• Journal of Power Electronics
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• 제9권5호
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• pp.679-690
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• 2009

The paper presents a new photovoltaic inverter for stand-alone induction motor application. The proposed system is composed of two stages. First stage is for the photovoltaic dc power feeding and second stage is dedicated to the motor-inverter subsystem and control technique. A direct torque control (DTC) with a novel switching strategy for motor torque ripple minimization is introduced. The novel DTC strategy is based on selecting a suitable voltage vector group for motor torque ripple minimization. A three-level voltage source inverter (VSI) is used instead of a two level inverter because the first has more available vectors and lower ripples in the output current and flux than the second, thus it has lower torque ripples. The photovoltaic array and battery bank are sized and the configuration is indicated based on sun-hour methodology. Simulation results show a comparison between three systems; two level VSI with conventional DTC strategy, three level VSI with conventional DTC, and the proposed system that has a novel DTC switching strategy applied to three level VSI. The results show that the proposed system has lower ripples in the current, flux and torque of the motor.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.79-79
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• 2013

Quantum-structures with nanoparticles have been attractive for various electronic and photonic devices [1,2]. In recent, nonvolatile memories such as nano-floating gate memory (NFGM) and resistance random access memory (ReRAM) have been studied using silicides, metals, and metal oxides nanoparticles [3,4]. In this study, we fabricated nonvolatile memories with silicides (WSi2, Ti2Si, V2Si) and metal-oxide (Cu2O, Fe2O3, ZnO, SnO2, In2O3 and etc.) nanoparticles embedded in polyimide matrix, and photovoltaic device also with SiC nanoparticles. The capacitance-voltageand current-voltage data showed a threshold voltage shift as a function of write/erase voltage, which implies the carrier charging and discharging into the metal-oxide nanoparticles. We have investigated also the electrical properties of ReRAM consisted with the nanoparticles embedded in ZnO, SiO2, polyimide layer on the monolayered graphene. We will discuss what the current bistability of the nanoparticle ReRAM with monolayered graphene, which occurred as a result of fully functional operation of the nonvolatile memory device. A photovoltaic device structure with nanoparticles was fabricated and its optical properties were also studied by photoluminescence and UV-Vis absorption measurements. We will discuss a feasibility of nanoparticles to application of nonvolatile memories and photovoltaic devices.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.1099-1106
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• 2017

본 논문에서는 신재생 에너지원인 태양광 발전을 위한 3상 인버터의 전력변환기술을 연구하였다. 태양광 인버터로는 정전압 공급 방식의 전압형 인버터, 제어기법으로는 SPWM 제어기법이 채택되었다. 태양광 인버터의 SPWM 제어기로는 강력한 고속 데이터 연산능력을 가지는 DSP가 채택되었으며, 배터리의 충전에 일정량의 전류를 공급하기 위해서 태양광 컨트롤러가 사용되었다. 끝으로, DSP를 주제어장치로 하는 소용량 3상 태양광 인버터 시스템이 시험, 제작되었으며, 실험을 통해서 SPWM 기반의 전력변환기능이 검증되었다.

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.606-613
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• 2010

This paper proposes a novel current-based maximum power point tracking (CMPPT) method for a single-phase photovoltaic power conditioning system (PV PCS) by using a modified incremental conductance method. The CMPPT method simplifies the entire control structure of the power conditioning system and uses an inherent current source characteristic of solar cell arrays. Therefore, it exhibits robust and fast response under a rapidly changing environmental condition. Digital phase locked loop technique using an all-pass filter is also introduced to detect the phase of grid voltage, as well as the peak voltage. Controllers of dc/dc boost converter, dc-link voltage, and dc/ac inverter are designed for coordinated operation. Furthermore, a current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. A 3 kW prototype PV PCS is built, and its experimental results are given to verify the effectiveness of the proposed control schemes.

• Current Photovoltaic Research
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• 제2권2호
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• pp.48-52
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• 2014

A photovoltaic cell of CuPc:P3HT:PCBM was introduced to extend the light absorption in the visible wavelength between 300~500 and 550~800 nm. By fabricating the photovoltaic cells of ITO / PEDOT:PSS / CuPc:P3HT:PCBM / BCP / Al with small-molecular and polymer donating materials blended layer, we demonstrated a high PCE of 4.20% with high Jsc of $10.05mA/cm^2$. This performance of photovoltaic cell with the blended layer of small-molecular and polymer can be competitive with that of tandem cells.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.161-166
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• 2021

To prevent accidents caused by changes in the surrounding environment or other factors, various protection facilities are installed at the photovoltaic connection module. The main causes of fire are sparks due to foreign substances inside the photovoltaic connection module through high temperature rise and dew condensation in the photovoltaic connection module, and fire due to heat from the power diode. The proposed method can predict the fire by measuring flame, carbon dioxide, carbon monoxide, temperature, humidity, input voltage, and current on the photovoltaic connection module, and when the fire conditions are reached, fire alarm and power off can be sent to managers and users in real time to prevent fire in advance.

