Robust fault diagnosis for closed-loop grid-connected inverter based on sliding mode observer and identifier

In recent years, many challenges have been faced in locating and identifying faulty components in inverter circuits. A variety of fault observers are used to monitor the fault state of the system. This paper studies the design of the sliding mode fault observer and identifier for closed-loop grid-connected inverter. First, the closed-loop grid-connected inverter system is mathematically modeled. Then the fault model of the system is analyzed. Thirdly, the fault detection sliding mode observer is designed by solving linear matrix inequalities, which has good robustness. By choosing a suitable adaptive law, sliding mode adaptive fault identifiers are designed for different circuit fault components. After the fault observer observes the circuit fault, the fault identifier can identify the specific location of the faulty component in the circuit. Finally, the effectiveness of the designed fault observer and identifier are verified in simulation platform. Compared with existing studies, the fault observer and identifier in this paper can accurately locate faulty components in the system without the influence of deforming load, and the output of the fault residual estimation function is more accurate.