Eddy Current Effects on the Design of Rotor-Magnetic Bearing Systems

1995 ◽  
Vol 117 (B) ◽  
pp. 162-170 ◽  
Author(s):  
C. Kim ◽  
A. B. Palazzolo ◽  
A. Kascak ◽  
G. Brown
Keyword(s):  
Eddy Current ◽  
Magnetic Bearing ◽  
System Stability ◽  
Design Tools ◽  
Test Results ◽  
Flexible Rotor ◽  
New Methods ◽  
Novel Approach ◽  
Accurate Design ◽  
Effective Operation

The recent growth of magnetic bearing applications in the chemical, utility and aerospace industries requires more accurate design tools to insure reliable and effective operation as components of the overall rotor bearing system. This paper provides a novel approach for simulating a flexible rotor suspended in magnetic bearings, accounting for eddy current effects. The manuscript discusses some magnetic bearing fundamentals, leading up to the new methods for modeling. Test results show very good correlation with theory and confirm the importance of considering eddy current effects. Surface conductivity and frequency dependent permeability effects on the B field in the magnet gaps are shown to be very significant on overall system stability. The results in the manuscript should be very useful to the design or test rotor dynamicist.

Eddy Current Effects on the Design of Rotor-Magnetic Bearing Systems

1995 ◽  
Vol 117 (B) ◽  
pp. 162-170 ◽  
Author(s):  
C. Kim ◽  
A. B. Palazzolo ◽  
A. Kascak ◽  
G. Brown
Keyword(s):  
Eddy Current ◽  
Magnetic Bearing ◽  
System Stability ◽  
Design Tools ◽  
Test Results ◽  
Flexible Rotor ◽  
New Methods ◽  
Novel Approach ◽  
Accurate Design ◽  
Effective Operation

The recent growth of magnetic bearing applications in the chemical, utility and aerospace industries requires more accurate design tools to insure reliable and effective operation as components of the overall rotor bearing system. This paper provides a novel approach for simulating a flexible rotor suspended in magnetic bearings, accounting for eddy current effects. The manuscript discusses some magnetic bearing fundamentals, leading up to the new methods for modeling. Test results show very good correlation with theory and confirm the importance of considering eddy current effects. Surface conductivity and frequency dependent permeability effects on the B field in the magnet gaps are shown to be very significant on overall system stability. The results in the manuscript should be very useful to the design or test rotor dynamicist.

A Multiobjective Adaptive Controller for Magnetic Bearing Systems

2010 ◽  
Vol 132 (12) ◽  
Author(s):  
M. Necip Sahinkaya ◽  
Abdul-Hadi G. Abulrub ◽  
Clifford R. Burrows ◽  
Patrick S. Keogh
Keyword(s):  
Adaptive Controller ◽  
Optimization Method ◽  
Magnetic Bearing ◽  
System Stability ◽  
Flexible Rotor ◽  
Whole Process ◽  
Performance Specifications ◽  
Displacement Transducers ◽  
Value Decomposition

The paper considers three issues in flexible rotor and magnetic bearing systems, namely, the control of rotor vibration, control of transmitted forces, and prevention of rotor contact with auxiliary bearings. An adaptive multiobjective optimization method is developed to tackle these issues simultaneously using a modified recursive adaptive controller. The proposed method involves automatic tuning of the weighting parameters in accordance with performance specifications. A two-stage weighting strategy is implemented, involving base weightings, calculated from a singular value decomposition of the system’s receptance matrices, and two adjustable weighting parameters to shift the balance between the three objective functions. The receptance matrices are functions of rotational speed and they are estimated in situ. The whole process does not require prior knowledge of the system parameters. Real-time implementation of the proposed controller is explained and tested by using an experimental flexible rotor magnetic bearing system. The rotor displacements were measured relative to the base frame using four pairs of eddy current displacement transducers. System stability is ensured through local PID controllers. The proposed adaptive controller is implemented in parallel, and the effectiveness of the weighting parameters in changing the balance between the transmitted forces and rotor vibrations is demonstrated experimentally.

