Active Control of Gear Noise Using Magnetic Bearings for Actuation

2002 ◽  
Author(s):  
Marty Johnson ◽  
Mary Kasarda ◽  
Travis Bash
Keyword(s):  
Active Control ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Rotating Shaft ◽  
Noise And Vibration ◽  
Gear Noise ◽  
Gear Mesh ◽  
Four Square ◽  
Control Forces ◽  
Substantial Control

This paper investigates experimentally the active control of gear noise and vibration using magnetic bearing actuators in a feedforward active control scheme. The dynamic forces caused by gear meshing can produce large noise and vibration signatures that can cause annoyance and also fatigue mechanical components. In this work active magnetic bearings were used as actuators to introduce control forces very close to the source of the disturbance i.e. directly onto the rotating shaft. The proximity of the actuators to the source ensures that substantial control can be achieved using a small number of actuators. A four-square gear rig was constructed in order to test the control methodology experimentally. A proximity sensor placed near the gear teeth was used as a reference sensor and used to drive the two magnetic bearing actuators through a time domain filtered X-LMS control system to minimize the outputs from both vibration and pressure error sensors. At one microphone over 20 dB of reduction in acoustic levels was achieved at the gear mesh frequency and an overall reduction of 6 dB was demonstrated at four microphones. It is also shown that gear mesh noise and sideband frequencies can be simultaneously controlled.

scholarly journals Dynamic characteristics of triaxial active control magnetic bearing with asymmetric structure

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 9-13 ◽  
Author(s):  
Atsushi Nakajima ◽  
Katsuhiro Hirata ◽  
Noboru Niguchi ◽  
Masayuki Kato
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Active Control ◽  
Dynamic Characteristics ◽  
Negative Pressure ◽  
Axial Direction ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Asymmetric Structure ◽  
Element Analysis

Abstract Supporting forces of magnetic bearings are lower than those of mechanical bearings. In order to solve these problems, this paper proposes a new three-axis active control magnetic bearing (3-axis AMB) with an asymmetric structure where its rotor is attracted only in one axial direction due to a negative pressure of fluid. Our proposed 3-axis AMB can generate a large suspension force in one axial direction due to the asymmetric structure. The performances of our proposed 3-axis AMB are computed through 3-D finite element analysis.

Fault detection and tolerance in synchronous vibration control of rotor—magnetic bearing systems

2001 ◽  
Vol 215 (12) ◽  
pp. 1401-1416 ◽  
Author(s):  
M N Sahinkaya ◽  
M O T Cole ◽  
C R Burrows
Keyword(s):  
Vibration Control ◽  
Magnetic Bearing ◽  
Open Loop ◽  
Magnetic Bearings ◽  
Control Technique ◽  
Effective Control ◽  
System Response ◽  
Rotor Support ◽  
Measured System ◽  
Control Forces

The use of magnetic bearings in rotating machinery provides contact-free rotor support, and allows vibration control using both closed-loop and open-loop strategies. One of the simplest and most effective methods to reduce synchronous lateral vibration when using magnetic bearings is through an open-loop adaptive control technique, in which the amplitude and phase of synchronous magnetic control forces are adjusted automatically to minimize the measured vibrations along the rotor. However, transducer malfunction, or faults in the signal-processing channels, may cause the controller to adapt incorrectly, with unwanted and possibly catastrophic effects. It is shown that an extension to the control strategy, which utilizes the variances of the measured system response and identified parameters, enables the faults to be detected and accounted for so that a modified control action can achieve continued and effective control of the synchronous vibration. The approach is extended further to identify changes in external factors, such as unbalance and rotor dynamics. Various faults and perturbations are examined experimentally, and the ability of the controller to detect and compensate for these changes is demonstrated.

