• Title, Summary, Keyword: High efficiency

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Wireless Energy Transmission High-Efficiency DC-AC Converter Using High-Gain High-Efficiency Two-Stage Class-E Power Amplifier

  • Choi, Jae-Won;Seo, Chul-Hun
    • Journal of electromagnetic engineering and science
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    • v.11 no.3
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    • pp.161-165
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    • 2011
  • In this paper, a high-efficiency DC-AC converter is used for wireless energy transmission. The DC-AC convertter is implemented by combining the oscillator and power amplifier. Given that the conversion efficiency of a DC-AC converter is strongly affected by the efficiency of the power amplifier, a high-efficiency power amplifier is implemented using a class-E amplifier structure. Also, because of the low output power of the oscillator connected to the input stage of the power amplifier, a high-gain two-stage power amplifier using a drive amplifier is used to realize a high-output power DC-AC converter. The high-efficiency DC-AC converter is realized by connecting the oscillator to the input stage of the high-gain high-efficiency two-stage class-E power amplifier. The output power and the conversion efficiency of the DC-AC converter are 40.83 dBm and 87.32 %, respectively, at an operation frequency of 13.56 MHz.

Development of High Efficiency Boiler with High Safety (안전성이 높은 고효율 보일러 개발에 관한 연구)

  • Jung, Won
    • Journal of Applied Reliability
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    • v.11 no.1
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    • pp.83-95
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    • 2011
  • Boiler efficiency has a direct impact on energy consumptions, which results in lower cost of operations and services. Usually high efficiency boilers are regarded as boilers with an efficiency of greater than 90%. However, it is likely that normal boilers are running at significantly lower efficiencies than this. This paper presents a process of developing a highly efficient energy consumption boiler. We adopt direct heat method while normal boilers are designed as indirect heat method. The submerged combustion method is considered to design for very high efficient boiler.

PRESENT AND FUTURE OF SUPER HIGH-EFFICIENCY TANDEM SOLAR CELLS

  • Yamaguchi, Masafumi
    • Electrical & Electronic Materials
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    • v.11 no.11
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    • pp.37-45
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    • 1998
  • In this paper, present status of super high-efficiency tandem solar cells has been reviewed and key issues for realizing super high-efficiency have also been discussed. In addition, the terretrial R&D activities of tandem cells, in the New Sunshine Program of MITI(Ministry of International Trade and Industry) and NEDO(New Energy and Industrial Technology Development Organization) in Japan are reviewed briefly. The mechanical stacked 3-junction cells of monolithically grown InGaP/GaAs 2-junction cells and InGaAs cells have reached the highest efficiency achieved in Japan of 33.3% at 1-sun AM1.5. This paper also reports high-efficiency InGaP/GaAs 2-junction solar cells with a world-record efficiency of 26.9% at AM0, 28$^{\circ}C$ and radiation damage recovery phenomena of the tandem cell performance due to minority-carrier injection under light illumination or forward bias, which causes defect annealing in InGaP top cells. Future prospects for realizing super-high efficiency and low-cost tandem solar cells are also described.

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The Analysis of Contract-Foodservice Operational Efficiency using Data Envelopment Analysis and Efficiency-Profit Matrix (다점포 운영 푸드서비스 기업의 효율성 측정에 관한 연구 - DEA 및 효율, 수익 매트릭스 분석을 중심으로 -)

  • Kim, Tae-Hee;Park, Ju-Yeon
    • Journal of the East Asian Society of Dietary Life
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    • v.20 no.5
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    • pp.823-835
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    • 2010
  • The research aimed to measure the efficiency of using multi stores in a foodservice company using by DEA (data envelopment analysis) which is a new management science technique. The study also attempted to identify relevant variables affecting DEA efficiency in order to suggest methods for improving efficiency. The data were collected from 148 contract foodservice operations, which were operated in similar fashion in October 2009. The DEA efficiency was calculated as an output-oriented BCC Model. Sales, and CSI (customer satisfaction index) were used as output variables whereas food cost, labor cost, and management expense were used as input variables to calculate the DEA efficiency. Operation process variables of the unit consisted of the were consist of ratio of regular employee, ratio of housekeeper, meal counts, meal price, food cost per meal, contract period, number of menu items, forecasting accuracy, order accuracy, inventory turnover, use of processed food, deviation of food cost, number of new menus, and number of events. According to the BCC score and profitability, units were classified into four groups: High efficiency-high profitability (HEHP), High efficiency-low profitability (HELP), Low efficiency-high profitability (LEHP), and Low efficiency-low profitability (LELP). The HEHP group contained 54 units, which mostly contracted management fee type and had a high meal price. The units were also very large and, served three meals. Twenty of the units were operated with high labor cost: most of these were factories and hospitals. The LEHP group contained 20 units, that were mainly office stores of large scale and medium price. Fifty-four LELP group had a low meal price. A high performance group must have high efficiency, profitability, and satisfaction. The BCC score was over 0.969, the meal price was over 4,116 won, the food cost was over 2,077 won, and meal counts per month were over 10,212 meals.

