scholarly journals Finite Element Solutions for Magnetic Field Problems in Terfenol-D Transducers

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2808
Author(s):  
Duo Teng ◽  
Yatian Li
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Permanent Magnets ◽  
Eddy Currents ◽  
Iron Alloy ◽  
Current Response ◽  
Bias Magnetic Field ◽  
Field Range ◽  
Eddy Current Losses

An appropriate magnetic design helps ensure that the Terfenol-D (Terbium- Dysprosium-Iron alloy) rods in giant magnetostrictive transducers have the perfect magnetostriction ability. To determine the optimum Terfenol-D rod state, a segmented stack configuration comprised by the Terfenol-D rods and NdFeB (neodymium-iron-boron) permanent magnets is presented. The bias magnetic field distributions simulated through the finite element method indicate that the segmented stack configuration is one effective way to produce the desired bias magnetic field. Particularly for long stacks, establishing a majority of domain to satisfy the desired bias magnetic field range is feasible. On the other hand, the eddy current losses of Terfenol-D rods are also the crucial to their magnetostriction ability. To reduce eddy current losses, the configuration with digital slots in the Terfenol-D rods is presented. The induced eddy currents and the losses are estimated. The simulations reveal that the digital slots configuration decreases the eddy current losses by 78.5% compared to the same size Terfenol-D rod with only a hole. A Terfenol-D transducer prototype has been manufactured using a Terfenol-D rod with a mechanical prestress of about 10 MPa and a bias magnetic field of about 42 kA/m. Its maximum transmitting current response of 185.4 dB at 3.75 kHz indicates its practicability for application as an underwater projector.

scholarly journals Prediction of Eddy Current Losses in Cooling Tubes of Direct Cooled Windings in Electric Machines

Mathematics ◽  
2019 ◽  
Vol 7 (11) ◽  
pp. 1096 ◽  
Author(s):  
Mohamed Nabil Fathy Ibrahim ◽  
Peter Sergeant
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Electric Machines ◽  
Iron Core ◽  
Commercial Software ◽  
Eddy Current Losses ◽  
Switched Reluctance ◽  
Element Simulation ◽  
Core Losses

The direct coil cooling method is one of the existing cooling techniques for electric machines with concentrated windings, in which cooling tubes of conductive material are inserted between the windings. In such cases, eddy current losses are induced in those cooling tubes because of the time variant magnetic field. To compute the cooling tubes losses, either a transient finite element simulation (mostly based on commercial software), or a full analytical method, which is more complex to be constructed, is required. Instead, this paper proposes a simple and an accurate combined semi-analytical-finite element method to calculate the losses of electric machines having cooling tubes. The 2D magnetostatic solution of the magnetic field is obtained e.g., using the free package “FEMM”. Then, the eddy current losses in the tubes are computed using simple analytical equations. In addition, the iron core losses could be obtained. In order to validate the proposed method, two cases are investigated. In Case 1, a six-toothed stator of a switched reluctance machine (SRM), without rotor, is employed in which six cooling tubes are used while in Case 2 a complete rotating SRM is studied. The proposed method is validated by a 2D transient simulation in the commercial software “ANSYS Maxwell” and also by experimental measurements. Evidently, the proposed method is simple and fast to be constructed and it is almost free of cost.

scholarly journals Design of eddy current brake for electric motorcycle braking system

2021 ◽  
Vol 12 (1) ◽  
pp. 41
Author(s):  
Mufti Reza Aulia Putra ◽  
Muhammad Nizam ◽  
Dominicus Danardono Dwi Prija Tjahjana
Keyword(s):  
Magnetic Field ◽  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Motor Vehicles ◽  
Braking Performance ◽  
Braking System ◽  
Fem Method ◽  
The Magnetic Field ◽  
Aluminum Disk

Braking systems in motor vehicles generally use a braking system that utilizes friction. The braking performance will decrease caused by using friction rapidly. To overcome this, as an alternative, an electromagnetic braking system can be used by utilizing eddy currents, such as eddy current brakes (ECB). Eddy currents are generated when the rotor pass the magnetic field of the electromagnet. The research aim is to design an ECB system. The performance of the disk design will be determined in this study. The study is about the tendency of the ECB properties. The finite element (FEM) method is used by modeling ECB performance. The experimental results were used to validate the result. The test showed the results of braking using aluminum disk showed the best performance in 12.03 Nm. From these results, the combination of the disks is needed by an appropriate disk design.

Calculation of eddy current losses using the electrodynamic similarity laws

2014 ◽  
Vol 63 (1) ◽  
pp. 107-114
Author(s):  
Dariusz Koteras
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Numerical Calculations ◽  
Eddy Current Losses ◽  
Similarity Laws ◽  
Good Agreement ◽  
Element Method

Abstract The results of the eddy currents losses calculations with using electrodynamics scaling were presented in this paper. Scaling rules were used for obtain the values of the eddy currents losses. For the calculations Finite Element Method was used. Numerical calculations were verified by measurements and a good agreement was obtained

An Analytical Method to Calculate the Eddy Current Losses of Transformer Shielding Coil

2012 ◽  
Vol 229-231 ◽  
pp. 884-887
Author(s):  
Bao Dong Bai ◽  
Ying Ying Gao ◽  
Jia Yin Wang
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Eddy Current ◽  
Analytical Method ◽  
Analytical Formula ◽  
The Finite Element Method ◽  
Eddy Current Losses ◽  
Leakage Magnetic Field ◽  
Current Equation

This paper mainly researches the eddy current losses of transformer shielding coil by adopting for analytical method. This method calculates the conductor’s boundary conditions directly by using the analytical solution of the leakage magnetic field, which is generated into the conductor eddy current equation for the analytical formula, then compared the analytical method with the finite element method to fix the analytical formula, the relevant theories are applied to analyze the results of using two different shielding to reduce the losses and find the effectively measures.

