scholarly journals Analytical Analysis of a Novel Brushless Hybrid Excited Adjustable Speed Eddy Current Coupling

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 308 ◽  
Author(s):  
Yibo Li ◽  
Heyun Lin ◽  
Hai Huang ◽  
Hui Yang ◽  
Qiancheng Tao ◽  
...  
Keyword(s):  
Eddy Current ◽  
Eddy Currents ◽  
Core Loss ◽  
Element Analysis ◽  
Copper Loss ◽  
Faraday’S Law ◽  
Speed Regulation ◽  
Adjustable Speed ◽  
Current Coupling ◽  
Drive Systems

A novel brushless hybrid excited adjustable speed eddy current coupling is proposed for saving energy in the drive systems of pumps and fans. The topology and operation principle of the coupling are presented. Based on the real flux paths, the fluxes excited by permanent magnet (PM) and field current are analyzed separately. A magnetic circuit equivalent (MEC) model is established to efficiently compute the no-load magnetic field of the coupling. The eddy current and torque are calculated based on the proposed MEC model, Faraday’s law, and Ampere’s law. The resultant magnetic fields, eddy currents, and torques versus slip speeds under different field currents are studied by the MEC-based analytical method and verified by finite element analysis (FEA). The copper loss, core loss, and efficiency were investigated by FEA. The analytically predicted results agree well with the FEA, and the analysis results illustrate that a good speed regulation performance can be achieved by the proposed hybrid excited control.

Loss Calculation and Software Design Based on the Combination of Electric Circuit and Electromagnetic Field Solution in High Speed Permanent Magnet Machine

2015 ◽  
Vol 741 ◽  
pp. 521-525
Author(s):  
Xiao Guang Kong ◽  
Li Ping Fan ◽  
Yan Qiu Fu
Keyword(s):  
Electromagnetic Field ◽  
Software Design ◽  
High Frequency ◽  
High Speed ◽  
Core Loss ◽  
Electric Circuit ◽  
Mathematics Model ◽  
Element Analysis ◽  
Copper Loss ◽  
Field Solution

Mathematics model of loss for high speed machine is discussed. Calculation method of core loss and high-frequency additional copper loss of winding based on finite element analysis is introduced. Experiment results of losses are presented. In order to realize calculation and analysis, a method of PM machine by calling ANSYS and MATLAB based on VB of the combination of electric circuit and electromagnetic field solution is presented in this paper. The design and feature analysis of high speed PM machine takes an example to validate the accuracy and advantage.

scholarly journals General 3D Analytical Method for Eddy-Current Coupling with Halbach Magnet Arrays Based on Magnetic Scalar Potential and H-Functions

Energies ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 8458
Author(s):  
Xiaoquan Lu ◽  
Xinyi He ◽  
Ping Jin ◽  
Qifeng Huang ◽  
Shihai Yang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Eddy Current ◽  
Analytical Method ◽  
Eddy Currents ◽  
Scalar Potential ◽  
Fourier Decomposition ◽  
Field Distributions ◽  
Current Coupling ◽  
Current Calculation ◽  
Laplacian Equations

Rapid and accurate eddy-current calculation is necessary to analyze eddy-current couplings (ECCs). This paper presents a general 3D analytical method for calculating the magnetic field distributions, eddy currents, and torques of ECCs with different Halbach magnet arrays. By using Fourier decomposition, the magnetization components of Halbach magnet arrays are determined. Then, with a group of H-formulations in the conductor region and Laplacian equations with magnetic scalar potential in the others, analytical magnetic field distributions are predicted and verified by 3D finite element models. Based on Ohm’s law for moving conductors, eddy-current distributions and torques are obtained at different speeds. Finally, the Halbach magnet arrays with different segments are optimized to enhance the fundamental amplitude and reduce the harmonic contents of air-gap flux densities. The proposed method shows its correctness and validation in analyzing and optimizing ECCs with Halbach magnet arrays.

The Simulation Study on Temperature Field Distribution of 220 kV Gas Insulated Switchgear

2021 ◽  
Vol 16 (5) ◽  
pp. 797-805
Author(s):  
Bao-Ming Gao ◽  
Zheng-Yu Li ◽  
Jin-Wen Gao ◽  
Hao Liang ◽  
Zhi Yan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Eddy Current ◽  
Temperature Rise ◽  
Heat Dissipation ◽  
Eddy Currents ◽  
Coupling Effect ◽  
Eddy Current Loss ◽  
Element Analysis ◽  
Current Loss

Under working conditions, the conductive rods in the GIS flow through the power frequency alternating current. Due to the coupling effect of the magnetic field and electric field between the metal aluminum shell and the conductive rod, induced eddy currents are generated in the metal shell of the GIS. The heat generated by the current heating effect of the GIS conductive rod and the eddy current loss of the metal casing will cause the temperature rise of GIS equipment. Due to the limited volume, the heat dissipation capacity of GIS is poor. Excessive temperature rise will accelerate the insulation aging of GIS equipment, and even damage its insulation, which will affect safe operation. In order to obtain the temperature change law of GIS, related influencing factors such as eddy current loss, skin effect, proximity effect, convective heat transfer of SF6 gas, and gravity of SF6 gas are comprehensively considered. The finite element analysis is used to research and discuss GIS magnetic field distribution, eddy current, temperature distribution and SF6 gas velocity. The initial value of the temperature of each part is set to 293.15 K (20 °C), and the temperature in the GIS is calculated to gradually decrease from the inside to the outside under the rated AC current of 3150 A. The temperature at the conductive rod position is the highest at 335.32 K, and the temperature at the housing position is the lowest at 294.65 K.

