• Title/Summary/Keyword: Photovoltaic DC-DC Power Converter

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Development of Neural Network Controller for Maximum Power Point Tracking of PV System (PV 시스템의 최대전력점 추적을 위한 신경회로망 제어기 개발)

  • Ko, Jae-Sub;Choi, Jung-Sik;Jung, Dong-Hwa
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.23 no.1
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    • pp.41-48
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    • 2009
  • This paper presents an Neural Network(NN) controller for Maximum Power Point Tracking (MPPT) of PV supplied DC motor. A variation of solar irradiation is most important factor in the MPPT of PV system. That is nonlinear, aperiodic and complicated. NN was widely used due to easily solving a complex math problem. Proposed photovoltaic system consists of NN, DC-DC converter, DC motor and load(cf, pump). NN algorithm apply to DC-DC converter through an Adaptive control of Neural Network, calculates Converter-Chopping ratio using an Adaptive control of NN. The results of an Adaptive control of NN compared with the results of Converter-Chopping ratio which are calculated mathematical modeling and evaluate the proposed algorithm. The experimental data show that an adequacy of the algorithm was established through the compared data.

High Efficiency High-Step-up Single-ended DC-DC Converter with Small Output Voltage Ripple

  • Kim, Do-Hyun;Kim, Hyun-Woo;Park, Joung-Hu;Jeon, Hee-Jong
    • Journal of Power Electronics
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    • v.15 no.6
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    • pp.1468-1479
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    • 2015
  • Renewable energy resources such as wind and photovoltaic power generation systems demand a high step-up DC-DC converters to convert the low voltage to commercial grid voltage. However, the high step-up converter using a transformer has limitations of high voltage stresses of switches and diodes when the transformer winding ratio increases. Accordingly, conventional studies have been applied to series-connect multioutput converters such as forward-flyback and switched-capacitor flyback to reduce the transformer winding ratio. This paper proposes new single-ended converter topologies of an isolation type and a non-isolation type to improve power efficiency, cost-effectiveness, and output ripple. The first proposal is an isolation-type charge-pump switched-capacitor flyback converter that includes an extreme-ratio isolation switched-capacitor cell with a chargepump circuit. It reduces the transformer winding number and the output ripple, and further improves power efficiency without any cost increase. The next proposal is a non-isolation charge-pump switched-capacitor-flyback tapped-inductor boost converter, which adds a charge-pump-connected flyback circuit to the conventional switched-capacitor boost converter to improve the power efficiency and to reduce the efficiency degradation from the input variation. In this paper, the operation principle of the proposed scheme is presented with the experimental results of the 100 W DC-DC converter for verification.

Three-Port Converters with a Flexible Power Flow for Integrating PV and Energy Storage into a DC Bus

  • Cheng, Tian;Lu, Dylan Dah-Chuan
    • Journal of Power Electronics
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    • v.17 no.6
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    • pp.1433-1444
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    • 2017
  • A family of non-isolated DC-DC three-port converters (TPCs) that allows for a more flexible power flow among a renewable energy source, an energy storage device and a current-reversible DC bus is introduced. Most of the reported non-isolated topologies in this area consider only a power consuming load. However, for applications such as hybrid-electric vehicle braking systems and DC microgrids, the load power generating capability should also be considered. The proposed three-port family consists of one unidirectional port and two bi-directional ports. Hence, they are well-suited for photovoltaic (PV)-battery-DC bus systems from the power flow viewpoint. Three-port converters are derived by combining different commonly known power converters in an integrated manner while considering the voltage polarity, voltage levels among the ports and the overall voltage conversion ratio. The derived converter topologies are able to allow for seven different modes of operation among the sources and load. A three-port converter which integrates a boost converter with a buck converter is used as a design example. Extensions of these topologies by combining the soft-switching technique with the proposed design example are also presented. Experiment results are given to verify the proposed three-port converter family and its analysis.

