• Title/Summary/Keyword: Constant voltage

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Design and Analysis of 20 W Class LED Converter Considering Its Control Method (제어 방식에 따른 20 W급 LED Converter 설계 및 분석)

  • Jeong, Young-Gi;Kim, Sung-Hyun;Park, Dae-Hee
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.25 no.1
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    • pp.53-57
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    • 2012
  • In this paper, by designing 20 W class driving circuit for driving high-power LED (Light Emitting Diode), we are going to comparatively carry out the analysis of characteristics for power circuit according to each design method. In this case, 200 V 60 Hz was performed as input data. The electrical characteristics such as voltage, current and ripple are checked for constant current circuit and constant voltage circuit in the LED module. In addition, as the ripple has an influence on illumination of LED light, low temperature working (-20 [$^{\circ}C$]) and high temperature working(80 [$^{\circ}C$]) are measured to make sure the ripple characteristics in accordance with temperature. In low temperature operation -20 [$^{\circ}C$] measurements, both constant current circuit and constant-voltage circuit were less impacted on input fluctuation, whereas in the high temperature operation 80 [$^{\circ}C$], current voltage in constant voltage circuit was surge after 430 [hour]. Voltage current ripple of constant current circuit was much less than constant voltage circuit, therefore we can show that constant current circuit is more stable.

An Efficient Battery Charging Algorithm based on State-of-Charge Estimation using 3-Phase AC-DC Boost Converter (3상 AC-DC 승압형 컨버터를 이용한 SOC 추정 기반의 효율적 배터리 충전 알고리즘)

  • Lee, Jung-Hyo;Won, Chung-Yuen
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.29 no.9
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    • pp.96-102
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    • 2015
  • This paper presents battery charging method using 3-phase AC-DC boost converter. General battery charging method is that charging the battery voltage to the reference voltage according to the constant current(CC) control, when it reaches the reference voltage, charging the battery fully according to the constant voltage(CV) control. However, battery chaging time is increased because of the battery impedance, constant current charging section which shoud take the large amount of charge is narrow, and constant voltage charging section which can generate insufficient charge is widen. To improve this problem, we proposes the method to reduce the charging time according to the SOC(State of Charge) estimation using battery impedance.

A New Approach for Constant DC Link Voltage in a Direct Drive Variable Speed Wind Energy Conversion System

  • Jeevajothi, R.;Devaraj, D.
    • Journal of Electrical Engineering and Technology
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    • v.10 no.2
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    • pp.529-538
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    • 2015
  • Due to the high efficiency and compact mechanical structure, direct drive variable speed generators are used for power conversion in wind turbines. The wind energy conversion system (WECS) considered in this paper consists of a permanent magnet synchronous generator (PMSG), uncontrolled rectifier, dc-dc boost converter controlled with maximum power point tracking (MPPT) and adaptive hysteresis controlled voltage source inverter (VSI). For high utilization of the converter's power capability and stabilizing voltage and power flow, constant DC-link voltage is essential. Step and search MPPT algorithm which senses the rectified voltage ($V_{DC}$) alone and controls the same is used to effectively maximize the output power. The adaptive hysteresis band current control is characterized by fast dynamic response and constant switching frequency. With MPPT and adaptive hysteresis band current control in VSI, the DC link voltage is maintained constant under variable wind speeds and transient grid currents respectively.

Secondary Indirect Constant Voltage Control Technique for Hybrid Solid State Transformer using Primary Side Information (하이브리드 반도체 변압기의 1차측 정보를 이용한 2차측 간접 정전압 제어 기법)

  • Lee, Taeyeong;Yun, Chun-Gi;Cho, Younghoon
    • The Transactions of the Korean Institute of Power Electronics
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    • v.25 no.5
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    • pp.420-423
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    • 2020
  • This study proposes an indirect constant voltage control algorithm for hybrid solid-state transformers (HSSTs) by using primary side information. Considering the structure of HSSTs, measuring voltage and current information on the primary side of a transformer is necessary to control the converter and inverter of the power converter. The secondary side output voltage is measured to apply the conventional secondary side constant voltage control algorithm, and thus, the digital control board requires the same rated insulation voltage as that of the transformer. To solve this problem, the secondary voltage of the transformer obtained from the tap voltage is used. Moreover, output voltage decreases as load increases because the proposed indirect constant voltage control scheme does not consider the cable impedance between the secondary output terminal and the load. This study also proposes a technique for compensating the secondary output voltage by using the primary current of the transformer and the resistance value of the cable. An experiment is conducted using a scale-down HSST prototype consisting of a 660 V/220 V tap transformer. The problem of the proposed indirect constant voltage control strategy and the improvement effect due to the application of the compensation method are compared using the derived experimental results.

Voltage Gain and Efficiency Analysis of Piezoelectric Transformer using Lumped constant Equivalent Circuit (집중 등가회로를 사용한 압전 변압기의 승합비 및 효율 해석)

  • 류주현;이용우;윤광희;정희승;정영호;박창엽
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.11 no.10
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    • pp.849-854
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    • 1998
  • The load characteristics on the voltage gain and efficiency were analyzed using a lumped constant equivalent circuit of the piezoelectric transformer. These analytical results were confirmed by experiments. Theoretical values of voltage gain were nearly constant with experimental ones. However, It was shown that theoretical values of efficiency is higher than experimental ones.

