• 전기학회논문지
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• 제57권10호
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• pp.1782-1789
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• 2008

This paper presents the design of acoustic resonance(AR) free and dimmable electronic ballast for 1kW Metal-Halide Lamp(MHL). The proposed Ballast consists of a Full-Bridge(FB) rectifier, a passive power factor correction(PFC) circuit, a full-bridge inverter, an ignitor using LC resonance and a control circuit for frequency modulation and dimming control. Whereas a passive PFC provides advantages in terms of high reliability and low cost for constructing the circuit, it is difficult to supply a stable voltage because of the output voltage ripple that occurs with a period of 120Hz. Although the ballast can be designed with a small size and a light weight if it is driven at a switching frequency between 1 and 100 kHz, AR will occur if the eigenvalue frequency of the lamp coincides with the inverter's operation frequency. The operation frequency was modulated in real time according to the output voltage ripple to compensate for the variation in power supplied to the lamp and eliminate AR. For dimming, the method, which modulated drive frequency of FB inverter using the control of DC level by microprocessor, was used. The Dimming ranged at least from 600W to 1kw as rated power of the lamp with 4 stages. Performance of the proposed technique was validated through numerical analysis, computer simulation using Pspice and by applying it to an electronic ballast for a prototype 1kW MHL.

• 전기학회논문지
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• 제65권11호
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• pp.1806-1812
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• 2016

We propose an interior permanent magnet syhchronous motor (IPMSM) with arc-shape ferrite permanent magnets (PMs) as a substitute for the rare-earth permanent magnet, and determine its optimal design through parametric study. First, we use 2D finite element analysis to analyze 4-poles and 6-slots initial model according to performance requirements and design parameters. The current angle of the maximum average torque considered in the analysis is different compared with the current angle of the minimum torque ripple. Thus, the parametric study for optimal rotor design is performed by varying the thickness and the offset radius of the PMs according to current angle. In particular, a narrow bridge is required in conventional IPMSM for reducing flux leakage; however, the increase in cogging torque in the analysis model saturates the narrow bridge (large offset radius). Therefore, we suggest an appropriate shape considering limiting conditions such as DC link voltage, average torque, torque ripple, and cogging torque taking into account performance requirements.

• 전기학회논문지P
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• 제65권4호
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• pp.285-291
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• 2016

A light-emitting diode (LED) has been increasingly applied to various industrial fields and general lightings because of its high efficiency, low power consumption, environment-friendly characteristic and long lifetime. To drive the LED lighting, a power converter with the constant output current is needed. Among many power converters, the flyback converter is chosen by many converter designers due to high power density, structural simplicity, and miniaturization. In this converter, an electrolytic capacitor is generally chosen for the stabilization of the DC voltage because of having the large capacitance and the low price. However, the disadvantages are the short expected life time and 120Hz ripple currents on the converter output node. In this paper, a single-stage dimmable PFC DCM flyback converter without the electrolytic capacitor is proposed to prolong the lifetime of the LED driver. For the long lifetime of the converter, the polyester film capacitor with the small capacitance is substituted for the electrolytic capacitor on the output node and an LC resonant filter is added to damp 120Hz ripple current. The proposed converter is verified through the simulation and the experimental works.

• 전기학회논문지
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• 제61권11호
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• pp.1625-1633
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• 2012

In the lighting industry, a Lighting Emitting Diode (LED) is increasingly used because of many advantages and a eco-friendly product comparing with the conventional lighting. However, the LED lighting has to include various AC/DC converters because the direct current is used for the LED lighting. Among a lot of power converters, the flyback converter is widely used for the LED lighting and includes some electrolytic capacitors for the voltage regulation. But the electrolytic capacitor has shorter lifetime than the LED element. It makes the expected life-time of the converter having the electrolytic capacitor shorter than the LED element. This paper proposes the single-stage PFC flyback converter without electrolytic capacitors. To verify the performance of the proposed converter, simulated and experimental works were carried out.

• 전기전자학회논문지
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• 제23권2호
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• pp.407-412
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• 2019

LED 조명은 많은 장점으로 인하여 다양한 분야에서 사용이 점점 증가되고 있다. 특히 플라이백 컨버터는 전력밀도와 구조적 단순성 그리고 소형화가 가능하여 많은 컨버터 설계자들에게 LED 조명용 드라이버로 선택되어지고 있다. 또한 컨버터의 직류출력전압을 안정화하기 위하여 저렴한 가격의 정전용량이 큰 전해커패시터를 사용한다. 전해 커패시터를 갖는 전력변환기를 LED 조명시스템에 적용할 경우에 일반적으로 LED의 수명이 짧아지는 결과를 가져온다. 제안하는 논문은 LED 수명연장과 컨버터 출력리플을 감소시키기 위하여 소용량의 필름 커패시터 LC 필터를 컨버터에 적용하였다.

• 전력전자학회논문지
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• 제3권1호
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• pp.36-45
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• 1998

공진형 인버터의 직류 링크단의 전압 상승을 직류 공급 전압 이내로 제한하고, 공진형 인덕터의 전류 내량을 줄이기 위한 간단한 전압 억제형 공진형 인버터를 제안하였다. 이 전압 인버터를 영구 자석형 동기 전동기(PMSM)에 적용하여 이산 펄프 제어 방법중의 하나인 예측형 전류 제어 방법에 의해 실험과 시뮬레이션을 통하여 제안된 인버터의 동작을 보이고, 그 결과를 CRDM(Current Regulated Delta Modulation)방법에 의한 결과와 비교하였다.

