• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.462-464
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• 1994

In this paper, noble electrical equivalent circuit ultrasonic motor is applied by model of parallel one from mechanical equation of piezoelectric device and characteristics estimation is done by equivalent converter. Uitrasonic motor is driven by oscillation circuit of two-phase high frequency inverter. Operating frequency of inverter is described by tracking control method of resonance frequency, according to change of load, temperature etc.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.791-794
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• 2004

This paper made an induction heating inverter. The inverter is the $20\~40[kHz]$ a resonant inverter which uses a high frequency. We use this inverter and use induction heating. A phasor shift ordered a gate signal to adjust an inverter's output. We verified an output waveform according to the situation of a gate signal through the simulation. We made the inverter really and got the result.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_1
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• pp.559-567
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• 2020

As the renewable energy market grows, grid-connected inverters have been improving and expanding in several fields in recent years because energy conversion devices are the main components of solar systems. In this paper, a high-precision new grid-connected three-phase inverter system is proposed. The proposed system consists of a main inverter, a sub inverter and a transformer. The main inverter operates at a low switching frequency and high power and transmits power to the grid. A sub-inverter connected in series with the transmission line through a matching transformer operates at lower power than the main inverter to provide input values to the transformer. The transformer acts as a power supply according to the voltage compensation value. This study is based on the principle of operation of the UPFC(Unified Power Flow Controller) structure used to regulate power flow in AC transmission lines. The grid-connected inverter system proposed in this paper is implemented with high precision and high resolution. The proposed system was verified through its ability to enhance and ensure the safety of the proposed system through simulation and experiment.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.3
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• pp.40-49
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• 2011

This paper presents novel circuit topology of half-bridge soft-switching PWM inverter type DC-DC high power converter for DC bus feeding power plants. The proposed DC-DC power converter is composed of a typical voltage source-fed, half-bridge high frequency PWM inverter with a high frequency planar transformer link PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode-equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC bus lines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, high switching frequency IGBTs can actually be selected in the frequency range of 40[kHz] under the principle of soft-switching. The performance evaluations of the experimental setup are illustrated practically.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.153-158
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• 1998

In this paper, a prototype of the auxiliary resonant commutated snubber circuit(ARCS) with a high frequency transformer power regeneration loop is described for voltage source type sinewave inverter system. This is a new soft switching topology developed for three phase voltage source soft-switching inverter, active power filter and reactive power compensator has significant advantage of current rating reduction for auxiliary active switching devices. In addition, this paper presents a novel prototype of voltage-source soft switching space vector-modulated inverter with ARCS mentioned above, which is more suitable and acceptable for high-power utility interactive power conditioning, along with a digital control scheme. The steady-state operating analysis of ARCS has the remarkable features and the practical design procedure of this resonant snubber are illustrated on the basis of computer simulation analysis. The operating performance evaluations in the steady-state of this three phase voltage source soft switching inverter are discussed and compared with the three phase voltage source hard switching inverter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.1
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• pp.90-97
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• 2001

A high frequency resonant inverter consisting of iliree unit Half-Bridge serial resommt inverter used as power source of induction heatmg at high frequency is presented in this paper. As a output [Dwer control strategy, sequencial time-sharing gate contml methcd is applied. This methcd is TDM(Time Division Multiplexing), which is broadly used with digital and analog signals transmission in communication system 1be analysis of the proposed circuit is generally described by using the normalized pararmenters. Also, the principle of basic operating and the its characteristics are estimated by the parameters such as switching frequency, load resistance. Also, according to the calculated characteristics value, a method of the circuit design and operating characteristics of the inverter is proposed. This paper proves the validity of theoretical analysis through the Pspice. This proposed inverter show that it can be practically used in future as power source system for induction heating application, DC-DC converter etc. r etc.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.675-677
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• 2000

In the paper the eddy current loss in brushless DC motor due to switching frequency supplied by PWM inverter, is analyzed. The compensated conductivity is used in order to analyze the eddy current loss in brushless DC motor which has lamination structure. The eddy current loss is deceased when switching frequency supplied by PWM inverter is gradually increased from 1.2kHz up to 12kHz. The high switching frequency of PWM inverter make the output wave into a similar sine wave and this leads to the decreasing eddy current loss.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1133-1135
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• 1992

This paper describes high frequency inverter using zero voltage switching(ZVS). The ZVS operation is achieved to reduce the switching stress and switching loss under high speed switching. The proposed circuit configuration and performance are discussed. Its operation characteristics are evaluated through computer-aided simulation.

• Journal of radiological science and technology
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• v.24 no.2
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• pp.5-11
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• 2001

Most of X-ray generator had used rectifier type transformer with high tension generator which is supplied in a clinical diagnosis. Because the ripple rate of tube voltage is high, X-ray generating efficiency is very low. In these days, high tension generator for inverter type X-ray generator is being supplied from a broad which uses semi-conductor switching element for the electric power that have a high speed switching ability to solve these problem. But, semi-conductor element with large capacity is used with X-ray tube's large consumption power and diffusion is difficult in the small size hospital because production cost is going up by doing digital control through DSP. Therefore, this paper designed and manufactured CR type voltage divider for feedback control of tube voltage with high frequency resonance type inverter and for high tension transformer with high frequency. It was to make economical diffusion type X-ray generator which has wide output voltage and load extent. It was preyed that the X-ray generator had the stability of X-ray tube's output characteristics.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.12
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• pp.113-121
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• 1996

This paper presents a 37.5kVA (125kVp, 300mA) high frequency inverter type power supply for diagonostic X-ray generator with two HFHV (high-frequency high-voltage) isolating transformers. The output regulations, X-ray tuve voltage and tube current, are obtained by two high frequency inverters with the each other feedback PI controller and operating time switch for selecting shooting time and synchronizing two inverters. The operating modes and design consideration of the proposed power supply are given. Issues in the design of two HFHV isolating transformersfors high volage genrating and filament heating are discussed. Experimental results are presented to verify the performance of the designed power supply for varying load conditions. The proposed apparatus has several advnatages, e.g., the fast rising time of tube voltae, accuracy and reduced component size etc.