Vibration control of inverter motor by dynamic absorbers

This paper deals with the quenching problem of electromagnetic vibration of the motor stator in the wide frequency region around the natural frequency using two dynamic absorbers. The iron stator of motor is modeled by circular ring, and two dynamic absorbers are installed on the outside of iron stator to quench the forced vibration caused by the rotating distributed electromagnetic force. The solutions of forced vibration are obtained by the theoretical analysis, and those are compared with the solutions obtained by the finite element method and numerical integration. Following was made clear: (1) By installing two dynamic absorbers which have not only different natural frequencies and different damping ratios but also different masses each other, the iron stator is quenched better than by installing the same dynamic absorbers. (2) It is possible to obtain nearly optimum quenching effect with a pair of dynamic absorbers with equal masses. (3) The mechanism of the above-mentioned vibration quenching method using two different dynamic absorbers is made clear. (4) In the case using the dynamic absorbers those have small values of damping ratios, about 25 degrees is better as angle made by the two dynamic absorbers. (5) The characteristics of resonance curves obtained by the theoretical analysis using ring theory and those obtained by the finite element method and numerical integration agreed well each other.