For a linear induction motor(LIM), the constants of each phase are different due to the structure. In this paper, a vector control analysis method of a LIM taking into consideration its asymmetrical constants are proposed. And, in order to prove the propriety of proposed vector control method and to analyze the dynamic characteristics of LIM's vector control, FEM taking into account of movement and using stator tapped winding is used in the analysis region. So, It is confirmed that the proposed asymetrical constants vector control theory and simulation method of mixing with FEM is appropriate to dynamic characteristics analysis of LIM.

In this paper, we study the computation of the electric field of dielectric analysis models with the conductivity on its surface. The finite element formulation describes a sinusoidal electrodynamic field computation. One term is added to this functional in order to take the conductivity on its surface into accounts. The electric field computations of the dielectric analysis model are done first with the surface conductivity and second with the volume conductivity. Also, it is shown that a surface conductor with sufficiently large conductivity can be substituted with a floating equipotential line. This method is applied to an insulator in arbitrary shape with the conductivity on its surface.

In order to achieve a essential requirement for the driving system of electric vehicles, that is, starting pick-up ability, a wound-type induction motor with double-rotor structure is proposed. Slip Power Recovery system is adopted to improve the efficiency in the low speed range and to control speed of this system. Theoretical analysis and experimental results from 300[W] prototype motor is presented to verify the improvement of pick-up ability and high-efficiency driving characteristics through the wide speed range, especially under the low speed range.

It is necessary to analyze exactly the torque ripple components in the harmonics as to decrease the torque ripple. Lower harmonics influence mainly on torque ripple. Among the harmonics, the pairs of 5's, 7's and 11's, 13's are dominant, and the magnitude of each pairs of current harmonics are very significant. Therefore, for decreasing the torque ripple, current harmonic pairs of 6n ${\pm}$1's orders must be simultaneously eliminated. In the case of eliminating one of current harmonic pairs, even though the magnitude of the current harmonics is small, It has great effect on torque ripple.

This paper presents compression algorithm of a system matrix for electromagnetic analysis by the finite element method. Generally the solution of the finite element analysis is the more accurate the more number of nodes. The memory of a computer limit to number of nodes. Therefore it is needed the technique of compress the system matrix. This algorithm is useful to handle non-zero-terms that can be generated during the application of boundary condition.

This paper describes a 7.5T magnetic flux density superconducting wiggler that minimize net angular deflection and displacement of an electron rotating along the orbit at storage ring in Pohang Light Source. It consist of dipole superconducting magnet,high uniformity flux distribution due to current source supply,cryostat,vacuum chamber,measurement system. In this paper magnet design procedure, manufacturing, experimental results are contained.

This paper is dealing with development of H/W and S/W of Retro-Fit NC lathe controller. Especially, S/W program is handling the tool nose radius compensation. A test of S/W program execution in the developed H/W has been made and its result showed a reasonable application in real practice.

In this paper, we investigated transient fault currents in a magnetic coupling High-Tc superconducting current limiter(HCL). It has an important effect on the reliability and stability of the power system. In order to analyze transient fault characteristics of HCL, we fabricated a magnetic coupling HCL and tested it in different fault conditions. An important parameter of design and manufacture which makes HCL inherently reliable is reduction of inrush fault currents. Without inrush fault currents, the currents flowing under such conditions can be limited to a desired-value within one cycle. Inrush fault current depends on saturation, normal spot propagation velocity, turns ratio and the fault angle.

This paper presents the design and characteristics analysis of induction machine for diesel-electric hybrid vehicle powertrain. Diesel-electric hybrid vehicles are very efficacious in reduction of consumption energy, environment pollution and saftly yields with high dynamic of machines. However, their sophisticated construction requires from designers both complex made-technology and control strategy which would be able to put into practice this requirements. These problems are still considered in processing the design and analysis of induction machine. The requirements for a given volume, input power to weight ratio, high efficiency and wide speed range are met by the induction machine.

The model interrupters of $SF_6$ gas electromagnetic contactor whose ratings are the voltage of 7.2kV and the short circuit current of 4.0kA have been designed and manufactured on the basis of theoretical and computational analysis for its development. The eddy current analysis, the magnetic field analysis and the calculation of the rotational force on arcs have been conducted using FLUX2D package. The short circuit current interrupting tests have been conducted to the model interrupters using the simplified capacitive synthetic test circuit in KERI. The results show that the model interrupters have a sufficient interrupting capability and the new design concept is proper for a good interrupting performance.

Tubular coils are widely used in various electromagnetic applications. For the purpose to obtain the mechanical output power, one of the two sets of coil arrays, called drive, is generally fixed while the other, called sleeve or projectile, is not fixed and easy to move. Among the three force components acting on the coil arrays, the radial one used to affect as a stress on the surfiace of the sleeve, or a restoring force if it is off-centered. The system under transient state or intended pulsed input power is likely to have the worst condition in mechanical stress, and it is necessary to design the mechanical strength of the sleeve within the permanent deformation limit. This paper is focused on the presentation of analytic expressions for the stress on surface of the sleeve.

AC servo motors are widely used for various mechatronic devices such as FA, OA and robot machines. To obtain more accurate simulation results, a method of analysis for AC servo motor is described using transient magnetic formulation coupled with external circuit equation of the motor. The external circuit of the motor to be analyzed is described using FLUX2D program and linked to multiple finite element regions. The simulation results show that transient magnetic analysis coupled with extenal circuit has more accurate than those results from magnetostatic.

The inherent performance of Ultrasonic Motor(USM) which is on of highlighted a directly-driven positioning servo motor/actuator. In this paper, the speed of control USM based on neural network control. The neural network control can roughly be classified as the direct control and indirect control schemes. An indirect control scheme is adopted for Ultrasonic Motor speed control. A back propagation algorithm is used to train neural network controller. The Simulation results show that this neural network control system can provide good dynamical responses.

This paper describes the flux density in air gap, harmonic torques occurring by inadequate slot combination of induction motor using the fourier series. The analysis uses DFT(Discrete Fourier transform) to analyze harmonic orders of flux density. It is certified that the harmonic flux density has the same result using Fourier series and FEM.

This paper deals with characteristics of magnet that the levitation and guidance forces at static state and we tested and evaluated its. Also we compared to effect of levitation force with material and shape of guide way, focus on evaluation and method of test for the magnet of Urban Transit Maglev vehicle.

This paper deals with the dynamic characteristics of LIM which is controlled by constant V/f ratio and the characteristics of the Inverter acted as interface between the utility power system and LIM. Though open-loop control method is less reliable than closed-loop control method, it's commonly used because it is simple and cheap. This paper shows the consideration for dynamic characteristics of LIM under open-loop control and for Inverter.

This paper presents the characteristics of linear induction motors fed by a voltage source PWM inverter. In the calculation, 2D finite element method is used considering the movement by moving mesh. Integro-differential approach is adopted for the copper loss calculation considering the skin effect.

Dynamic characteristics of the vector controlled induction motor has been analysed using d-q equivalent circuit. However, for the design of the induction motor, the analysis of an accurate response characteristic are needed. In this paper, dynamic characteristic analysis method using 2-D Finite Element Method (FEM), which takes the motion equation of the rotor into account and considers the physical motion of the rotor by an automatic subdivision of mesh, are explained.

