• 대한전자공학회논문지
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• 제13권2호
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• pp.5-13
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• 1976

개소린 엔진 자동차의 연료절차, 공해감소, 보수경감을 목적으로 용량방전점화장치(CDI)를 해석적 및 실험적으로 설계하는 과정을 기술하였다. 특히 방전시스템에 대한 간단한 모델을 사용함으로써 점화코일의 입출력전압, 전류를 계산하였다. 그 결과 실험치와 비교하였으며 이로 부터 최적점화조건을 만족하기 위한 방전용량, SCR 및 다이오드의 정격과 DC-DC 콘버터의 소요출력전압을 결정하였다. 또 과도한 dv/dt 및 di/dt에 대한 SCR의 보호회로를 해석하고 그 결과를 관측된 결과를 관측된 결과와 비교하였는데 이로써 SCR선택과 보호회로 및 트리거 회로 설계가 용이하게 된다. 더우기 DC-DC콘버터의 거동에 대한 실험적 결과를 해석하므로써 콘버터 설계를 간이화하였다. 실용적인 CDI장치를 시작하였으며 이것은 실험실 및 노상 시험에서 만족할만한 성능을 나타냈다. 그 시험결과도 아울러 보고한다. An analytical and experimental design procedure is described for the Capacitor Discharge Ignition (CDI) System with a view to fuel saving ann reduction of gas exhaustion and maintenance need. Specifically, the input and output voltage and current of a given ignition coil were calculated by using a simplified circuit model for the discharging system. The results were compared with the experimental results, from which ratings of the charging capacitor, the SCR and the diodes and the required output valtage of the DC·DC converter were determined so as to satisfy the optimum ignition conditions. Protection circuits for excessive dv/dt and di/dt for the SCR were also analyzed and the results were compared with the observed results, which facilitate selection of the SCR and design of the protection circuit and the trigger circuit. Also, design of the DC·DC converter was simplified based on the analysis and experimental results of the behavior of the converter, An experimental, yet practical CDI system was built, which showed satisfactory performance in the laboratory and field tests. The results were also reported.

• Journal of electromagnetic engineering and science
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• 제17권4호
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• pp.191-196
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• 2017

Microwave wireless power transmission (MWPT) is a promising technique for low and medium power applications such as wireless charging for sensor network or for biomedical chips in case with long ranges or in dispersive media such. A key factor of the MWPT technique is its efficiency, which includes the wireless power transmission efficiency and the radio frequency (RF) to direct current (DC) voltage efficiency of RF-DC converter (which transforms RF energy to DC supply voltage). The main problem in designing an RF-DC converter is the nonlinear characteristic of Schottky diodes; this characteristic causes low efficiency, higher harmonics frequency and a change in the input impedance value when the RF input power changes. In this paper, rather than using harmonic termination techniques of class E or class F power amplifiers, which are usually used to improve the efficiency of RF-DC converters, we propose a new method called "optimal input impedance" to enhance the performance of our design. The results of simulations and measurements are presented in this paper along with a discussion of our design concerning its practical applications.

• 전력전자학회논문지
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• 제21권1호
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• pp.19-26
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• 2016

In this study, a bidirectional DC-DC converter for idle stop and go (ISG) is developed to reduce fuel consumption. A three-phase non-isolated half-bridge converter is selected through a design method by considering efficiency and volume. According to the state of charge of the batteries at both the low-voltage and high-voltage sides, buck mode, which charges a low-voltage battery from the generated motor energy, and boost mode, which provides power to the motor from the low- and high-voltage battery sides, are required in the ISG system. Hence, an autonomous and seamless bidirectional control method using a variable current limiter is proposed for mode change. A 1.8 kW engineering sample of the proposed converter has been built and tested to verify the validity of the proposed concept. The maximum efficiencies, including gate driver and control circuit losses, are 96.4% in charging mode and 96.1% in discharging mode.

