Experimental study on vibration control of spur geared rotor system with active magnetic bearings

Abstract

The gearbox vibrations and noise caused by variation of contact forces often causes failure in the components of gearbox, which are then transmitted to the surrounding structures. The concept of active control of gearbox vibrations with piezoelectric actuators at the mounting points has been analysed earlier in several studies, then with certain limitations. There has been little research on how Active Magnetic Bearings (AMBs) might mitigate gear vibrations. AMBs are used in this study to investigate active internal shaft vibration control caused by rotor unbalance, gear runout, transmission error, which usually resides within the gearbox. Hence, minimizing the effect of vibrational amplitude at gear mesh frequency and its harmonics to have quieter gear operation. A mathematical model is developed for the torsional-lateral dynamic analysis of a spur geared rotor-AMB system. Responses are computed numerically with different gear-rotor faults. Based on the mathematical model, setted up an experimental test rig in the laboratory, and the effectiveness of the proposed model is compared with and without the application of AMBs. The approach is based on active control of the shaft transverse vibration with an electromagnetic actuator. The control forces are applied to the rotor shafts supported on conventional rolling element bearings by an eight-pole radial AMB, as an auxiliary component and a closed-loop linear output feedback control is employed for stable, reliable, and robust operation. A linear PID controller working on differential mode is used to generate the appropriate control signals and the experimental results are presented. It was found that there is a considerable amount of reduction in the geared rotor vibration levels and correspondingly in overall measured gear noise levels.