A Voltage-Based Open-Circuit Fault Diagnosis Approach for Single-Phase Cascaded H-Bridge Rectifiers

Aiming at the higher priority to detect and protect against fault conditions for the single-phase cascaded H-bridge rectifiers (SPCHBR) in the power electronic traction transformer (PETT), this paper has proposed a voltage-based open-circuit fault diagnosis approach to detect and locate failure modules and faulty switches of the SPCHBR. According to the control features of the model predictive control (MPC), the measured and estimated values of the input-side voltage for H-bridge modules are obtained to generate voltage residuals, which include fault information of faulty modules. And then, combining the voltage residuals with switching states, the count comparisons are designed to detect faulty modules. What's more, faulty switches can be accurately located by matching fault features with specific switching signals after the failure modules are detected. The proposed diagnostic approach needs no additional sensors. Meanwhile, multiple faulty switches can also be isolated within one line cycle of the grid current. The simulation results have verified the availability of the proposed diagnostic algorithm.