Modeling Eddy-Current Damping Force in Magnetic Levitation Systems With Conductors

2017 ◽  
Author(s):  
Mohammad Khodabakhsh ◽  
Mehran Ebrahimian ◽  
Bogdan Epureanu
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
Eddy Currents ◽  
Magnetic Levitation ◽  
Analytical Models ◽  
Damping Force ◽  
Element Analysis ◽  
Wide Range ◽  
Eddy Current Damping ◽  
Damping Effects

An analytical method is used to develop a model to calculate steady-state eddy-current damping effects in two configurations of magnetic levitation (maglev) systems. The eddy-current based force (eddy-current force) is used for high precision positioning of a levitated permanent magnet in maglev systems. In these systems, the motion of the levitated permanent magnet and changes of the coil’s currents, generate eddy current in the conductors. The proposed analytical model is used to calculate both effects. A conductive cylindrical shell around the levitated object is implemented as a new technique to generate eddy currents in maglev systems. The model is also employed to obtain eddy-current damping effects in a system with a conductive plate beneath the levitated object. The analytical models match results from high fidelity finite element analysis (FEA) with acceptable accuracy in a wide range of operations. Advantages of the two configurations are discussed.

Modeling of a New Active Eddy Current Vibration Control System

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Henry A. Sodano ◽  
Daniel J. Inman
Keyword(s):  
Magnetic Field ◽  
Vibration Control ◽  
Electric Fields ◽  
Eddy Current ◽  
Eddy Currents ◽  
Vibration Suppression ◽  
Frequency Doubling ◽  
Damping Force ◽  
Theoretical Derivation ◽  
Eddy Current Damping

There exist many methods of adding damping to a vibrating structure; however, eddy current damping is one of few that can function without ever coming into contact with that structure. This magnetic damping scheme functions due to the eddy currents that are generated in a conductive material when it is subjected to a time changing magnetic field. Due to the circulation of these currents, a magnetic field is generated, which interacts with the applied field resulting in a force. In this manuscript, an active damper will be theoretically developed that functions by dynamically modifying the current flowing through a coil, thus generating a time-varying magnetic field. By actively controlling the strength of the field around the conductor, the induced eddy currents and the resulting damping force can be controlled. This actuation method is easy to apply and allows significant magnitudes of forces to be applied without ever coming into contact with the structure. Therefore, vibration control can be applied without inducing mass loading or added stiffness, which are downfalls of other methods. This manuscript will provide a theoretical derivation of the equations defining the electric fields generated and the dynamic forces induced in the structure. This derivation will show that when eddy currents are generated due to a variation in the strength of the magnetic source, the resulting force occurs at twice the frequency of the applied current. This frequency doubling effect will be experimentally verified. Furthermore, a feedback controller will be designed to account for the frequency doubling effect and a simulation performed to show that significant vibration suppression can be achieved with this technique.

MODELING OF EDDY CURRENT LOSS AND TEMPERATURE OF THE MAGNETS IN PERMANENT MAGNET MACHINES

2011 ◽  
Vol 20 (07) ◽  
pp. 1287-1301 ◽  
Author(s):  
XIAOFENG DING ◽  
CHRIS MI
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
Hybrid Electric Vehicle ◽  
Eddy Current Loss ◽  
Analytical Models ◽  
Element Analysis ◽  
Synchronous Motors ◽  
Pwm Inverter ◽  
Current Loss ◽  
Excessive Heat

The eddy current loss in the magnets of permanent magnet (PM) motors in a hybrid electric vehicle (HEV) and plug-in HEV is usually not taken into consideration in traditional motor design and analysis. However, due to the high conductivity of the rare-earth magnet, neodymium-iron-boron (NdFeB), and slot/tooth harmonics, there is eddy current loss generated inside the magnets. This loss may not attribute very much to the efficiency of the motor, but the temperature-rise inside the magnets caused by this loss can lead to the unpredictable deterioration of the magnets, such as the degradation of performance and potential demagnetization. In addition, the output voltage of pulse-width-modulated (PWM) inverter contains abundant high frequency harmonics, which induce excessive loss in the magnets. The excessive heat in PM motor induced by the eddy current loss combined with other losses can degrade the performance of the machine. This paper presents the modeling and analysis of eddy current loss in surface-mounted-magnets PM synchronous motors (SPMSM) and interior-magnets PM synchronous motors (IPMSM), operated by PWM inverter supply. Analytical methods are implemented, in conjunction with time-stepped finite-element analysis (FEA) for the calculation of eddy current loss in the magnet. Based on the calculated losses in the machines, simplified analytical models are developed as thermal circuits with network of interconnected nodes, thermal resistances and heat sources representing the heat processes within the SPMSM and IPMSM, to predict the temperature of the magnets. The predicted machine temperatures are found to be consistent with the experimental measurement.

