The Modelling And Experimental Testing Of The Vertical Dynamic Response Of An Elevator System With A 2:1 Roping Configuration

Vertical vibrations affect passenger comfort during an elevator travel. Hoist ropes, due to their flexibility, loading conditions, and relatively low internal damping characteristics, largely determine the resonances within the system and, therefore, the amount of vibration. In this work the results of a study to investigate the vertical vibration caused by torque ripple generated at the drive system and transmitted through the suspension ropes to the car is presented. The machine torque ripple and the radial forces generated at the machine air-gap between the stator and the rotor are computed using FEM simulation. The 2:1 roping configuration system is modelled as an assemblage of one-dimensional distributed subsystems, the rope segments, with lumped inertia elements (car, counterweight, traction sheave, pulleys) at their ends, and acting together as a single system due to constraints imposed between adjacent subsystems. The eigenvalue problem is solved analytically and the natural frequencies and corresponding mode shapes obtained. The acceleration response at the suspended masses and at the drive machine end in a laboratory rig is measured during the system travel. The experimental results confirm the FEM simulation results obtained concerning the excitation frequencies. It is confirmed as well that the excitation frequencies close to the natural frequencies of the system are particularly magnified at the setup rig.