Identification of Shaft Stiffness and Inertias in Flexible Drive Systems

Abstract

This letter presents an identification method for motor drive systems with flexible shafts and couplings using frequency response measurement. The drive system can be approximated as a two-mass non-rigid mechanical system to model the lowest resonant frequency with three parameters to be identified: the motor side inertia, the load side inertia, and the shaft stiffness. The proposed method does not require knowledge of the total inertia as many other techniques require. However, additional known inertia is added or removed from the load side assembly. The frequency response measurement is carried out with and without additional inertia to identify the resonant and anti-resonant frequencies. It is shown that this procedure directly identifies the two inertias and shaft stiffness and can be utilized to assist in the commissioning of electrical drives.