Inter turn short circuit detection at higher modulation indexes including six step operation

Inverter fed induction machine drives have become one of the most important part in industrial applications. The devices are usually operated near or at the rated vales. Additionally high dynamic operations, overload cycles and the fast switching inverter are putting additional stress to all machines components. The stator winding system is one of the most critical components. Faults in the winding system of a machine can cause a dramatic damage due to their fast developing behavior. An early detection of winding faults can reduce these consequences. In this paper a method is presented to achieve reliable fault detection on stator winding faults focused on application at higher speed levels where immediate detection is imperative. Higher inverter modulation indexes provide the possibility to estimate the transient leakage inductance in each PWM modulation cycle. This parameter contains the information on machine asymmetries. Specific signal processing steps provide a high sensitive fault indicator.