The Dynamic Analysis of an Energy Storage Flywheel System With Hybrid Bearing Support

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Hongchang Wang ◽  
Shuyun Jiang ◽  
Zupei Shen
Keyword(s):  
Control System ◽  
Energy Storage ◽  
Active Control ◽  
High Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Squeeze Film ◽  
Transmitted Force ◽  
Hybrid Bearing ◽  
Active Control System

Active magnetic bearings and superconducting magnetic bearings were used on a high-speed flywheel energy storage system; however, their wide industrial acceptance is still a challenging task because of the complexity in designing the elaborate active control system and the difficulty in satisfying the cryogenic condition. A hybrid bearing consisting of a permanent magnetic bearing and a pivot jewel bearing is used as the support for the rotor of the energy storage flywheel system. It is simple and has a long working life without requiring maintenance or an active control system. The two squeeze film dampers are employed in the flywheel system to suppress the lateral vibration, to enhance the rotor leaning stability, and to reduce the transmitted forces. The dynamic equation of the flywheel with four degrees of complex freedom is built by means of the Lagrange equation. In order to improve accuracy, the finite element method is utilized to solve the Reynolds equation for the dynamic characteristics of the squeeze film damper. When the calculated unbalance responses are compared with the test responses, they indicate that the dynamics model is correct. Finally, the effect of the squeeze film gap on the transmitted force is analyzed, and the appropriate gap should be selected to cut the energy loss and to control vibration of the flywheel system.

scholarly journals Instability Study of Magnetic Journal Bearing under S-CO2 Condition

2021 ◽  
Vol 11 (8) ◽  
pp. 3491
Author(s):  
Dokyu Kim ◽  
SeungJoon Baik ◽  
Jeong Ik Lee
Keyword(s):  
High Pressure ◽  
High Speed ◽  
Journal Bearing ◽  
Magnetic Bearing ◽  
Operating Conditions ◽  
Magnetic Bearings ◽  
Brayton Cycle ◽  
Functional Requirements ◽  
Rotating Shaft ◽  
Levitation Performance

A supercritical CO2 (S-CO2)-cooled Brayton cycle is under development for distributed power applications for remote regions. In order to successfully develop it, issues of controlling shaft levitation with bearings have to be solved. From several studies, magnetic bearings have been suggested for reliable levitation performance with reduced cost and complexity. However, several studies on magnetic bearing show that instability issues under high-pressure fluid and high-speed operating conditions may exist. The purpose of this research is to provide background for understanding the instability of magnetic bearings under S-CO2 conditions and propose functional requirements of the magnetic bearing. Thus, the rotating shaft with magnetic bearings operating under high pressure fluid was first analyzed. To test the theory, a magnetic bearing test rig was constructed. By comparing experimental data to the analysis results, the analysis results were verified. Therefore, the analysis results can be used for predicting instability in the future and can contribute to the development of better magnetic bearing controllers.

Design of Magnetic Bearings for Rotor Systems With Harmonic Excitations

1991 ◽  
Author(s):  
D. Dhar ◽  
L. E. Barrett
Keyword(s):  
Harmonic Excitation ◽  
Magnetic Bearing ◽  
Least Square ◽  
Magnetic Bearings ◽  
Rotor Systems ◽  
Bearing Stiffness ◽  
Control Forces ◽  
Stiffness And Damping ◽  
Flexible Rotor Systems ◽  
Modal Coordinates

Abstract This paper presents a method for calculating the control forces and the bearing stiffness and damping coefficients to control the response of multi-mass flexible rotor systems mounted on magnetic bearings and subjected to unbalance or harmonic excitation forces. The capability for inclusion of hydrodynamic bearings is retained to model seal effects or to permit the design of magnetic bearings for hybrid systems. Control forces at the magnetic bearing locations are evaluated based on the desired shaft response specified by the modal coordinates. These forces are determined such that the error between the desired response and the achieved response is minimized in a least-square sense. Equivalent bearing coefficients are calculated from the control forces and the achieved response, which when superimposed on the nominal bearing coefficients yield the resultant magnetic bearing coefficients required for control. An example case is presented where control of rotor response has been attempted at the first and the second unbalance critical speeds. The results demonstrate appreciable improvement in response using magnetic bearings.

A Test Stand for Dynamic Characterization of Oil-Free Bearings for Modern Gas Turbine Engines

2002 ◽  
Author(s):  
Erik E. Swanson ◽  
James F. Walton ◽  
Hooshang Heshmat
Keyword(s):  
Gas Turbine ◽  
High Speed ◽  
Dynamic Test ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Medium Size ◽  
Rotating Shaft ◽  
Foil Bearings ◽  
Rotor Bearing ◽  
Dynamic Simulator

