Detection of Broken Rotor Bars in Induction Motors Using Unscented Kalman Filters

Determining the number of broken bars due to the failure or the number of ring segments of the rotor cage of the asynchronous motor is the important problem during the operation of such machine. UKF filter, used to achieve this goal, gave exact information: numbers of broken bars and ring segments. For receiving such exact information the filter needed the measurements of the stator currents and currents of the additional one-winding coils placed at stator teeth and loaded by big resistance (similar to 1 k Omega). The measurement of the rotation speed of the rotor and connected with this the angle of the machine shaft rotation was needed also. The method of determining the numbers of broken bars and ring segments of the rotor and the method of detecting only the broken bars of the rotor cage were tested. The presented method can be used for protecting big and expensive asynchronous drives.