Analysis and Modeling of Eddy Current Damping for Short-Stroke DC Linear Motor

2013 ◽  
Vol 416-417 ◽  
pp. 300-304
Author(s):  
Dong Hua Pan ◽  
Jia Xi Liu ◽  
Feng Jing Shen ◽  
Li Yi Li ◽  
Ming Na Ma
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Eddy Currents ◽  
Linear Motor ◽  
Force Model ◽  
Equivalent Resistance ◽  
Damping Force ◽  
Conductive Material ◽  
Charge Model ◽  
Eddy Current Damping

Eddy currents induced in a conductor in a changing magnetic field produce a damping force proportional to the heat generated in the conductive material. In this paper, the damping force of short-stroke DC Linear Motor (DCLM) is researched, and then model of damping force is established. In the preliminary work, the analytical expression of magnetic field distribution is obtained by the charge model, so the eddy current inducted in the conductor is calculated. Then the damping force is obtained after the equivalent resistance and inductance of conductors are calculated. The formula of damping force is obtained to optimize damping structure of short-stroke DCLM. The accuracy of damping force model is proved by the experiment.

Performance analysis of magnetic gear with Halbach array for high power and high speed

2020 ◽  
Vol 64 (1-4) ◽  
pp. 959-967
Author(s):  
Se-Yeong Kim ◽  
Tae-Woo Lee ◽  
Yon-Do Chun ◽  
Do-Kwan Hong
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
High Power ◽  
High Speed ◽  
Torque Ripple ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss ◽  
Halbach Array ◽  
Magnetic Gear

In this study, we propose a non-contact 80 kW, 60,000 rpm coaxial magnetic gear (CMG) model for high speed and high power applications. Two models with the same power but different radial and axial sizes were optimized using response surface methodology. Both models employed a Halbach array to increase torque. Also, an edge fillet was applied to the radial magnetized permanent magnet to reduce torque ripple, and an axial gap was applied to the permanent magnet with a radial gap to reduce eddy current loss. The models were analyzed using 2-D and 3-D finite element analysis. The torque, torque ripple and eddy current loss were compared in both models according to the materials used, including Sm2Co17, NdFeBs (N42SH, N48SH). Also, the structural stability of the pole piece structure was investigated by forced vibration analysis. Critical speed results from rotordynamics analysis are also presented.

scholarly journals Design of a 3-RPR Flexure System for Optical Switch Assembly

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Guiyue Kou ◽  
Mouyou Lin ◽  
Changbao Chu
Keyword(s):  
Permanent Magnets ◽  
Optical Switch ◽  
Low Cost ◽  
Mechanical Vibration ◽  
Analytical Models ◽  
Assembly System ◽  
Sensors And Actuators ◽  
Damping Force ◽  
Element Analysis ◽  
Compact Size

In the MEMS optical switch assembly, the collision is likely to happen between the optical fiber and the U-groove of the chip due to the uncontrollable assembly errors. However, these errors can hardly be completely eliminated by the active control using high precision sensors and actuators. It will cause the large acting force and part damage, which further leads to the assembly failure. To solve this question, this paper presents a novel low-cost three-degree-of-freedom (three-DOF) passive flexure system to adaptively eliminate the planar assembly errors. The flexure system adopts three parallel kinematic chains with a novel 3-RPR structure and has a compact size with a diameter of 125 mm and thickness of 12 mm. A novel eddy current damper with the structure of Halbach array permanent magnets (PMs) is utilized to suppress the adverse mechanical vibration of the assembly system from the background disturbances. Analytical models are established to analyze the kinematic, static, and dynamic performances of the system in detail. Finally, finite element analysis is adopted to verify the established models for optimum design. The flexure system can generate a large deformation of 1.02 mm along the two translational directions and 0.02° along the rotational direction below the yield state of the material, and it has much higher natural frequencies than 200 Hz. Moreover, the large damping force means that the designed ECD can suppress the system vibration quickly. The above results indicate the excellent characteristics of the assembly system that will be applied into the optical switch assembly.

