Different procedures for the diagnosis of rotor fault in closed loop induction motors drives

This paper deals with different procedures that can be applied to diagnose the severity degree of rotor faults in closed loop controlled induction machines. A solution based on Field Oriented Control (FOC) was investigated in order to validate the robustness of the diagnostic procedures towards the regulator parameters. Different diagnostic procedures were investigated, that rely on different diagnostic indexes. Specifically a few electric quantities are considered as possible fault alert signals: the spectral analysis of manipulated and controlled variables, the voltage homopolar components (voltage zero sequence), and the spectral analysis of motor input current due to a high frequency voltage injection. It turns out that the last quantity is a simple and effective index able to detect and quantify the fault severity degree. The procedures based on the above mentioned quantities are validated by experiments made with a DSP based Current Controlled Voltage Source Inverter (CCVSI) supplying an induction machine with three rotors in different health conditions.