Some diagnosis methods for voltage source inverters in variable speed drives with induction machines - a survey

Status monitoring and performance diagnosis for variable speed ac drives today is a need, more or less, depending on their application. Diagnosis can help to avoid unplanned standstill, to make possible to run an emergency operation in case of a fault or to keep the time to repair short in case of a fault. For the voltage source inverter several faults are possible. In this paper, these faults and their diagnosis are covered. Possible faults and remedial strategies are listed. It is enumerated, which faults in today´s standard protection systems are diagnosed. The main faults, in general not covered in these systems, are the transistor open circuit fault and the dc bus capacitor fault. In these fields diagnosis methods are under research. Some of the various reports of research groups in this field are outlined here as a survey with respect to function and properties.