• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.163-164
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• 2011

In this paper, a new half-bridge zeta converter employing a center-tapped rectifier is proposed. The proposed converter provides a bidirectional powering path in the rectifier. As a result, its improved rectifier voltage waveform reduces the output filter inductor size. Also, it maintains a wide ZVS range due to the characteristic of the conventional single-ended half-bridge zeta converter. The operational principles, the theoretical analysis, and the design considerations of the proposed converter are analyzed. To verify the performance of the proposed converter, experimental results from a 180W prototype are presented.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1734-1737
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• 2015

Insulating characteristics of Cl₂-He mixture gases in gas discharges were analysed to evaluate ability of these gases for using in medium voltage and many industries. These are electron transport coefficients, which are the electron drift velocity, density-normalized longitudinal diffusion coefficient, and density-normalized effective ionization coefficient, in Cl₂-He mixtures. A two-term approximation of the Boltzmann equation was used to calculate the electron transport coefficients for the first time over a wide range of E/N (ratio of the electric field E to the neutral number density N). The limiting field strength values of E/N, (E/N)_lim, for these binary gas mixtures were also derived and compared with those of the pure SF₆ gas.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.10
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• pp.1096-1100
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• 2012

In the phase-shift measurement method, the distance light travels can be obtained based on the phase difference between the reference signal and the measured signal. When the object having various colors is measured, the intensity of the measured signal much varies even at the same distance, and it causes different phase delay due to wide dynamic range input to a signal processing circuit. In this work, an measured intensity control method is proposed to solve this phase delay problem.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.10 no.6
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• pp.81-87
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• 1996

This paper is to develop a digital inverter using microcontroller for a Switched Reluctance Motor (SRM) driver. The closed-loop speed control system with fixed switching angle and variable voltage control is used to from a flat-topped phaes current and to simplfiy the drive system. This could be driven in a wide speed range with flat-topped current. Mifcrocontroller os used to be compact and to have a flexbility in the control system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.7
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• pp.49-57
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• 2008

This paper presents a voltage source type half-bridge series resonant high frequency (HF) inverter for induction heated fixing roller in copy machines. This high-frequency inverter works under zero current soft switching (ZCS) commutation and has wide power regulation range due to employing a pulse density modulation (PDM) scheme. Transient and steady state operating modes of the inverter are presented in this paper together with its PDM-based power regulation system. Experimental operating performances of the developed HF-ZCS inverter as well as power losses and actual efficiency are discussed and compared with computer simulation results.

• Proceedings of the KIPE Conference
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• 2004.07a
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• pp.364-368
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• 2004

A new high efficiency DC/DC converter is proposed, which is derived from the conventional half-bridge converter. The proposed converter has good ZVS condition compared with the conventional half-bridge converter, and shows a high efficiency by solving the unbalance voltage stress and current stress problem of secondary rectifier diode of the conventional half-bridge converter. In this paper, the basic operations of the proposed converter is analyzed compared with that of the conventional half-bridge converter, and the excellent performance of the proposed converter is verified by the experimental results with the 42W prototype of the power supply for PDP Sustain Driver.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.382-384
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• 2008

Hold-up time is a special requirement for the front end DC/DC converter in a server power supply. It forces the converter with the variable switching frequency to operate in a wide switching frequency range, which makes the regulation difficult and reduces the power density. In this paper a novel frequency controlled half bridge converter with the hold-up time extension circuit is proposed. During the hold-up time, the auxiliary switches are turned on, thus the resonant inductance is reduced and the voltage conversion ratio is increased. Therefore, the output capacitor of the power factor correction (PFC) circuit can be decreased, and the converter can have high power density. The proposed converter is verified by experimental results from a prototype with 700W, 400V input, and 12V output.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.283-286
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• 1988

This paper describes the PWM cycloconverter which can provide step-up ac-ac direct conversion in a wide output frequency range. With input reactor and output capacitor. the input and output ports are exchanged. And sine PWM scheme is applied to the converter. To analyze the converter operation the state equations are derived using dq transformation. Simulated results show that both the output voltage and frequency can be controlled by adjusting the modulating functions.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.321-324
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• 1988

This paper presents the result of driving performance analysis of PMSM type AC servo motor based on control system using a microprocessor. The experiment using the microprocessor is tested with a 120[v], 200[w] PMSM type AC servo motor. The PWM signal generated in the microprocessor for the servo motor voltage is chapped by power transistor modules to change the AC servo motor speed. The torque of the AC servo motor with a permanent magnet can be easily controlled over a wide range by changing the AC servo motor current.

• Proceedings of the KIPE Conference
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• 2012.11a
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• pp.213-214
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• 2012

속도 범위가 넓은 고속 PMSM의 정현파 구동용 인버터에서 전동기 전류 리플과 인버터 스위칭 손실을 저감시키는 방법으로서, 중저속에서 직류 링크전압을 감소시키는 방법을 제안한다. 직류 링크전압 조절용 컨버터를 이용하며, 직류 링크 전압과 전동기 속도 사이의 관계를 설정하고 이를 제어 알고리듬에 반영한다. 제안된 기법에 의한 전류 리플 저감효과를 시뮬레이션으로 확인한다.