This paper presents the cogging torque analysis of the permanent magnet type AC servo motor which have the closed slot structure. Generally, existence of the slot opening causes the cogging torque. But the cogging torque exists in this type motor(having closed slot structure) because the bridge part is saturated by the rotor flux. In this paper, the finite element analysis is used to calculate the cogging torque and the rated torque. As the size of the bridge part-the thickness and the width-changes, the cogging torque and the rated torque are obtained repeatedly like as upper procedures. Finally, the trends of the cogging torque and the rated torque versus the size of the bridge part are obtained from this analysis procedures. By this approach, the optimal geometry of the bridge part can be found which minimize the cogging torque satisfying the required value of the rated torque.

This paper describes the characteristics of electromagnetic forces of Combined superconducting maglev system. Generation of the levitation, the propulsion and the guidance force by a single coil is proved by the phasor- analysis. It is also shown that double-layered configuration has better characteristics in efficiency, pulsation of the forces and drag ratio than single-layered configuration.

The squirrel cage rotors for induction motors may have several faults such as broken bars, bad spots in end ring, abnormal skew caused by improper processing. These faults have bad effect on the performance of the induction motor. This paper proposes the detecting technique of these faults by analyzing the current of the detecting electric magnet, using 2-D finite element method taking account of the rotor movement.

The controller for magnetically suspended vehicles considering the speed characteristics is presented. Generally, the attraction force of magnet is determined by input current and air gap. However, when MAGLEV runs at high speed, induced eddy currents in the rail decrease the attraction force. Thus control characteristics of MAGLEV become deteriorated. Therefore, the variation of attraction force according to speed must be considered. Thus we analyzed the speed characteristics of the magnet by FEM. Also, we study on the control characteristics according to speeds, and design the controller considering the decline of levitation force using Neural Network.

For the accurate analysis of induction motors driven by PWM-type inverter, a time-stepping finite element method is presented in this paper. Since the PWM-type source voltage is not sinusoidal, the time harmonic method can not be used. Therefore, we used a time-stepping method, where the space harmonics due to the slot structure can be analyzed and each time-step size is determined from each increase of rotor position. As a numerical example, an induction motor of 20 Hp, 3 phase and 6 pole is analyzed. First, numerical results of the time-stepping finite element analysis are compared to those of conventional equivated circuit analysts. Next, the stator current characteristic obtained from PWM voltage source is compared to that from sinusoidal voltage source.

This paper describes the precise position control of the linear DC motor for carrier. We analyze the switching line of seek mode control and propose the modified switching line according to the mass and distance. Experimental results demonstrate that good performance is achieved by the proposed controller.

This paper investigates the force on a rectangular AC supercoducting coil moving above and parallel to a conducting plate of finite thickness. Expressions are developed for the levitation and drag forces on the coil a a function of speed and frequency. The levitation force are generated at all speed including stand still in a AC supercoducting coil. The levitation and drag forces on a rectangular AC supercoducting coil are compared with those on a rectangular DC supercoducting coil moving above and parallel to a conducting plate.

The electromagnetic force of magnetic plunger for electromagnetic pump system are calculated by finite element method which consider the eddy current, the plunger motion. The mechanical motion equation are solved Rune-Kutta method, and coupled with the finite element method. With the external circuit equation dynamic simulation of the pump system are achieved. Electrostatic flux is verified by comparing with other commercial analysis software. Similar analysis of other type solenoidal actuators can be done by this procedure.

In a permanent magnet motor, cogging torque arises from the intersection of the rotor magnets with the steel teeth on the stator. This paper describes design measures which can be taken to reduce the cogging torque. In this paper for the optimal shape design of brushless DC motor, evolution strategy is investigated to find the dimension of stator of BLDC motor that minimizes the cogging torque. The corresponding field analysis is performed by two-dimensional finite element method.

Outer-rotor type brushless motor is designed to run at more constant speed because of large inertia comparing with inner-rotor type. The constant speed is acquired by increasing inertia. Also, the generating torque is proportional to the rotor volume, i. e. rotor diameter. The main idea in this study is to design and analyze the outer-rotor type brushless motor by permeance method with given outer dimension.

This paper deals with calculation of surface charge density on current carrying conductors by FEM. The proposed algorithm is formulated by equation of continutity in conductor region and maxwell's equations outside, respectively, Surface charge density is calculated by electric scalar potential and boundary condition for electrostatic fields.

This paper is to describe a method for calculating resistance of cage rotor end-ring, based on 3-D finite element method using magnetic vector potential $\vec{A}$ and electric scalar potential ${\phi}$. The induced current of a cage rotor flows through the bars of a cage rotor. The current completes their closed paths by passing around the end-ring. The end-ring may contribute a significant influence to the performance of machine. The resistance under consideration of skin effect is calculate by using Joule's loss equation.

A superconducting current generator, or a superconducting rectifier(SCR) is used as a current source to energize a superconducting magnets in SMES, MRI. We selected a full-wave SCR among various SCR models and analyzed its operational characteristics by computer simulation. In process of pumping the current, the improvement of performance is dependent on how much bigger the open resistance of the switch is in comparison to load coil impedance when one of two switches become active. Faster transfer can he seen in resistive commutation mode by shortening the time elapsed for the resistance to arrive at certain level from zero state. Although recovery time for the switch has no direct effect on current pumping, optimal switch design is needed to increasing operational frequency.

This paper deals with development of high torque and high accurate stepping motor and control system which is adopted heavy equipment engine speed control. In the process of development, only pure domestic technics is involved, all the parts are supplied in domestic industries, and successfully accomplished to mass production. In order to confirm product liability, circumferential test,such as vibration test impact test,thermal test,and field test are thoroughly fulfilled.

This paper describes new tecknique to obtain optimum value in calculating space harmonics in the motor design. First, develops general procedure in calculating slot harmonics, MMF harmonics, and systhesis of them. And then, trains Artificial Neural Network by classical method. Once trained ANN, it also computing different input data more quickly.

A curious resistivity anomaly in high curie point barium-lead-titanate materials with positive temerature coefficient of resistivity (PTCR) has been observed just below the curie point, besides the normal PTCR anomaly. The additional resistivity anomaly was observed in the resistivity-temperature characteristics.

This paper considers backing structure of non-contact steel plate using magnectically levitation and aspect-quality factor is defined by estimation of electromagnet-aspect attraction steel plate. Characteristics of attraction power is studied in cylindrical electromagnet, U-type electromagnet, E-type electromagnet by aspect-quality factor. Designing and manufacturing electromagnet attraction steel plate, propriety of experimental results is confirmed.

In this paper, We have designed the new Two-Double 1-2 phase exciting method. And We have developed the chopper constant current drive circuit in order to apply Two-Double 1-2 phase exciting method to 4-phase Stepping Motor.

The calculations of the temperature rise in the armature have long been considered among some of the most important problems in the design of the rotating machine. Despite the many methods of calculation propose, very few have been used in the actual design. In most cases, These methods are inadequate for measuring a wide range of temperature distribution because of the complicated structure of the machine. In this paper, the armature is divided into seven portions, and the thermal equivalent circuit is introduced as a simulation of the armature. The test machine is 1000Kw salient-pole synchronous generator.

A comprehensive analytical study of total-intake current waveforms is described. In particular, the characteristics of the modulation envelope of the waveforms are the subject of detailed investigation. It is shown that the lower modulation envelope of the total intake current is capable of providing a signal suitable for use in stabilising a variable-reluctance stepping motor.

