Kyung-Il Woo

Finite element analysis of direct thrust-controlled linear induction motor

This paper describes the finite element analysis of a direct thrust-controlled linear induction motor (LIM). The time-stepping finite element method and the moving mesh technique are used to calculate the dynamic characteristics of the LIM during direct thrust control. Because the LIM has an end effect, a thrust correction coefficient is introduced to predict actual thrust in control. The simulation results, the thrust and the stator flux linkage are shown and the stator current is compared experiments.

Analysis of magnetization of magnet in the rotor of line start permanent magnet motor

Line start permanent magnet motor (LSPM) is an effective model of a high-efficiency motor at a constant velocity. Post-assembly magnetization is necessary to reduce manufacture costs. The purpose of this paper is to design the magnetizing fixture and analyze the magnetization characteristics. First, the magnetizing fixture reducing the eddy current is designed. Second, the magnetization of NdFeB magnetized by the designed fixture is analyzed. The time-stepping finite-element method combined with the Preisach model is used to analyze the magnetizing magnetic field intensity and to calculate the magnetization vector. With the magnetization vector, the surface flux density and back-electromagnetic force of the LSPM are calculated and compared with experiment results, which, in turn, agree well with the analysis results.

Electromagnetic Field and Thermal Linked Analysis of Interior Permanent-Magnet Synchronous Motor for Agricultural Electric Vehicle

This paper presents a 3D numerical analysis of the thermal transient behavior of the air-cooled interior permanent-magnet synchronous motor (IPMSM) for agricultural electric vehicle (AEV) using finite-element method (FEM). The air-cooled IPMSM is investigated the temperature variation for the insulation of winding coil and demagnetization of permanent-magnet during the rated operation. Therefore, the prediction of a motor temperature is necessary at the motor design stage. This paper shows a good agreement both the numerical calculation and experimental results. The proposed method, electromagnetic field and thermal linked analysis, is able to predict the temperature distribution of IPMSM with the rated 7.5 kW continuous power.

Improvement of torque characteristics of permanent magnet wind generator by FEM and optimization

This paper focuses on the improvement of the torque characteristics of the outer rotor direct drive permanent magnet wind generator that is a radial flux machine with output power of low speed and high torque, 3(kW) 90(rpm) by FEM and optimization. The optimization technique is used to find out a design solution through the comparison of cogging torques according to the shape variation such as the open slot width and the pole arc ratio. In this technique the problem is to mini mize the objective function. The automatic process that includes the automatic ACAD file drawing and mesh generation with reg ard to the shape variation is also used. The revised generator is obtained from a preliminary model. The cogging torque characteristics of the revised model and the preliminary model and the dynamic characteristics are analyzed. From the simulation result s, it is shown that the cogging torque characteristic of the revised model is better than that of the preliminary one. The prototype was manufactured and the simulation result such as induced voltage is agrees with that of the experimental one.

Study on the Evaluation of Uncertainty for the Efficiency of 0.75[kW] Class Three Phase Induction Motor

In the last few years, the regulations for efficiency grade of the three phase induction motor are internationally being discussed and upgraded for the protection of environment and energy saving. So the efficiency improvement and the reliable test result are essential to determine the premium grade three phase induction motor. While a study on developing the efficiency motor is active, there is little research about the guarantee for efficiency. So in this paper, the dispersion characteristic of the efficiency is studied using uncertainty theory for the three phase induction motor to improve the reliability of efficiency. The values such as input voltage, current, speed, torque were obtained by loss separation method to evaluate the uncertainty. From the result, it was known that the important loss factor could affect the uncertainty is the stray loss.

Torque Characteristics Analysis of Synchronous Reluctance Motor by Winding Function Theory

In this paper, torque characteristics analysis of Synchronous Reluctance Motor with the cylindrical rotor type by winding function theory(WFT) is described. The stator is same as one of the induction motor. From the d-axis, q-axis flux density distribution, to calculate self and mutual inductances needed to calculate the torque of the machine by using winding function theory the new equivalent geometry of rotor was proposed. D-axis, q-axis flux densities, self inductance and torque characteristics were obtained. From the comparison with results of finite element analysis the proposed method was verified.

Dynamic finite element analysis of a single-sided linear induction motor with joint in the secondary conductor

Recently, the linear induction mtor(LM1 is k n g applied in transportation s y s t n convrym systcm[il. factory automation, achlators, etc. In these applications, shun primary is on the moving p?lt and a law secondary is an the stationary pan[21. In applicatiun where a very lung mondary conductar is reymued, many alumnium sheets are jointed side-by-side. The Junction between the aluminium sileets cmte discontinuity in the secondary eddy current nununifom and cause fluctuation of t h s t and n o d force of LIM. The papers dealing with lhc joint effect suppsing that all lhe electromagnetcc quantities vary smusaidallyI31, contml algorithm to ampensate far joints effect[41 have been presented. In this paw, LimstepPing finite element analysis of LIM with joint m the secondary is presented. od is defixd at each Eecondwy cunductar fm eddy current analysis and the moving mesh technique is used for simulation to take account of movement.

Power Balancing Control Method of A Residential Distributed Generation System using Photovoltaic Power Generation and Polymer Electrolyte Fuel Cells

Output power in photovoltaic systems changes steeply with the change of the sun intensity. The change of output power has influence on the electric power quality of the system. This paper proposes a residential distributed generation system using photovoltaic power generation and polymer electrolyte fuel cells(hybrid systems). In order to level the output power which changes steeply the polymer electrolyte fuel cells are connected to the photovoltaic power generation system in parallel. Thus the generated power of all the system can be leveled. However, the steep generated power in the photovoltaic power generation system can not be leveled. Therefore, the electric double layer capacitor(EDLC) is connected in parallel with the hybrid systems. It is confirmed by the simulation that the proposed distributed generation system is available for a residential supply.

A Study on the Efficiency Evaluation Standard and Regulation for Electric Motor Systems

Electric motor systems account for more than half of all electric systems and the amount of energy consumption of those is almost 70 percent of total energy consumption of electric motor systems in industry. As electric motor systems are very responsible for global electricity savings and environment protection. Many international organizations are supporting standards and policy development processes to improve the efficiency of electric motor systems. Many standards are being developed at technical committee of IEC that has been required in order to support the implementation of efficiency regulations. High efficiency standards and levels for electric motor systems are slowly being introduced and compulsory in many countries. Therefore understanding the international efficiency evaluation standards and the regulation of electric motor systems of each country is important. This paper presents the current status and trends of international evaluation standards and regulations about the efficiency of electric motor systems.

Heating performance improvement of an induction heating rice cooker with magnetic flux concentrator

Nowadays, energy saving has been one of the important issues in home appliances. An electric rice cooker is especially one of major electrical energy consumption in home appliance of Asia. Because most consumer of the rice cooker are used to use a warmer function all day long. Therefore, a lot of efforts have been made to improve the energy efficiency of the rice cooker. Especially, induction heating (IH) technology has been applied to the rice cooker due to its advantages regarding efficiency, fast heating, safety, cleanness and accurate controlled heating. This paper presents the heating performance improvement of IH rice cooker with magnetic flux concentrator (MFC). A coupled thermal-electromagnetics 3D-FEA was carried out to model the MFC and predict the magnetic flux density and temperature of jar in the rice cooker.