Fault Diagnosis for Multilevel Inverter with Space Vector Recognition

The space vector of the output voltage delivers information about the functionality of a frequency inverter. In case of fault operation the space vector differs from the ideal shape (circle or hexagon). An efficient pattern recognition requires the filtered and unfiltered output voltage. The space vectors for different failure types (unsymmetrical phases, missing modulation signal, short-circuited or permanently switched off IGBT) can be simulated and stored. By comparison with the measured space vector a pattern recognition algorithm locates the failure very fast and precisely. This method could save a lot of time for the frequency inverter manufacturer. This automatic pattern recognition can be used not only for two-level but especially for three-level inverters.