A Multi-Objective Adaptive Controller for Magnetic Bearing Systems

2009 ◽  
Author(s):  
M. Necip Sahinkaya ◽  
Abdul-Hadi G. Abulrub ◽  
Clifford R. Burrows ◽  
Patrick S. Keogh
Keyword(s):  
Adaptive Controller ◽  
Optimization Method ◽  
Magnetic Bearing ◽  
Open Loop ◽  
System Stability ◽  
Flexible Rotor ◽  
Multi Objective ◽  
Whole Process ◽  
Performance Specifications ◽  
Value Decomposition

The paper considers three issues in flexible rotor and magnetic bearing systems, namely control of rotor vibration, control of transmitted forces, and prevention of rotor contact with auxiliary bearings. An adaptive multi-objective optimization method is developed to tackle these issues simultaneously using a modified recursive open loop adaptive controller. The proposed method involves automatic tuning of the weighting parameters in accordance with performance specifications. A two-stage weighting strategy is implemented involving base weightings, calculated from a singular value decomposition of the system’s receptance matrices, and two adjustable weighting parameters to shift the balance between the three objective functions. The receptance matrices are functions of rotational speed and they are estimated in situ. The whole process does not require prior knowledge of the system parameters. Real-time implementation of the proposed controller is explained and tested by using an experimental flexible rotor magnetic bearing system. The rotor displacements were measured relative to the base frame using four pairs of eddy current displacement transducers. System stability is ensured through local PID controllers. The proposed adaptive controller is implemented in parallel and the effectiveness of the weighting parameters in changing the balance between the transmitted forces and rotor vibrations is demonstrated experimentally.

Test and Theory Correlation Study for a Flexible Rotor on Fault-Tolerant Magnetic Bearings

2002 ◽  
Vol 124 (3) ◽  
pp. 359-366 ◽  
Author(s):  
Uhn Joo Na ◽  
Alan B. Palazzolo ◽  
Andrew Provenza
Keyword(s):  
Fault Tolerant ◽  
Correlation Study ◽  
Magnetic Bearing ◽  
Test Results ◽  
Flexible Rotor ◽  
Magnetic Forces ◽  
Failure State ◽  
Simulation Results ◽  
Test Verification ◽  
Good Agreement

This paper provides a new algorithm and test verification for implementing fault-tolerant operation of magnetically suspended, flexible shaft, rotating machinery. The currents to the magnetic bearing are redistributed in a manner so that the bearing actuator preserves the same linearized magnetic forces after some of its coils experience failure. The algorithm that searches a database for the appropriate failure compensation matrix utilizes a Boolean description of the failure state to quickly locate and download its target. The test results are shown to have good agreement with the system simulation results presented.

scholarly journals Three-Axis Inductive Displacement Sensor Using Phase-Sensitive Digital Signal Processing for Industrial Magnetic Bearing Applications

Actuators ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 115
Author(s):  
Teemu Sillanpää ◽  
Alexander Smirnov ◽  
Pekko Jaatinen ◽  
Jouni Vuojolainen ◽  
Niko Nevaranta ◽  
...  
Keyword(s):  
Signal Processing ◽  
Digital Signal Processing ◽  
Eddy Current ◽  
High Speed ◽  
Digital Signal ◽  
Magnetic Bearing ◽  
Air Gap ◽  
Sensor Design ◽  
Quadrature Demodulation ◽  
Displacement Sensors

Non-contact rotor position sensors are an essential part of control systems in magnetically suspended high-speed drives. In typical active magnetic bearing (AMB) levitated high-speed machine applications, the displacement of the rotor in the mechanical air gap is measured with commercially available eddy current-based displacement sensors. The aim of this paper is to propose a robust and compact three-dimensional position sensor that can measure the rotor displacement of an AMB system in both the radial and axial directions. The paper presents a sensor design utilizing only a single unified sensor stator and a single shared rotor mounted target piece surface to achieve the measurement of all three measurement axes. The sensor uses an inductive measuring principle to sense the air gap between the sensor stator and rotor piece, which makes it robust to surface variations of the sensing target. Combined with the sensor design, a state of the art fully digital signal processing chain utilizing synchronous in-phase and quadrature demodulation is presented. The feasibility of the proposed sensor design is verified in a closed-loop control application utilizing a 350-kW, 15,000-r/min high-speed industrial induction machine with magnetic bearing suspension. The inductive sensor provides an alternative solution to commercial eddy current displacement sensors. It meets the application requirements and has a robust construction utilizing conventional electrical steel lamination stacks and copper winding.

scholarly journals Application of Deep Reinforcement Learning to Predict Shaft Deformation Considering Hull Deformation of Medium-Sized Oil/Chemical Tanker

2021 ◽  
Vol 9 (7) ◽  
pp. 767
Author(s):  
Shin-Pyo Choi ◽  
Jae-Ung Lee ◽  
Jun-Bum Park
Keyword(s):  
Reinforcement Learning ◽  
Reaction Force ◽  
Measurement Data ◽  
System Stability ◽  
Main Bearing ◽  
Shaft System ◽  
Novel Approach ◽  
Design Changes ◽  
Prediction Techniques ◽  
Shaft Deformation

