scholarly journals Adaptive Spindle Balancing Using Magnetically Levitated Bearings

1999 ◽  
Author(s):  
Patrick Barney ◽  
James Lauffer ◽  
James Redmond ◽  
William Sullivan ◽  
Rebecca Petteys
Keyword(s):  
High Speed ◽  
System Analysis ◽  
High Vacuum ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Physical Contact ◽  
Frictional Drag ◽  
Experimental Implementation ◽  
Amb System ◽  
Differential Control

Abstract A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools. The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller.

Influences of Assault Blocks on Rotor Vibrations in AMB System

2015 ◽  
Vol 9 (1) ◽  
pp. 496-503
Author(s):  
Zhu Yili ◽  
Zhang Yongchun
Keyword(s):  
High Speed ◽  
Dynamic Models ◽  
Dynamic Stiffness ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Control Methods ◽  
Rotor Vibration ◽  
Dynamic Simulations ◽  
Amb System ◽  
Theoretical Results

In an active magnetic bearing (AMB) system, the rotor always rotates at extremely high speed which always accompany with huge vibrations and noises. Most of the former researches associated with reducing the rotor vibrations are mainly focused on the control methods of AMB. A new method of installing series of assault blocks in the rotor is proposed to reduce the rotor vibrations. Firstly, the dynamic models of rotor supported by AMB considering the influences of assault blocks are established. Then, both dynamic simulations with and without assault blocks are carried out separately using the real-time AMB support dynamic stiffness. The rotor vibration displacements are mainly analyzed. Finally, relevant experiments are made to verify the theoretical results. Both theoretical and experimental results validated the advantages of using assault blocks.

Design, Modeling, Fabrication, Back-to-Back Test of a Magnetic Bearing System for High-Speed BLDCM Application

2015 ◽  
Vol 137 (11) ◽  
Author(s):  
Bangcheng Han ◽  
Shiqiang Zheng
Keyword(s):  
High Speed ◽  
Mechanical Design ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Resistive Load ◽  
Test Results ◽  
Test Setup ◽  
Brushless Dc ◽  
Amb System ◽  
Rotor Assembly

This paper describes in detail the design, construction, and testing of an active magnetic bearing (AMB) system for high-speed permanent magnet (PM) brushless DC motor (BLDCM) application. A back-to-back (BTB) test setup which consists of two BLDCMs connected by a high-speed flexible coupling is designed and built: the first one acts as the motor and the other one acts as the generator with resistive load. The dynamic model of the rigid rotor supported by AMBs, and its electromagnetic and feedback control design aspects are also provided. Mechanical design aspects are rotor assembly, radial AMB (RAMB), and thrust AMB (TAMB). Finally, full-loaded test results of the AMBs are given using the BTB experimental test setup that adopts two 100 kW electric machines supported by AMBs.

Development of Exclusive Controller and HILS for Active Magnetic Bearing System

2012 ◽  
Vol 241-244 ◽  
pp. 1365-1369
Author(s):  
Seok Jo Go ◽  
Chi Yen Kim ◽  
Min Kyu Park ◽  
Young Jin Lee ◽  
Bin Yao
Keyword(s):  
High Speed ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
System Response ◽  
Current Output ◽  
Linear Current ◽  
Amb System ◽  
Fast Control ◽  
And Control ◽  
Bearing System

The active magnetic bearing system has been studied for long period. Comparing with long research history, the AMB application into industrial field is shown slowly for various causes. One of primary factor is to make up exclusive controller which can generate fast linear current output. Thus, this paper developed the exclusive AMB controller mounted high speed DSP which can operate so fast control calculation that improve system response ability. Especially, to consider the fusion of AMB system and control software, the development is conducted in HILS system with dSPACE from the beginning. Although HILS system is adopted, the developed ABM controller simplified the whole system and could make up optimized control algorithm promptly by measuring and applying the system gain and characteristics of them monitored by the HILS system in real time.

