Short-Circuit Fault Diagnosis of a Three-Phase Current-Source Inverter

The development of the wide-band gap devices has led to the re-emergence of current-source inverters (CSIs). With the modernization of future power systems, the importance of the reliability of power converters is critical. Fault identification is vital to enhancing the reliability of the system. A prominent failure mode in power converters occurs due to the semiconductor device failure. The normal and fault mode operation of the converter is discussed for the three short-circuit fault conditions observed in current-source inverters. This paper proposes a method to detect and locate the short-circuit fault of a MOSFET switch, a diode switch, and a current switch comprising of both MOSFET and diode simultaneously, in a CSI. A fault detection method that involves checking the ratio of the average value of the ac currents and average value of the reference currents in one fundamental cycle to threshold limits is used to detect and identify the location of the fault. This method does not need additional voltage or current sensors for implementing the proposed algorithm. The effectiveness of the proposed method is shown in simulation and experimental results are provided to validate the same. This proposed method for fault identification improves the system reliability of CSIs.