Primary Source Inductive Energy Analysis Based Real-Time Multiple Open-Circuit Fault Diagnosis in Two-Level Three-Phase PWM Boost Rectifier

Two-level three-phase boost rectifiers are widely used in industrial applications due to their superior performance. According to the survey reports, the transistors often suffer from open-circuit failures due to the lifting of bonding wires caused by thermic cycling, resulting in output fluctuation and current harmonics. This paper proposes a real-time, robust fault diagnosis method for single and multiple transistors open-circuit faults based on the primary inductances energy analysis. Three-phase primary voltages are divided into six states during a period; under healthy condition, the primary source inductances energy storage and release are normal in every state. When transistor open-circuit occurs, they will be abnormal in some states because the primary source electrical circuit will be nonconductive due to connected diode reserve truncation. Line-to-line currents are used to monitor the energy storage condition of primary inductances. Fast detection and isolation are achieved and little tuning effort is needed in the proposed method. Experiments are carried out and the results show high effectiveness, robustness, and merits of the fault diagnosis method.