Hyeon-Jae Shin

Analytical Torque Calculations and Experimental Testing of Permanent Magnet Axial Eddy Current Brake

This paper discusses the braking torque and normal force analysis of axial flux permanent magnet (AFPM)-type eddy current brakes (ECB) on the basis of an analytical field computation using a space harmonic method. On the basis of the magnetic vector potential and a 2D polar coordinate system, permanent magnets considering the eddy current effect are obtained. Additionally, by utilizing the derived analytical field solutions, the braking torque and normal force are predicted. Finite element analysis is employed to confirm the validity of the analysis and compare it with the experimental results obtained from the prototype AFPM-type ECB.

Vibration Analysis and Measurements Through Prediction of Electromagnetic Vibration Sources of Permanent Magnet Synchronous Motor Based on Analytical Magnetic Field Calculations

This study is devoted to the analysis of the vibration characteristics of a permanent magnet synchronous motor (PMSM) through investigation into its electromagnetic vibration sources. For this purposed, we derive analytical solutions for the magnetic fields generated by permanent magnets (PMs) in terms of a magnetic vector potential and a two-dimensional (2-D) polar coordinate system. A 2-D permeance function is also introduced in order to consider slotting effects. The electromagnetic vibration sources such as torque ripple, cogging torque, and radial force density are analyzed using these solutions. The analytical results are validated extensively with finite element (FE) analyses. The fast Fourier transformation (FFT) analysis is employed for investigating the specific harmonic orders of the electromagnetic vibration sources that affect the vibration of the PMSM. Finally, mechanical modal analysis results and test results such as vibration measurements are obtained to confirm the validity of the analysis methods presented in this paper.

Torque analysis and measurements of a permanent magnet type Eddy current brake with a Halbach magnet array based on analytical magnetic field calculations

This paper presents the torque analysis and measurements of a permanent magnet (PM) type eddy current brake (ECB) with a Halbach magnet array based on analytical magnetic field calculations. On the basis of a magnetic vector potential and using a two-dimensional (2D) polar coordinate system, the analytical solution for magnetic flux density, including the eddy current reaction is evaluated. Based on these solutions, the magnetic torque is also determined analytically. A 2D finite element analysis is employed to validate the method used. Practical issues in the analytical study of the PM type ECBs, such as the maximum braking torque, the required rotor speed, and the segment-dependent, are fully discussed. Finally, the braking torque as a function of the rotor speed is measured to verify the results of the analytical study.

Torque Analysis and Measurements of Cylindrical Air-Gap Synchronous Permanent Magnet Couplings Based on Analytical Magnetic Field Calculations

This paper presents the torque analysis and measurements of cylindrical air-gap synchronous permanent magnet couplings based on analytical magnetic field calculations. Employing a magnetic vector potential and a 2-D analytical model with two polar coordinate systems, we obtain the magnetic fields produced by permanent magnets. Then, the analytical torque solutions are derived using these magnetic field solutions and a Maxwell stress tensor method. The analytical results are validated by nonlinear 2-D and 3-D finite element results. Finally, torque measurements are presented to show the effectiveness of the analysis.

Nb‐added high‐coercivity Nd‐Fe‐B melt‐spun ribbon with high remanence

The effects of composition and additives on the microstructures and magnetic properties of Nd‐Fe‐B melt‐spun ribbons were studied. Experimental results have revealed that homogeneous grain structure with fine grain size was obtained on composition close to 2‐14‐1 stoichiometry with additives. It was also found that Nb was very effective in increasing both remanence and coercivity in a Nd‐Fe‐B melt‐spun ribbon. A high‐energy product of 151.2 kJ/m3 (19.0 MGOe) was obtained from an isotropic (Nd0.5Pr0.5)12Fe72Co8B6Nb2 melt‐spun ribbon with a remanence of 0.926 T and a coercivity exceeding 1200 kA/m (∼15 kOe).

Design and Analysis of Axial Permanent Magnet Couplings Based on 3D FEM

Magnetic couplings are of considerable interest for many industrial applications because they can transmit torque from a primary driver to a follower, without mechanical contact. In particular, as they allow torque to be transmitted across a separation wall, axial permanent magnetic couplings (APMCs) are well suited for use in isolated systems such as vacuums or high-pressure vessels. This paper deals with the design and analysis of APMCs based on 3D finite element (FE) analysis. Finally, confirming that 3D FE results for the torque of the designed APMCs are validated extensively with the measured results, the validity of the design of the APMCs that satisfies the required specifications is confirmed. With the many advantages mentioned above, a permanent magnet coupling can be applied to a variety of industries.

Electromagnetic Vibration Analysis and Measurements of Double-Sided Axial-Flux Permanent Magnet Generator With Slotless Stator

This paper examines the effects of the electromagnetic source on the vibration of a double-sided axial permanent magnet generator with a slotless stator depending on the ac and dc-load conditions. The slotless machine has no cogging torque. Most of the vibration originates from the torque ripple and axial force distributions, which result from the current load conditions. The 3-D finite element analysis results are compared with voltage, current, and torque measurements. The order tracking analysis of the vibration test data clearly demonstrates the dependence of the critical harmonics on the load conditions.

Electromagnetic Analysis and Experimental Testing of a Tubular Linear Synchronous Machine With a Double-Sided Axially Magnetized Permanent Magnet Mover and Coreless Stator Windings by Using Semianalytical Techniques

This paper presents the electromagnetic analysis and experimental testing of a tubular linear synchronous machine (TLSM) with a double-sided axially magnetized permanent magnet (AMPM) mover and coreless stator winding by using semianalytical techniques. Using a simple result based on the finite element method (FEM), characteristics of the TLSM with AMPM can be calculated with the semianalytical method easily. The magnetic flux density in the air gap is obtained by using a magnetic vector potential, a 2-D polar coordinate system, and the results of the magnetostatic calculation based on FEM. Based on these solutions, the electromotive force (EMF) is also determined analytically. Then, 2-D FEM is employed to validate the semianalytical method. Finally, experimental testing of the EMF measurements is performed to confirm the results of the semianalytical techniques.

Torque analysis of axial flux PM type eddy current brake based on analytical field computations

This paper deals with torque analysis of axial flux permanent magnet (AFPM) type eddy current brake (ECB) based on analytical field computation. On the basis of a magnetic vector potential and a two-dimensional (2-D) polar coordinate system, analytical solutions for normal and tangential flux density due to permanent magnet (PM) considering eddy current effect are obtained. And then, using derived analytical field solutions, braking torque and normal force characteristics according to rotor speed are also predicted. A three-dimensional (3-D) finite element (FE) analysis is employed to confirm the validity of analyses. Finally, this paper investigates influence of design parameters on the performances of the AFPM type ECB.

Characteristic Analysis of Tubular-Type Permanent-Magnet Linear Magnetic Coupling Based on Analytical Magnetic Field Calculations

This paper presents a characteristic analysis of a tubular-type permanent-magnet (PM) linear magnetic coupling (TLMC) based on analytical magnetic field calculations. First, the analytical solutions for magnetic fields generated by PM are derived on the basis of a magnetic vector potential and a 2-D polar coordinate system. Next, the magnetic force is also determined on the basis of these solutions. The magnetic field and force obtained by the analytical method are compared with those obtained by the finite-element analysis and experiment, which validates the analysis methods presented in this paper.