Abstract：Power switch open-circuit faults are significant challenges that can severely compromise the reliability and operational safety of inverters. Such faults disrupt the normal functioning of the inverter and can lead to broader system failures if not addressed promptly and accurately. Therefore, an effective fault diagnosis method is essential for ensuring the accurate implementation of fault-tolerant control, which is critical for maintaining the safety and efficiency of power systems that rely on inverter technology. To address the shortcomings of existing open-circuit fault diagnosis methods for three-phase four-wire systems, a novel fault location method is proposed that utilizes common-mode voltage residuals as a single-class diagnostic variable. This approach simplifies the diagnostic process while ensuring accurate fault identification, making it a practical solution for real-world applications. Firstly, the characteristics of single-switch faults in the three-phase four-wire T-type inverter are analyzed, and the common-mode voltage residual associated with these faults is constructed based on a simplified circuit representation. Subsequently, various fault modes that may occur in the inverter's power switches are examined. By analyzing the distinct characteristics of each fault mode, a new metric termed the “pulse area” is introduced as a quantitative measure for assessing common-mode voltage residuals generated during different switching faults. Accurately quantifying these residuals enhances the ability to differentiate between fault conditions and improves the precision of the diagnostic approach. Furthermore, to refine the diagnostic method, an adaptive threshold diagnosis area is established to illustrate the differences in voltage residuals under each specific switch fault condition. This adaptive approach allows for real-time adjustments to the diagnostic thresholds based on observed voltage behaviors, thereby increasing the reliability of fault detection. Subsequently, fault detection and location variables are designed to ensure precise positioning of the fault switch. Finally, to verify the effectiveness and robustness of the proposed diagnosis method, a prototype of a 10 kW three-phase four-wire T-type inverter is developed. Experimental tests under various common working conditions demonstrate that the proposed method can reliably detect and locate open-circuit faults with a high degree of accuracy. The results indicate that this method can be integrated into existing systems to enhance their fault diagnosis capabilities. The following conclusions can be drawn: (1) Compared to existing fault diagnosis methods, the proposed method uses the common-mode voltage residual as the sole diagnostic variable, thereby reducing the number of required diagnostic variables and simplifying the algorithmic flow. (2) The proposed method quantitatively analyzes the relationship between the common-mode voltage residual and the detection threshold in the context of open-circuit faults, accounting for multiple error-influencing factors. This enhances the model's adaptability to errors and improves the robustness of the algorithm. (3) The proposed method estimates the inverter output common-mode voltage residual as a diagnostic variable by constructing a circuit model without requiring additional sensors. When a fault occurs, the common-mode residual exhibits significant transient changes, ensuring the rapidity of the diagnosis. Moreover, this diagnostic approach can be extended to multi-tube fault diagnosis in three-phase four-wire inverters, and future work can focus on in-depth theoretical analysis and experimental validation.
肖凡, 蒋毅, 彭星, 涂春鸣, 郭祺. 基于共模电压残差的三相四线制T型逆变器功率开关开路故障诊断方法[J]. 电工技术学报, 2025, 40(20): 6672-6685.
Xiao Fan, Jiang Yi, Peng Xing, Tu Chunming, Guo Qi. An Open Circuit Fault Diagnosis Method of Three-Phase Four-Wire -Type Inverter Based on Common-Mode Voltage Residuals. Transactions of China Electrotechnical Society, 2025, 40(20): 6672-6685.
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