Research on Coil Impedance of Self-Inductive Displacement Sensor Considering Core Eddy Current

The inductive displacement sensor is widely used in active magnetic bearing (AMB) systems to detect rotor displacement in real time, and the performance of the sensor directly affects the performance of AMB. At present, most theoretical studies on the working principle of inductive displacement sensor are based on a traditional mathematical model, ignoring the influence of the core magnetic resistance and core eddy current, which will lead to a certain error between the theoretical analysis of the sensor output characteristics and the actual situation. In this regard, based on the theory of electromagnetic field and circuit, an improved theoretical model of the inductive sensor was established in this paper by introducing the complex permeability, by which the influence of core eddy current on magnetic field can be taken into account. In order to verify the improved model, an eight-pole radial self-inductive displacement sensor with an air gap of 1 mm was designed. Then the electromagnetic field of the designed sensor was simulated by a finite element software and the GW LCR-6100 measuring instrument was used to measure the changes of the inductance and resistance of the designed sensor core coils with the rotor displacement at 20–100 kHz. The results demonstrated that there is a good linear relationship between the impedance change of the sensor coils and the rotor displacement within the measurement range of −0.4 ~ +0.4 mm. At the same time, compared with the traditional model, the sensitivity of the improved theoretical model is closer to the results from FEM and experiment, and the accuracy of the sensitivity of the improved theoretical model can be approximately doubled, despite there are certain differences with the experimental situation. Therefore, the improved theoretical model considering complex permeability is of great significance for studying the influence of core eddy current on the coil impedance of sensor.

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An Synergistic Dynamic 2D FEM Model of an Active Magnetic Bearing with Three Electromagnets

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.214.106 ◽

2014 ◽

Vol 214 ◽

pp. 106-112 ◽

Cited By ~ 1

Author(s):

Adam Krzysztof Pilat

Keyword(s):

Electromagnetic Field ◽

Differential Equations ◽

Electromagnetic Force ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Comsol Multiphysics ◽

Mesh Deformation ◽

Arbitrary Lagrangian Eulerian ◽

Fem Model ◽

Mathematical Formulas

This elaboration presents a dynamic model of an Active Magnetic Bearing (AMB) developed in COMSOL Multiphysics. The electromagnetic field is calculated on the basis of Partial Differential Equations (PDEs). The calculated electromagnetic force is applied to the rotor, which is free to move. The Arbitrary Lagrangian-Eulerian (ALE) method for mesh deformation is applied to achieve rotor motion on the bearing plane. The planar rotor motion is described by a set of Ordinary Differential Equations (ODEs) solved in parallel to the electromagnetic field calculations. To enable rotor levitation, three local PD controllers are applied. The mathematical formulas of the control action are coded in the form of COMSOL equations and embedded into the rotor motion ODEs.

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Design and Implementation of Redundant Sensors in Active Magnetic Bearing

Volume 2: Plant Systems, Structures, Components and Materials ◽

10.1115/icone25-67758 ◽

2017 ◽

Author(s):

Zhengang Shi ◽

Jiaji Yang ◽

Ni Mo ◽

Xingnan Liu ◽

Yan Zhou

Keyword(s):

High Reliability ◽

Short Circuit ◽

Stability Control ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Displacement Sensor ◽

Special Equipment ◽

Design And Implementation ◽

Displacement Sensors ◽

Redundancy Design

With the advantages of frictionless, no need of lubrication, no pollution, low consuming and long life, active magnetic bearing (AMB) is applied in the primary helium circulator of the High Temperature Gas-Cooled Reactor-Pebble bed Module (HTR-PM), which is under construction in Shidao Bay Nuclear Power Plant. Active magnetic bearing is a typical mechatronic system with interconnection of mechanical and electronic components with the function of picking up signals, processing and producing. Displacement sensor is an important component to pick up signals for stability control, and also the most susceptible part to fail due to variation of air temperature and vibration of high rotation speed. However, rotating system can’t run normally if a single sensor fails in AMB without redundancy design. For security considerations, higher reliability is required in some special equipment, especially in primary helium circulator of HTR-PM. Design and implementation of redundant sensors is an effective method. This paper reviewed the present research of fault diagnosis and redundant control of displacement sensors, simulation of coil’s short-circuit and open-circuit fault was made with MATLAB/SIMULINK. Parameters were optimized for fault diagnostic circuit by Multisim. Based on the high reliability demand, redundancy design was applied both on structure and control system in AMB. Schematic drawing and PCB board were finished by Altium Design, and experiments were carried out. The result showed that if the coils of sensor failed, AMB system could still work normally by switching to the redundant sensors automatically.