The enlargement of ships has increased the relative hull deformation owing to draft changes. Moreover, design changes such as an increased propeller diameter and pitch changes have occurred to compensate for the reduction in the engine revolution and consequent ship speed. In terms of propulsion shaft alignment, as the load of the stern tube support bearing increases, an uneven load distribution occurs between the shaft support bearings, leading to stern accidents. To prevent such accidents and to ensure shaft system stability, a shaft system design technique is required in which the shaft deformation resulting from the hull deformation is considered. Based on the measurement data of a medium-sized oil/chemical tanker, this study presents a novel approach to predicting the shaft deformation following stern hull deformation through inverse analysis using deep reinforcement learning, as opposed to traditional prediction techniques. The main bearing reaction force, which was difficult to reflect in previous studies, was predicted with high accuracy by comparing it with the measured value, and reasonable shaft deformation could be derived according to the hull deformation. The deep reinforcement learning technique in this study is expected to be expandable for predicting the dynamic behavior of the shaft of an operating vessel.

PEBB System Stability Margin Monitoring

2002 ◽  
Vol 8 (2) ◽  
pp. 261-276 ◽  
Author(s):  
Xiaogang Feng ◽  
Zhihong Ye ◽  
Fred C. Lee ◽  
Dushan Borojevic
Keyword(s):  
Stability Margin ◽  
System Stability ◽  
Linear Control ◽  
Small Signal ◽  
System A ◽  
Novel Approach ◽  
Implementation Approach ◽  
Dc Bus ◽  
Response Current ◽  
Measurement Approach

PEBB (power electronics building block) systems are typical nonlinear systems. Under the conventional but still popular linear control design, the system stability margin varies from one operating point to another. This paper introduces a novel approach to monitoring the DC bus stability margin of a PEBB system online. At the steady state of the system, a small-signal perturbation current î p is injected into the DC bus, and the load-side response current î L is measured. By checking the validation |î L ( jw)| < |î p ( jw)|, the system stability margin can be examined. Experiments on a 48 V DC DPS demonstrate the proposed measurement approach. An implementation approach is also proposed for an 800 V DC PEBB-based testbed system.

Preliminary Investigations of Machine Frame Vibration Damping Using Eddy Current Principle

2016 ◽  
Vol 821 ◽  
pp. 288-294 ◽  
Author(s):  
George Juraj Stein ◽  
Peter Tobolka ◽  
Rudolf Chmúrny
Keyword(s):  
Mathematical Model ◽  
Natural Frequency ◽  
Eddy Current ◽  
Asynchronous Motor ◽  
Oscillatory System ◽  
Vibration Damping ◽  
Combined Effects ◽  
Magnetic Forces ◽  
Novel Approach ◽  
Vibration Attenuation

A novel approach to vibration attenuation, based on the eddy current principle, is described. The combined effects of all magnetic forces acting in the oscillatory system attenuate frame vibrations and, concurrently, decrease the damped natural frequency. A mathematical model of the forces balance in the oscillatory system was derived before. Some experimental results from a mock-up machine frame excited by an asynchronous motor are presented.

Dynamic Analysis of Flexible Rotor Suspended by Active Magnetic Bearings With LQR Controller

2018 ◽  
Author(s):  
Yixin Su ◽  
Yanhui Ma ◽  
Qian Shi ◽  
Suyuan Yu
Keyword(s):  
Dynamic Characteristics ◽  
Beam Theory ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Flexible Rotor ◽  
Linear Quadratic ◽  
State Response ◽  
Lagrange’S Equation ◽  
Linear Quadratic Regulation ◽  
Lqr Controller

Dynamic characteristics of active magnetic bearing (AMB)-flexible rotor system are closely related to control law. To analyze dynamic characteristics of flexible rotor suspended by AMBs with linear quadratic regulation (LQR) controller, a simple and effective method based on numerical calculation of unbalanced response is proposed in this article. The model of flexible rotor is established based upon Euler-Bernoulli beam theory and Lagrange’s equation. Disc on the rotor and its Gyro effect are taken into account. LQR controller based on error and its derivative is developed to control electromagnetic force of AMB at each degree of freedom (DOF) in real time. Under the unbalanced exciting force, the steady-state response and transient response in time domain of each node of flexible rotor at 0–4000 rad/s are calculated numerically. The critical speeds of rotor are obtained by identification method quickly and easily.

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