Composition of a magnetic-bearing system for horizontal shaft and its experimental results

1983 ◽  
Vol 103 (5) ◽  
pp. 121-128 ◽  
Author(s):  
Fumio Matsumura ◽  
Yoshimi Tanaka ◽  
Mamoru Kido ◽  
Yuji Akiyama
Keyword(s):  
Magnetic Bearing ◽  
Experimental Results ◽  
Horizontal Shaft ◽  
Bearing System

Modal Testing and Parameter Identification of Active Magnetic Bearing System

1995 ◽  
Author(s):  
Chong-Won Lee ◽  
Young-Ho Ha ◽  
Cheol-Soon Kim ◽  
Chee-Young Joh
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Modal Testing ◽  
Modal Parameters ◽  
Bearing System

Abstract Complex modal testing is employed for parameter identification of a four-axis active magnetic bearing system. In the test, magnetic bearings are used as exciters while the system is in operation. The experimental results show that the directional frequency response function, which is properly defined in the complex domain, is a powerful tool for identification of bearing as well as modal parameters.

Experimental Self-Sensing Results for a Magnetic Bearing

2001 ◽  
Author(s):  
Dominick T. Montie ◽  
Eric H. Maslen
Keyword(s):  
Critical Role ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Experimental Results ◽  
Magnetic Saturation ◽  
Estimation Technique ◽  
Magnetic Actuator ◽  
Linear Region ◽  
Bearing System ◽  
Hybrid Estimator

Experimental results are presented for a self-sensing magnetic bearing system operated in both the linear and saturation regions. When the magnetic actuator operates exclusively in the linear region, a simple, inexpensive analog estimation technique is implemented. When operating conditions are expected to drive the bearing into magnetic saturation, a digital-analog hybrid estimator is introduced. It follows that expected operating conditions of the magnetic bearing system determine the necessary complexity of the position estimator. Further, the performance of the analog hardware plays a critical role in the operation of the estimator from the perspective of signal gain and phase. Such hardware issues, as they relate to estimator performance, are discussed. Recommendations for improved estimator performance in conjunction with reduced estimator cost and complexity follow.

Rigid Mode Vibration Control and Dynamic Behavior of Hybrid Foil-Magnetic Bearing (HFMB) Turbo Blower

2016 ◽  
Author(s):  
Sena Jeong ◽  
Jungwan Kim ◽  
Doyoung Jeon ◽  
Yong Bok Lee
Keyword(s):  
Vibration Control ◽  
Dynamic Behavior ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Low Speed ◽  
Vibration Stability ◽  
Turbo Blower ◽  
Foil Bearing ◽  
Aerodynamic Instability ◽  
Bearing System

In this study, experimental and analytical analyses of the vibration stability of a 225 kW class turbo blower with a hybrid foil-magnetic bearing (HFMB) were performed. First, critical speed and unbalance vibration responses were examined as part of the rotordynamic research. Then, an experimental double-suction turbo blower with an HFMB was built. The turbo blower consisted of an impeller at each end and a permanent magnet motor in the center. Its shaft diameter was 71.5 mm, its total length was 693 mm, and the weight of the rotor was 17.8 kg. The air foil bearing (AFB) utilized was 50 mm long and had a 0.7 aspect ratio. The results of analyses indicate that rigid mode (conical mode) occurred close to 8,036 rpm, and the results of natural frequency analysis and dynamic behavior prediction of the rotor-bearing system were similar to those obtained experimentally. However, in the experiments conducted, excessive vibration and rotor motion instability occurred in the range 12,000–15,000 rpm, which resulted from insufficient dynamic pressure caused by the length of the foil bearing being too short. Consequently, as the rotor speed increased, excessive rotor motion attributable to aerodynamic and bearing instability became evident. This study therefore focused on improving rotordynamic performance by rectifying rigid mode unstable vibration at low speed, 20,000 rpm, and asynchronous vibration due to aerodynamic instability by using HFMB with vibration control. Although the normal operating speed is 39,000 rpm, the experiments were conducted at 20,000 rpm. The experimental results obtained were compared for each bearing type (AFB and HFMB) to improve the performance of the vibration in the low speed region. The experimental results show that the HFMB technology results in superior vibration stability for unbalance vibration and aerodynamic instability in the range 12,000–15,000 rpm (200–250 Hz). The remarkable vibration reduction achieved from vibration control of the hybrid foil-magnetic rotor-bearing system show that oil-free turbomachinery can achieve excellent performance.

scholarly journals Nonlinear Behavior of a Magnetic Bearing System

1995 ◽  
Vol 117 (3) ◽  
pp. 582-588 ◽  
Author(s):  
L. N. Virgin ◽  
T. F. Walsh ◽  
J. D. Knight
Keyword(s):  
Degrees Of Freedom ◽  
Initial Conditions ◽  
Nonlinear Behavior ◽  
Analytical Techniques ◽  
Magnetic Bearing ◽  
Forced Response ◽  
The Mathematical Model ◽  
Two Degree Of Freedom ◽  
Sensitivity To Initial Conditions ◽  
Bearing System

This paper describes the results of a study into the dynamic behavior of a magnetic bearing system. The research focuses attention on the influence of nonlinearities on the forced response of a two-degree-of-freedom rotating mass suspended by magnetic bearings and subject to rotating unbalance and feedback control. Geometric coupling between the degrees of freedom leads to a pair of nonlinear ordinary differential equations, which are then solved using both numerical simulation and approximate analytical techniques. The system exhibits a variety of interesting and somewhat unexpected phenomena including various amplitude driven bifurcational events, sensitivity to initial conditions, and the complete loss of stability associated with the escape from the potential well in which the system can be thought to be oscillating. An approximate criterion to avoid this last possibility is developed based on concepts of limiting the response of the system. The present paper may be considered as an extension to an earlier study by the same authors, which described the practical context of the work, free vibration, control aspects, and derivation of the mathematical model.

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