual evaluation fault diagnosis method based on hypothesis test was proposed for the open circuit fault diagnosis of NPC three-level inverter. Firstly, the parity space method was used to equalize the inverter system, obtain the state variable estimate to achieve analytic reconstruction, and calculate the residual through the parity vector. Next, the residual signals were divided into samples. The statistical characteristic of each sample was calculated as the residual performance. The threshold was calculated according to the probability distribution obeyed by the samples and the given fault alarm rate. The fault detection was realized by comparing the threshold and residual performance. The simulation and experimental platform results show that the proposed method can achieve fault detection under the specified fault diagnosis rate. The maximum diagnosis time is not more than three fourths of the fundamental wave period.