A Development Of Utility Vehicle Controller With Photovoltaic Power System (태양광 발전 겸용 유틸리티 차량용 컨트롤러의 개발)

  • 김태엽;안호균
    • The Transactions of the Korean Institute of Power Electronics
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    • v.5 no.5
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    • pp.467-474
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    • 2000
  • This paper describes the development of 7he utility vehicle controller using combination system of battery and photovoltaic power for increasing operation time. In order to keep interchangeability, low cost and high performance, a separately excited DC Motor is controlled without velocity and current measurements by $\mu$-processor. For the parallel operation between the solar cell and battery, dc-dc converter is used, which is applied to the maximum power Point tracking(MPPT) and current control algorithm. By the simulation and experimental results of trial product, the vapidity of the proposed system is verified.

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Rapid response control A Utility Interactive Photovoltaic Generation System (계통연계형 태양광발전 시스템의 속응성 제어)

  • Chung, Choon-Byeong;Jeon, Kee-Young;Lee, Sang-Hyun;Han, Kyung-Hee
    • Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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    • 2007.11a
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    • pp.279-285
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    • 2007
  • Since the residential load is an AC load and the output of solar cell is a DC power, the photovoltaic system needs the DC/AC converter to utilize solar cell. In case of driving to interact with utility line, in order to operate at unity power factor, converter must provide the sinusoidal wave current and voltage with same phase of utility line. Since output of solar cell is greatly fluctuated by insolation, it is necessary that the operation of solar cell output in the range of the vicinity of maximum power point. In this paper, DC/AC converter is three phase PWM converter with smoothing reactor. And then, feedforward control used to obtain a superior characteristic for current control and digital PLL circuit used to detect the phase of utility line.

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Design of a 2kW Bidirectional Synchronous DC-DC Converter for Battery Energy Storage System (배터리 에너지 저장장치용 고효율 2kW급 양방향 DC-DC 컨버터 설계)

  • Lee, Taeyeong;Cho, Byung-Geuk;Cho, Younghoon;Hong, Chanook;Lee, Han-Sol;Cho, Kwan-Yuhl
    • The Transactions of the Korean Institute of Power Electronics
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    • v.22 no.4
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    • pp.312-323
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    • 2017
  • This paper introduces the bidirectional dc-dc converter design case study, which employs silicon-carbide (SiC) MOSFETs for battery energy storage system (BESS). This converter topology is selected as bidirectional synchronous buck converter, which is composed of a half bridge converter, an inductor, and a capacitor, where the converter has less conduction loss than that of a unidirectional buck and boost converter, and to improve the converter efficiency, both the power stage design and power conversion architecture are described in detail. The conduction and switching losses are compared among three different SiC devices in this paper. In addition, the thermal analysis using Maxwell software of each switching device supports the loss analyses, in which both the 2 kW prototype analyses and experimental results show very good agreement.

A Feasibility Study on DC Microgrids Considering Energy Efficiency (에너지 효율분석을 통한 DC 마이크로그리드의 타당성 검토)

  • Yu, Cheol-Hee;Chung, Il-Yop;Hong, Sung-Soo;Chae, Woo-Kyu;Kim, Ju-Yong
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.60 no.9
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    • pp.1674-1683
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    • 2011
  • More than 80% of electric loads need DC electricity rather than AC at the moment. If DC power could be supplied directly to the terminal loads, power conversion stages including rectifiers, converters, and power adapters can be reduced or simplified. Therefore, DC microgrids may be able to improve energy efficiency of power distribution systems. In addition, DC microgrids can increase the penetration level of renewable energy resources because many renewable energy resources such as solar photovoltaic(PV) generators, fuel cells, and batteries generate electric power in the form of DC power. The integration of the DC generators to AC electric power systems requires the power conversion circuits that may cause additional energy loss. This paper discusses the capability and feasibility of DC microgrids with regard to energy efficiency analysis through detailed dynamic simulation of DC and AC microgrids. The dynamic simulation models of DC and AC microgrids based on the Microgrid Test System in KEPCO Research Institute are described in detail. Through simulation studies on various conditions, this paper compares the energy efficiency and advantages of DC and AC microgrids.