• Current Photovoltaic Research
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• 제1권2호
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• pp.126-139
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• 2013

New national certified license tests for the facility management of new and renewable energy is given from this year. There are three national certified licenses including craftsman, industrial engineer and engineer. The subjects for the craftsman are photovoltaic facility for written exam and practical business of photovoltaic facility for writing exam. The subjects for the industrial engineer are theory, construction, management and law of the photovoltaic system for written exam and practical business of photovoltaic system for writing exam. The subjects for the engineer add one more subject compared with the industrial engineer, such as design of photovoltaic system. The first tests were given in september 28 in this year. The tests will be given three in 2014.

• Journal of Power Electronics
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• 제15권4호
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• pp.920-928
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• 2015

Transformerless solar inverters have a higher efficiency than those with an isolation link. However, they suffer from a leakage current issue. This paper proposes a family of single phase six-switch transformerless inverter topologies with an ac bypass circuit to solve the leakage current problem. These circuits embed two unidirectional freewheeling current units into the midpoint of a full bridge inverter, to obtain a freewheeling current path, which separates the solar panel from the grid in the freewheeling state. The freewheeling current path contains significantly fewer devices and poor performance body diodes are not involved, leading to a higher efficiency. Meanwhile, it is not necessary to add a voltage balancing control method when compared with the half bridge inverter. Simulation and experiments are provided to validate the proposed topologies.

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2743-2750
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• 2011

Lanthanide(III)-cored complex as a wavelength conversion material has been successfully designed and synthesized for highly efficient dye-sensitized solar cells, for the first time, since light with a short wavelength has not been effectively used for generating electric power owing to the limited absorption of these DSSCs in the UV region. A black dye (BD) was chosen and used as a sensitizer, because BD has a relatively weak light absorption at shorter wavelengths. The overall conversion efficiency of the BD/WCM device was remarkably increased, even with the relatively small amount of WCM added to the device. The enhancement in $V_{oc}$ by WCM, like DCA, could be correlated with the suppression of electron recombination between the injected electrons and $I_3{^-}$ ions. Furthermore, the short-circuit current density was significantly increased by WCM with a strong UV light-harvesting effect. The energy transfer from the Eu(III)-cored complex to the $TiO_2$ film occurred via the dye, so the number of electrons injected into the $TiO_2$ surface increased, i.e., the short-circuit current density was increased. As a result, BD/WCM-sensitized solar cells exhibit superior device performance with the enhanced conversion efficiency by a factor of 1.22 under AM 1.5 sunlight: The photovoltaic performance of the BD/WCM-based DSSC exhibited remarkably high values, $J_{sc}$ of 17.72 mA/$cm^2$, $V_{oc}$ of 720 mV, and a conversion efficiency of 9.28% at 100 mW $cm^{-2}$, compared to a standard DSSC with $J_{sc}$ of 15.53 mA/$cm^2$, $V_{oc}$ of 689 mV, and a conversion efficiency of 7.58% at 100 mW $cm^{-2}$. Therefore, the Eu(III)-cored complex is a promising candidate as a new wavelength conversion coadsorbent for highly efficient dye-sensitized solar cells to improve UV light harvesting through energy transfer processes. The abstract should be a single paragraph which summaries the content of the article.

• 한국산학기술학회논문지
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• 제11권8호
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• pp.2999-3004
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• 2010

LED는 다른 광원에 비해 동작수명이 길고, 친환경적이며, 에너지 효율이 높은 장점을 가지고 있다. 최근 LED 기술의 발전으로 인해 고휘도, 고용량의 LED가 개발됨에 따라, 표시장치에만 적용되던 LED를 조명장치에도 적용하는 기술이 확산되고 있다. 조명장치에 적용되는 파워 LED는 발열문제로 인한 소손을 막기 위해 구동전류를 일정한 전류값 이하로 제어할 필요성이 있다. 본 논문은 파워 LED의 구동전류를 설정된 값 이하로 제어하는 전류제 한 기능을 갖는 파워 LED 태양광 보안등 개발에 관한 연구이다. 태양광 발전에 의해 생산된 전력을 DC12[V] 축전지에 저장한 후, 야간에 승압형 DC-DC 컨버터를 통해 DC24[V]로 승압시켜 파워 LED로 공급한다. 태양광 보안등 제어기, 승압형 DC-DC 컨버터, 72[W]급 파워 LED 램프를 개발하여 동작을 확인하고 관련 데이터를 도출함으로써 제안된 시스템의 타당성을 입증하였다.