Gyu-Tak Kim

Analysis of irreversible magnet demagnetization in line-start motors based on the finite-element method

This paper deals with the analysis for the irreversible demagnetization characteristics of a ferrite-type permanent magnet in the line-start motor using the two-dimensional finite-element method (2-D FEM). The demagnetizing currents are calculated from the transient analysis in the combination voltage equation with mechanical dynamic equation, and peak currents are applied to the irreversible demagnetization analysis computed by 2-D FEM. The nonlinear characteristic of the magnetic core is considered as well as that of a permanent magnet on the B-H curve in the analysis of irreversible demagnetization.

Improved parameter modeling of interior permanent magnet synchronous motor based on finite element analysis

This paper presents an investigation of the parameter modeling on the basis of an improved finite element (FE) analysis in which the variable frequency characteristic in field weakening is considered in interior permanent magnet synchronous motors (IPMSM). The parameters of IPMSM have a nonlinear characteristic under variable load conditions and due to the current phase angle in a system fed inverter. From the analysis of FE, a new vector control algorithm is proposed by a neural network using a variable inductance estimator. The performances of variable frequency are simulated by using the proposed algorithm, and the validity of the proposed FE analysis is compared with experimental results.

Detent force minimization techniques in permanent magnet linear synchronous motors

Detent force produced in permanent magnet linear machines generally causes an undesired vibration and noise. This paper analyzes detent force and thrust in permanent magnet linear synchronous motor by using various detent force minimization techniques. A two-dimensional finite-element analysis is used to predict detent force and thrust due to structural factors and nonlinearity. Moreover, moving node techniques for the drawing models is used to reduce modeling time and efforts.

A novel design of an air-core type permanent magnet linear brushless motor by space harmonics field analysis

This paper presents a novel design technique and characteristic analysis of an air core type Permanent Magnet (PM) linear motor based on Space Harmonics Field analysis methodology. In the Space Harmonics Field analysis, Poisson equation is solved by the spatial distribution of current and PM, which is replacedly Equivalent Magnetizing Current (EMC). The process of magnetic field analysis is applied to the motor design and steady state analysis considering the driving characteristic. The validity of the proposed technique is confirmed with 2-D Finite Element (FE) analysis and experimental results.

Design of slotless-type PMLSM for high power density using divided PM

A slotless permanent magnet linear synchronous motor (PMLSM) has a low power density due to having a large air-gap structurally. In this paper, an increase of power density of the slotless-type PMLSM is presented by inserting the core between each phase windings. The permanent magnet (PM) is divided into two pieces to reduce detent force and eliminate high-order space harmonics affecting the thrust ripples. All analysis values are calculated with two-dimensional finite-element method.

Design and analysis of air core type permanent magnet linear brushless motor by using equivalent magnetizing current

This paper presents the design and steady state analysis method of an air core-type permanent magnet (PM) linear brushless motor based on the equivalent magnetizing current (EMC) method. The phenomena of air core-type motors by the variety of foil shape under constant magnetomotive force (MMF) has been analyzed and the analysis process is applied to the design and static state analysis considering commutation thrust ripple. The validity of the proposed technique is confirmed with 2-D finite element (FE) analysis and experimental results.

Minimization Design of Normal Force in Synchronous Permanent Magnet Planar Motor With Halbach Array

This paper deals with the characteristics analysis and the normal force minimization of a synchronous permanent magnet planar motor (SPMPM) with a Halbach magnet array. The characteristics such as flux density, back-EMF and thrust are evaluated and compared with experimental values. The measured values of back-EMF are in good agreement with the simulation ones, but the experimental results of thrust are much smaller than those of simulation due to the friction force generated by the normal force. The normal force is minimized by using a genetic algorithm, and it is greatly decreased from 672.83 N to 144.24 N.

Orbital analysis of rotor due to electromagnetic force for switched reluctance motor

The purpose of this paper is to analyze the orbital response of rotor due to unbalanced electromagnetic force for switched reluctance motor (SRM). In order to reduce vibration of SRM, it is necessary to predict the mechanical dynamic behavior of the rotor-bearing system. So the orbit of the rotor according to rotation speed is analyzed by using the finite element method (FEM), and unbalanced electromagnetic force induced by dynamic eccentricity is calculated by the Maxwell stress tensor. From the results, the stability behavior of the rotor caused by unbalanced electromagnetic force is evaluated.

Permanent-magnet linear brushless motor by using equivalent magnetizing current

This paper presents a design and steady-state analysis method of a slotless-type permanent-magnet linear brushless motor based on the equivalent magnetizing current method. The phenomena of the slotless-type motor by the variety of coil shape under a constant magnetomotive force has been analyzed and the analysis process is applied to the design and static-state analysis considering commutation thrust ripple. The validity of the proposed technique is confirmed with two-dimensional finite-element analysis and experimental results.

EMTDC Based Simulation of 10 MW Class Grid-Connected Superconducting Wind Turbine Generator

It is believed that the size of wind turbines on offshore wind farms can be increased up to 10 MW. A superconducting synchronous generator (SCSG) is advantageous to a large-scale wind turbine because of its weight and volume. In this paper, a grid-connected large-scale superconducting wind turbine generator is analysed under varying wind speeds. A 10 MW SCSG is designed by the finite elements method (FEM). The parameters of the designed SCSG are calculated and applied to a modeled SCSG in a Power System Computer Aided Design/Electromagnetic Transients including DC. The electric and dynamic performances of superconducting wind turbine generators are analysed in this simulation. This paper shows the effectiveness of the grid-connected superconducting wind turbine generator for offshore applications.