A Novel Input and Output Harmonic Elimination Technique for the Single-Phase PV Inverter Systems with Maximum Power Point Tracking (최대출력추종 제어를 포함한 단상 태양광 인버터를 위한 새로운 입출력 고조파 제거법)

  • Amin, Saghir;Ashraf, Muhammad Noman;Choi, Woojin
    • Proceedings of the KIPE Conference
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    • 2019.07a
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    • pp.207-209
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    • 2019
  • This paper proposes a grid-tied photovoltaic (PV) system, consisting of Voltage-fed dual-active-bridge (DAB) dc-dc converter with single phase inverter. The proposed converter allows a small dc-link capacitor, so that system reliability can be improved by replacing electrolytic capacitors with film capacitors. The double line frequency free maximum power point tracking (MPPT) is also realized in the proposed converter by using Ripple Correlation method. First of all, to eliminate the double line frequency ripple which influence the reduction of DC source capacitance, control is developed. Then, a designing of Current control in DQ frame is analyzed and to fulfill the international harmonics standards such as IEEE 519 and P1547, $3^{rd}$ harmonic in the grid is directly compensated by the feedforward terms generated by the PR controller with the grid current in stationary frame to achieve desire Total Harmonic Distortion (THD). 5-kW PV converter and inverter module with a small dc-link film capacitor was built in the laboratory with the proposed control and MPPT algorithm. Experimental results are given to validate the converter performance.

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MPPT Control of Photovoltaic using Neural Network (신경회로망을 이용한 태양광 발전의 MPPT 제어)

  • Ko, Jae-Sub;Choi, Jung-Sik;Jung, Chul-Ho;Kim, Do-Yeon;Jung, Byung-Jin;Chung, Dong-Hwa
    • Proceedings of the KIEE Conference
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    • 2008.04c
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    • pp.221-223
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    • 2008
  • This paper presents a maximum power point tracking(MPPT) of Photovoltaic system with chopping ratio of DC-DC converter considered load. A variation of solar irradiation is most important factor in the MPPT of PV system. That is nonlinear, aperiodic and complicated. The paper consists of solar radiation source, DC-DC converter, DC motor and load(cf, pump). NN algorithm apply to DC-DC converter through an adaptive control of neural network, calculates converter-chopping ratio using an adaptive control of NN. The results of an adaptive control of NN compared with the results of converter-chopping ratio which are calculated mathematical modeling and evaluate the proposed algorithm. The experimental data show that an adequacy of the algorithm was established through the compared data.

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Seamless Transfer Method of MPPT for Two-stage Photovoltaic PCS (태양광 발전 시스템의 무순단 MPPT 운전 모드 절체 기법)

  • Park, Jong-Hwa;Jo, Jongmin;An, Hyunsung;Cha, Hanju
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.67 no.2
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    • pp.233-238
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    • 2018
  • This paper proposes a seamless MPPT operation mode transfer method of photovoltaic system. The photovoltaic system consists of a DC-DC boost converter, a DC-Link, and a 3-level neutral point clamp (NPC) type inverter. The PV voltage fluctuates due to the output characteristics of the solar pane1 depending on the irradiation amount and the temperature. The photovoltaic system requires seamless MPPT mode transfer method that the discontinuity does not occur in order to supply the stable power to system without affecting the fluctuation of the PV voltage. MPPT operation is divided into two modes by the voltage reference. Under the condition that the PV voltage is below 650V, the DC-DC boost converter performs MPPT through duty control based on perturb & observe (P&O) method, and the inverter conducts DC-link voltage and grid current controls in synchronous reference frame. On the other hand, when the PV voltage exceeds above 650V, inverter performs MPPT in accordance with the variation of DC-link voltage control while the converter stops operating. Two MPPT operation modes is smoothly transferred through the proposed method that DC-link voltage or grid current commands are appropriately adjusted from the certain criteria. The feasibility of the MPPT operation mode transfer method is verified using a 10kW solar photovoltaic system, experimental results have good performances that the fluctuation of PV current is reduced to 100%.