This paper is a study on inductive superconducting fault current limiter design.. We have created simulation for an imaginery power system with inductive superconducting fault current limiter. Then input variables for characteristic analysis and actual manufacturing, and output variables for design results was assigned. Using the results from these variables, the design criterion was determined which was fed into concept design arising from characteristic analysis to determine the inductance of limiting coil and normal state resistance value of triggering coil. These result was put back into design details to finally give out the design result for inductive superconducting fault current limiter.

Electrical transmission and distribution networks must withstand an occasionally abnormal condition such as a fault, with prejudicial consequences for the line, transformers or generators. And the improvement of reliability and quality of the delivered power from an electric utility motivates the development of new technologies in power applications. As a part of these studies, the usefulness and utility of a superconduction fault current limiter(SFCL) are shown. The SFCL is applied to 22.9KV three-phase power system and performed short circuit studies. The verified quench characteristic of SFCL is adopted for fault simulation and the results are compared with those of system which have not SFCL.

A superconducting parallel bifilar winding with one strand in each branch was tested and analyzed. When the superconducting parallel bifilar winding was quenched by fault current, it showed the so-called 'fast quench' and the results of experiment well explained the resistance curve. Also the experiments confirm that the current redistribution of magnetically coupled strands develops new normal zones after the initial quench, and that the size of normal zones at an early stage increases almost linearly as dI/dt increases. By these results, we could explain the resistance rise of superconducting parallel bifilar winding when it is quenched by the current above the critical value.

Inductive high-Tc superconducting fault current limiter using YBCO superconducting ring in the secondary part has many advantages in power networks. It is based on the superconducting to normal transition and this paper describes its operational characteristics and experimental results, especially focused on the harmonic component analysis and recovery time. We fabricated and tested it under various conditions for the analysis of transient fault characteristics. And for the analysis of harmonics we used FFT methods. The superconducting ring was quenched in 240Arms and fault current was effectively limited to the lower current level. In addition, it was fast recovered when the fault condition was removed and after fault the system had odd harmonics.

A superconducting parallel bifilar winding shows the phenomenon which is known as 'fast quench'. We analyzed the temperature characteristics on the winding by computer simulation, and confirmed theses by experiment. The temperature of the quenched point rose gradually as the source voltage was increased. The temperature changed radically as first, but had a gentle slope after a few milliseconds. As the source voltage was large, the initial quenched length also increased. The points in this quenched length showed almost the same temperature. but the points where initial quench had not occurred showed radical temperature gradient. We could observe that the temperature of the whole wire increased simultaneously as the fast quench occurred on the superconducting parallel bifilar winding, because a number of quenched points in that wire appeared at the same time.

This paper describes the test results of magnetic field distributions of superconducting MRI magnet in an insert dewar. To get a very high homogeneous magnetic field, various shim coils are installed besides the main magnet. The operating currents of each shim coils are obtained from the exact measurements of the magnetic field. In this paper, we report the test results of the magnetic field distribution measurements with various shim coils.

The design of a 16 tesla/ 45mm bore superconducting magnet is presented. The system consists of an 8.2 tesla(at 4.2K) outer NbTi coil with a bore I.D. of 261mm, a winding O.D. of 453mm and the length of 430mm which is connected in series with a 5.6 tesla(at 4.2K) middle and a 4.7 tesla(at 4.2K) inner insert coil constructed of multifilamentary $Nb_{3}Sn$. The middle and inner insert coil will be reacted after winding. Also, epoxy impregnation will be accomplished at $Nb_{3}Sn$ coils using a low viscosity crack resistant epoxy which is forced into the coil with a series of vacuum and over atmosphere pressure cycle.

A superconducting 2 tesla MRI magnet for the animal magnetic resonance imaging has been developed as a basic model for the application of the precise supercoducting magnet technology. MRI cryostat with 210mm room temperature bore was designed and manufactured for this magnet. The cryostat was designed basically not only to extract the principal design parameters at the performance test but also for the convenience of the manufacturing. The most extinct feacture of the cryostat is that it does not have $LN_{2}$ tank and the 77K thermal shield is cooled by circuling $LN_{2}$ through copper pipe which is welded around the shield plate. It results in reduction of the total cryostat size(about 30%).

The stabilization of the conductor in superconducting power cable is very important from the view point of protection. In this study, critical thicknesses of superconducting layer of $Nb_{3}Sn$ conductor and stabilizer Cu have been estimated under the adiabatic condition. The bending stress of $Nb_{3}Sn$/SUS composite superconducting tape on the curvature radius was also evaluated.

In order to study the basic I-V behavior and quench characteristics, we fabricated two kinds of small superconducting coils which were wound with different superconductors. In this study, it was made clear that the propagation. velocity of normal zone preferentially depends on the operation current rather than heat pulse energy and also increases exponentially with respect to operation current.

We fabricated superconducting magnet for MRI and tested it using automatic field mapping system. This magnet has 20cm diameter of room temperature bore for the sample access. In this paper, the fabrication of MRI magnet system and the test results of field homogeneity are described.

A superconducting power cable is one of the promising ways for transmitting huge electric power efficiently in the future. We performed a conceptual design of 154kV, 3GVA class superconducting power cable. The AC loss of superconductor was estimated by using the Bean model. The cross sectional area of stabilizer was calculated under the adiabatic condition. In this paper, the results of the conceptual design of superconducting power cable is described.

In order to develop a medium voltage class gas circuit breaker by our own technology, we designed and manufactured the model interrupters using the hybrid arc extinguishing principle which adopts the thermal expansion principle in the large current region and the arc rotation principle by permanent magnet in the small current region. As the results of the first year research out of three years' research period, the main design parameters such as the volume of thermal expansion chamber, the distance between fixed contact and nozzle, the length of nozzle throat, the nozzle expansion angle and the magnitude of permanent magnet etc. have been determined. 4 types of model interrupters have been designed and manufactured considering the main design parameters. The 25kA short-circuit test and capacitive current breaking test have been performed for the model interrupters and the test results analyzed to improve the model interupters.

In this paper, the principle of the magnetic flux generation which influences the magnitude of the arc rotation in the interrupter of rotary arc type gas circuit breaker(GCB) is explained. The several factors making the phase difference between arc current and generated flux are analyzed and used to design and manufacture the rotary arc type model GCB. The magnetic flux density is calculated for the model GCB and the calculated result compared with that of the measured one.

This paper proposes the circuit of the simple synthetic testing facility using LC resonance circuit. The analyzed results of the circuit which can be useful for the design stage of the testing facility are also shown. EMTP has been used to analyze the circuit. Two cases of short-circuit test results obtained from the simple synthetic testing facility in KERI are shown with the waveforms of current and voltage. The results also indicate that the simple synthetic testing facility using LC resonance circuit can be easily designed and used very usefully for the research and development for the switchgears.

Slot field harmonics exist in air gap due to inevitable slot constructure of induction motors. They give rise to noise by the electromagnetic vibration and mechanical pulsation. We calculate the slot field harmonics for varying the ratio of slot width vs teeth pitch using the carter's coefficent. We computate the flux density in air gap by FEM(Finite Element Method) and analyze it in frequency domain using DFT(Discrete Fourier Transform). We develop the new algorithm mixing FEM with DFT.

An additional consideration for using general Induction Motor are about copper loss by harmonic component of source, and increase of iron loss due to switching frequency in semiconductor devices, so that these losses come to be significant elements on design for motors used for variable V/F. In this paper, therefore, the effects of the losses are discussed, in the case the source is generated by square wave and PWM Inverter.

