Jeong-Jong Lee

Characteristic Analysis of Claw-Pole Machine Using Improved Equivalent Magnetic Circuit

Magnetic field analysis of claw-pole machines using improved equivalent magnetic circuit (EMC) is presented in this paper. On the basis of 3-D geometry, improved EMC, which consists of magneto motive-force (MMF) source and permeance considering main and leakage flux distribution, is composed and field analysis is performed. Nonlinear characteristics of magnetic core are considered for precise analysis results. Three-dimensional finite element analysis (FEA) is performed to verify calculated results and flux density in rotor and stator areas are compared. In addition, calculated and experimental back-EMF versus MMF of field and rotor speed is compared. From the verification with calculated and experimental results, it is proved that improved EMC compared with 3-D FEA provided reasonable results in initial design of claw-pole machine having asymmetric structure.

Effect of diffusion barrier in the thermally annealed exchange-biased IrMn-CoFe electrode in magnetic tunnel junctions

Exchange-biased electrodes IrMn/Ta(2 /spl Aring/)/CoFe/AlO/sub x/ and IrMn/CoFe/Ta(2 /spl Aring/)-AlO/sub x/ used in a magnetic tunnel junction were annealed at 300/spl deg/C to study the Mn diffusion characteristics. Auger electron spectroscopy and X-ray photoelectron spectroscopy analysis of the annealed electrodes show that the Ta diffusion barrier effectively blocked the Mn migration, regardless of the barrier location. Also concluded from the study was that the Mn migration is largely enhanced by the preferential oxidation of Mn.

A method to estimate hysteresis torque using core loss

This paper presents a analysis method to estimate the hysteresis torque of a permanent magnet motor using core loss data without hysteresis loop. In the motor which is used in the electric power steering system, the analysis of hysteresis torque is important to predict accurate offset torque including bearing friction. In this paper, hysteresis loss is computed by core loss that is obtained from experiment at low frequencies. Hysteresis torque is calculated as hysteresis loss is divided by motor speed. This method is quite simple than method which use the Preisach model for calculating hysteresis torque. Finally, the validity of this method is verified by the comparison with test results.

Characteristics and radial magnetic force of interior permanent magnet synchronous motor according to pole/slot combinations

This paper presents motor characteristics and radial magnetic force (RMF) of interior permanent magnet synchronous motors (IPMSM) according to pole/slot combinations. Three IPMSM of 15, 18, 24 slots with 16 poles are selected; 16 poles 15 slots and 18 slots provide high winding factor and 16 poles 24 slots is a general pole-slot combination. Using finite element analysis (FEA) and equivalent circuit analysis, output characteristics and motor parameters such as back electro-motive force (bemf), inductance, etc. are compared, and RMF in air gap causing noise and vibration is investigated. It is expected that presented study results help with appropriate choice of pole and slot number of IPMSM.

An improved AC standstill method for testing inductances of interior PM synchronous motor considering cross-magnetizing effect

An inductance measurement method for interior permanent magnet synchronous machine (IPMSM) is proposed in this paper. In this method, the motor is measured at standstill condition, and only a 3-phase voltage source, an oscilloscope and a DC voltage source are required. Depending on the deductive dq-axis voltage equations in the stationary frame of reference, the dq-axis inductances at different current magnetite and vector angle can be calculated by the measured 3-phase voltages and currents. And hence, the saturation and cross-magnetizing effect of the inductances are measurable. This paper introduces the principle equations, experiment setup, data processing, and results comparison on the concentrated-winding and distributed-winding IPMSMs.

Magnetic field analysis of polar anisotropic ferrite bonded magnet to outer rotor type brushless dc motor considering magnetizing process

In this paper, we propose an analytical method of polar anisotropic ferrite bonded magnet to outer rotor type brushless dc motor considering magnetizing process. The characteristics of polar anisotropic magnets are different from cored type ones which have uniform magnetization direction. Consequently, the magnetization directions of ferrite bonded magnet are analyzed by finite element analysis for magnetization procedure. Additionally, the overhang effect of the magnet is calculated by using 3-D FEA. The validity of the analysis method is verified by comparing the analyzed results with measured ones.

Core loss distribution of three-phase induction motor using numerical method

This paper presents core loss analysis of 3-phase induction motors used for industry applications. The core loss is affected by the time rate of the change of magnetic flux density. Generally core loss is spread out in stator and rotor core. And, rotor core toss is less than stator core because of constant field flux density of rotor. Tooth core loss density is large than yoke core loss because tooth has harmonic distortion of flux density. In this paper, transient finite element method used to analyze the magnetic flux density waveform in order to analysis the flux density according to varying time. Core losses in each element are evaluated using core loss curve tested by and Epstein test apparatus. Its result is shown the distribution of core loss density and partial thermal source.

Development of an IPMSM for in-wheel type electric vehicles

This paper deals with a design approach to an interior permanent magnet synchronous motor (IPMSM) used in in-wheel motor drive systems of electric vehicles. The approach is divided into three parts overall. First, the constant power region of IPMSM and gear ratio are investigated in order to meet the specifications of the in-wheel motor system. Second, the range of inductance and back-EMF to satisfy the given design conditions of the IPMSM is estimated. Finally, the preliminary geometry satisfying the range is decided by PM type, current density, and fill factor and so on, and then the detailed design is carried out by means of finite element analysis in consideration of magnetic saturation.

An improved AC standstill inductance test method for interior PM synchronous motor considering cross-magnetization effect

An improved AC standstill inductance measurement method for interior permanent magnet synchronous machine (IPMSM) is proposed in this paper. Only the 3-phase voltage source, oscilloscope, and DC voltage source are required, rather than the dynamometer and inverter in the other methods. Depending on the deduced q- and d-axis voltage equations in the stationary reference frame, the q- and d-axis inductances at different current magnetite and vector angle can be calculated by the measured 3-phase voltages and currents. Thus, the saturation and cross-magnetizing effect of the inductances are measurable. This paper will introduce the principle equations, experiment setup, data processing, and results comparison.

Hysteresis modeling using multi-Preisach model in electromagnetic computation

This paper presents particle interaction of hysteresis model with multi-Preisach model. A conventional analysis method is calculated using Everett density with the Gaussian distribution or the Cauchy distribution. In this paper, we propose fine method called multi-Preisach model method to calculate hysteresis model using several experiment data line. Multi-Preisach hysteresis model is provide the convenient and accurate novel method.