Gyu-Hong Kang

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.

A Novel Cogging Torque Reduction Method for Interior Type Permanent Magnet Motor

This paper presents a novel design method to reduce cogging torque of interior type permanent magnet (IPM) motor. In the design method, the optimal notches are put on the rotor pole face, which have an effect on variation of permanent magnet (PM) shape or residual flux density of PM. Through the space harmonics field analysis, the positions of notches are found and the optimal shapes of notches are determined by using finite element method (FEM). The validity of the proposed method is confirmed by experiments.

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 study on iron loss analysis method considering the harmonics of the flux density waveform using iron loss curves tested on Epstein samples

This paper deals with a study on an iron loss analysis method in the single-phase line-start permanent magnet synchronous motor. The iron loss is affected by the time rate of the change of magnetic flux density at the motor cores. The distribution and changes in magnetic flux densities of the motor are computed by using a two-dimensional finite element method. Discrete Fourier Transform (DFT) is used to analyze the magnetic flux density waveforms in each element of the analysis model. Iron losses in each element are evaluated using iron loss curves tested by an Epstein test apparatus. The total iron loss can be obtained by the summation of the iron losses in all the elements.

Vibration Reduction of IPM-Type BLDC Motor Using Negative Third Harmonic Elimination Method of Air-Gap Flux Density

This paper proposes a harmonic elimination method for vibration and noise minimization of an interior-type permanent-magnet motor, achieved by alternating the distribution of the radial flux density. The minimization of vibration and noise is realized by forming optimal notches corresponding to the shape of the magnetic field on the rotor pole face. The variations in vibration are computed by a nonlinear finite element method, and the validity of the analysis and rotor shape design is confirmed by performing vibration and performance experiments.

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.

Finite Element Computation of Magnetic Vibration Sources in 100 kW Two Fractional-Slot Interior Permanent Magnet Machines for Ship

The design of an interior permanent magnet (IPM) machine, in particular, its pole and slot combination, determines the nature of its magnetic forces, which influences not only the torque but also acoustic noise and vibration characteristics. Vibrations can shorten bearing life and are an especially important parameter in marine applications, which have strict regulations such as on electromagnetic compatibility. In this study, two-dimensional(2D) finite element analysis (FEA) was used to model magnetic vibration sources in two 100-kW marine fractional-slot IPM machines with different pole and slot combinations (8 pole-12 slot and 10 pole-12 slot). The magnetic forces were calculated according to rotor position, current phase angle, and load. The results are validated by experiments.

Stator and Rotor Shape Designs of Interior Permanent Magnet Type Brushless DC Motor for Reducing Torque Fluctuation

This paper presents the stator and rotor shape designs in interior permanent magnet (IPM) type brushless dc (BLDC) motor for reducing torque fluctuation. The partly enlarged air-gap made by rotor unequal out diameter and stator core structure with pole shoe modification is introduced. The torque ripple reduction is achieved by upgrading torque value at minimum torque position and their detail characteristics are compared. The final stator and rotor shape of IPM type BLDC motor is decided by design of experiments (DOE) process. The magnetic field and torque characteristics are analyzed by 2 dimensional (2D) finite element analysis (FEA) and their performances are validated by experimental results.

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.