Hybrid (hydrodynamic + permanent magnetic) journal bearings

2007 ◽  
Vol 221 (8) ◽  
pp. 881-891 ◽  
Author(s):  
H Hirani ◽  
P Samanta
Keyword(s):  
Permanent Magnets ◽  
Load Capacity ◽  
Rapid Development ◽  
Experimental Studies ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Axial Thrust ◽  
Hydrodynamic Bearing ◽  
Load Carrying

Survey of patents on bearings indicates the maturity of hydrodynamic and rapid development of magnetic bearings. Active magnetic bearings are costlier compared with permanent magnetic bearings. To understand the performance characteristics of permanent magnetic bearings, an experimental setup has been developed. Experimental studies on radial permanent magnetic bearings demonstrated the drawbacks, such as high axial thrust and low load capacity. This has led the authors to hybridize the permanent magnet with hydrodynamic technology and to explore the possibility of achieving the low starting torque of a permanent magnetic bearing and the medium to high load carrying capacity of a hydrodynamic bearing in a single bearing arrangement. Simulation is carried out in order to reduce axial force-effect and enhance the radial force supported by the permanent magnetic bearing. Results of simulation on permanent magnetic bearing have been compared with that of published research papers. Finally an algorithm has been developed to investigate the coupling of forces generated by permanent magnets and hydrodynamic actions. Results of load sharing have been reported. The experimentally measured displacements of the shaft running at 500, 2000, and 3000 r/min have been plotted. The effect of hydrodynamics on shaft orbit has been illustrated.

Magnetic Bearing Using Rotation Magnetized Direction Configuration

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
K. P. Lijesh ◽  
Harish Hirani
Keyword(s):  
Rare Earth ◽  
Carrying Capacity ◽  
Permanent Magnets ◽  
Load Capacity ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Magnetic Bearing ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Ring Magnet

Passive magnetic bearing (PMB), made of high remanence rare earth permanent magnets, is brittle in nature; therefore, precautions must be taken to reduce the chances of vibration transmitting to the permanent magnets. In the present work, a rotation magnetized direction (RMD) structure made of aluminum ring and square shaped magnetic pieces has been proposed. A comparative study of load carrying capacities of sector magnets and square magnets has been presented. Three-dimensional (3D) Coulombian model was solved to estimate the load carrying capacity. Theoretical and experimental studies on the load carrying capacities of full ring magnet (more prone to cracking) and the proposed structure have been presented to prove the superiority of the proposed structure. In addition to load capacity, comparison between amplitudes of vibration at different frequencies, orbit plots, and time taken for breakage of the magnets at the resonance frequency has been presented.

Single Plane Radial, Magnetic Bearings Biased With Poles Containing Permanent Magnets

2003 ◽  
Vol 125 (1) ◽  
pp. 178-185 ◽  
Author(s):  
Andrew Kenny ◽  
Alan B. Palazzolo
Keyword(s):  
Power Loss ◽  
Permanent Magnets ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Single Plane ◽  
Side Load ◽  
Coil Inductance ◽  
Coil Resistance ◽  
Radial Magnetic Bearing

Magnetic bearings biased with permanent magnets have lower coil resistance power losses, and the magnets can also be used to help support a constant side load. In this paper, the performance of a single plane radial magnetic bearing biased with permanent magnets in several poles is presented. Although it has less load capacity and stiffness than a similarly sized electrically biased single plane heteropolar bearing, it does not require bias current, and its ratio of load capacity to coil resistance power loss is significantly better. This type of permanent magnet bearing has only a single plane of poles. It can be distinguished from the homopolar bearing type which has two planes and which can also be biased with permanent magnets. Magnetic circuit models for the novel single plane bearing are presented along with verification by finite element models. Equations for the key performance parameters of load capacity, stiffness, coil inductance and resistive power loss are also presented.

