Sensor Fault Diagnosis and Fault-Tolerant Approach Based on State Observer for Single-Phase Cascaded H-Bridge Rectifiers

This paper presents a fast and reliable fault diagnosis and fault-tolerant approach for grid current and dc-link voltages sensor faults in the single-phase cascaded H-bridge rectifiers (SPCHBR). Firstly, a state observer with the mixed logic dynamic (MLD) model is established for obtaining the observed sensor signals and system residuals. And then normalized residuals are generated to diagnose and isolate single or multiple sensor faults online by comparing different residuals with thresholds. Moreover, fault-tolerant control is realized by redesigning the observer gain and substituting the observed values for the measured values. The proposed approach can accomplish the accurate location of the faulty sensors and system reconfiguration within half of the current fundamental period. The effectiveness and availability of the proposed approach has been verified by MATLAB/Simulink.