• Title/Summary/Keyword: low power mode

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The Development of Real-Time Harmonic Analysis Algorithm in Distribution Transformer (배전용 변압기의 실시간 고조파 분석 알고리즘 개발)

  • Park, Chul-Woo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.27 no.3
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    • pp.43-49
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    • 2013
  • Recently harmonics flowing into power system is increasing as the usage of semiconductor equipments and switching mode power equipments are increasing. Harmonics cause problems such as heat increasing and reduction in capacity of transformers, especially the harmonics flowing into a distribution transformer can lead to the lifetime reduction of transformer. In this paper, we are about to develop a device that can monitor harmonics in real-time as it is affixed to a distribution transformer. Unlike the existing expensive harmonic analysis device, a new harmonic analysis algorithm is proposed in order to implement low-cost equipment. The real-time harmonic analysis algorithm proposed in this paper allows implementation on low performance microcontrollers, thus it can monitor the harmonic in real-time as it is individually affixed to the transformer. Therefore, it would improve the reliability of the transformer and stable power system operation would be possible as it can prevent the transformer accidents in advance.

Performance Evaluation of Distributed MAC Protocol Algorithm for Efficient Multimedia Transmission (효율적인 멀티미디어 전송을 위한 분산방식 MAC 프로토콜 성능분석)

  • Kim, Jin Woo;Lee, Seong Ro
    • Journal of Korea Multimedia Society
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    • v.17 no.5
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    • pp.573-581
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    • 2014
  • The salient features of UWB(Ultra WideBand) networks such as high-rate communications, low interference with other radio systems, and low power consumption bring many benefits to users, thus enabling several new applications such as wireless universal serial bus (WUSB) for connecting personal computers (PCs) to their peripherals and the consumer-electronics (CE) in people's living rooms. Because the size of multimedia data frame, WiMedia device must transmit the fragment of MSDU. However, when the fragment of MSDU is lost, WiMedia device maintains active mode for the time to complete the transmission MSDU, and there is a problem that unnecessary power consumption occurs. Therefore we propose new power management scheme to reduce unnecessary power consumption of WiMedia devices in the case that the fragment is lost.

A Study on the Characteristics of the Clutch Automation Mechanism of Hybrid Vehicles (하이브리드 차량용 클러치 자동화 기구의 특성 연구)

  • Lim, Won-Sik;Park, Sung-Cheon
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.21 no.5
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    • pp.778-783
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    • 2012
  • Due to the increase of oil price, the needs of the reduction of the fuel cost is rising. Therefore, necessity of hybrid vehicle that runs with engine and the electric motor is on the rise. In order to improve the performance of hybrid vehicle, many researches is carried out. Hybrid vehicles have been developed with the various layout such as serial type, parallel type, power split type, and multi-mode type. The multi-mode hybrid vehicles are designed to show the efficient driving characteristics at low speed and high speed. But the multi-mode system have the problem such as frequent clutch engagement. Frequent clutch engagement causes the shock of vehicles, and the shock inhibits the ride comfort. In this study, automation mechanism of clutch operation is proposed to mitigate the shock at engaging clutch. For this purpose, the dynamic characteristics of motor control is numerically analyzed by using Matlab/Simulink.

Design of A 3V CMOS Lowpass Filter Using the Improved Continuous-Time Fully-Differential Current-Mode Integrator (개선된 연속시간 Fully-Differential 전류모드 적분기를 이용한 3V CMOS 저역필터 설계)

  • 최규훈;방준호;조성익
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.22 no.4
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    • pp.685-695
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    • 1997
  • In this paper, a new CMOS continuous-time fully-differential current-mode integrator is proposed as a basic building block of the low-voltage high frequency current-mode active filter. The proposed integrator is composed of the CMOS complementary circuit which can extend transconductance of an integrator. Therefore, the unity gain frequency which is determined by a small-signal transconductance and a MOSFET gate capacitance can be expanded by the complementary transconductance of the proposed integrator. And also the magnitude of pole and zero are increased. The unity gain frequency of the proposed integrator is increased about two times larger than that of the conventional continuous-time fully-differential integrator with NMOS-gm. These results are verified by the small signal analysis and the SPICE simulation. As an application circuit of the proposed fully-differential current-mode integrator, the three-pole Chebyshev lowpass filter is designed using 0.8.$\mu$m CMOS processing parameters. SPICE simulation predicts a 3-dB bandwidth of 148MHz and power dissipation of 4.3mW/pole for the three-pole filter with 3-V power supply.