A novel squirrel cage eddy current coupling with adjustable radial air gap and its performance analysis

2021 ◽  
Vol 67 (3) ◽  
pp. 279-297
Author(s):  
Zhiqiang Xiong ◽  
Jin Yao
Keyword(s):  
Performance Analysis ◽  
Permanent Magnet ◽  
Eddy Current ◽  
Air Gap ◽  
Electromagnetic Torque ◽  
Relative Magnetic Permeability ◽  
Speed Regulation ◽  
Squirrel Cage ◽  
Axisymmetric Structure ◽  
Current Coupling

A novel squirrel cage eddy current coupling with adjustable radial air gap was presented, which can change the output speed by changing the air gap thickness in radial direction between the copper strips and the permanent magnet. It has the advantages of no axial force in speed regulation and less eccentric force in axisymmetric structure. The 2-D electromagnetic torque model of the rotor was established, and the influence of the air gap thickness on the electromagnetic torque was also studied by finite element method. Further, a novel method to solve the dynamic equation of the eddy current coupling was proposed based on the effect of air gap thickness and relative speed on torque characteristics, and was applied to the speed regulation performance analysis. In addition, the influence of the relative magnetic permeability of the permanent magnet back yoke and the internal rotor on the speed regulation performance was studied.

Iron loss and eddy-current loss analysis in a low-power BLDC motor with magnet segmentation

2012 ◽  
Vol 61 (1) ◽  
pp. 33-46 ◽  
Author(s):  
Adrian Młot ◽  
Mariusz Korkosz ◽  
Marian Łukaniszyn
Keyword(s):  
Low Power ◽  
Eddy Current ◽  
Heat Dissipation ◽  
Eddy Currents ◽  
Eddy Current Loss ◽  
Iron Loss ◽  
Bldc Motor ◽  
Element Analysis ◽  
Current Loss ◽  
Loss Analysis

Iron loss and eddy-current loss analysis in a low-power BLDC motor with magnet segmentation This paper considers a Brushless Direct Current (BLDC) machine prototype with six poles and 36 stator slots including a three phase double-layered distributed winding. Presented modifications of rotor construction are identified in order to achieve the best possible compromise of eddy-current losses and cogging torque characteristics. The permanent magnet (PM) eddy-current loss is relatively low compared with the iron loss; it may cause significant heating of the PMs due to the relatively poor heat dissipation from the rotor and it results in partial irreversible demagnetization. A reduction in both losses is achieved by magnet segmentation mounted on the rotor. Various numbers of magnet segmentation is analysed. The presented work concerns the computation of the no-load iron loss in the stator, rotor yoke and eddy-current loss in the magnets. It is shown that the construction of the rotor with segmented magnets can significantly reduce the PM loss (eddy-current loss). The eddy-current loss in PMs is caused by several machine features; the winding structure and large stator slot openings cause flux density variations that induce eddy-currents in the PMs. The effect of these changes on the BLDC motor design is examined in order to improve the machine performance. 3-D finite-element analysis (FEA) is used to investigate the electromagnetic behaviour of the BLDC motor.

scholarly journals Modelling and Measurement of a Moving Magnet Linear Motor for Linear Compressor

Energies ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 4030
Author(s):  
Xinwen Chen ◽  
Hanying Jiang ◽  
Zhaohua Li ◽  
Kun Liang
Keyword(s):  
Pressure Ratio ◽  
Core Loss ◽  
Cooling Capacity ◽  
Linear Motor ◽  
Element Analysis ◽  
Linear Compressor ◽  
Copper Loss ◽  
Fea Model ◽  
Motor Efficiency ◽  
Moving Magnet

For the purpose of efficiency improvement, a linear motor that performs a linear reciprocating motion can be employed to directly drive the piston in a reciprocating refrigeration compressor without crankshaft mechanism. This also facilitates the modulation of cooling capacity as the stroke and frequency can be readily varied in response to heat load. A novel design of moving magnet linear motor for linear compressor was analyzed in the paper. A finite element analysis (FEA) model was built to simulate the characteristics of the linear motor. Current and displacement signals were measured from a test rig and were defined in the transient FEA model. Transient motor force was simulated with the FEA model and good agreements are shown between the results from the FEA model and interpolated shaft force from static force measurements. Major Losses, such as copper loss and core loss were also computed. Motor efficiency decreased from 0.88 to 0.83 as stroke increased from 9 mm to 12 mm, while the pressure ratio remained unchanged. Comparisons were made between the present moving magnet linear motor and moving coil linear motors. Generally, the moving magnet linear motor demonstrates higher efficiency than moving coil motors, which have significantly higher copper loss. The present moving magnet design with simple structure could be further optimized to improve motor efficiency.

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.

Eddy Current Flows Around Cracks in Thin Plates for Nondestructive Testing

1982 ◽  
Vol 49 (2) ◽  
pp. 389-395 ◽  
Author(s):  
S. Mukherjee ◽  
M. A. Morjaria ◽  
F. C. Moon
Keyword(s):  
Current Density ◽  
Eddy Current ◽  
Eddy Currents ◽  
Low Frequency ◽  
Numerical Results ◽  
Thin Plates ◽  
Line Integral ◽  
Faraday’S Law ◽  
Induced Currents ◽  
Current Flows

The boundary element method is used to calculate the induced electric current flow around cracks in thin conducting plates. A low frequency approximation leads to a Poisson equation for the current density potential or stream function. A kernel is used which produces the correct singularity at the crack tip. The boundary condition on the crack, derived from Faraday’s law, requires the line integral of the current density around the crack to be zero. Numerical results for induced currents due to a circular induction coil ore given. These results show that hot spots, due to Joule heating, can occur at the tips of the crack. Comparison of numerical results with infrared scanning experiments of eddy currents in a cracked plate are given. It is hoped that the numerical method presented here will provide a tool to simulate both new and conventional nondestructive eddy current testing techniques.

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