Low Power Consumption Nonlinear Control with H∞ Compensator for a Zero-Bias Flywheel AMB System

2004 ◽  
Vol 10 (8) ◽  
pp. 1151-1166 ◽  
Author(s):  
S. Sivrioglu ◽  
K. Nonami ◽  
M. Saigo
Keyword(s):  
Power Consumption ◽  
Nonlinear Control ◽  
Digital Signal Processor ◽  
High Speed ◽  
Digital Signal ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Zero Bias ◽  
Control Approach ◽  
Amb System

A nonlinear control approach based on a control current switching rule is studied experimentally for an energy storage flywheel active magnetic bearing (AMB) system. In the proposed control, only one electromagnet in each axis of the AMB has a current flow at any given time, depending on the rotor displacement. This results in a power consumption that is lower than a linear control employing a bias current. The equation of motion for the rigid rotor-AMB system is transformed to have a decentralized structure for the control design. To compute nonlinear control currents, an H ∞ compensator is designed for each axis of the AMB. The proposed approach is experimentally verified using a high-speed digital signal processor.

Pseudospectral method-based optimal control for a nonlinear five degree of freedom active magnetic bearing system

2021 ◽  
pp. 014233122098653
Author(s):  
Sudipta Saha ◽  
Arunava Banerjee ◽  
Syed Muhammad Amrr ◽  
Mashuq un Nabi
Keyword(s):  
Optimal Control ◽  
Control Method ◽  
Pseudospectral Method ◽  
Magnetic Bearing ◽  
Degree Of Freedom ◽  
Active Magnetic Bearing ◽  
Physical Contact ◽  
Computational Time ◽  
Optimal Control Strategy ◽  
Amb System

Active magnetic bearings (AMB) are used to suspend the rotor freely inside the stator to avoid any physical contact between them. Thus, it helps in significantly reducing the wear and tear that may cause a system breakdown. With the advancement of power electronics and the implementation of advanced control techniques, the use of AMB in industrial applications has increased. This paper proposes an optimal control strategy for the five degree of freedom (DOF) AMB system. The time-energy consumption of input is minimized by the application of a relatively new optimal control method called the pseudospectral method (PSM). Since the AMB is a nonlinear system, therefore the implementation of classical optimal control strategies becomes challenging. Thus, the PSM first transforms the optimal control problem at non-uniform nodes and converts it into a nonlinear programming problem, which is relatively easier to tackle. The PSM, as demonstrated in this paper, is able to find optimal solutions using relatively fewer grid points which in turn reduces the computational time and converges to the solution faster. The simulation analysis for the AMB system using two different types of PSM, that is, Legendre PSM and the Chebyshev PSM illustrates the optimal performance of the proposed strategy.

Some Nonlinear Effects of Magnetic Bearings

1999 ◽  
Author(s):  
Norbert Steinschaden ◽  
Helmut Springer
Keyword(s):  
Equations Of Motion ◽  
Period Doubling ◽  
Path Following ◽  
Nonlinear Effects ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Active Magnetic Bearing ◽  
Nonlinear Phenomena ◽  
Amb System ◽  
Large Rotor

Abstract In order to get a better understanding of the dynamics of active magnetic bearing (AMB) systems under extreme operating conditions a simple, nonlinear model for a radial AMB system is investigated. Instead of the common way of linearizing the magnetic forces at the center position of the rotor with respect to rotor displacement and coil current, the fully nonlinear force to displacement and the force to current characteristics are used. The AMB system is excited by unbalance forces of the rotor. Especially for the case of large rotor eccentricities, causing large rotor displacements, the behaviour of the system is discussed. A path-following analysis of the equations of motion shows that for some combinations of parameters well-known nonlinear phenomena may occur, as, for example, symmetry breaking, period doubling and even regions of global instability can be observed.

An Evaluation of Stability Indices Using Sensitivity Functions for Active Magnetic Bearing Supported High-Speed Rotor

2006 ◽  
Vol 129 (2) ◽  
pp. 230-238 ◽  
Author(s):  
Naohiko Takahashi ◽  
Hiroyuki Fujiwara ◽  
Osami Matsushita ◽  
Makoto Ito ◽  
Yasuo Fukushima
Keyword(s):  
High Speed ◽  
Transfer Functions ◽  
Mimo System ◽  
Magnetic Bearing ◽  
Singular Value ◽  
Active Magnetic Bearing ◽  
Sensitivity Functions ◽  
Phase Lags ◽  
The Stability ◽  
Stability Indices