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Low Frequency Current Ripple Mitigation of Two Stage Three-Phase PEMFC Generation Systems

  • Deng, Huiwen;Li, Qi;Liu, Zhixiang;Li, Lun;Chen, Weirong
    • Journal of Power Electronics
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    • v.16 no.6
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    • pp.2243-2257
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    • 2016
  • This paper presents a two stage three-phase proton exchange membrane fuel cell (PEMFC) generation system. When the system is connected to a three-phase load, it is very sensitive to the characteristics and type of the load. Especially unbalanced three-phase loads, which result in a pulsating power that is twice the output frequency at the inverter output, and cause the dc-link to generate low frequency ripples. This penetrates to the fuel cell side through the front-end dc-dc converter, which makes the fuel cell work in an unsafe condition and degrades its lifespan. In this paper, the generation and propagation mechanism of low frequency ripple is analyzed and its impact on fuel cells is presented based on the PEMFC output characteristics model. Then a novel method to evaluate low frequency current ripple control capability is investigated. Moreover, a control scheme with bandpass filter inserted into the current feed-forward path, and ripple duty ratio compensation based on current mode control with notch filter is also proposed to achieve low frequency ripple suppression and dynamic characteristics improvement during load transients. Finally, different control methods are verified and compared by simulation and experimental results.

Analysis and Design Considerations for a High Power Buck Derived LED Driver with Extended Output Voltage and Low Total Harmonic Distortion

  • Lv, Haijun;Wu, Xinke;Zhang, Junming
    • Journal of Power Electronics
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    • v.17 no.5
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    • pp.1137-1149
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    • 2017
  • In order to reduce the cost, improve the efficiency and simplify the complicated control of existing isolated LED drivers, an improved boundary conduction mode (BCM) Buck ac-dc light emitting diode (LED) driver with extended output voltage and low total harmonic distortion is proposed. With a coupled inductor winding and a stacked output, its output voltage can be elevated to a much higher value when compared to that of the conventional Buck ac-dc converter, without sacrificing the input harmonics and power factor. Therefore, the proposed Buck LED driver can meet the IEC61000-3-2 (Class C) limitation and has a low THD. The operating principle of the topology and the design methodology of the ac-dc LED driver are presented. A 150 W ac-dc prototype was built in the laboratory and it shows that the input current harmonics meet the lighting standard. In addition, the THD is less than 16% at a typical ac input. The peak efficiency is higher than 96.5% at a full load and a normal input.

Transmission Control Scheme for Low Power Stations in IEEE 802.11b Wireless LAN (IEEE 802.11b 무선 랜에서 저 전력 스테이션을 위한 전송 제어 기법)

  • Song, Myong-Lyol
    • Journal of Internet Computing and Services
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    • v.9 no.2
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    • pp.43-50
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    • 2008
  • In IEEE 802.11b wireless LAN, stations keep synchronization by receiving beacons being periodically sent by the AP (access point) when they run in low power mode. Beacon transmission is delayed if wireless channel is busy at a scheduled TBTT (target beacon transmission time), and stations must be awake until they receive the delayed beacon. In this paper, we propose a scheme that stations get their transmission delayed if they have little time for successful data transmission by the next TBTT. Beacon transmission without delay is guaranteed at every TBTT with this method so that the awake time of low power stations to receive beacon can be reduced. The proposed method is simulated and its characteristics ore described with the analysis of the results. The measured results in terms of beacon delay show some enhancement in energy consumption.