The hybrid type LOA is electric machine which reciprocates the mover by thrust force produced by interaction of flux between coil current and permanent magnet. In this paper, the shape of LOA is designed conceptually and calculating algorithm of leakage inductance in the stator slot and magnetizing inductance between stator and mover is obtained. Using the conceptually designed LOA, the change of flux distribution is studied in consideration with movement of a mover.

The equivalent circuit of SLIM is composed of the circuit parameters. They can be obtained from the electromagnetic theory. The accelerating characteristics of SLIM are the best efficiency when synchronous speed changed continuously. The paper outlines a method of acceleration for an accelerated field system in which it is desired to reduce the overall length to a minimum, assuming a limit on the amount of heat which can be generated in the secondary member. The paper then shows that a primary unit designed to give several discrete field speeds only, as opposed to one with continuous speed variation, is not significantly inferior in performance to the latter but is much easier to manufacture.

A boost converter proposed in this paper operates with high power factor due to input current of sinusoidal waveform. If there were no input LPF, the current is got to be discontinuos form in proportion to AC input voltage magnitude under the constant duty factor switching. Thereupon, the harmonics of input current waveform is reduced and the LPF is made with few elaboration and the control circuit is simple. The switching devices in proposed circuit are operated with soft switching by the partial resonant method. The patial resonant circuit makes use of a reactor using step-up and a capacitor of loss-less snubber. The result is that switching loss is very low and efficiency of system is high.

This paper describes a soft switching using discontinuous inductor current. The soft switching snubber circuit provides ZCS and ZVS for main switch. For high power applications, the input ractifier is fed from a three-phase ac source. The Conventional switching method is hard switching technics, because of the device turn off is ocurred in maximum reactor current. In this time, switching losses are maximised by the hard switching. In generally, soft switching technique has been adjusted with the snubber condenser in order to compensates for this losses. So, it was compared hard switching with soft switching which has proposed in this paper for switching losses, distortion factor by the simulation.

소프트 스위칭 능동 클램프 회로와 위상 변위 제어회로를 이용하여 위상 변위 제어 클램프 모드 포워드 다중진공형 컨버터를 제안하였다. 제안된 컨버터는 일정한 스위칭 주파수에서 동작하므로 설계가 용이하고 주 스위치의 전압 스트레스를 입력 전압의 2-3배로 줄일 수 있다. 컴퓨터 시뮬레이션을 통해 제안된 회로의 이론적인 동작 파형을 확인하였으며 타당성을 입증하기 위하여 1MHz, 5V, 50W 위상 변위 제어 클램프 모드 포워드 다중공진형 컨버터를 제작하여 실험한 결과 주스위치의 최대 전압 스트레스는 입력전압의 3배로 저감하였고, 부하 전류가 증가함에 따라 주스위치에 걸리는 전압 스트레스와 전류 스트레스가 감소하며, 최고 84.2%의 효율을 얻었다.

In this paper, for a constant switching frequency, the configuration and the control strategy of the resonant buck-boost type converter are proposed by the combination of zero voltage switching(ZVS) and zero current switching(ZCS) with PWM method. Also, in the configuration of power control circuit, transformer is not used in the viewpoint of economy. And the circuit has fewer power switching elements than a general resonant power converter, simulation results and experiments make show the advantages mentioned.

The overall design criteria for the optimal design of a small LEO satellite power system are described in summary. The analysis result of the KITSAT-I whole orbit data suggests the efficient power opertion for KITSAT-I and also gives some crutial information for developing a new satellite power system.

Developed controller is the part of deflection yoke winding machine which controls the power to form the deflection yoke coil into desired shape after winding. So as to form the deflection yoke coil, it is needed to melt the bonding material which is spreaded on the coil. The heat melt the bonding material which is produced by flowing the current through the winded coil. Therefore, at first it is needed to peel off the enamel from the winded coil so as to flow the current, and then supply the power to produce the heat which form the winded coil into desired shape. Naturally developed controller is composed of the peeling part and the conduction and forming part. All of them consist of the inverter structure and control the output current. The peeling is achieved by low voltage and high AC current, the conduction and forming is by DC current. Developed controller also has a function that detect the resistance of the deflection yoke coil to prevent the damage of the load which is produced by poor peeling.

Recently according to the increasing critical loads such as communication and life support systems stable power supplying becomes more and more important. Therefore it is indespensable to stabilize power source using these instruments - AVR(Automatic Voltage Regulator) or UPS(Uninterrutible Power Supply). This paper deals with ON-LNE UPS which is composed of PWM converter for AC-DC conversion. Using a PWM converter have advantages of low current harmonics and high power factor. In this paper ON-LNE UPS using PWM converter is proposed and its characteristics are investigated.

This paper is concerned with High Frequency, High Voltage Generator for X-ray using zero-voltage soft-switching PWM DC-DC high-power converter by Resonant method, which makes the most of the parastic LC parameters of high-voltage transformer link, for diagnostic X-ray power generator. The converter circuit basically utilizes phase-shift pulse width modulated series Resonant full-bridge PWM DC-DC high-power converter operating at a constant frequency;25kHz. The converter output regulation is digitally controlled using DSP (Digital Signal Processor) for obtaining a fast rising time and adjust output voltage within a wide load range.

In this paper, The characteristic of Harmonic spectrum is studied for generally used three-phase diode rectifier. and filter design criteria is showen in the sense of THD, DPF, and PF. As the becoming of Automative and informative era, the demand of critical and stable control becomes more and more important. But much EMI emissions are generated for more critical and stable control in power electronic system these EMI emissions can be measured using LISN(Line Impedance Stabilization Network). So we are to investigate the behavior of Conducted EMI emission in Diode Rectifiers using LISN in frequency domain.

In this article a neural network adaptive observer is proposed and applied to the case of induction motor control. The high performance vector control drives require exact knowledge of rotor flux. Because rotor time constant is needed to observe rotor flux, the accurate estimation of rotor time constant is important. For these problems, proposed observer which comprises neural network flux observer and neural network torque observer is trained to learn the flux dynamics and torque dynamics and subject to further on-line training by means of a backpropagation algorithem. Therefore it has been shown that the robust control of induction motor neglects the rotor time constant variations.

This paper deals with the robust control system for parameter variations, fast responses and load torque variations. Frist, fuzzy-sliding adaptive control be used to. Fuzzy-sliding adaptive control is good at fast response. Second, there are many requests for selecting freely the moment of inertia, even though moment of inertia is determined with the materials, structure, shape, and size of the motors. Therefore we developed an inertia-lowering control system that uses torque observer to reduce the moment of inertia. Finally, using torque observer, torque control is done so as to compensate load torque. Consequently, the proposed system verified the superiority through the simulations using MATLAB.

This paper presents an algorithm that the gain of the slip calculator is correctly adjusted for the variation of the rotor resistance. In the indirect field oriented controller, if the gain (rotor resistance) of the slip calculator is set the incorrect value, the torque and the flux are not properly controlled. Using of the two torque angles (i.e. stationary torque angle and rotating torque angle), we estimate the rotor resistance, and then adjust the gain of the slip calculator for the variation of the rotor resistance. It has been realized to confirm the validity of the proposed algorithm by the simulation results.