scholarly journals Development and Experimental Validation of Auxiliary Rolling Bearing Models for Active Magnetic Bearings (AMBs) Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Anna Tangredi ◽  
Enrico Meli ◽  
Andrea Rindi ◽  
Alessandro Ridolfi ◽  
Pierluca D’Adamio ◽  
...  
Keyword(s):  
Load Capacity ◽  
Critical Phenomenon ◽  
Magnetic Bearing ◽  
Design Tool ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Short Period ◽  
Auxiliary Bearing ◽  
Bearing System

Nowadays, the search for increasing performances in turbomachinery applications has led to a growing utilization of active magnetic bearings (AMBs), which can bring a series of advantages thanks to their features: AMBs allow the machine components to reach higher peripheral speeds; in fact there are no wear and lubrication problems as the contact between bearing surfaces is absent. Furthermore, AMBs characteristic parameters can be controlled via software, optimizing machine dynamics performances. However, active magnetic bearings present some peculiarities, as they have lower load capacity than the most commonly used rolling and hydrodynamic bearings, and they need an energy source; for these reasons, in case of AMBs overload or breakdown, an auxiliary bearing system is required to support the rotor during such landing events. During the turbomachine design process, it is fundamental to appropriately choose the auxiliary bearing type and characteristics, because such components have to resist to the rotor impact; so, a supporting design tool based on accurate and efficient models of auxiliary bearings is very useful for the design integration of the Active Magnetic Bearing System into the machine. This paper presents an innovative model to accurately describe the mechanical behavior of a complete rotor-dynamic system composed of a rotor equipped with two auxiliary rolling bearings. The model, developed and experimentally validated in collaboration with Baker Hughes a GE company (providing the test case and the experimental data), is able to reproduce the key physical phenomena experimentally observed; in particular, the most critical phenomenon noted during repeated experimental combined landing tests is the rotor forward whirl, which occurs in case of high friction conditions and greatly influences the whole system behavior. In order to carefully study some special phenomena like rotor coast down on landing bearings (which requires long period of time to evolve and involves many bodies and degrees of freedom) or other particular events like impacts (which occur in a short period of time), a compromise between accuracy of the results and numerical efficiency has been pursued. Some of the elements of the proposed model have been previously introduced in literature; however the present work proposes some new features of interest. For example, the lateral and the axial models have been properly coupled in order to correctly reproduce the effects observed during the experimental tests and a very important system element, the landing bearing compliant suspension, has been properly modelled to more accurately describe its elastic and damping effects on the system. Furthermore, the model is also useful to characterize the frequencies related to the rotor forward whirl motion.

Comparison of three-pole AMB and HMB for magnetic suspended molecular pump

2018 ◽  
Vol 32 (34n36) ◽  
pp. 1840074
Author(s):  
Jintao Ju ◽  
Xiaobin Liu ◽  
Zegang Xu ◽  
Chao Gu ◽  
Yilin Liu
Keyword(s):  
Power Loss ◽  
High Vacuum ◽  
Three Dimensional ◽  
Radial Force ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Rotating Speed ◽  
Characteristics Analysis ◽  
Current Characteristics

Molecular pumps have been widely used in the vacuum metallurgy, coating, semiconductor manufacturing and many other fields in which the high vacuum, ultra-clean environment is needed. The application of magnetic bearings can bring many advantages for molecular pump, such as eliminating the friction, decreasing the power loss, lowering the maintenance costs, and increasing the rotating speed and service life. Besides, the magnetic bearings can fundamentally solve the vacuum chamber pollution problem which is caused by the backflow of lubrication oil steam. The three-pole magnetic bearings are the simplest structure of radial magnetic bearings and can be driven by three-phase converter which has the advantages of low costs, small volume and low power loss. In this paper, the performance of the three-pole active magnetic bearing (AMB) and hybrid magnetic bearing (HMB) are compared based on radial force–current characteristics analysis. Firstly, the mathematical model of three-pole AMB and HMB is built by equivalent magnetic circuit model, and the radial force–current characteristics are analyzed. Then, simulation by the three-dimensional (3D) finite element method (FEM) is performed. Finally, the experiment is conducted. The FEM results are consistent with the analytical results, showing that the nonlinearity and coupling of three-pole HMB are lower than three-pole AMB. The reason of causing nonlinearity and coupling is also discussed.

