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태양광 모듈의 대지전압 저감을 위한 새로운 스위칭 기법
임상길(Sang-Kil Lim),박병우(Byoung-Woo Park),박성미(Seong-Mi Park),박성준(Sung-Jun Park) 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.7
Recent solar inverter there is an increasing demand for high efficiency and economy. The alternative can be applied to the transformer-less type grid-connected inverter. In general, transformer-less grid-connected inverter to operate input side solar module connected floating. Due to that ground voltage raises between solar module and ground. As a result, it accelerates the PID(Potential Induced Degradation) phenomenon and thereby causes a risk of electric shock and if not inhibits the efficiency of photovoltaic solar modules. This paper proposed ground detect technique and switching technique which reduce ground voltage between solar modules and ground in transformer-less type grid connected inverter system. The proposed control method and technique was verified through the simulation results and experiment, using the Power SIM.
유도가열 시스템을 위한 새로운 전류형 풀-브릿지 공진형 인버터 설계
이상훈(Sang-Hun Lee),임상길(Sang-Kil Lim),송성근(Seung-Gun Song) 한국조명·전기설비학회 2012 조명·전기설비학회논문지 Vol.26 No.7
There are two types of inverters that are generally used in induction heating systems: voltage type inverters and high-frequency half-bridge inverters. This paper proposes a new resonant inverter for induction heating systems using the current type full-bridge method. The proposed method can remove capacitors at the input end, and enables unity power factor operation by preventing phase differences of voltage and current. Furthermore, Zero Voltage Switching (ZVS) which is in tune with current type inverter can be adopted and continuous power adjustment is possible through duty ratio changes and frequency modulation in switching operation. Simulations and experiments showed that the proposed current type full-bridge resonant inverter could be used for unity power factor control and ZVS operation in induction heating systems.
시분할 스위칭 기법을 이용한 양방향 DC/DC 컨버터에 관한 연구
박성준(Sung-Jun Park),송성근(Sung-Geun Song),임상길(Sang-Kil Lim),박성미(Seong-Mi Park) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.12
A number of new and renewable energy power plants have currently been under construction to cope with fossil fuel depletion, while various large-scale battery energy storage systems have been configured to complement the characteristically unstable output of new and renewable energy. In the meantime, as the scale of energy storage system increases, there is an urgent demand for bidirectional charge/discharge converters with large capacities, and relevant researches are actively going on. Interleaved converter is most generally used for this purpose because it enables not only the reduction of output current ripple, but also the increase of capacity through the parallel configuration of inductor and switch and diode. This paper proposes a new concept of DC/DC converter that allows the sharing of inductor and output capacitor by using a multi-phase switch. However, interleaved converter has the weak points that size and unit price increase as capacity increases, and that effective switching frequency is limited. The proposed DC/DC converter has a structure that can increase the effective switching frequency of not only output capacitor but inductor as well, and its merit of enabling the reduction of inductor capacity by reducing inductor current ripple was demonstrated.
태양광 LED 가로등용 비절연형 플라이백-부스트 콤비네이션 컨버터
황인(In Hwang),임상길(Sang-Kil Lim),박성미(Seong-Mi Park),송성근(Sung-Geun Song),원용관(Yong-Gwan Won) 한국조명·전기설비학회 2016 조명·전기설비학회논문지 Vol.30 No.9
This paper, proposes a non-insulated type flyback-boost combination converter that has the step-up and down function as a converter for an independent solar light LED pole light system. The proposed combination converter is composed with the use of one switch, and the step-up function works with discontinuous current mode. The proposed electric power circuit allows for improving the efficiency of converting energy by removing the RCD(Residual-current device) snubber of the existing flyback converter, connecting the terminal to output and transferring the stored energy in the leakage inductor of transformer to output. Simulations and experiments were conducted to validate the proposed circuit and the results were discussed.
모듈과 LED 전압 공유를 이용한 태양광 가로등 시스템
김광헌(Gwang-Heon Kim),임상길(Sang-Kil Lim),이정환(Jung-Hwan Lee),박성미(Seong-Mi Park),박성준(Sung-Jun Park),주홍주(Hong-Ju Ju) 한국조명·전기설비학회 2017 조명·전기설비학회논문지 Vol.31 No.4
In a stand-alone solar streetlight system, a DC/DC converter for battery charging and a DC/DC converter for LED lighting control are used independently. In this way, there is a limits to the utilization rate of solar power generation because the use of a DC/DC converter having only a volage ncrease or decrease function to reduce the number of power semiconductor devices makes it impossible to perform the maximum power estimation(MPPT) in all areas in the battery charger. In addition a DC/DC converter for LED lighting has a limitation in the design of the lighting voltage since LED lighting only operates at voltages lower or higher than the battery voltage. Therefore, in this study, we propose a novel power conversion system using a single bi-directional buck-boost DC/DC converter which uses the features of stand-alone solar streetlight of not running DC/DC converters for battery charging and DC/DC converters for LED lighting at the same time.
레동부(Tuan-Vu Le),임상길(Sang-Kil Lim),박성미(Seong-Mi Park),박성준(Sung-Jun Park),김광헌(Gwang-Heon Kim) 한국조명·전기설비학회 2018 조명·전기설비학회논문지 Vol.32 No.8
In this paper, we propose a new voltage sensing circuit using sensing opto-coupler and observation opto-coupler for low-priced battery voltage measurement. The proposed topology consists of an opto-coupler for sensing and an opto-coupler for observation, so that an accurate voltage can be detected by constructing an observer. It is confirmed that the rated current for sensing the voltage can be designed to be less than 300uA, which confirms that the power loss can be reduced during high voltage sensing. In addition, since the dielectric strength of the low cost opto-coupler is generally 5,000Vac, it is possible to construct a voltage sensor having an oscillating strength of about 7,000V. The validity of the proposed method was verified by creating a Psim simulation and an actual prototype.
에너지 회수 회로를 이용한 새로운 LED 구동드라이브 설계
한만승(Man-Seung Han),임상길(Sang-Kil Lim),박성준(Sung-Jun Park),이상훈(Sang-Hun Lee) 한국조명·전기설비학회 2011 조명·전기설비학회논문지 Vol.25 No.6
The high-power LED (Light Emitting Diode) which is recently gaining popularity as a digital light source has such advantages as low power consumption, long life, fast switching speed, and high efficiency. Thus, many efforts are being made to use the high-power LEDs for general lighting. This paper proposes LED driving circuit uses a DC/DC converter that can recover energy to compensate for the current variations caused by changes in LED equivalent resistance following a temperature change instead of serial resistance. The maximum input voltage of this DC/DC converter has low voltage variations by temperature change when the rated current is formed. In order to return current to the input side, we need a high boosting at low power. Thus, to improve the low efficiency of power converter, the power converter can be configured in such a way to gather the powers of low-capacity DC/DC converters and return the total power. Experiments showed that the proposed system improved efficiency compared to the conventional LED drive using the existing DC/DC converter.