• Title, Summary, Keyword: Power efficiency

Search Result 9,791, Processing Time 0.059 seconds

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
    • /
    • v.11 no.3
    • /
    • pp.161-165
    • /
    • 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.

Resource Use Efficiency of Electricity Sector in the Maldives

  • SHUMAIS, Mohamed
    • The Journal of Asian Finance, Economics, and Business
    • /
    • v.7 no.1
    • /
    • pp.111-121
    • /
    • 2020
  • The study measures the resource use efficiency of diesel based power generation in the Maldives and analyses factors which influence efficiency levels. Stochastic frontier analysis (SFA) technique is applied to data on 30 plants over two year period from 2016 to 2017. The study finds that technical efficiency scores varies from 0.44 to 0.98 across power plants. About 33 percent of the plants have scores below the mean technical efficiency score of 0.87. Empirical results indicate ownership and use of solar photovoltaic (PV) have an influence on improving efficiency levels. Privately owned power plants in resort islands obtained higher technical efficiency scores compared to public and community owned power plants. This is a significant finding as the first study that used power plants in tourist sector in a comparative study. Size of the power plants was not found significant, but relatively small installed capacities can also be efficient. This finding is important because in many inhabited islands installed capacities remain oversized compared to the load. The benchmarking exercise offers model power plants that are relatively efficient, for other power plants and policy makers in small islands to learn from.

Analysis of TV Standby Power for Development of Energy Efficiency Standard (TV 대기모드 효율기준 개발을 위한 대기전력 실태 분석)

  • Kim, Ik-Pyo;Ro, Kyoung-Soo
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
    • /
    • v.26 no.8
    • /
    • pp.18-26
    • /
    • 2012
  • Recently, there have been suggestions that power factor should be considered to increase the efficiency of electric power supply when evaluating the performance of the electric appliances in standby mode and the related studies have been conducted to improve the efficiency standard of standby power. But, they lack the analysis of the standby power characteristics with the changes of power factor. This study is conducted to analyze the standby power characteristics of TV which is a typical home appliance and reaches a conclusion that the apparent power can be a more reasonable index which reflects the efficiency of electric power supply. It is also found that LED TVs show the best performance in standby mode. Moreover, an example to set standby power standards on TVs to be applied in the future is suggested, considering the energy efficiency policies for appliances.

Exergy analysis of R717 high-efficiency OTEC power cycle for the efficiency and pressure drop in main components

  • Yoon, Jung-In;Son, Chang-Hyo;Yang, Dong-Il;Kim, Hyeon-Uk;Kim, Hyeon-Ju;Lee, Ho-Saeng
    • Journal of the Korea Society For Power System Engineering
    • /
    • v.17 no.5
    • /
    • pp.52-57
    • /
    • 2013
  • In this paper, an analysis on exergy efficiency of high-efficiency R717 OTEC power system for the efficiency and pressure drop in main components were investigated theoretically in order to optimize the design for the operating parameters of this system. The operating parameters considered in this study include turbine and pump efficiency, and pressure drop in a condenser and evaporator, respectively. As the turbine efficiency of R717 OTEC power system increases, the exergy efficiency of this system increases. But pressure drop in the evaporator of R717 OTEC power system increases, the exergy efficiency of this system decreases, respectively. And, in case of exergy efficiency of this OTEC system, the turbine efficiency and pressure drop in a condenser on R717 OTEC power system is the largest and the lowest among operation parameters, respectively.

High-Efficiency DC-DC Converter with Improved Dynamic Response Characteristics for Modular Photovoltaic Power Conversion (모듈형 태양광 발전을 위한 개선된 동적응답 특성을 지닌 고효율 DC-DC 컨버터)

  • Choi, Jae-Yeon;Choi, Woo-Young
    • The Transactions of the Korean Institute of Power Electronics
    • /
    • v.18 no.1
    • /
    • pp.54-62
    • /
    • 2013
  • This paper proposes a high-efficiency DC-DC converter with improved dynamic response characteristics for modular photovoltaic power conversion. High power efficiency is achieved by reducing switching power losses of the DC-DC converter. The voltage stress of power switches is reduced at primary side. Zero-current switching of output diodes is achieved at secondary side. A modified proportional and integral controller is suggested to improve the dynamic responses of the DC-DC converter. The performance of the proposed converter is verified based on a 200 [W] modular power conversion system including the grid-tied DC-AC inverter. The proposed DC-DC converter achieves the efficiency of 97.9 % at 60 [V] input voltage for a 200 [W] output power. The overall system including DC-DC converter and DC-AC inverter achieves the efficiency of 93.0 % when 200 [W] power is supplied into the grid.

