Unbalance Response of the Rotors Supported on Gas Foil Bearing Integrated with Active Magnetic Bearing

2019 ◽

Author(s):

Kamal Kumar Basumatary ◽

Karuna Kalita ◽

Sashindra K. Kakoty ◽

Seamus D. Garvey

Keyword(s):

High Speed ◽

Low Cost ◽

Current Source ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Electromagnetic Actuators ◽

Manufacturing Method ◽

Foil Bearings ◽

Foil Bearing ◽

Small Series

Abstract The hybrid Gas Foil Bearings combining the Gas Foil Bearing and Active Magnetic Bearing is a possibility for application in high-speed turbomachinery and a few developments have been made in this context. As such, the cost of conventional Gas Foil Bearing increases due to its requirement of precise manufacturing method and the coating material for the top foil and bump foil. In case of Active Magnetic Bearing, the normal electrical arrangement includes a multiplicity of independently controlled current sources usually at least four drives per bearing which increases its cost. Therefore, the hybrid Gas Foil Bearing will have much higher cost. In this work, a new electrical arrangement for the electromagnetic actuators of the hybrid Gas Foil Bearing has been proposed. The new arrangement requires only two drives per bearing and the bias current has been provided (in the same set of windings) through a simple rectifier with small series choke and shunt capacitor. As the number of drives required is less, the proposed bearing will have low cost. Implementing the new approach, the force vectors are achieved using only two current-source drives whereas the usual conventional arrangement requires four such drives. Numerical simulations are performed to explore the capabilities of the low cost bearing.

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Isotropic Optimal Control of Active Magnetic Bearing System

Journal of Dynamic Systems Measurement and Control ◽

10.1115/1.2802348 ◽

1996 ◽

Vol 118 (4) ◽

pp. 721-726 ◽

Cited By ~ 12

Author(s):

Cheol-Soon Kim ◽

Chong-Won Lee

Keyword(s):

Optimal Control ◽

System Analysis ◽

Control Method ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Control Effort ◽

Response Component ◽

Unbalance Response ◽

Control Scheme ◽

Bearing System

As a new rotor control scheme, isotropic control of weakly anisotropic rotor bearing system in complex state space is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Advantages of the scheme are that the controlled system always retains isotropic eigenstructure, leading to circular whirling due to unbalance and that it is efficient for control of unbalance response. And the system analysis and controller design becomes simple and yet comprehensive since the order of the matrices treated in the complex domain approach is half of that in the real approach. The control scheme is applied to a rigid rotor-active magnetic bearing system which is digitally controlled and the control performance is investigated experimentally in relation to unbalance response and control energy. It is found that the isotropic optimal control method, which essentially eliminates the backward unbalance response component, is more efficient than the conventional optimal control in that it gives smaller major whirl radius and yet it often requires less control effort.

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Vibration control of high-speed rotor supported by hybrid foil-magnetic bearing with sudden imbalance

Journal of Vibration and Control ◽

10.1177/1077546315592531 ◽

2015 ◽

Vol 23 (8) ◽

pp. 1296-1308 ◽

Cited By ~ 6

Author(s):

Sena Jeong ◽

Yong Bok Lee

Keyword(s):

Mass Loss ◽

Vibration Control ◽

High Speed ◽

Turbine Rotor ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Control Force ◽

Transient Vibration ◽

Stability Performance ◽

Foil Bearing

A hybrid foil-magnetic bearing (HFMB) was successfully studied as a vibration isolator by introducing a sudden imbalance or an unexpected disturbance during turbine/rotor operation. This HFMB is used to achieve stability during transient vibration behavior. The HFMB consists of two oil-free bearing technologies: an active magnetic bearing (AMB) and air foil bearing (AFB). Using both technologies takes advantage of the strengths of each bearing while compensating for their inherent weaknesses. In addition, the HFMB has good dynamic characteristics, and the damping can be adjusted using the appropriate gain selection for the AMB controller. Based on these unique features, dynamic stability can be enhanced, even if a sudden imbalance occurs while the rotor is operating. In this study, a rigid rotor was operated at up to 12,000 rpm and tested using a control algorithm to reduce the sudden imbalance vibration amplitudes. The experiment was conducted under the situation that the mass dropped out at 6,000 rpm. In order to validate the stability performance of the HFMB with a sudden mass loss, the vibration response results for the AFB and HFMB were compared. When applying the HFMB, the asynchronous vibration was suppressed, and the 1x vibration results showed reductions of almost 30%. When the sudden mass loss occurred, the magnetic control force was remarkably effective at reducing the asynchronous vibration of the rotor supported by the HFMB. In conclusion, it was experimentally verified that using the HFMB made sudden imbalance vibration control possible during rotor operation with an air foil bearing. In this respect, the HFMB has the characteristics of high stiffness/damping, which prevent rubbing and suppress excessive vibration due to a sudden imbalance event.

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Unbalance response of a magnetic suspended dual-rotor system

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410019858011 ◽

2019 ◽

Vol 233 (15) ◽

pp. 5758-5772

Author(s):

Dongxiong Wang ◽

Nianxian Wang ◽

Kuisheng Chen

Keyword(s):

Magnetic Bearing ◽

Rotor System ◽

Magnetic Bearings ◽

Active Magnetic Bearing ◽

Active Magnetic Bearings ◽

Maximum Displacement ◽

Critical Speeds ◽

Unbalance Response ◽

Rotor Imbalance ◽

Aero Engine

The magnetic suspended dual-rotor system applied in more electric aero-engine can eliminate the wear and lubrication system of mechanical bearings and solve the vibration control issue of system effectively, which provides the possibility to improve the performance of aero-engine significantly. This research focuses on the unbalance response of the magnetic suspended dual-rotor system. First, a structure of dual-rotor system supported by two active magnetic bearings and two permanent magnetic bearings is presented. With proportional derivative (PD) control adopted, the bearing characteristics of active magnetic bearings are modeled as the equivalent stiffness and equivalent damping, and the permanent magnetic bearings are modeled as elastic support. Then, the Riccati transfer matrix method with good numerical stability is used to establish the model of the magnetic suspended dual-rotor system unbalance response. Subsequently, the validity of the present formulation has been tested against some known results available in literature and the simulation results obtained by finite element method (FEM). Finally, the dynamic characteristics of the unbalance response are investigated. The results reveal that the influence of the inner rotor imbalance excitation on the magnetic suspended dual-rotor system unbalance response is much larger than that of the outer rotor imbalance excitation. In addition, the critical speeds increase with the proportional coefficient, and the derivative coefficient can affect the amplitudes of the unbalance response, but not critical speeds. From the perspectives of the maximum bearing capacity and maximum displacement of active magnetic bearing-rotor system, the possibility of the magnetic suspended dual-rotor system safely crossing the critical speeds of the first three orders is investigated.

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Isotropic Control of Rotor Bearing System

14th Biennial Conference on Mechanical Vibration and Noise: Vibration of Rotating Systems ◽

10.1115/detc1993-0208 ◽

1993 ◽

Author(s):

Cheol-Soon Kim ◽

Chong-Won Lee

Keyword(s):

State Space ◽

Transient Response ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Control Performance ◽

Complex State ◽

Unbalance Response ◽

Control Scheme ◽

Rotor Bearing ◽

Bearing System

Abstract A new rotor control scheme, the isotropic control of anisotropic rotor bearing system in complex state space, is proposed, which utilizes the concepts on the eigenstructure of the isotropic rotor system. Then the control scheme is applied to an active magnetic bearing system and the control performance is investigated in relation to control energy, transient response, and unbalance response. In particular, it is shown that the proposed method is efficient for control of unbalance response.

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