• 전기학회논문지
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• 제64권12호
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• pp.1776-1781
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• 2015

Electric power trains receive electric power from overhead cables via a pantograph system. Power collector system in trains increase the cross section of tunnel and require a massive coreless filter reactor in propulsion inverter because of the power disturbance by contact loss phenomenon of a train. In this paper we proposed a wireless train which can run to next station with charging energy of ultra-capacitor module block. We designed DC-DC converter to charge and discharge ultra-capacitor modules by using Next Train running test results and confirm the feasibility of the proposed system through simulation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.235-237
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• 2006

This paper proposes a DC-DC converter which is able to charge and discharge secondary batteries. The converter operates as a double-ended forward converter in charging process and as electrical isolated boost converter in discharging process. The converter is designed for continuous current operation. The switching frequency is selected as 100kHz to reduce the size of both the inductor and the capacitor.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1991년도 하계학술대회 논문집
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• pp.486-491
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• 1991

The photovoltaic modules have each maximum power point, which depending on the intensity of sunlight, modules temperature and etc. Cuk converter is used to obtain the maximum charging power from photovoltaic modules to storage batteries. This paper proposed to a new tracking control method by detecting its current and voltage in photovoltaic power generation system controlled by microprocessor, in order to operate at the maximum power point tracking(MPPT) even if the sunlight and the temperature are varied.

• Journal of Electrical Engineering and Technology
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• 제9권1호
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• pp.205-213
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• 2014

A wind generator (WG) maximum power point tracking (MPPT) system is presented here. It comprises of a variable-speed wind generator, a high-efficiency boost-type dc/dc converter and a control unit. The advantages of the aimed system are that it does not call for the knowledge of the wind speed or the optimal power characteristics and that it operates at a variable speed, thus providing high efficiency. The WG operates at variable speed and thus suffers lower stress on the shafts and gears compared to constant-speed systems. It results in a better exploitation of the available wind energy, especially in the low wind-speed range of 2.5-4.5 m/s. It does not depend on the WG wind and rotor-speed ratings or the dc/dc converter power rating. Higher reliability, lower complexity and cost, and less mechanical stress of the WG. It can be applied to battery-charging applications.

• 전력전자학회논문지
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• 제19권6호
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• pp.549-556
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• 2014

This study proposes a parallel operation strategy for small wind turbine systems. A small wind turbine system consists of blade, permanent magnet synchronous generator, three-phase diode rectifier, DC/DC buck converter, and the battery load. This configuration has reliability, simple control algorithm, high efficiency, and low cost. In spite of these advantages, the system stops when unexpected failures occur. Possible failures can be divided into mechanical and electrical parts. The proposed strategy focuses on the failure of electrical parts, which is verified by numerical analysis through equivalent circuit and acquired general formula of small wind power generation systems. Simulation and experimental results prove its efficiency and usefulness.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2008년도 하계학술대회 논문집
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• pp.277-279
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• 2008

In this paper, a novel active boost converter for SR drive is proposed. An active capacitor circuit is added in the front-end. Based on this active capacitor network, when boost switch turns off, this network seems as passive capacitor network. And the voltage of boost capacitor can keep balance with dc-link voltage automatically. In the capacitor network, discharging voltage is general dc-link voltage in parallel-connected capacitors; charging voltage is double dc-link voltage in series-connected capacitors. When boost switch turns on, two capacitors are connected in series, and discharging voltage is up to double dc-link voltage. So the fast excitation current can be obtained from this mode. Profit from fast excitation and fast demagnetization mode, the performance and output power can be improved. Some computer simulations are done to verify the performance of proposed converter.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2013년도 전력전자학술대회 논문집
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• pp.287-288
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• 2013

전기자동차용 급속 충전기에서 전력변환 효율은 절연형 DC-DC 컨버터에 의해 좌우된다. 이때 DC-DC 컨버터의 출력전압 범위가 넓기 때문에 기존의 LLC 공진 컨버터를 Region2에서 설계하는 경우 스위칭 주파수 범위가 매우 넓어지는 문제가 있다. 본 논문에서는 전기자동차용 급속충전기를 위한 넓은 충전전압 범위를 갖는 공진 컨버터 비교 및 최적 설계기법을 제안한다. 제안한 SRC below영역 설계는 모든 스위치와 다이오드의 ZCS 턴오프를 성취하므로 IGBT 사용 시 유리하다. 또한, 주파수 변동범위가 작으므로 주로 낮은 배터리 전압에서 동작하는 CC충전 모드 시 스위칭 손실을 줄일 수 있다. 설계 영역에 따른 LLC, SRC를 비교하여 손실을 분석하고 제안한 설계기법의 타당성을 검증하였다.