Design and Testing of a Permanent Magnet Biased Active Magnetic Bearing

1999 ◽  
Author(s):  
Ross W. Overstreet ◽  
George T. Flowers ◽  
Gyorgy Szasz
Keyword(s):  
Permanent Magnet ◽  
Permanent Magnets ◽  
Experimental Testing ◽  
Control Strategies ◽  
Active Vibration Control ◽  
Electrical Current ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Flux Flow

Abstract Magnetic bearings provide rotor support without direct contact. There is a great deal of current interest in using magnetic bearings for active vibration control. Conventional designs use electrical current to provide the bias flux, which is an integral feature of most magnetic bearing control strategies. Permanent magnet biased systems are a relatively recent innovation in the field of magnetic bearings. The bias flux is supplied by permanent magnets (rather than electrically) allowing for significant decreases in resistance related energy losses. The use of permanent magnet biasing in homopolar designs results in a complex flux flow path, unlike conventional radial designs which are much simpler in this regard. In the current work, a design is developed for a homopolar permanent magnet biased magnetic bearing system. Specific features of the design and results from experimental testing are presented and discussed. Of particular interest is the issue of reduction of flux leakage and more efficient use of the permanent magnets.

Dynamic Load Capabilities of Active Electromagnetic Bearings

1991 ◽  
Vol 113 (3) ◽  
pp. 598-603 ◽  
Author(s):  
K. R. Bornstein
Keyword(s):  
Dynamic Load ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Saturation Point ◽  
Dynamic Capacity ◽  
Static Capacity ◽  
Wide Range ◽  
Selection Of

Magnetic bearings are finding increasing use in a wide range of applications. It is well known that the static capacity of a bearing can be determined by its saturation point. The static capacity has often been the prime criterion for the selection of magnetic bearing size. The dynamic capacity of a bearing is a much more complicated function. This paper will develop equations to express the dynamic load capacity of a magnetic bearing in terms of its amplifier size, the frequency of excitation, the magnetic airgap, the method of force actuation, and certain nondimensional terms.

Optimized Realization of Fault-Tolerant Heteropolar Magnetic Bearings for Active Vibration Control

1999 ◽  
Author(s):  
Uhn Joo Na ◽  
Alan Palazzolo
Keyword(s):  
Lagrange Multiplier ◽  
Global Minimum ◽  
Fault Tolerant ◽  
Load Capacity ◽  
Active Vibration Control ◽  
Fault Tolerant Control ◽  
Optimization Method ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Control Voltage

Abstract The nature of coupling in the heteropolar magnetic bearings permits other remaining active coils in the stator to assume actions of the failed coils to produce the same force resultants. This fault-tolerant control usually reduces load capacity because the redistribution of the magnetic flux which compensates for the failed coils leads to premature saturation in the stator or journal. Distribution matrix of voltages which consists of redefined biasing voltage vector and two control voltage vectors can be optimized in the manner that peak flux density is minimized. An elegant optimization method using Lagrange Multiplier is presented in this paper. The redistribution matrices calculated with Lagrange Multiplier method were compared with Maslen and Meeker’s solutions, local minima are guaranteed and also the global minimum can be obtained if an effective global minimum searching algorithm is used. The linearized control forces can be realized up to certain combination of 5 poles failed for the 8 pole magnetic bearing. Position stiffness and voltage stiffness are calculated for the fault-tolerant magnetic bearings. Simulations show that fault-tolerant control of the multiple poles failed magnetic bearings with a horizontal flexible rotor can be stabilized with reduced load capacity.