This paper presents continuous control concept of unsymmetrical 2 phase induction machine(I.M.). For 2 phase driving of the unsymmetrical I.M., variable voltage and variable frequency inverter is needed. In this paper, a new 12 step PWM 2 phase inverter was proposed. And then, proposed inverter fed 2 phase driving of unsymmetrical I.M. was studied, expecially on average torque and pulsation torque. This system has merits like higher fundamental component and better harmonic characteristics. The simulation was done on this issue and experimental research is on the way.

The new hybrid scheme for electric bus is presented in this paper. This system is composed of a three-phase AC induction motor, one inveter and one system controller. The motor can be acted as starter, motor itself, alternator, generator and retarder. Various functions are simulated. The design stage has been finished. And the various experimental tests are undertaken now.

A robust nonlinear speed control of a permanent magnet synchronous motor(PMSM) is presented. A perturbed dynamic model including the influence of parameter variations and speed measurement error on the nonlinear speed control of a PMSM is derived. Based on this model, a boundary layer integral sliding mode controller to improve the robustness and performance of the nonlinear speed control of a PMSM is proposed and compared with the conventional controller.

The inverter for UPS system is required to satisfy pure sinusoidal output voltage with very low THD(Total Harmonic distortion). This paper proposes a TMS320c31 digital signal processor based predictive instantaneous control scheme of inverter. The proposed scheme is able to satisfy the conditions; high capability, high efficiency, low audible noise and robustness of inverter. The transient state characteristics of proposed inverter has been improved. in case of power failure or recovery, nonlinear load, sudden load change or parameters variations. Finally, the performance of the proposed inverter is shown and discussed by simulation and experiment.

This paper deals with the high efficiency drive of a vector controlled inverter fed induction motor system for electric vehicles. The loss equation is derived from the voltage equations in synchronously rotating reference frame. The ratio of the d-axis and q-axis component currents should be maintained constant to maximize the efficiency at a specified speed. Digital simulations are curried out and the results are compared with those of the conventional constant flux control.

Recently, developments of high-speed semiconductor Switches as power MOSFET, power IGBT, power SIT have enwidenen the performance of classical inverter configuration, and also allowed the practical application of new inverter configuration, with improved performance and wider operating zones. The paper is study on VVVF type high-frequence inverter using self turn-off devices.

This paper proposes a new method to reduce the torque ripple in vector controlled inverter fed synchronous motor systems. In three phase voltage source inverter systems, all the three line currents are generally not measured and the currents of two lines are measured through two sensors and two A/D converters. The measured currents may contain some error due to the non-ideality of the current sensors and A/D converters, and the error coefficient of two line currents are not same. As a result, the developed torque contains the torque ripple. The proposed method can eliminate the torque ripple by setting the error coefficient to same value. To verify the proposed method, digital simulations are carried out.

The Fuzzy-Neural Controller is constructed to resolve some dificulties taking place in decision of membership functions, input and output gains and an inferenced method for desinging fuzzy logic controller. In addition Neural network emulator is used to emulate induction motor forward dynamics and to get error signal at fuzzy-neural controller output layer. Error signal is backpropagated through neural network emulator. A back propagation algorithm is used to train fuzzy-neural controller and emulator. The experimental results show that this control system can provide good dynamical responses.

In this paper, a new speed estimation method of induction motors based on the very quick torque control is proposed to realize speed sensorless control. The proposed method can be realized very simply by detecting primary motor current and voltage command at every sampling time. As the method need not the differential value of primary current in a arithmetic of voltage command, it can be expected to promote the precision of speed estimation in low speed area, especially. Through the numerical simulation, the validity of the proposed method was successfully confirmed.

A novel phase error predictor is proposed for servo system in home-use VCRs. The multirate system in VCRs is converted into a single period sampling system with faster sampling time by using the proposed novel phase error predictor. And the disturbances can be measured much faster. From the experimental results, we can see that the performance of the control system is improved greatly. The phase lock time of the proposed servo system is ten times faster than that of the conventional system.

A scheme of observer-based MFAC(Model Following Acceleration Control) system is proposed for the DC servo position control system. The proposed system is competed of MFAC, feedback controller, and reduced-order state observer. As the servo motor is controlled by the acceleration command, the total servo system becomes the acceleration control system. Simulation results show that the proposed system have robust properties against parameter variations and external disturbances.

A voltage source PWM converter with battery charging and AC/DC power conversion ability is proposed in this paper. The proposed voltage source PWM converter is independently controlled by active and reactive components and implemented by DSP controller. In UPS application the mathematical model of the voltage source PWM converter has been derived. Finally, the performance of the voltage source converter is shown and discussed through experimental results.

This paper proposes a novel PWM technique for a three phase current fad type converters. A minor loop compensation method is introduced to compensate leading current and to minimize input line current (Iu) distortion resulting from the resonance between AC filter capacitor and source inductance of power system. This PWM converter has excellent characterics as next. The control system is simply designed, and the operation with unity power factor can be easily obtained by automatic compensating the leading current of the filter circuit. Also. the three phase sinusoidal input current can be obtained.

Hybrid active filters utilize passive filters to reduce the voltage rating and hence the VA rating of the active filter converter. A novel hybrid active filter topoloty to minimize utility current harmonics at high power levels is presented in this paper. The proposed topology combines both passive and active filters to obtain the lowest converter VA rating as compared to the converter rating in the active filter and the series-active hybrid filter configurations. This is demonstrated with experimental results from a laboratory model. Simulation results showing the effect of passive filter impedance are presented.

Recent environmental pollutions have intensified the need to develop zero emission vehicles. The most effect method of such solutions is EV. EV is high energy efficiency, easy to maintain, repair and is possible to make high performance control. However, because energy density of batteries is constrained and the distance covered one charge is short range. Also because EV has disadvantage of poor accelation ability, development of high performance battery is required for large scale use of EV. EV charger analogous to gas apparatus must also be developed immediately. Charger is discriminate between on-vehicle type and off-vehicle type. As off-vehicle type is able to charge fast and safe, inductive charging is considered. This paper aims to develope off-vehicle inductive charging system. Therefore, it achieved power factor correction converter, high frequency DC/AC inverter control algorithm development which gives proof validity through simulation and formulated the basic concept of high frequency transformer design for inductive charging.

In this paper, a instantaneous speed measurement methode using a three phase sinusoidal taco-generator is described and it's simulations are developed. The proposed methode can easily detect the motor speed by using that the output voltage of taco-generator is propotion to the motor speed. Because the proposed methode consists of some calculation, the proposed system can be implemented with analog devices or micro processor conveniently. From the simulation resualts, the proposed measurement methode can acculately detect the real motor speed over wide range.

A robust nonlinear control technique for brushless DC(BLDC) motors is presented using a feedback linearizing technique. The nonlinear model of the BLDC motor is first linearized far the exactly known system by an input-output linearizing method. Then, the robust control is designed for the unknown parts of the system using the Lypunov second method. By employing the proposed control scheme, the a robust control performance against the parameter uncertainties is obtained and therefore a robust feedback linerizing control of the BLDC motor is realized. The effectiveness of the proposed control scheme is well demonstrated through the comparative simulations.