Modeling of eddy current losses in the iron core of electrical machines by a finite element homogenization method

2018 ◽  
Vol 12 (133) ◽  
pp. 24
Author(s):  
Vương Đặng Quốc
Keyword(s):  
Finite Element ◽  
Eddy Current ◽  
Eddy Currents ◽  
Source Region ◽  
Homogenization Method ◽  
Magnetic Flux Density ◽  
Iron Core ◽  
Eddy Current Losses ◽  
Density Distributions ◽  
High Frequency Effects

A finite element homogenization method is proposed for the magetodynamic h-conform finite element forumulation to compute eddy current losses in electrical steel laminations. The lamination stack is served as a source region carrying predefined current density and magnetic flux density distributions presenting the eddy current losses and skin effects in each lamination. In order to solve this problem, the stacked laminations are converted into continuums with which terms are associated for considering the eddy current loops produced by both parallel and perpendicular fluxes. An accurate model of accuracy is developed via an accurate analytical expression of the eddy currents and makes the method adapted to both low and high frequency effects to capture skin depths of fields along thicknesses of the laminations.

A new analytical approach to determine slotting based eddy current losses in permanent magnets of PMSM taking into account axial and circumferential segmentation

2015 ◽  
Vol 34 (2) ◽  
pp. 398-412 ◽  
Author(s):  
Cornelius Bode ◽  
Wolf-Rüdiger Canders ◽  
Markus Henke
Keyword(s):  
Eddy Current ◽  
Analytical Approach ◽  
Permanent Magnets ◽  
Eddy Currents ◽  
3D Fem ◽  
Eddy Current Losses ◽  
Content Type ◽  
High Frequencies ◽  
Reaction Field ◽  
3D Fea

Purpose – The purpose of this paper is to calculate slotting-based eddy currents in permanent magnet excited synchronous machine (PMSM) taking into account axial and circumferential segmentation of magnets. Design/methodology/approach – An analytical approach to calculate eddy current losses in PM caused by slotting harmonics of PMSM is presented. The eddy current reaction field is taken into account as well as axial and circumferential segmentation of the magnets. Findings – The analytical model provides results comparable to 3D-FEM calculations even at high frequencies at reduced computation costs. To generalize the results the magnetic Reynold’s number is introduced. Originality/value – Taking into account the axial and circumferential segmentation in the PDE; the approach is much more accurate compared to known approaches; accuracy is comparable to 3D-FEA.

Rotor Eddy Current Losses Analysis on BPMSM Using FEM

2012 ◽  
Vol 150 ◽  
pp. 85-89
Author(s):  
Tao Zhang ◽  
Huang Qiu Zhu
Keyword(s):  
Magnetic Field ◽  
Finite Element Method ◽  
Finite Element ◽  
Permanent Magnet ◽  
Relative Motion ◽  
Eddy Current ◽  
High Speed ◽  
Necessary Conditions ◽  
Eddy Current Losses ◽  
Research Results

It is important to clarify the rotor eddy current losses in bearingless permanent magnet synchronous (BPMSM) for temperature rising to induce irreversible demagnetization. In this paper, the torque and radial suspension force producing mechanisms of BPMSM are introduced. The relative motion relationships among radial suspension force, rotor magnetic field and suspension winding magnetic field are analyzed. The necessary conditions of producing stable controllable radial suspension force in single direction are concluded. The rotor eddy current losses in BPMSM with PB=PM+1 and PB=PM-1 are calculated and compared using 2D time-steeping finite element method. The research results have shown that the BPMSM with PB=PM+1 is the most suitable for high speed operation with the minimum eddy current losses in rotor.

Analysis and Experiment of the Eddy Current Losses for Canned Motor

2011 ◽  
Vol 383-390 ◽  
pp. 7521-7525
Author(s):  
Yue Jun An ◽  
Guo Ming Liu ◽  
Hong Liang Wen ◽  
Wen Qiang Zhao ◽  
Li Ping Xue ◽  
...  
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Electromagnetic Field ◽  
Eddy Current ◽  
Empirical Formula ◽  
Eddy Currents ◽  
Characteristic Parameters ◽  
Material Characteristic ◽  
Eddy Current Losses ◽  
Canned Motor

Induced eddy currents in can cause loss when the canned motor runs, the loss make the motor`s temperature rise, directly affect the canned motor pump and the entire transmission system security. Empirical formula estimates eddy current losses which has a big error, it is difficult to meet the engineering requirements. For the canned motor with Hastelloy-C alloy or Sus316L cans, analyzed electromagnetic field and calculated can loss using a finite element method of Ansoft. The paper developed four prototypes, and obtained the experimental value of can loss via simple no-load experiment by the loss separation method. The results are compared with simulation value show that the accuracy of FEM is higher accurately than empirical formula; Analysis shows that dimension of a model and can material characteristic parameters such as the resistivity influence on the calculated error of FEM, the paper proposes to correct the error in the case of considering can material characteristic parameters.

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