Investigation on Eddy Current Braking Systems – A Review

2014 ◽  
Vol 592-594 ◽  
pp. 1089-1093 ◽  
Author(s):  
G.L. Anantha Krishna ◽  
K.M. Sathish Kumar
Keyword(s):  
Permanent Magnet ◽  
Eddy Current ◽  
Eddy Currents ◽  
Adhesion Force ◽  
Field Application ◽  
Train Control ◽  
Braking System ◽  
Braking Torque ◽  
Wave Forms ◽  
Transportation Applications

The changing magnetic field will induce eddy currents in the conductor. These currents will dissipate energy in the conductor and generate drag force. It is found that Aluminium is the best material as conductor compared to Copper and Zinc. Also, it is found that the larger thickness of disc, more number of turns of electromagnet and higher electrical conductivity of conductor influences the generation of greater braking torque. Conventional braking system relies on adhesion force between rail and wheel. It is found that a brake built up from permanent magnet pieces that combine both magnetic rail brake and eddy current brake permits the most profitable braking action through the whole range of acceptable speeds. Permanent magnet eddy current brake uses Neodymium - Iron - Boron (NdFeB) magnets. The analysis of permanent magnet eddy current shows that the parallel magnetised eddy current topology has the superior braking torque capability. In electrically controlled eddy current braking system subjected to time varying fields in different wave forms, the triangular wave field application resulted in highest braking torque. Electromagnetic brakes were found to interfere with the signalling and train control system. Permanent magnet eddy current brakes are a simple and reliable alternative to mechanical or electromagnetic brakes in transportation applications. Greater the speed greater is the eddy current braking efficiency. Hence, author intends to work on the development and investigation of permanent magnet eddy current braking system.

scholarly journals 3D harmonic modeling of eddy currents in segmented conducting structures

2019 ◽  
Vol 38 (1) ◽  
pp. 2-23 ◽  
Author(s):  
C.H.H.M. Custers ◽  
J.W. Jansen ◽  
M.C. van Beurden ◽  
E.A. Lomonova
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Three Dimensional ◽  
Spatial Period ◽  
Content Type ◽  
Current Distributions ◽  
Wide Range ◽  
Conductivity Function ◽  
Electromagnetic Quantities

PurposeThe purpose of this paper is to describe a semi-analytical modeling technique to predict eddy currents in three-dimensional (3D) conducting structures with finite dimensions. Using the developed method, power losses and parasitic forces that result from eddy current distributions can be computed.Design/methodology/approachIn conducting regions, the Fourier-based solutions are developed to include a spatially dependent conductivity in the expressions of electromagnetic quantities. To validate the method, it is applied to an electromagnetic configuration and the results are compared to finite element results.FindingsThe method shows good agreement with the finite element method for a large range of frequencies. The convergence of the presented model is analyzed.Research limitations/implicationsBecause of the Fourier series basis of the solution, the results depend on the considered number of harmonics. When conducting structures are small with respect to the spatial period, the number of harmonics has to be relatively large.Practical implicationsBecause of the general form of the solutions, the technique can be applied to a wide range of electromagnetic configurations to predict, e.g. eddy current losses in magnets or wireless energy transfer systems. By adaptation of the conductivity function in conducting regions, eddy current distributions in structures containing holes or slit patterns can be obtained.Originality/valueWith the presented technique, eddy currents in conducting structures of finite dimensions can be modeled. The semi-analytical model is for a relatively low number of harmonics computationally faster than 3D finite element methods. The method has been validated and shown to be computationally accurate.

Modeling of Eddy Current Damper Composed of Spherical Magnet and Conducting Shell

2006 ◽  
Author(s):  
Yoshihisa Takayama ◽  
Atsuo Sueoka ◽  
Takahiro Kondou
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Magnetic Force ◽  
Eddy Currents ◽  
Reaction Force ◽  
Damping Force ◽  
Magnetic Damping ◽  
Conducting Plate ◽  
Direction Of Movement ◽  
Eddy Current Damper

If a conducting plate moves through a nonuniform magnetic field, eddy currents are induced in the conducting plate. The eddy currents produce a magnetic force of drag, known as Fleming's left-hand rule. This rule means that a magnetic field perpendicular to the direction of movement generates a magnetic damping force. We have fabricated the eddy current damper composed of the spherical magnet and the conducting shell. The spherical magnet produces the axisymmetric magnetic field, and the shape of the conducting shell appears to combine a semispherical shell conductor and a cylinder conductor. When the eddy current damper works, the conducting shell is fixed in space, and the spherical magnet moves under the conducting shell. In this case, since there are magnetic flux densities perpendicular to the direction of movement, eddy currents flow inside the conducting shell, and then a magnetic force is produced. The reaction force of this magnetic force acts on the spherical magnet. In our study, eddy current dampers composed of a magnet and a conducting plate have been modeled using infinitesimal loop coils. As a result, magnetic damping forces are obtained. Our modeling has three merits as follows: the equation of a magnetic damping force is simple in the equation, we can use the static magnetic field obtained using FEM, the Biot-Savart law or experiments and the equation automatically satisfies boundary conditions using infinitesimal loop coils. In this study, we explain simply the principle of this method, and model an eddy current damper composed of a spherical magnet and a conducting shell. The analytical results of the modeling agree well with the experimental results.

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