• Journal of Power Electronics
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• v.18 no.3
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• pp.802-816
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• 2018

A digital direct phase-shift control (DDPSC) method based on the phase-shifted full-bridge LLC (PSFB-LLC) converter is presented. This work combines DDPSC with the conventional linear control to obtain a hybrid control strategy that has the advantages of linear control and DDPSC control. The strategy is easy to realize and has good dynamic responses. The PSFB-LLC circuit structure is simple and works in the fixed frequency mode, which is beneficial to magnetic component design; it can realize the ZVS of the switch and the ZCS of the rectifier diode in a wide load range. In this work, the PSFB-LLC converter resonator is analyzed in detail, and the concrete realization scheme of the hybrid control strategy is provided by analyzing the state-plane trajectory and the time-domain model. Finally, a 3 kW prototype is developed, and the feasibility and effectiveness of the DDPSC controller and the hybrid strategy are verified by experimental results.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.3
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• pp.372-378
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• 2012

This paper deals with a 3-phase voltage disturbance generator for a performance test of custom power devices such as dynamic voltage restorers (DVR), dynamic uninterruptable power supplies (UPS), etc. The operating principle of the proposed circuit is described in each mode of voltage sag, swell, outage, and unbalance. The main components of the proposed disturbance generator are silicone controlled rectifier (SCR) thyristors, variable autotransformers, and transformers. Therefore, the disturbance generator can be implemented with a considerably low cost compared to the conventional pulse width modified (PWM) inverter and converter type generators. Furthermore, it has good features of high reliability with simple structure, high efficiency caused by no PWM switching of the SCR thyristors, and easy control with a wide variation range. To verify the validity of the proposed scheme, simulations and experiments are carried out.

• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.301-304
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• 2001

Wind power generation system is one of the most useful energy resource using natural environment. One of the biggest problem we encountered is toot the wind speed is fluctuating sharply according to the weather conditions rather than it is stable. In this paper we do the equivalent modeling the mechanical energy of wind power turbine according to wind speed into the synchronous generator. We analyse the equivalent modeling output part of rectifier into DC/DC converter input part theoretically. We analyse a battery charging characteristics for power storage enabling the supply of stable power to the load. We design a system and do the modeling of it analytically so that it supplies a stable power to the load by constructing a DC-AC inverter point. Also we make a small size model usable in actual wind power generation system of 30kw and make an experiment and confirm its validity.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.7 no.1
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• pp.30-36
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• 1993

A simple discontinuous conduction mode(DCM) flyback type active power factor corrector for low power supply resents an effective resistive load to its power input. It is therefore well suited as an inexpensive high power factor rectifier for office equipment. An equivalent circuit model for the Active Power Factor Corrector based on the "Loss Free Resistor" concept is presented. This simple model correctly describes the basic power processing properties of the Active Power Factor Corrector, including input port resistor emulation, output port power some characteristics.teristics.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.17 no.1
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• pp.1-9
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• 2003

In this paper, prototype of high-power-factor single-stage electronic ballast for fluorescent lamp is designed and implemented. A new low cost single stage high power factor electronic ballast for fluorescent lamps is based on integration of two-boost converter and LC type high frequency resonant inverter. The proposed ballast is combined by simple construction, because full bridge rectifier diode is eliminated and simple control circuit is applied. Boost converter operate in the voltage of positive and negative half cycle respectively at line frequency (60㎐), operation in discontinuous conduction mode performs high power factor. The experimental results show the good performance as PF 0.99, THD 15.4%, and CF 1.65 at output 63.5〔W〕.

• Proceedings of the KIEE Conference
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• summer
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• pp.869-871
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• 2004

This paper presents Single Phase Switched Reluctance Motor Optimum Design using Response Surface Methodology and 2-D Finite Element Method that is coupled with the circuit equation of the rectifier and converter. Moreover, A design process for SPSRM has been proposed. The optimum process has been performed with geometric parameters (${\beta_s}\;&\;{\beta_r}$) that influence the inductance variation for design variables. In this paper, SPSRM performances have been analyzed according to variations of electric and geometric parameters after determining design models in terms of efficiency and power factor maximization.

