Kyoung-Chul Min’s research while affiliated with Chungnam National University and other places

This paper reports on the analysis of eddy current loss of a magnetic coupling (MC) that uses a Halbach array permanent magnet (PM). An MC is a kind of non-contact magnetic devices (NCMDs). When the conductive materials of NCMDs are exposed to timevarying magnetic fields, eddy currents are induced in the conductive materials, leading to losses. An analysis of the eddy current loss is therefore required, and for MCs, the analysis of eddy current loss is particularly more important. We obtain the magnetic field solutions of the Halbach magnetized PM based on the magnetic vector potential and two-dimensional (2D) polar-coordinate system. In addition, using the derived magnetic field solutions, we derive analytical solutions for eddy current loss using the equivalent electrical resistance that is calculated from the magnet volume and conductivity. A 2D finite-element analysis (FEA) is employed to confirm the validity of the analytical results of the eddy current density and eddy current loss. Finally, we investigate the influence of the number of Halbach segments on the eddy current loss induced on the MC.

This paper deals with torque analysis of magnetic spur gear with radial magnetized permanent magnets based on analytical method. The analysis is implemented in three parts: First, on the basis of magnetic vector potential and a two-dimensional (2D) polar-coordinate system, the magnetic field solution due to permanent magnet of source gear are obtained. And by using derived magnetic field solutions, the analytical solutions for external magnetic field distribution which affects load gear are obtained. Second, by using coordinate conversion, external magnetic field which is on the primary coordinate system is converted to the secondary coordinate system. Finally, the load gear is reduced to equivalent current densities, and the torque is computed on these currents in the external field of the source magnet. These analytical results are validated by comparing with the 2-D finite element analysis (FEA).

This paper deals with eddy current loss of magnetic coupling with radial permanent magnet (PM) using analytical method such as a space harmonic method. Superposition of two kinds analysis model is used to analyze eddy current loss induced in inner PM and outer PM of magnetic coupling. When the eddy current is induced, the environmental temperature increases, and the permanent magnet(PM) characteristics are degraded because the performance of PM is greatly influenced by temperature rise. Hence, the calculation of eddy current loss becomes an important factor in the magnetic coupling. In order to analyze eddy current loss, first, on the basis of the magnetic vector potential and two-dimensional(2-D) polar-coordinate system, the magnetic field solutions of the radial magnetized PM are obtained. And we obtain the analytical solutions for the eddy current density produced by permanent magnet. Lastly, analytical solutions for eddy current loss are derived by using equivalent, electrical resistance calculated from magnet volume and analytical solution for eddy current density. This analytical results are validated by comparing with the 2-D finite element analysis (FEA).