Open-Circuit Fault Diagnosis of More Electric Aircraft Static Inverter Based on Sliding Mode Observer

The three-phase four-leg static inverter is extensively utilized in More Electric Aircraft (MEA) due to its ability to handle unbalanced loads. However, since the four-leg inverter has an additional leg compared to the three-leg inverter, its fault diagnosis becomes more complicated, and there is a scarcity of researchers studying this area. To address this issue, this study proposes a fault diagnosis method based on an interval sliding mode observer (SMO) for detecting open-circuit faults in the three-phase four-leg static inverter used in MEA. The proposed method establishes a novel interval SMO, which accurately and quickly estimates the system state variables. The residual difference between the actual value and observed value of the state variable is then calculated for fault diagnosis and identification. Simulation and experimental results demonstrate that this method can rapidly and accurately detect open-circuit faults in the power switch of the three-phase four-leg static inverter.