A multi-purpose rotor-bearing dynamic simulator was designed and fabricated for the purpose of experimentally evaluating and validating performance of advanced oil-free and back-up bearings under realistic dynamic conditions. The rotor-bearing dynamic test rig is capable of operation to 25,000 RPM, has a 54 kg test rotor, is designed to simulate a medium size aero gas turbine engine rotor, and incorporates an electromagnetic loader/shaker capable of applying both static and dynamic loads to the rotating shaft. Testing was completed with the rotor fully supported by magnetic bearings, compliant foil bearings, hybrid foil/magnetic and Zero Clearance Auxiliary Bearings. These tests demonstrated numerous advances in oil-free bearing technology. The first ever achievements include: operation of a rotor with a mass in excess of 50 kg supported solely by foil bearings, operation of hybrid foil/magnetic bearings to high speed, continued operation following simulated magnetic bearing failures for a fully hybrid foil/magnetic bearing support system, and operation of a rotor supported solely by Zero Clearance Auxiliary Bearings. Data from several tests of the bearing systems are presented.

Design of Magnetic Bearings for Rotor Systems With Harmonic Excitations

1993 ◽  
Vol 115 (3) ◽  
pp. 359-366 ◽  
Author(s):  
D. Dhar ◽  
L. E. Barrett
Keyword(s):  
Harmonic Excitation ◽  
Magnetic Bearing ◽  
Least Square ◽  
Magnetic Bearings ◽  
Rotor Systems ◽  
Bearing Stiffness ◽  
Control Forces ◽  
Stiffness And Damping ◽  
Flexible Rotor Systems ◽  
Modal Coordinates

This paper presents a method for calculating the control forces and the bearing stiffness and damping coefficients to control the response of multi-mass flexible rotor systems mounted on magnetic bearings and subjected to unbalance or harmonic excitation forces. The capability for inclusion of hydrodynamic bearings is retained to model seal effects or to permit the design of magnetic bearings for hybrid systems. Control forces at the magnetic bearing locations are evaluated based on the desired shaft response specified by the modal coordinates. These forces are determined such that the error between the desired response and the achieved response is minimized in a least-square sense. Equivalent bearing coefficients are calculated from the control forces and the achieved response which when superimposed on the nominal bearing coefficients yield the resultant magnetic bearing coefficients required for control. An example case is presented where control of rotor response has been attempted at the first and the second unbalance critical speeds. The results demonstrate appreciable improvement in response using magnetic bearings.

Optimized Realization of Fault-Tolerant Heteropolar Magnetic Bearings

2000 ◽  
Vol 122 (3) ◽  
pp. 209-221 ◽  
Author(s):  
Uhn Joo Na ◽  
Alan Palazzolo
Keyword(s):  
Fault Tolerant ◽  
Load Capacity ◽  
Fault Tolerant Control ◽  
Optimization Method ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Control Voltage ◽  
Distribution Matrix ◽  
Control Forces ◽  
Multiple Poles

Flux coupling in heteropolar magnetic bearings permits remaining active coils to assume actions of failed coils to produce force resultants identical to the un-failed actuator. 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. A distribution matrix of voltages which consists of a redefined biasing voltage vector and two control voltage vectors can be optimized in a manner that reduces the peak flux density. An elegant optimization method using the Lagrange multiplier is presented in this paper. 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 achieved with reduced load capacity. [S0739-3717(00)01103-X]

Disturbance Accommodating Controllers for Rotating Mechanical Systems

1986 ◽  
Vol 108 (1) ◽  
pp. 24-31 ◽  
Author(s):  
K. D. Reinig ◽  
A. A. Desrochers
Keyword(s):  
Active Control ◽  
Center Of Mass ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Rotor Shaft ◽  
Mass Imbalance ◽  
Shaft System ◽  
Control Schemes ◽  
Bearing Force ◽  
Large Rotor

The use of magnetic bearings for supporting a rotor-shaft system has led to increasing interest in active control schemes. In this work, two disturbance accommodating controllers are developed which minimize the vibration of the system due to the mass imbalance of the rotor. The first controller generates an estimate of the disturbance force arising from this mass imbalance and then cancels its effect through the magnetic bearings. This keeps the rotor displacement at zero but often at the expense of high bearing forces. The second controller remedies this by estimating the eccentricity and then applying a force to the controlled shaft end to offset the effect of the eccentricity. This requires the controlled shaft end to follow a path so that the rotor shaft pivots about the center of mass. Thus, the center of mass of the system does not translate and so a disturbance force never occurs. Therefore, a small magnetic bearing force can be used to control the vibration of a large rotor. Both methods are compared to conventional bearing strategies.

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