• 한국진공학회지
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• 제9권3호
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• pp.290-295
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• 2000

KAIST-TOKAMAK에서 재현성이 좋은 저항가열 플라즈마를 발생시키는데 필요한 전이온화(pre-ionization)에 응용하기 위해 2.45 GHz 마그네트론을 사용하여 간편한 마이크로파 발생장치를 개발하였다. 장치에 사용한 마그네트론은 출력 500 W, 주파수 2.45 GHz이며, 일반적인 가정용 전자오븐(microwave oven)에 사용된다. 기존의 가정용 마그네트론은 음극(cathode)과 양극(anode)사이에 걸리는 고전압이 60 Hz의 주기를 갖기 때문에 약 16ms마다 약 8 ms 동안만 주기적으로 마이크로파를 발생한다. 이 마그네트론을 사용하여 토카막 전이온화에 충분할 정도로 연속적으로 발생되는 마이크로파를 얻기 위해서 음극과 양극사이에 개량된 회로로 리플전압이 작은 DC 고전압(5 kV 1 A)을 인가하였다. 본 논문에서는 주기적으로 생성.소멸하는 ECH 플라즈마와 연속적인 ECH 플라즈마를 발생시켜 랑뮈어탐침과 광증배관(PMT)을 이용한 이온 포화전류와 $H_\alpha$/ 방출(emission)을 측정하여 마이크로파 발생장치의 특성을 조사하였다.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.239-245
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• 2016

본 논문에서는 스마트기기의 배터리를 전원으로 갖는 12 V 승압형 PWM 변환기를 설계하고 컨버터를 구성하는 각 소자들의 손실을 계산하여 가장 안정적인 동작을 하는 설계 값을 도출하였다. 12 V 승압형 PWM 변환기는 저항, 커패시터 및 인덕터 등의 여러 수동소자를 비롯하여, 다이오드, 전력 스위치용 파워 MOS 트랜지스터와 PWM 신호제어를 위한 IC를 사용하여 구현하였다. 컨버터를 구성하는 주요 소자들의 이론적인 계산 값과 회로설계 해석프로그램인 PSPICE를 사용한 시뮬레이션 결과를 비교하고 각 소자 값들을 변화시키며 결과 파형을 분석한다. 분석한 컨버터를 실제 PCB 보드에 구성하고 디지털 오실로스코프와 DMM 멀티미터를 사용하여 측정하였고, SPICE 시뮬레이션을 통해 얻은 결과 값과 비교하였다. 설계한 컨버터에서 사용한 제어용 IC 칩은 TI(텍사스 인스트루먼트) 사의 LM3481을 사용하여 설계를 구현하였고, 5V 입력, 12V의 출력 값을 가지는 것을 확인하였다. 모의실험과 동일한 조건에서 출력전압, 리플전압 및 부하, 입력전압 변도율 등의 특성에 대한 측정결과는 SPICE 시뮬레이션 결과와 일치하는 것을 확인하였다.

• 전력전자학회논문지
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• 제17권5호
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• pp.401-408
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• 2012

A simple on-line elimination strategy of the dead time and inverter nonlinearity using the current slope information is presented for a PWM inverter-fed IPMSM (Interior Permanent Magnet Synchronous Motor) drive. In a PWM inverter-fed IPMSM drive, a dead time is inserted to prevent a breakdown of switching device. This distorts the inverter output voltage, resulting in a current distortion and torque ripple. In addition to the dead time, inverter nonlinearity exists in switching devices of the PWM inverter, which is generally dependent on operating conditions such as the temperature, DC link voltage, and current. The proposed scheme is based on the fact that the d-axis current ripple is mainly caused by the dead time and inverter nonlinearity. To eliminate such an influence, the current slope information is determined. The obtained current slope information is processed by the PI controller to estimate the disturbance caused by the dead time and inverter nonlinearity. The overall system is implemented using DSP TMS320F28335 and the validity of the proposed algorithm is verified through the simulation and experiments. Without requiring any additional hardware, the proposed scheme can effectively eliminate the dead time and inverter nonlinearity even in the presence of the parameter uncertainty.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2668-2670
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• 1999

In the past, the PWM converter had a large switching loss by hard switching and difficult to high frequency operation. The resonance converter to decrease the switching loss and EMI is required the frequency control and needed to reduce the voltage or current stress at each parts. So, this paper propose the 3-phase boost converter and the method to compensated input power factor by control the amplitude - an instantaneous value of the DC inductor current -and control the switching frequency that a modulation error by the ripple of the DC inductor current. The proposed 3-phase PWM boost converter of single phase control type can takes higher capacity and compensate the power factor by using Feed back controller at each phase for the existing 3-phase bridge rectifier type. Moreover the 3-phase full bridge type using the rectifier at each 3-phase circuit will be small size reactor and compensate input power factor by minimize harmonic components of each phase.