In the case of driving the SLIM(Single-sided Linear Induction Motor) as the VVVF inverter, the performance of SLIM, which is a thrust, normal force and so on, varies according to a slip frequency as a function of the external load. It is impossible that the open-loop control method control the speed of a SLIM accurately. So that, this paper is proposed the speed control method of a SLIM for a automatic conveyor system with the slip frequency vector control method. To analyze the dynamic characteristics of a SLIM, the state equation is derived from the equivalent circuit of the SLIM, ignored the end effect. The slip frequency and the normal force of SLIM are constantly controlled at the steady state. The simulated results is compared with the experimental values.

The new power train system for electric vehicle is introduced in this paper. This system includes two light weighted and high-efficient motor, two space vector PWM inverter, one system controller using CAN controller and DSP320C50. These are developed by KERI cooperated with 5 major industry companies, 5 universities including 2 foreign universities. The reliability and performance are proven by the test rig. The reference data will be collected for further researches.

LPM(Linear pulse motor) was developed as a prototype. In this paper, the design results of prototype and its dynamic characteristics are shown. The prototype was designed by using permeance analysis and the thrust value was also confirmed by comparing with the analysis results of the finite element method. To verify the performance of LPM. dynamic characteristics were measured. In slewing characteristic of the LPM, the thrust value of prototype LPM is higher than commercial level. A X-Y table was structured as a application of the prototype LPM. A controller and user's interface was also developed. By using this control system, the position error of X-Y table was checked. The repeat position error in linear movement was under than ${\pm}$ 100 micron.

In this paper, a vector control method for a AC-Excited BLSM(Brushless Synchronous Motor) is proposed. The BLSM has a feature that separate exciter is not needed for excitation. The proposed method is described in two parts as follow, one is the design of drive and the other is a modeling for its implementation. Rotor flux is estimated using indirect sensing method based on voltage equation in the synchronously rotation reference frame. And rotor position is calculated from rotor angular velocity and stator current. Through computer simulation results of this proposed system, it is shown that the BLSM drive has a ability of precision torque control from the static and dynamic performance.

In this paper, a disturbance observer with binary control is proposed to suppress the chattering of sliding mode observer in estimation of the external disturbance. Binary control has the properly of chattering alleviation in addition to advantages of the conventional sliding mode control. As a simulation result, it is confirmed that the robust and high precision position control is possible by the proposed binary observer.

This paper describes a current control method for a single-phase PWM inverter. The proposed PWM inverter utilizes the instantaneous control method which is based on the real-time digital feedback control and the microprocessor-based deadbeat control. For the deadbeat current controller, the system's order becomes a high order and increases computation delay time. Therefore, The delay time produces current ripple. To minimize the current ripple, a new method based on deadbeat control theory for current regulation is proposed. It is constructed by a reduced-order state observer which predicts the output current in next sampling instant.

The pulse width modulated inverters based on fully digitalized method are becoming an industrial standard. This paper describes a real time generation of fully digitalized PWM pulses and its realization by single chip microprocessor. To verify the effectiveness of the proposed technique, the algorithm is implemented by using single chip microprocessor, 8097BH. The proposed method is compared with the well known triangular comparison method through experimental results, and the speed control of a motor is experimentally done by voltage-to-frequency constant control based on the proposed PWM generation method.

Most of the elevator door controllers have been controlled by DC Motors as an actuator. Recently, The control system using AC induction motor and general purpose inverter has been applied to control of elevator door. But there are some difficulties in making use of this system, such as adjustment of door speed pattern, door open-close time, and security of passenger safety. In order to solve these problems, a special inverter has, been developed with an encoder feedback. From the result of field-test, we proved that a special inverter with encoder feedback device has come to considerable effect. Until now about 1,200 sets of these inverters are operated in Korea and about 100 sets are operated in South-east Asia.

PWM(Pulse-Width Modulation) is frequently used as control method for inverter. In control of active silencer studied presently, PWM control method can be applied. This paper presents its possibility. As operating source of loudspeaker, inverter is used instead of audio amplifier and PWM controller controls the inverter to make canceling sound. This paper presents that active silencer of inverter-type using the PWM control method makes the canceling sound to acoustic noise and cancels the acoustic noise.

A simple drive circuit without position sensors for a switched reluctance motor is presented. The turn on and turn off points are determined by detecting the rate of change of the active phase current. The drive circuit consists of a current sensing resistor, RC filter, comparator, OP Amp, and OR gates. It is verified through the experiments that the switched reluctance motor with the proposed sensorless drive circuit is well operated in wide speed ranges.

This paper describes the practical implementation of switched reluctance motor drive for a wide range of operation speeds. The angle controller is designed by one-chip microprocessor 8051 for various real time applications. Algorithm to control the speed of SRM and to maintain the speed under the changed load is proposed.

Switched reluctance motors and drives are increasingly used in high speed applications due to their robust mechanical structures, low inertia, and reduction in the rotor losses. The turn-on angle has to be advanced as the motor speed increases, but it may cause the starting problem in some rotor positions. In this paper, the characteristics of the maximum speed and input voltage with the advance angle at high speeds is investigated. To overcome the starting problem and reduce the torque ripple, conduction overlapping is added in adjacent phases. The effectiveness of conduction overlapping is verified through the simulation and experiments.

A new gate drive circuit of classic converter for a switched reluctance motor is presented. Conventional gate drive circuit usually consists of the isolated power supplies and signal transferring devices for isolation, such as photo coupler, pulse transformer, and gate drive chips. The proposed gate drive circuit consists of resistors, capacitors, and zenor diodes without isolated power supplies, that make the drive circuit simple and reduce the material cost. The operational modes are classified and analyzed. The characteristics of the phase current and the gate signal of upper switches is investigated with the variation of duty ratio through the experiments.

In this paper, several inverter power circuit that are suitable for switched reluctance motor(SRM) drives are analyzed and compared with each other, Because the converter choice depends on the motor design, the analysis and selection are done for 6/4 SRM. Not considered in this paper is another class of inverter topologies for motor with bifilar windings. The proposed converter is applied to 3phase, 6/4 SRM.

A high performance motor drive system must have a good speed command tracking, a insensitivity to a parameter variation and sampling time. In this paper, a robust speed controller for an induction motor is proposed. The speed controller is fuzzy-sliding adaptive controller and its system continuously is varied. That is, only P gain act in dynamic state, I gain in steady-state. Because this system is a sort of adaptive control system, global stability analysis is used to Lyapunov function. Consequently, in this paper application of fuzzy sliding adaptive controller to induction motor controlled by vecter control is presented and the control system is digitally implemented within DSP.

An adaptive feedback linearization technique of a PM synchronous motor with specified output dynamic performance is proposed. The adaptive parameter estimation is achieved by a model reference adaptive technique where the stator resistance and flux linkage can be estimated with the current dynamic model and the state observer. Using these estimated parameters, the linearizing control inputs are calculated and a nonlinear coupled model of a PM synchronous motor is input-output linearized. The resultant model has the load torque disturbance. To get ti perfect decoupled model, the load torque is estimated. The adaptation laws are derived by the hyperstability theory and positivity concept. The robustness of the proposed control scheme will be proven through the computer simulations.

A Linear Induction Machine(LIM) is the motor which is developed from an rotary induction machine. Usually, the electromagnetic field of an LIM is analyzed by Maxwell's equations. The structure of an LIM is different from a conventional rotary machine, an LIM has some particular characteristics such as the end effects. Hence, the mathematical analysis of an LIM is very complicated and the implementation of the equivalent model is difficult. In this paper, the dynamic equations and the equivalent model of a Double-sided short primary LIM(DLIM) is obtained by the winding function and a d-q theory. The validity of the proposed methodology is verified by numerical analysis.