Steady-State Control of Hybrid Foil-Magnetic Bearings

2012 ◽  
Author(s):  
Ye Tian ◽  
Yanhua Sun ◽  
Lie Yu
Keyword(s):  
Steady State ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
State Control ◽  
Foil Bearings ◽  
Foil Bearing ◽  
State Controller ◽  
Steady State Control ◽  
And Control

A hybrid foil-magnetic bearing is combination of a foil bearing and a magnetic bearing, which takes advantages of both bearings while compensating each other the weaknesses. It is a solution of friction and wear of foil bearings at low speeds and limited load capacity of magnetic bearings. Furthermore, load sharing and control of dynamics can be achieved in a hybrid foil-magnetic bearing. However, in the hybrid foil-magnetic bearing, the journal should run at certain eccentricity and attitude angle in order to take part of the loads, but the magnetic bearing would attempt to force the journal to the reference position at all times while using a conventional PID controller. Therefore, it is necessary to design a new control algorithm to overcome the contradictions. In this paper, the steady-state characteristics of a hybrid foil-magnetic bearing were analyzed. Then a searching algorithm was presented and a steady-state controller was designed to determine the steady-state working position of the hybrid foil-magnetic bearings. Finally, simulations were done to verify performances of the searching algorithm and designed steady-state controller, and the results show its validity.

Multi-Objective Optimization Design of Nonlinear Magnetic Bearing Rotordynamic System

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Wan Zhong ◽  
Alan Palazzolo ◽  
Xiao Kang
Keyword(s):  
Power Loss ◽  
Optimization Design ◽  
Hot Spot ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Control Law ◽  
Steady State Operation ◽  
Mass Minimization ◽  
Compact Design

Nonlinear vibrations and their control are critical in improving the magnetic bearings system performance and in the more widely spread use of magnetic bearings system. Multiple objective genetic algorithms (MOGAs) simultaneously optimize a vibration control law and geometrical features of a set of nonlinear magnetic bearings supporting a generic flexible, spinning shaft. The objectives include minimization of the actuator mass, minimization of the power loss, and maximization of the external static load capacity of the rotor. Levitation of the spinning rotor and the nonlinear vibration amplitude by rotor unbalance are constraint conditions according to International Organization for Standardization (ISO) specified standards for the control law search. The finite element method (FEM) was applied to determine the temperature distribution and identify the hot spot of the actuator during steady-state operation. Nonlinearities include magnetic flux saturation, and current and voltage limits of power amplifiers. Pareto frontiers were applied to identify and visualize the best-compromised solutions, which give a most compact design with minimum power loss whose vibration amplitudes satisfy ISO standards.

Magnetic Bearing Design for Reduced Power Consumption

1996 ◽  
Vol 118 (4) ◽  
pp. 839-846 ◽  
Author(s):  
E. H. Maslen ◽  
P. E. Allaire ◽  
M. D. Noh ◽  
C. K. Sortore
Keyword(s):  
Power Consumption ◽  
Permanent Magnet ◽  
Gas Turbines ◽  
Load Capacity ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Fluid Film ◽  
Total Power ◽  
Total Power Consumption ◽  
Bearing Design

Magnetic bearings have relatively low power consumption compared to fluid film and rolling element bearings. They are now candidates for supporting gas turbines and aeropropulsion engines. This paper describes the design and construction of permanent magnet biased, actively controlled magnetic bearings for a flexible rotor. The rotor was originally supported in fluid film bearings consuming as much as 3000 watts of power. For the magnetic bearing, both permanent magnets and electromagnets are used in a configuration which effectively provides the necessary fluxes in the appropriate air gaps to support the rotor. The theoretical development related to the bearing design is presented along with some experimental performance results. The results include measurements of power consumption, load capacity, bearing linearized coefficients, and the dynamic response of the rotor. The measured total power consumption, excluding shaft losses, was 210 watts in the permanent magnet biased bearing.

Sign in / Sign up

Export Citation Format

Share Document