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Research on New Displacement Sensor Used in Active Magnetic Bearing Systems

Lecture Notes in Electrical Engineering - Nuclear Power Plants: Innovative Technologies for Instrumentation and Control Systems ◽

10.1007/978-981-10-7416-5_22 ◽

2017 ◽

pp. 174-187

Author(s):

Lian-Xiao Xue ◽

Kai Zhang ◽

Yang Xu

Keyword(s):

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Displacement Sensor

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Circularity Error Analysis of Axial Displacement Sensor Detecting Surface for Active Magnetic Bearings of 10MW High Temperature Gas-Cooled Reactor (HTR-10GT)

Volume 2: Plant Systems, Construction, Structures and Components; Next Generation Reactors and Advanced Reactors ◽

10.1115/icone21-16098 ◽

2013 ◽

Author(s):

Jingjing Zhao ◽

Yan Zhou ◽

Zhe Sun ◽

Suyuan Yu

Keyword(s):

High Temperature ◽

Degrees Of Freedom ◽

Magnetic Bearing ◽

Axial Displacement ◽

Working Environment ◽

Active Magnetic Bearing ◽

Displacement Sensor ◽

Displacement Sensors ◽

Circularity Error ◽

High Temperature Gas

The 10MW high temperature gas-cooled test module reactor (HTR-10GT) with the core made of spherical fuel elements was designed and constructed by the Institute of Nuclear and New Energy Technology of Tsinghua University in China. In the HTR-10GT, turbo-compressor and generator rotors are connected by a flexible coupling and a decelerator. The rotors, restricted by actual instruments and working environment, must be supported without any contact and lubrication. Active magnetic bearing (AMB), is the best way to suspend and stabilize the position of rotors of HTR-10GT. In AMB system, the displacement sensors are designed for converting measured physical value into proportional electric signals and transferring it into the control and monitoring system. The characteristics and influence of circularity error of the axial displacement sensor detecting surface is analyzed according to AMB with five degrees of freedom. In order to reduce the circularity error of the magnetic bearing system, the sensor detecting surface requires high-precision machining.

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INDUCTIVE LINEAR DISPLACEMENT SENSOR IN ACTIVE MAGNETIC BEARING

Environment Technology Resources Proceedings of the International Scientific and Practical Conference ◽

10.17770/etr2019vol3.4070 ◽

2019 ◽

Vol 3 ◽

pp. 151

Author(s):

Sergei Loginov ◽

Dmitriy Fedorov ◽

Igor Savrayev ◽

Igor Plokhov ◽

Andrey Hitrov ◽

...

Keyword(s):

Control System ◽

High Speed ◽

High Reliability ◽

Magnetic Bearing ◽

Linear Displacement ◽

Magnetic Bearings ◽

Active Magnetic Bearing ◽

Displacement Sensor ◽

Main Trend ◽

Active Magnetic Bearings

Active magnetic bearings are increasingly used in various fields of industry. The absence of mechanical contact makes it possible to use them in ultra-high-speed electric drives. The main trend of active magnetic bearings development is the improvement of the control system. The main problem of the control system is the displacement sensor (most of them has low accuracy and large interference). The sensor must have the following properties: simple in realization, high linearity of the characteristic, high sensitivity and noise immunity, high reliability. At the present time there is no sensor that satisfies all these conditions. Most manufacturers use various kinds of filters to get an accurate position signal. This increases the response time of the control system. Thus, problem of designing and modeling the position sensor, considered in the article is topical.

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Position servo controller design and implementation using low cost eddy current sensor for single axis active magnetic bearing

Journal of Ambient Intelligence and Humanized Computing ◽

10.1007/s12652-018-1064-0 ◽

2018 ◽

Vol 10 (9) ◽

pp. 3481-3492 ◽

Cited By ~ 1

Author(s):

P. Raghunathan ◽

E. Logashanmugam

Keyword(s):

Eddy Current ◽

Controller Design ◽

Low Cost ◽

Magnetic Bearing ◽

Active Magnetic Bearing ◽

Current Sensor ◽

Design And Implementation ◽

Eddy Current Sensor ◽

Position Servo ◽

Servo Controller

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The FEM Calculation of Iron Loss in the Active Magnetic Bearing

Volume 1: Plant Operations, Maintenance, Engineering, Modifications, Life Cycle and Balance of Plant; Nuclear Fuel and Materials; Plant Systems, Structures and Components; Codes, Standards, Licensing and Regulatory Issues ◽

10.1115/icone22-30085 ◽

2014 ◽

Author(s):

Peicai Wu ◽

Xingnan Liu ◽

Guojun Yang ◽

Zhengang Shi

Keyword(s):

Eddy Current ◽

Power Loss ◽

Core Loss ◽

Eddy Current Loss ◽

Magnetic Bearing ◽

Silicon Steel ◽

Hysteresis Loss ◽

Active Magnetic Bearing ◽

Iron Loss ◽

Current Loss

The active magnetic bearing (AMB) is a new kind of high-performance bearing which suspends the rotor with controlled electromagnetic force. It was chosen to support the rotor of the helium blower in HTR-PM instead of conventional bearings. The power losses in the active magnetic bearings compose of three components: copper loss, iron loss and windage loss. In this paper, the iron loss, which composes of the eddy current loss and the hysteresis loss, is researched. The power loss of silicon steel lamination (35H300) was measured. Experimental data was taken over a range of 50Hz to 25,000Hz (sinusoidal current) for several magnetic field intensities. According to the experimental data, the eddy current loss and hysteresis loss increase with the frequency. And the hysteresis loss in the silicon steel lamination occupies the major part when the frequency of current is low, however the growth rate of eddy current is much faster than that of the hysteresis loss. And the FEM calculation of power loss in the magnetic bearing, which rotor and stator are made from silicon steel lamination (35H300), is also presented. The result shows the core loss of magnetic bearing also follow the separation theory. We can separate the core loss of magnetic bearing into two parts: hysteresis loss and eddy current loss. It will be very useful to calculate the power loss in the magnetic bearing.

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