• Journal of Power Electronics
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• v.10 no.6
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• pp.611-620
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• 2010

This paper presents a new architecture, called "Power Electronics Remote Wiring and Measurement Laboratory (PermLAB)", that translates a common gateway interface (CGI) string from a remote web user to a web server connected to a 3-dimension switching matrix board, can be used to switch on and off, and to control a cluster of instruments and components. PermLAB addresses real-time connection, switching, and data acquisition over the Internet instead of using simulated data. A software procedure uses a signature system to identify each instrument and component in a complex system. The Web-server application is developed in HTML, JavaScript and Java, and in C language for the CGI interface, which resides in a controller portion of LabVIEW. The LabVIEW software fully integrates the Web sever, LabVIEW data acquisition boards and controllers, and the 3-dimensional switching matrix board. The paper will analyze a half-wave rectifier (AC - DC converter) circuit connected over the Internet using the PermLAB. PermLAB allows students to obtain real data by real-time wiring of real circuits in the laboratory using a "virtual breadboard" on the Web. The software for the Web-based 3-dimensional system is flexible, portable, can be integrated into many laboratory applications or expanded, and easily accessible worldwide.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.163-164
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• 2014

본 논문에서는 능동 클램프 회로를 이용한 위상천이 풀-브리지 컨버터(Phase-shift Full-Bridge Converter)의 스위치 제어 방법을 제안한다. 기존의 위상천이 풀-브리지 컨버터는 2차측 정류 스위치에서 스파이크 전압이 발생하며, 순환 전류(Circulating current)로 인한 도통 손실이 발생하는 단점을 지닌다. 위의 문제를 극복하는 회로로서 2차 측에 능동 클램프 회로를 적용하는 방법이 연구되었다. 하지만, 낮은 부하에서 클램프 커패시터의 전압이 상승하여, 2차 측 소자의 전압 스트레스가 증가하고, EMI 문제가 발생되는 단점을 지닌다. 본 논문에서는 위상천이 풀-브리지 컨버터의 2차 측에 능동 클램프 회로 및 동기 정류 스위치(Synchronous rectifier switch)를 적용하여, 클램프 커패시터의 전압 상승을 억제하는 해결 방안을 제시하며, 능동 클램프 회로의 스위치 제어 방법을 제안한다. 또한, 회로의 구조, 동작 원리 및 스위치 제어 방법을 설명하고, 모의 실험을 수행하여 타당성을 검증한다.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1391-1401
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• 2017

In this paper, a secondary resonance half-bridge dc-dc converter with an inductive output filter is presented. The primary side of such a converter utilizes asymmetric pulse width modulation (APWM) to achieve zero-voltage switching (ZVS) of the switches, and clamps the voltage of the switch to the input voltage. In addition, zero current switching (ZCS) of the output diode is achieved by a half-wave rectifier circuit with a filter inductor and a resonant branch in the secondary side of the proposed converter. Thus, the switching losses and diode reverse-recovery losses are eliminated, and the performance of the converter can be improved. Furthermore, an inductive output filter exists in the converter reduce the output current ripple. The operational principle, performance analysis and design equation of this converter are given in this paper. The analysis results show that the output diode voltage stress is independent of the duty cycle, and that the voltage gain is almost linear, similar to that of the isolation Buck-type converter. Finally, a 200V~380V input, 24V/2A output experimental prototype is built to verify the theoretical analysis.

• Proceedings of the KIEE Conference
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• summer
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• pp.205-207
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• 2004

This paper proposes a new SSHG(Sag/swell and Harmonic Generator) injecting voltage by using series inverter. The proposed SSHG composes series inverter, DC capacitor as energy storage, rectifier and voltage clamp circuit. This SSHG is designed to generate typical power disturbances, such as voltage sag/swell, over/under voltage and voltage flicker. Also it is designed to generate unexpected voltage phase jumping waveform by controlling the series inverter. In this paper, three kinds of control methods for the proposed 2MVA SSHG are given. Typical voltage sag and swell waveforms are implemented by adopting simple control method. Also the voltage flicker is generated by changing the amplitude of the injected voltage in random. Owing to the limited bandwith of the proposed SSHG, high frequency transient waveforms can be obtained by using the open loop control. The simulation and experimental results are given to verify the operation of the proposed SSHG, Finally, conclusions are given.