Method to detect the critical bending speed of an induction motor by using static rotor eccentricity for deriving the roller bearing stiffness
- The paper shows a method how to detect the first critical bending speed of induction rotors supported in roller bearings, by using the electromagnetic excitation due to static rotor eccentricity. The advantage of using this kind of excitation is that the so produced electromagnetic force acts with double electrical supply frequency (2f1). Therefore, it is possible to excite the first bending mode by variating the electrical supply frequency f1, while the rotor is operated below the first critical bending speed. With the information about natural frequency of the first bending mode of the rotor, it is now possible to calculate the real roller bearing stiffness in reverse.