• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.309-312
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• 2000

Single-phase multi-level AC-DC converter is proposed that is composed of diode bridge and switch. The number of the supply current level is depending on the individual current level of the converter. A converter circuit the number of the level is equal to $\textrm{2}^{M+1}$-1 The proposed circuit has converter with 31 current levels. When the number of current level is increased smoother sinusoidal waveform can be obtained directly and it is possible to control the supply current almost continuously from zero to maximum without step changes of generating high voltage as pulse width modulation switching loss is decreased it has an advantage in large capacity. it is illustrated technique are confirmed the validity and effectiveness through the simulation & experiments

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.22-24
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• 2006

Of all the proposed resonant techniques, the well-known phase-shifted full bridge converter remains one of the most attractive because it offers an easy way of achieving ZVS with a minimum of extra components added, which is essential for the high power applications. This paper describes the design of a digital controller for a Phase Shifted Full-bridge PWM Converter. The small-signal model is derived incorporating the effects of phase-shift control and the utilization of the transformer leakage inductance and power FET junction capacitances to achieve the zero-voltage resonant switching. Based on the derived small-signal model, the digital controller is designed in the discrete domain. The performance of designed controller is verified through the simulation.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.326-329
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• 2002

In this paper, a single-phase inverter using a diode bridge-type resonant circuit to implement ZVT(Zero Voltage Transition) switching is presented. The current control algorithm is analyzed about how to design the circuit with auxiliary switch which can ZVT operation for the main power switch. The simulation and experimental results would be shown to verify the proposed current algorithm, because the main power switch is turn on with ZVT and the hi-directional inverter is operated.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.214-215
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• 2010

본 논문은 공진 인버터를 적용한 HID램프를 구동하기 위한 전자식 안정기를 설계하고 구현하였다. 제안된 전자식 안정기는 스위치 턴온 오프시의 손실을 줄이기 위해서 소프트 스위칭 기법인 ZVS(Zero-Voltage Switching)을 도입하였다. 점등은 LC필터의 공진주파수범위에서 풀브리지 인버터 제어에 의한 공진으로 이루어 진다. 점등후에 컨버터는 저주파수 구형파로 동작한다. 공진 기동시의 LC필터의 공진주파수는 ($f_o$=160kHz)이고, 고조파를 감소시키고 음향공진현상을 피하기 위한 벅컨버터 스위칭 주파수(고주파수 : 50~60kHz 와 저주파수 : 170Hz)를 선택하였다. 실험을 통해 공진 인버터를 적용한 HID램프용 전자식 안정기가 안정적으로 동작함을 확인하였다.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.546-548
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• 2005

This paper proposes a unity power factor ZVT PWM single-phase rectifier. The ZVT soft switching are achieved by using a simple ZVT circuit, and the reduced conduction losses are achieved by employing a single-stage converter, instead of a typical double-stage converter composed of front end diode rectifier and cascaded boost rectifier. Furthermore, thanks to good features such as simple PWM control at constant frequency, low switch stress and low VAR rating of commutation circuits, it is suitable for high power applications. The principle of operation is explained in detail, and simulation results of the new converter are also included.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.363-366
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• 1996

A FB-ZVS(Full Bridge Zero Voltage Switching) PWM DC/DC converter for electric vehicles is simulated and implemented in this paper. The converter considered is a step-down DC/DC converter with the ratings of 312/13.5V and 1.35kW. The steady state operation of this converter is divided into six operating modes in case of continuous current mode and eight operating modes in case of discontinuous current mode. Digital simulations using PSpice are carried out to verify the steady-state analysis. A prototype converter was built in the laboratory. MOSFETs were used for swithching devices and fast recovery diodes to reduce the charge storage problem of a pn-junction.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.181-182
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• 2014

본 논문에서는 동기 정류 스위치를 사용한 임계 도통 모드 부스트 PFC 컨버터의 디지털 제어 기법을 제안한다. 상태 궤적 분석을 통해 입력전압 전 범위의 영전압 스위칭 조건을 구하였으며, 총 입력 전하 분석을 통하여 높은 역률을 위한 스위치 추가 온-타임을 도출하였다. 제안하는 제어 기법은 디지털 제어기를 이용한 $230V_{rms}$ 입력, 400V/200W 출력 프로토타입에서 타당성을 입증하였다. 그 결과 동기 정류기를 이용한 임계 도통 모드 부스트 PFC 컨버터는 높은 역률 및 효율을 갖는다.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.431-432
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• 2020

철도차량 하부에 부착되는 전장품 무게는 차량의 바퀴 및 베어링 등 철도차량 수명에 큰 영향을 주기 때문에 경량화는 필수적이다. 본 논문에서는 철도 차량용 보조전원장치의 경량화를 위해 LLC 공진형 컨버터를 적용한 보조전원장치 시스템과 제어알고리즘을 제안한다. 제안하는 알고리즘은 고속스위칭을 위해 입력단 벅 컨버터를 이용하여 가선 전압을 감압시키고 이후 LLC 공진형 컨버터를 통해 인버터 입력단 전압을 제어한다. 또한, 공진형 컨버터 손실을 최소화하기 위해 ZVS(Zero Voltage Switching) 동작을 하며, 공진 탱크의 최적 설계도 제안한다. 본 논문에서 제안하는 알고리즘은 시뮬레이션 및 실험으로 검증한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.216-223
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• 2006

The high efficiency full-bridge LLC resonant converter using a contact-less transformer Is proposed for the photovoltaic power generation system. For the series resonance with a series capacitor, the LLC resonant converter utilizes the leakage inductance and magnetizing inductance of a contact-less transformer Unlike the conventional series resonant converter operated to the continuous resonant current at above resonance frequency, the proposed converter operates to the discontinuous resonant current at the narrow frequency control range below resonance frequency. Due to the discontinuous mode resonant current, the proposed converter can be achieved the zero voltage switching (ZVS) in the primary switches and the zero current switching (ZCS) in the secondary rectification diodes without my auxiliary circuit. In this paper, the experimental results of the proposed full-bridge LLC resonant converter using a contact-less transformer are verified on the simulation based on the theoretical analysis and the 150W experimental prototype.

• Journal of Advanced Marine Engineering and Technology
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• v.33 no.8
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• pp.1261-1267
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• 2009

The Direct Torque Control[DTC] controls torque and flux by restricting the flux and torque errors within respective hysteresis bands, and motor torque and flux are controlled by the stator voltage space vector using optimum inverter switching table. And the Current Error Compensation method is on the basis of compensating current difference between the induction motor and its numerical model, in which the identical stator voltage is supplied for both the actual motor and the model so that the gaps between stator currents of the two can be forced to decay to zero as time proceeds. Consequently, the rotor speed approaches to the model speed, namely, setting value and the system can control motor speed precisely. This paper proposes a new sensorless speed control of induction motor using DTC and Current Error Compensation, which requires neither shaft encoder, speed estimator nor PI controllers. And through computer simulation, confirm effectiveness of proposed method.