studdyon the Field Efficiency of the Plowing Operation of the Power Tillers in accordance withthe Various Field Dimensions. (보장구획의 장단변화에 따른 경운기의 기종별 이경작업 효력에 관한 연구)

  • 최규홍;김종관
    • Journal of Biosystems Engineering
    • /
    • v.2 no.1
    • /
    • pp.49-54
    • /
    • 1977
  • In order to obtain the field efficiency of the power tiller plowing on the various size of and its length-width field tests were performed with 8ps.10ps. power tiller popularly used in the korean rural area, and Satoh 5ps. made in Japan, Land Master 5ps. made in England were tested to compare with the field efficiency of the above power tillers. The results obtained in this tests were as follows ; 1. In considering of the resting time and the refueling time and others, the field efficiency of Satoh was the highest among the power tillers as to be 80%, at the 8ps. power tiller 76.5%, at the 10ps. power tiller 79.3% and the lowest field efficiency was obtained at the Land Master as 75.7%. 2. The field efficiency of the each power tiller increased as the ratio of the length to width of the field was increased. 3. The increasing rate of field efficiency was much bigger in the below the ratio of 5 : 1 but at the upper ratio increased above, the ratio was nearly constant. 4. The field efficiency of the power tiller was higher at the smaller power tiller than the larger, except the Land Master , because of easily operating and turning of the power tiller by virtue of its lighter weight.

  • PDF

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
    • /
    • v.15 no.2
    • /
    • pp.82-88
    • /
    • 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.

Characteristics of Power Efficiency of Tractor Driveline (트랙터 전동라인의 전동효율 특성 분석)

  • 류일훈;김대철;김경욱
    • Journal of Biosystems Engineering
    • /
    • v.27 no.1
    • /
    • pp.19-24
    • /
    • 2002
  • According to the field test, the transient power transmission efficiency of a tractor driveline fluctuated in a range of 56 to 86% and the mean value was about 72.5%. Therefore, the constant efficiency model commonly used for a simulation of power performance was not proper far predicting such a variable of efficiency. In order to predict power efficiency more accurately, new concepts of the maximum efficiency and drag torque were introduced and a new model based on the these concepts was proposed. The difference between measured and model-predicted efficiencies was about 1.5% in average with a standard deviation of 1.1%. The new power efficiency model was expected to enhance the accuracy of predicting power transmission efficiencies of tractor drivelines.

High-Efficiency Power Conditioning System for Grid-Connected Photovoltaic Modules

  • Choi, Woo-Young;Choi, Jae-Yeon
    • Journal of Power Electronics
    • /
    • v.11 no.4
    • /
    • pp.561-567
    • /
    • 2011
  • This paper presents a high-efficiency power conditioning system (PCS) for grid-connected photovoltaic (PV) modules. The proposed PCS consists of a step-up DC-DC converter and a single-phase DC-AC inverter for the grid-connected PV modules. A soft-switching step-up DC-DC converter is proposed to generate a high DC-link voltage from the low PV module voltage with a high-efficiency. A DC-link voltage controller is presented for constant DC-link voltage regulation. A half-bridge inverter is used for the single-phase DC-AC inverter for grid connection. A grid current controller is suggested to supply PV electrical power to the power grid with a unity power factor. Experimental results are obtained from a 180 W grid-connected PV module system using the proposed PCS. The proposed PCS achieves a high power efficiency of 93.0 % with an unity power factor for a 60 Hz / 120 Vrms AC power grid.

QoE-aware Energy Efficiency Maximization Based Joint User Access Selection and Power Allocation for Heterogeneous Network

  • Ji, Shiyu;Tang, Liangrui;Xu, Chen;Du, Shimo;Zhu, Jiajia;Hu, Hailin
    • KSII Transactions on Internet and Information Systems (TIIS)
    • /
    • v.11 no.10
    • /
    • pp.4680-4697
    • /
    • 2017
  • In future, since the user experience plays a more and more important role in the development of today's communication systems, quality of experience (QoE) becomes a widely used metric, which reflects the subjective experience of end users for wireless service. In addition, the energy efficiency is an increasingly important problem with the explosive growth in the amount of wireless terminals and nodes. Hence, a QoE-aware energy efficiency maximization based joint user access selection and power allocation approach is proposed to solve the problem. We transform the joint allocation process to an optimization of energy efficiency by establishing an energy efficiency model, and then the optimization problem is solved by chaotic clone immune algorithm (CCIA). Numerical simulation results indicate that the proposed algorithm can efficiently and reliably improve the QoE and ensure high energy efficiency of networks.