This paper consists of the position control of induction motor using Generalized Predictive Control. Full order flux observer is also used for the purpose of estimating rotor fluxes. By using Generalized Predictive Control algorithm, the improved position control is realized in this paper. The proposed control method has been implemented by a 32 bit floating point TMS320C31 DSP chip.

In this paper a drive strategy of AC Servo Motor using Fuzzy method was proposed. Since the transfer function of the plant is nonlinear and very complicated, there are difficultly in driving the system with real time. The performance of out method is confirmed by computer simulation and experimental results. The high performance and high accuracy of the driving system. Fuzzy is designed and proposed.

This paper describes current controlled PWM technique of IPM synchronous motors for a wide variety of speed control applications. They are however limited in their ability to operate in the power limited regime where the available torque is reduced as the speed is increased above its base value. This paper reviews the operation of the IPMSM drives when they are constrained to be within the permissible envelope of maximum inverter voltage and current to produce the rated power and to provide this with the highest attainable rotor speed. This paper proposes a new field-weakening control algorithm using phase current feedback to improve the torque characteristics and to reduce the torque ripple of IPMSM in the constant power region. The improved torque characteristics of speed control strategy with current feedback control algorithm is analyzed and the performance is investigated by the computer simulation results.

The starting characteristics of single phase induction motor(SPIM) is described by control of phase and voltage. Auxiliary winding voltage is controlled by DC amplifier and phase is integrator. These processes enable comparison of torque with slip in each voltage and phase angle variations. Simulation and experimentation results of the motor's torque-slip characteristics using the controlled auxiliary winding voltage and phase angle arc shown and discussed. As a results, starting time is fast and main winding current is small when auxiliary winding voltage is low than rating voltage and starting characteristics is good in phase angle $90^{\circ}$.

This paper proposes a simple identification method of the rotor time constant to solve the degradation of motor performance due to the difference between the rotor time constant of a controller and actual one in slip frequency type vector control scheme. The proposed method is based on rotor induced voltage equations and it is confirmed that immunity of the stator resistance thermal variation. The simulation results show that the proposed method suitably identifies the rotor time constant in steady state as well as in transient state.

In this paper, vector control of induction motor drives using space current vector PWM is presented. The scheme gives advantages, besides robustness to inverter arm-shoot, sinusoidal input current and voltage for induction motors. In addition, space vector PWM for CSI produces faster transient response than conventional pattern PWM. Also, a modulation index control is proposed.

A zero voltage switching (ZVS) three level resonant pole inverter is presented for high power GTO inverters. The concept of auxiliary resonant commutated pole(ARCP) for two level inverter is extended to the three level inverter. The proposed auxiliary commutation circuit consists of one resonant inductor and two bi-directional switches, which provides ZVS condition to the main devices without increasing device voltage or current stresses. The auxiliary device operates with zero current switching(ZCS) which enables use of the low cost thyristors. The proposed circuit can handle higher voltage and higher power(1-10MVA) comparing to the two level one. Operation and analysis of the proposed circuit are illustrated. Experimental results with 10 KW, 4 kHz prototype are presented to verify the principle of operation.

This paper is concerned on developing low-voltage high-current DC-DC converter using FB-ZVS PWM Converter. The converter output is 28V, 100A and regulated by phase-shift control method. IGBT is used by the main switching device and high frequency transformer is made for operating at 30kHz switching frequency. When the load vary widely, converter's ZVS characteristic is expressed by experiment result.

A new three-level push-pull type quantum series resonant rectifier for the power factor correction is proposed. The proposed single phase rectifier enables a zero-current switching operation of all the power devices allowing the circuit to operate at high switching frequencies and high power levels. With the proposed control technique, an unity power factor and greatly reduced line current harmonics can be obtained.

This paper presents equipment for charging and discharging with high power factor and high efficiency. This equipment is consisted of $3{\phi}$ SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor charging-discharging System.

A voltage-temperature limit circuit for the Ni-H2 battery is designed and analyzed for the maximum and the minimum voltage deviations at the worst case of the EOL(end of life). It is demonstrated that the magnitude of voltage deviations due to circuit device tolerances are kept less than 0.3v at the worst case. The maximum and the minimum battery voltages are simulated for the environmental temperature range of $0^{\circ}C-30^{\circ}C$ by using MATHCAD. They are 34.67v and 29.851v, respectively.

Many new electronic products are required to have a near unity power factor and a distortion free input current waveform. In this paper, a high performance single phase PWM AC/DC converter with input power factor correction is proposed. This proposed control strategy has many advantages which include one semiconduction switch, simplified control circuit, high performance features and continuous input current. The experimental results are included to verify the validity of this approach.

The advancement of power semiconductor devices has given great attribution to the performance and reliability or power conversion systems. But contemporary power devices have room for improvement. So much interest and endeavor are being applied to develop an improved power devices. The MOS-Controlled Thyristor(MCT)is a recently developed power device which combines four layers thyristor structure and MOS-gate. Owing to advantages compared to other devices in many respects, the MCT attracts much notice recently. Nowadays, in designing and manufacturing power conversion systems, the importance of circuit simulation for reducing cost and time is incensed. And to excute the simulation that resemble the real system as much as possible, to develop a model of power device that provides properly static and dynamic characteristics is important. So, this paper presents a PSPICE model of the MCT considering dynamic characteristics.

The current mode controlled DC/DC converter using fuzzy logic controller is proposed. With the proposed control method, the robust and safty guaranteed operation are achieved. For comparison with conventional controller, the PI controller is selected. By the computer simulation results, the validities of the proposed control method will be shown.

A new control scheme based on dead beat control with adaptive parameter estimation for PWM Inverter is proposed. The proposed scheme updates dead beat control parameters continouously, and make PWM inverter excellent performance at any load or parameter condition. Simulation results show very attractive features in this proposed scheme.

An improved predictive control technique using adaptive load estimation is proposed. The conventional predictive control technique has not concerned load variations and system parameters. Thus control performances are undesirable such as large current ripples and offset. In this paper the proposed controller employing a simple adaptive algorithm to estimate load is expected to be useful to overcome the problems of conventinal predictive controller.

This paper present fuzzy control technique for the control of output voltage and improvement of UPS wave forms. General UPS has the harmonics in carrier because of output of PWM signal using analog circuit. Output voltage is controlled by selecting PWM data to improve these problems, PWM signal discreted is written on ROM and analog circuit is removed at the system and output voltage is controlled by selecting PWM data by fuzzy controller.

An UPS must be synchronized in frequency and phase relationship with the mains power supply. This paper describes and tests a digital phase-locked loop(DPLL) circuit of the open-loop method designed by full software with TMS320c31 digital signal processor. finally, the performance of the proposed DPLL is shown and discussed through simulation and experiment.

A novel type of single phase multi-step inverter is proposed, which has twelve-stepped levels of the output voltage. In this inverter the waveform of the output votage has smaller harmonic contents than those of a conventional six-step inverter. In this paper a new multi-step technique is analyzed. This new multi-step technique of the twelve-stewed single phase voltage source inverter has the advantage compared with the conventional six-step inverter, and the experimental results are proved by the calculation using spectrum-analyzer.

In general, the reactive power is controlled by amplitude of the output voltage. This paper propose that the multiple voltage source inverter have controllable power factor made by load vary at receive-stage as lagging and leakage control.