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DEVELOPMENT OF COMBIND WELDING WITH AN ELECTRIC ARC AND LOW POWER CO LASER

  • Lee, Se-Hwan;Massood A. Rahimi;Charles E. Albright;Walter R. Lempert
    • Proceedings of the KWS Conference
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    • 2002.10a
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    • pp.176-180
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    • 2002
  • During the last two decades the laser beam has progressed from a sophisticated laboratory apparatus to an adaptable and viable industrial tool. Especially, in its welding mode, the laser offers high travel speed, low distortion, and narrow fusion and heat-affected zones (HAZ). The principal obstacle to selection of a laser processing method in production is its relatively high equipment cost and the natural unwillingness of production supervision to try something new until it is thoroughly proven. The major objective of this work is focused on the combined features of gas tungsten arc and a low-power cold laser beam. Although high-power laser beams have been combined with the plasma from a gas tungsten arc (GTA) torch for use in welding as early as 1980, recent work at the Ohio State University has employed a low power laser beam to initiate, direct, and concentrate a gas tungsten arcs. In this work, the laser beam from a 7 watts carbon monoxide laser was combined with electrical discharges from a short-pulsed capacitive discharge GTA welding power supply. When the low power CO laser beam passes through a special composition shielding gas, the CO molecules in the gas absorbs the radiation, and ionizes through a process known as non-equilibrium, vibration-vibration pumping. The resulting laser-induced plasma (LIP) was positioned between various configurations of electrodes. The high-voltage impulse applied to the electrodes forced rapid electrical breakdown between the electrodes. Electrical discharges between tungsten electrodes and aluminum sheet specimens followed the ionized path provided by LIP. The result was well focused melted spots.

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A 41dB Gain Control Range 6th-Order Band-Pass Receiver Front-End Using CMOS Switched FTI

  • Han, Seon-Ho;Nguyen, Hoai-Nam;Kim, Ki-Su;Park, Mi-Jeong;Yeo, Ik-Soo;Kim, Cheon-Soo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.16 no.5
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    • pp.675-681
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    • 2016
  • A 41dB gain control range $6^{th}$-order band-pass receiver front-end (RFE) using CMOS switched frequency translated impedance (FTI) is presented in a 40 nm CMOS technology. The RFE consists of a frequency tunable RF band-pass filter (BPF), IQ gm cells, and IQ TIAs. The RF BPF has wide gain control range preserving constant filter Q and pass band flatness due to proposed pre-distortion scheme. Also, the RF filter using CMOS switches in FTI blocks shows low clock leakage to signal nodes, and results in low common mode noise and stable operation. The baseband IQ signals are generated by combining baseband Gm cells which receives 8-phase signal outputs down-converted at last stage of FTIs in the RF BPF. The measured results of the RFE show 36.4 dB gain and 6.3 dB NF at maximum gain mode. The pass-band IIP3 and out-band IIP3@20 MHz offset are -10 dBm and +12.6 dBm at maximum gain mode, and +14 dBm and +20.5 dBm at minimum gain mode, respectively. With a 1.2 V power supply, the current consumption of the overall RFE is 40 mA at 500 MHz carrier frequency.

Design of Active Power Factor Corrector for Low Power Supply by Loss Free Resistor Concept (무손실 저항개념을 이용한 저전력 전원설비용 능동 역률보정기의 설계)

  • 임영철;정영국;최찬학;나석환;이건식;장영학
    • The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.7 no.1
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    • pp.30-36
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    • 1993
  • A simple discontinuous conduction mode(DCM) flyback type active power factor corrector for low power supply resents an effective resistive load to its power input. It is therefore well suited as an inexpensive high power factor rectifier for office equipment. An equivalent circuit model for the Active Power Factor Corrector based on the "Loss Free Resistor" concept is presented. This simple model correctly describes the basic power processing properties of the Active Power Factor Corrector, including input port resistor emulation, output port power some characteristics.teristics.

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