一种具有自动定时调光功能的路灯用高压钠灯电子镇流器

介绍一种具有自动定时调光功能的路灯用高压钠灯电子镇流器,论述电路的基本工作原理和控制策略,通过单片机控制实现电子镇流器的点火、恒功率、调光和保护控制。然后给出一个额定功率为400W的高压钠灯电子镇流器的实验结果。     

电子镇流器的调光方法

该文对日光灯电子镇流器中传统的频率控制调光方法和新近取得专利的电压控制调光方法,进行了比较和评定。在宽的调光范围内,记录并对比了基于这两种调光方法的2×36 W电子镇流器的功率因数、能量效率、电子损耗、单位功率光通量(lm/W)以及峰值系数。结果发现,通过灯的调光对比在很多方面,电压调光控制法比频率控制法好得多,尤其电压调光法比频控方法,具有更高的能量效率和更多的单位功率光通量,电压控制调光的显著特点是随着灯功率的减小,其电子损耗也减小。     

照明控制技术的发展及应用现状

文章对照明控制方式、照明灯具和网络中的控制技术做出了总结,着重介绍了智能照明控制系统中各种网络协议的发展和应用,以及照明控制技术的无线化、网络化发展趋势,并对照明控制技术的发展进行了展望。     

LED照明调光装置设计与实现

采用单片机控制三路D\A转换输出,对LED红、绿、蓝三基色进行调节,实现对半导体照明色彩和亮度宽范围、高精度的调节,同时通过串并转换扫描方式使一套系统可对多个LED分别控制,实现其在高精度控光和控色的基础上可组成任意的静、动态图案或画面。     

A cost‐effective PWM dimming method for LED lighting applications

This paper presents a novel cost‐effective pulse‐width‐modulation (PWM) dimming method for light‐emitting diode (LED) lighting applications. High efficiency, high power factor, circuit simplicity, and low cost can be achieved by a Flyback power factor correction converter with the studied adaptive PWM dimming method. The operation principles and design considerations of the proposed LED dimming method are analyzed and discussed. A 45 W laboratory prototype has been built and tested to verify the feasibility of the proposed scheme. Copyright © 2013 John Wiley & Sons, Ltd.     

Impact of renewed solar dimming on streamflow generation in monsoon dominated tropical river basins

From 1950s to 1980s, various observational studies around the globe found a significant decrease in surface solar radiation (SSR), which reversed in late 1980s for most of the countries including India. SSR observations at 12 stations located across India revealed that a much stronger dimming has reappeared during the last decade (2006–2015) after a brightening during 1996–2005. In the present study, effects of renewed solar dimming on actual evapotranspiration and runoff were analyzed using a semi-distributed hydrological model, Soil and Water Assessment Tool (SWAT) in 24 river basins (ranging from 1260 to 40000 km²) located in peninsular India. For these river basins, calibration (2003–2009) and validation (2010–2014) were performed using the observed daily discharge data, obtained from water resources information system (WRIS) of India, with a 3 year warm up period (2000–2002). The sequential uncertainty domain parameter fitting algorithm (SUFI-2) of SWAT-CUP (calibration and uncertainty program) was used with modified Nash–Sutcliffe efficiency (MNS) as the objective function to calibrate 13 model parameters, which can potentially affect streamflow. In nearly all the river basins, the p- and r-factor of 95 percentage prediction uncertainty (PPU) were more than 0.7 and less than 1, respectively. At daily timescale, MNS values were more than 0.5 in most of the river basins, reaching up to 0.66 and 0.71 during calibration and validation periods, respectively. Calibrated model was used to analyze the water balance of these river basins and different sets of experiments (with observed SSR trends) were performed to find SSR impacts on it. The model was simulated with and without the observed declines in SSR trends. The average change in SSR (in terms of evaporation equivalent) was −267.93 ± 100.92 mm/day/year (−5.62 ± 2.12%) with maximum reaching up to −417.12 mm/day/year (−8.99%). Due to this SSR change, actual evaporation was reduced resulting in 18.97 ± 9.78 mm/day/year (4.13 ± 2.50%) change in percolation. The percolation changes were higher for river basins having areas covered by forests and cropland/woodland, and having loam and sandy-clay soils. The increase in runoff generated was 6.90 ± 3.42 mm/day/year (2.14 ± 1.58%) with a maximum of 15.25 mm/day/year (7.56%) whereas corresponding increase in streamflow was found to be 9.93 ± 5.27 mm/day/year(4.21 ± 2.38%) with a maximum of 26.71 mm/day/year (11.86 %). The study reveals that the recent observed SSR changes are significant enough to have resulted in increased streamflow in the monsoon dominated tropical river basins of India.     

基于单片机的LED自适应调光系统

随着社会的发展人们对照明的要求越来越高,照明越来越普遍化、多样化、耗能化,能源缺乏问题也随之成为社会关注的焦点,LED作为一种新型光源,具有高效节能、绿色环保、使用寿命长等优点,代表着未来照明技术的发展方向。本设计是一种基于单片机STC12C5A60S2的LED自适应调光系统,通过光敏传感器感知外界光强,单片机系统依据此信号以PWM控制方式联合大功率LED驱动芯片ULN2003实现LED灯亮度调节的设计,从而实现光线强度的自动调节,以达到节能的目的。     

基于BP神经网络的紫外光源自适应固化控制研究

为解决紫外光动态固化技术中的固化不充分或反固化反应等问题,提出一种基于BP算法的LED紫外光源多参数自适应控制方法.利用神经网络优异的非线性逼近能力,并结合优化后的BP算法构建一个3输入2输出的网络预测模型.通过与多元线性回归和多元非线性回归模型的对比显示,BP神经网络算法有更高的拟合度.最后将57组数据导入训练好的模...     

基于U-OFDM的室内可见光通信系统调光控制方法

作为未来短距离无线通信有效可选方案的可见光通信,照明控制是其面临的主要挑战之一.在分析了采用连续电流调节(CCR)和脉冲宽度调制(PWM)两种调光控制技术的OFDM系统工作原理的基础上,提出了一种新的室内可见光高速通信调光控制系统设计方案.该方案将照明应用中的两种调光技术引入到功率效率高、误码性能好的单极性光OFDM(Unipolar OFDM)系统中,在提供良好传输性能的同时实现了照明信号的连续调节和线性调节功能.仿真实验表明,提出的方案调光控制性能与非对称消波光OFDM (ACO-OFDM)系统接近,而误码性能则优于后者,即U-OFDM调光控制系统可在不牺牲照明质量的同时获得更好的误码性能.     

基于反馈控制的高能效LED驱动电路设计

为了提高可调光发光二极管（LED）的灵活性和能量效率,提出了一种基于反馈控制的LED驱动器。该驱动电路采用了自适应电压调节技术,使线性电流调节器的功率损耗降到了最低。并设计了相应的基于电阻数字模拟转换器的数字控制机制,可用于馈送dc–dc转换器的模拟反馈输入。实验结果显示,提出的数字控制方法灵活性和稳定性较高,且能够有效控制调节速度。当输入电压为26 V时,LED驱动器能够提供较宽的5~40 V输出电压范围,获得了较大的灵活性。在输出电流为680 mA时,稳定状态下的精确度超过97.7%,频率为1 kHz且最短的接通持续时间为4 μs,系统的峰值效率达94.1%。