CS PWM converter is appropriate for the high power and high precision current control. The input/output filters of the CS PWM converter limit the output DC current range and may destroy the system with filter resonance, and make the system equation more complicated. In this paper, the systematic and simple filter design method which considers not only the harmonic attenuation but the total system performance also is proposed.

From the cost-effective product point of view, it is very important to design a new current controller with the highest utilization factor of current capacity of power devices. This paper deals with a state-deadbeat current controller for PWM converters, which shows the fastest current control response without overshoot irrespective of the saturation of control voltage. No-overshoot control response means that the current capacity could be fully utilized in the control sense. Simulational results done by Matlab's Simulink show good current control characteristics.

This paper presents a new approach in the design of multiple power output electronic ballasts for compact fluorescent lamps which power output range of 11W, 15W, 20W by using equivalent resistance and RLC equivalent circuit concept and frequency control. A multiple power output electronic ballast which adopts half-bridge inverter topology is set up to compare the results of PSpice simulation with experimental ones. Starting characteristics of lamp voltage, lamp current and light output are better than the existing electronic ballasts, and therefore is verified the validity of the proposed method.

An analysis of a new load resonant inverter considering stray inductance is given. There are several different types for load resonant inverters. They can offer zero turn-on as well as zero turn-off switching losses, yielding high efficiency at high power and high frequencies. However, they didn't consider the influences of stray inductance. In conventional topology using lossless snubber capacitor, stray inductances result in very high frequency resonant current. Especially, these influences can be problematic in high power system such as induction heating system with large current of some 10A associated with it. These currents increase EMI problem, give harmful effects in gate driver's operation and increase loss of dc-link capacitor as well as snubber capacitor. Therefore, the effect of stray inductances should be treated and reduced. This paper presents a new load resonant inverter topology, which can reduce the effect of stray inductances.

The electric arc welding machine with high-frequency inverter is studied in this paper which could make more saving in energy than conventional ones with inherent low efficiency. The inverter circuit has been already adopted to special welding machines such as MIG and TIG for improving operating performances so much. But this adoption has not be applied to conventional ac arc welding machine until now. The proposed technology for higher efficiency is to apply the high frequency inverter, together with noise-cut transformer. Overall output characteristics are investigated in aspect of cost and circuit performance. The proposed system is conducted practical experiments using PWM controller.

This paper proposes an analysis of an inverter circuit which has an induction heating load. Two major kinds of the inverters are E-class quasi resonant and half-bridge type. The analyses of induction heating load property and operation property are introduced. A simulation program which implements those properties is also introduced. The results of the simulation program are verified through experimental results.

In all areas of power electronics, power conversion technology is a substantial need for increasing the performance and high power semiconductor technology is rapidly developing fast switching power devices with increasing voltage and current limits. This paper described a study on the series resonant inverter using power MOSFET and its application.

Active Power Filters(APF) have been developed for several years to solve the harmonics disturbance problems on power system networks. This paper studies observer based digital algorithm and PWM technique for three phase current source APF by simulation. Both switching or outside white noises affect seriously at control signal for APF control system. Hence observer algorithm to reduce noises is used. A technique of generation gating patterns for the CSI topologies based on carrier PWM techniques is applied. The requirements imposed on gating signals are satisified by the appropriate combination of single phase switching patterns and short pulse generator.

This paper was to determine the feasibility of controlling subsynchronous resonance(SSR) by the fast modulation of series compensation capacitors. The presence of subsynchronous currents in the system was detected by a subsynchronous relay which was modeled by the transient analysis of control systems (TACS) in the electromagnetic transients program (EMTP). The capacitor segments were switched by bi-directional thyristor swtiches. The paper proved that effective control of SSR can be obtained only by the detuning of the system and the removal or blocking of subsynchronous energy from the system.

In this paper, a mew maximum power point tracker (MPPT) using Fuzzy Controller is proposed to improve energy conversion efficiency. Temperature compensation effect means that Photovoltaic voltage is change in condition irradiation, temperature and ect. Fuzzy algorithm is applied to control Boost MPPT converter by Temperature compensation effect. In this paper, temperature compensation range is $-40^{\circ}C{\sim}+100^{\circ}C$.

In a recently as renewable energy source photovoltaic(PV) system using solar energy has been very widely researched because of its pollution-free and infinity. Especially many researches are intensively focused on small scale utility interactive PV system which can use dead space and easily make power stabilized from unstable natural energy source. In this system one of the most important matters is islanding protection. Islanding phenomenon appears when power failure occurs. For the safety of utility interactive PV system must has the function of not only system protection but also detection of islanding. This paper describes parallel operating alghorithm using reactive power variation method and twin peak band pass filter. This alghorithm is verified useful by simulation.

Since the residential load is an AC load, while the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell and must provide the sinusoidal wave current and voltage with unity power factor in the case of driving to Interact with utility line. It is always necessary for the output of solar cell to operate in the vicinity of maximum power point, since it is greatly fluctuated by insolation. This paper treats that we will constitute a single phase PWM voltage source inverter and trace the modulation index which always maximize the output of solar cell in propotion to insolation variation and prove it by simulation that we can provide current wave, which is nearly sinusoidal wave with unity power factor, for load and utility line.

This paper dscribes a detail simulation model with EMTP (Electro-Magnetic Transients Program) which is very effective to analyze the interaction between the ac transmission line and STATCON (static condenser). The SATCON was represented by two voltage-source converters connected in parallel and sharing an energy storage dc capacitor bank. The voltage source converters was modeled with ideal gate turn-off switches. The power system was represented by a detail generator model and a distributed tramnsmission line model for detail performance analyses. Analysis results show that the conceived simulation model is very effective to analyze the interaction between the ac transmission line and STATCON, and to evaluate the performance of STATCON.

Increasing the transfortation efficiency is very important issue in railway system. Speed-up of train and shortage of headway can be its solution. Headway can vary with blocksection length, characteristics of the railway and signalling systems. Safety braking distance needed for passenger's safety is very important factor in block section division method. In this study, basic block section division program was developed with the differential ratio of braking distance resulted by grade value of the track. More complete block section division program is going to be developed by the help of experienced experts.

Catenary/pantograph system consists of overhead lines which have non-uniform elasticity and pantographs which move at high speed and give force to the lines, therefore happen to be failed in contacts between both from time to time. In this study, as the first step to develop a dynamic simulation program, the general theory is discussed for catenary/pantograph system and appropriate modelling. And comparison is conducted with the references after making a program which referred to the contact force equation algorithm. On this algorithm, the unknown contact force is computed by the equations which was induced as combining catenary and pantograph motion equations expressed in finite difference form. Another simulation program based on the assumed contact forces algorithm was developed. In this algorithm, numerical integraion of both the overhead line and pantograph equations, which without combining, are effected for two assumed values of contact force. The correct contact force is then obtained from these two sets of results by linear interpolation to satisfy the contact condition. Through the comparative review on the outputs from this program, it is verified that this algorithm is reliable.

ATS Systems is activated against the over-running and the crashes between trains. Up to now, ATS Systems have been constituted analog systems adopting the changed frequency method or amplitude modulation, which is impossible to give any essential informations. In this paper, it is dealt with. digital ATS Systems which are replaced the former ATS Systems in the advanced nation of railways. Especially, this paper shows the possibility of any developments for the digital ATS Systems by the experiment of digital ATS systems by Frequency Shift Keying method.