High Efficiency Drive Technique for Synchronous Reluctance Motors Using a Neural Network

  • Urasaki Naomitsu;Senjyu Tomonobu
    • Journal of Power Electronics
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    • v.6 no.4
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    • pp.340-346
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    • 2006
  • A high efficiency drive technique for synchronous reluctance motors (SynRM) using a neural network (NN) is presented in this paper. High efficiency drive condition depends on the mathematical model of SynRM. A NN is employed as an adaptive model of SynRM. The proposed high efficiency drive technique does not require an accurate mathematical model of SynRM. Moreover, the proposed method shows robustness against machine parameter variations because the training algorithm of the NN is executed on-line. The usefulness of the proposed method is confirmed through experimentation.

Optimization for High Efficiency of Point Contact Solar Cell (후면전극형 태양전지의 고효율화를 위한 최적화 연구)

  • Ahn, Byoung-Sub;Kang, Ey-Goo
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.24 no.5
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    • pp.345-350
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    • 2011
  • This paper was carried about optimization for high efficiency of point contact solar cell. We have studied on the characteristics of power converter according to each parameter for the optimization for high efficiency of point contact solar cell on this study. We have 25.1352% of convert efficiency after adapt optimal parameters as mentioned in point body and superior conclusion is drawn by comparison with general efficiency has within 20%. At this time, the value of parameter is 100 um cell pitch, 0.01 um AR coating, 0.9 um N+ FSF thickness., etc. This study will continue to go on for optimization for efficiency in future, as it looks now, the results of this study would contribute to the business of high efficiency of point contact solar cell.

A 2.4 GHz-Band 100 W GaN-HEMT High-Efficiency Power Amplifier for Microwave Heating

  • Nakatani, Keigo;Ishizaki, Toshio
    • Journal of electromagnetic engineering and science
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    • v.15 no.2
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    • pp.82-88
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    • 2015
  • The magnetron, a vacuum tube, is currently the usual high-power microwave power source used for microwave heating. However, the oscillating frequency and output power are unstable and noisy due to the low quality of the high-voltage power supply and low Q of the oscillation circuit. A heating system with enhanced reliability and the capability for control of chemical reactions is desired, because microwave absorption efficiency differs greatly depending on the object being heated. Recent studies on microwave high-efficiency power amplifiers have used harmonic processing techniques, such as class-F and inverse class-F. The present study describes a high-efficiency 100 W GaN-HEMT amplifier that uses a harmonic processing technique that shapes the current and voltage waveforms to improve efficiency. The fabricated GaN power amplifier obtained an output power of 50.4 dBm, a drain efficiency of 72.9%, and a power added efficiency (PAE) of 64.0% at 2.45 GHz for continuous wave operation. A prototype microwave heating system was also developed using this GaN power amplifier. Microwaves totaling 400 W are fed from patch antennas mounted on the top and bottom of the microwave chamber. Preliminary heating experiments with this system have just been initiated.

Efficiency Characteristics of DC-DC Boost Converter Using GaN, Cool MOS, and SiC MOSFET (GaN, Cool MOS, SiC MOSFET을 이용한 DC-DC 승압 컨버터의 효율 특성)

  • Kim, Jeong Gyu;Yang, Oh
    • Journal of the Semiconductor & Display Technology
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    • v.16 no.2
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    • pp.49-54
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    • 2017
  • In this paper, recent researches on new and renewable energy have been conducted due to problems such as energy exhaustion and environmental pollution, and new researches on high efficiency and high speed switching are needed. Therefore, we compared the efficiency by using high speed switching devices instead of IGBT which can't be used in high speed switching. The experiment was performed theoretically by applying the same parameters of the high speed switching devices which are the Cool MOS of Infineon Co., SiC C3M of Cree, and GaN FET device of Transform, by implementing the DC-DC boost converter and measuring the actual efficiency for output power and frequency. As a result, the GaN FET showed good efficiency at all switching frequency and output power.

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Design Principles and Validation of a Human-sized Quadruped Robot Leg for High Energy Efficiency (에너지 효율적인 인간 크기 4족 보행 로봇의 설계와 검증)

  • Yeom, Hoyeon;Ba, Dang Xuan;Bae, Joonbum
    • The Journal of Korea Robotics Society
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    • v.13 no.2
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    • pp.86-91
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    • 2018
  • This paper presents about design efforts of a human-sized quadruped robot leg for high energy efficiency, and verifications. One of the representative index of the energy efficiency is the Cost of Transport (COT), but increased in the energy or work done is not calculated in COT. In this reason, the input to the output energy efficiency should be also considered as a very important term. By designing the robot with customized motor housing, small rotational inertia, and low gear ratio to reduce friction, high energy efficiency was achieved. Squatting motion of one leg was performed and simulation results were compared to the experimental results for validation. The developed 50 kg robot can lift the weight up to 200 kg, and during squatting, it showed high energy efficiency. The robot showed 71% input to output energy efficiency in positive work. Peak current during squatting only appears to be 0.3 A.