In active magnetic bearing (AMB) systems, stability is the most important factor for reliable operation. Rotor positions in radial direction are regulated by four-axis control in AMB, i.e., a radial system is to be treated as a multi-input multioutput (MIMO) system. One of the general indices representing the stability of a MIMO system is “maximum singular value” of a sensitivity function matrix, which needs full matrix elements for calculation. On the other hand, ISO 14839-3 employs “maximum gain” of the diagonal elements. In this concept, each control axis is considered as an independent single-input single-output (SISO) system and thus the stability indices can be determined with just four sensitivity functions. This paper discusses the stability indices using sensitivity functions as SISO systems with parallel/conical mode treatment and/or side-by-side treatment, and as a MIMO system with using maximum singular value; the paper also highlights the differences among these approaches. In addition, a conversion from usual x∕y axis form to forward/backward form is proposed, and the stability is evaluated in its converted form. For experimental demonstration, a test rig diverted from a high-speed compressor was used. The transfer functions were measured by exciting the control circuits with swept signals at rotor standstill and at its 30,000 revolutions/min rotational speed. For stability limit evaluation, the control loop gains were increased in one case, and in another case phase lags were inserted in the controller to lead the system close to unstable intentionally. In this experiment, the side-by-side assessment, which conforms to the ISO standard, indicates the least sensitive results, but the difference from the other assessments are not so great as to lead to inadequate evaluations. Converting the transfer functions to the forward/backward form decouples the mixed peaks due to gyroscopic effect in bode plot at rotation and gives much closer assessment to maximum singular value assessment. If large phase lags are inserted into the controller, the second bending mode is destabilized, but the sensitivity functions do not catch this instability. The ISO standard can be used practically in determining the stability of the AMB system, nevertheless it must be borne in mind that the sensitivity functions do not always highlight the instability in bending modes.

Dynamic Modeling and Analysis of Active Magnetic Bearings

2014 ◽  
Vol 494-495 ◽  
pp. 685-688
Author(s):  
Rong Gao ◽  
Gang Luo ◽  
Cong Xun Yan
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Modeling ◽  
Magnetic Bearing ◽  
Integrated System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Modeling And Analysis ◽  
Amb System ◽  
Mathematics Method

Active magnetic bearing (AMB) system is a complex integrated system including mechanics, electronic and magnetism. In order to research for the basic dynamic characteristic of rotor supported by AMB, it is necessary to present mathematics method. The dynamics formula of AMB is established using theory means of dynamics of rotator and mechanics of vibrations. At the same tine, the running stability of rotor is analyzed and the example is presented in detail.

scholarly journals Nonlinear Vibrations of a Rotor-Active Magnetic Bearing System with 16-Pole Legs and Two Degrees of Freedom

2020 ◽  
Vol 2020 ◽  
pp. 1-29 ◽  
Author(s):  
W. Zhang ◽  
R. Q. Wu ◽  
B. Siriguleng
Keyword(s):  
Perturbation Method ◽  
Electromagnetic Force ◽  
Nonlinear Vibrations ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Time Varying ◽  
Asymptotic Perturbation Method ◽  
Amb System ◽  
Asymptotic Perturbation ◽  
Quadratic And Cubic Nonlinearities

The asymptotic perturbation method is used to analyze the nonlinear vibrations and chaotic dynamics of a rotor-active magnetic bearing (AMB) system with 16-pole legs and the time-varying stiffness. Based on the expressions of the electromagnetic force resultants, the influences of some parameters, such as the cross-sectional area Aα of one electromagnet and the number N of windings in each electromagnet coil, on the electromagnetic force resultants are considered for the rotor-AMB system with 16-pole legs. Based on the Newton law, the governing equation of motion for the rotor-AMB system with 16-pole legs is obtained and expressed as a two-degree-of-freedom system with the parametric excitation and the quadratic and cubic nonlinearities. According to the asymptotic perturbation method, the four-dimensional averaged equation of the rotor-AMB system is derived under the case of 1 : 1 internal resonance and 1 : 2 subharmonic resonances. Then, the frequency-response curves are employed to study the steady-state solutions of the modal amplitudes. From the analysis of the frequency responses, both the hardening-type nonlinearity and the softening-type nonlinearity are observed in the rotor-AMB system. Based on the numerical solutions of the averaged equation, the changed procedure of the nonlinear dynamic behaviors of the rotor-AMB system with the control parameter is described by the bifurcation diagram. From the numerical simulations, the periodic, quasiperiodic, and chaotic motions are observed in the rotor-active magnetic bearing (AMB) system with 16-pole legs, the time-varying stiffness, and the quadratic and cubic nonlinearities.

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