Comprehensive Diagnosis Method for Power Switch and Sensor Faults in Single-Phase Two-Level Rectifiers of High-Speed Train Traction Systems

The single-phase two-level rectifier (SP-2LR) is a critical component in high-speed train traction systems, significantly influencing the performance and stability of the trains. This article addresses the fault diagnosis of SP-2LR in high-speed train traction systems by proposing a comprehensive fault diagnosis strategy primarily focused on open-circuit (OC) faults and sensor faults. Initially, by augmenting the SP-2LR system and applying matrix transformations, the strategy successfully decouples OC faults within the augmented system. Subsequently, a reduced-order sliding mode observer (SMO) is designed to achieve precise estimation of system states and sensor faults. Furthermore, this article presents a method for detecting OC faults and sensor faults based on the residual of the grid-side current and its norm threshold. Leveraging the estimated sensor fault values enables an effective differentiation between sensor faults and OC faults, and ultimately, the strategy accomplishes specific localization of faulty power switches and accurate identification of grid-side current sensor (GS-CS) faults and dc-side voltage sensor (dc-VS) faults, respectively. The experimental results demonstrate that this diagnostic method can simultaneously diagnose OC faults, GS-CS faults, and dc-VS faults with low algorithmic complexity and without requiring extensive data, additional hardware, or extra operations. The detection time for OC faults is less than 0.05 of a fundamental period, demonstrating fast detection speed. Moreover, the method also exhibits excellent robustness under unfavorable conditions, such as grid-side voltage fluctuations, load resistance variations, and grid-side filter resistance changes.