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Voltage Gain and Efficiency Ana1ysis of Piezoelectric Transformer using Lumped Constant Equivalent Circuit (Rosen형 압전 트랜스포머의 집중등가회로를 사용한 승압비 및 효율 해석)

  • 김만성;류주현;정회승;박창엽;정영호
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 1998.06a
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    • pp.183-189
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    • 1998
  • In this paper, The load characteristics on the voltage gain and efficiency were analyzed sing an lumped constant equivalent circuit of the piezoelectric transformer. These analytical results are confirmed by experiments. Theoretical values of voltage gain were nearly constant with experimental ones. However, It was shown that theoretical values of efficiency had higher values than experimental ones.

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Constant Current & Constant Voltage Battery Charger Using Buck Converter (벅 컨버터를 이용한 정전류 정전압 배터리 충전기)

  • Awasthi, Prakash;Kang, Seong-Gu;Kim, Jeong-Hun;Park, Sung-Jun
    • Proceedings of the KIPE Conference
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    • 2012.07a
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    • pp.399-400
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    • 2012
  • The proposed battery charger presented in this paper is suitable for Lead-Acid Battery and the dc/dc buck converter topology is applied as a charger circuit. The technique adopted in this charger is constant current & constant voltage dual mode, which is decided by the value of voltage of proposed battery. Automatic mode change function is detected by the percentage value of level of battery charging. CC Mode (Constant Current Mode) is operated when charging level is below 80% of the total charging of Battery voltage and above 80% of battery voltage charging, CV Mode (Constant Voltage Mode) is automatically operated. As the charging level exceeds 120%, it automatically terminates charging. The feedback signal to the PWM generator for charging the battery is controlled by using the current and voltage measurement circuits simultaneously. This technique will degrade the damage of proposed type of battery and improve the power efficiency of charger. Finally, a prototype charger circuit designed for a 12-V 7-Ah lead acid battery is constructed and tested to confirm the theoretical predictions. Satisfactory performance is obtained from simulation and the experimental results.

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A Jitter Characteristic Improved PLL with RC Time Constant Circuit (저항-커패시턴스 시정수 회로를 이용하여 지터 특성을 개선한 위상고정루프)

  • An, Seong-Jin;Choi, Yong-Shig
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.2
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    • pp.133-138
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    • 2017
  • This paper presents a jitter characteristic improved phase locked loop (PLL) with an RC time constant circuit. In the RC time constant circuit, LPF's voltage is inputted to a comparator through small and large RC time constant circuits. The signal through a small RC time constant circuit has almost same loop filter output voltage. The signal through a large RC time constant circuit has the average value of loop filter output voltage and does as a role of reference voltage to the comparator. The output of the comparator controls the sub-charge pump which provide a current to LPF. When the loop filter output voltage increases, the sub-charge pump discharges the loop filter and decreases loop filter output voltage. When the loop filter output voltage decreases, the sub-charge pump charges the loop filter and increases loop filter output voltage. The negative feedback loop reduces the variation of loop filter output voltage resulting in jitter characteristic improvement.

A Study on Synchronized AC Source Voltage Regulator of Voltage Fed Inverter using a Photovoltatic Effect

  • Hwang, Lak-Hoon;Lee, Chun-Sang;Kim, Jong-Lae;Jang, Byong-Gon
    • Proceedings of the KIPE Conference
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    • 1998.10a
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    • pp.547-553
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    • 1998
  • In this paper, we composed of utility interactive pv generation system of voltage source inverter, and represented uninterrutible power supply (UPS) equipment maintaining constant voltage, using a pulse width modulation(PWM) voltage fed inverter, as power source disconnection, voltage variation and output current variation with load variation. This system is driven by being synchronized voltage fed inverter and AC source, and in the steady state of power source charge battery connected to dc side with solar cell using a photovoltaic (PV) that it was so called constant voltage charge. In addition, better output waveform was generated because of PWM method, and it was proved to test by experiment maintained constant output voltage regardless of AC source disconnection, load variation, and voltage variation of AC power source.

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Loop Filter Voltage Variation Compensated PLL with Charge Pump (전하펌프를 이용한 루프 필터 전압변화 보상 위상고정루프)

  • An, Seong-Jin;Choi, Yong-shig
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.20 no.10
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    • pp.1935-1940
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    • 2016
  • This paper proposes a phase-locked loop (PLL) to minimize the loop filter output voltage fluctuation by using a comparator including RC time constant circuits. The voltage variation of loop filter is inputted to RC time constant circuits which have two RC time constants, large and small. While a small RC time constant circuit quickly conveys the output voltage variation of loop filter, a large RC time constant circuit conveys slowly the output voltage variation of loop filter and its output looks like constant voltage. The output signal of the comparator controls the sub charge pump and reduces the input voltage variation of voltage-controlled oscillator (VCO). Therefore, the proposed PLL generates a phase noise reduced signal. It has been designed with a 1.8V supply voltage, 0.18um multi - metal and multi - poly layer CMOS process and proved by Hspice simulation.