Il-Jung Kim

Dynamic and Experimental Performance of Linear-Switched Reluctance Machine With Inductance Variation According to Airgap Length

This paper deals with the dynamic and experimental performance of a linear-switched reluctance machine with inductance variation according to airgap length. First, analytical solutions for flux density due to mover winding currents are derived for the case when the mover is located at an aligned and unaligned position. And then, using the inductance at an aligned and unaligned position obtained from 2-D analytical solutions and Fourier series expansion proposed in this paper, we predict the inductance profile of the linear-switched reluctance machine (LSRM) analytically. Finally, with the experiment of manufactured LSRM, the validity of the characteristic equations is demonstrated, and the operating experiment is performed by manufacturing the operating circuit for the experiment of the operating characteristic according to the airgap length.

Characteristics Analysis of Induction Generator with a Change in Rotor Speed

Squirrel cage induction motor is the main driving system of industrial field and familiar with its use in a large variety of applications. However, many engineer are unfamiliar with the induction generator, even though no difference exists between both machines except for the mode of operation. But an induction generator is commonly used for micro & small hydro power applications due to its simplicity, reliability, low cost and robustness. Input and output of induction motor has turned against at the induction generator operation. Rotation speed of induction generator is small faster than induction motor. As output of induction machines increases with the increasement of speed, so loss is same. Actually, generator efficiency is lower than motor at this condition. If induction generator is connected with mechanical load, total efficiency is decreased. In this paper, we analyzed that input, output, torque and efficiency is different from each other above and below synchronous speed.

Characteristics Analysis of Power Capacitor at Sag & Swell

Power capacitor has been used to compensate for the low power factor of inductive load and to reduce harmonics generated by the power conversion device with reactor. Power quality is mainly referred to the voltage quality and it is very important for the stable operation of load. But if voltage rms is temporary changed, it acts on capacitor as an electrical stress. In this paper, we analyzed that capacitor can be given by voltage, current and capacity`s variance under the sag and swell condition. If reactor is connected at capacitor, sag can be aside from the question. But it can act an amount of stress on capacitor in the swell region.

The Torque Characteristics Analysis of the Single-Phase Switched Reluctance Motor According to the Starting Method

The single-phase switched reluctance motor(SRM) has only one inductance variation and the positive torque is generated in the restricted section. So, it cannot be started by itself. To solve this problem, many researchers have addressed the several starting method for the single-phase SRM. This paper is focused on the torque characteristics of the single-phase SRM according to starting method. The four major starting method - permanent magnet, saturable stator pole, to grade the rotor, stepped rotor pole - is selected to analyze the torque characteristics. The analysis model of each starting method is designed to changed the pole shape or inserting other material in the basic model. The torque characteristics of each analysis model is obtained by using FEM analysis. The FEM analysis is performed at incremental rotor positions over half inductance cycle in any one pole with 250AT, 500AT, 750AT. The distortion factor of each analysis model is analyzed through the FFT to compare the distortion between basic model and four analysis model.

Voltage and current characteristics analysis of passive filter

Industrial power distribution system includes so many kind of non-linear loads. Non-linear load produces harmonic components of current during the energy conversion transition. Passive filter is widely used for reducing of harmonics in the users power systems. This filter frequently gets out of order by the electrical stress. There is voltage increase when capacitor and reactor are applied in the users filter systems. If increased voltage is above stipulated values, they have a severe influence on the life of reactor. This paper describes that the voltage and current of capacitor used for filter is within the limits of allowable values, but reactor is beyond the limit and reveals spike voltage. Therefore this phenomenon brings about premature fault of reactor.

Characteristic Analysis of Permanent Magnet Linear Generator by using Space Harmonic Method

This paper deals with characteristics analysis of a permanent magnet (PM) linear generator using analytical methods for wave energy harvesting. The wave energy is carried out from the movement of a yo-yo system. A linear generator using permanent magnets to generate a magnetic force itself does not require a separate power supply and has the advantage of simple maintenance. In addition to the use of a rare earth, a permanent magnet having a high-energy density can be miniaturized and lightweight, and can obtain high energy-conversion efficiency. We derived magnetic field solutions produced by the permanent magnet and armature reaction based on 2D polar coordinates and magnetic vector potential. Induced voltage is obtained via arbitrary sinusoidal input. In addition, electrical parameters are obtained, such as back-EMF constant, resistance, and selfand mutual-winding inductances. The space harmonic method used in this paper is confirmed by comparing it with finite element method (FEM) results. These facilitate the characterization of the PM-type linear generator and provide a basis for comparative studies, design optimization, and machine dynamic modeling.

Electromagnetic analysis and experimental testing of a light switchwith a permanent magnet generator for energy harvesting based on three dimensional finite element model

This paper presents a small-size permanent magnet generator for an energy harvester. The generator is suitable for a switch, as it uses a magnetic force as the retention force and the force of motion to recognize switch operation. In addition, the induced voltages have positive or negative values depending on the switching direction. It is possible to monitor switch operation for achieving intelligent power consumption. Finally, measurements of the generated voltage are presented to reveal the effectiveness of the energy harvester.

Analysis and Design of high-efficiency Permanent Magnet Synchronous Motor/Generator for Renewable Energy Application

In renewable energy system such as flywheel energy storage system, wind power and solar power, the motor/generator is the important key for offering the electric energy to the electric loads. For example, the heavy and large flywheel is rotated by electromagnetic torque of pemanent magnet synchronous motor (PMSM) and, in case of a breakdown of electric current, the PMSM used as generator supplies electric energy for the various electric utilities using mechanical rotation energy of the flywheel. Thus, design of a motor/generator should be performed in effort to reduce cogging torque and electromagnetic loss for high efficiency. In our paper, a slotless permanent magnet synchronous motor/generator (SPMSM/G) with output power 15kW at the rotor speed 18000rpm is designed from electromagnetic analysis and dynamic performance analysis. In analytical approach, design parameters such as back electro-motive force (back EMF), inductance and electromagnetic torque are derived from analytical method which is one of the electromagnetic analysis method. And using the design parameters, this paper deal with system design considering the driving characteristics and electric load in required power. Finally, the analytical results are verified by the experiment and finite element method (FEM).