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开关电源变压器温升测试的探讨 总被引:1,自引:0,他引:1
一、绪论
通常在安全标准中,对电子产品在正常工作条件下和故障条件下的温升采用热电偶或电阻法进行测量.由于目前市场上的在线电阻测试仪器适用于在工频条件下的测试,因此对于工作在高频率下的开关电源脉冲变压器(简称开关变压器)绕组温升的测量还存在一定的问题.本文仅对如何确保开关变压器绕组温升测量的准确性进行探讨. 相似文献
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开关电源国外已广泛用于彩色电视机中,但国内还比较少;尤其线路简单无需启动线路的自激振荡形式的开关电源,这是我们所求的。我们试制的开关电源,就是这样一种形式。本文简述了一般的工作原理,给出了试验线路及测试结果,对开关变压器的最小电感量及初级电流进行了计算,从而确定了变压器的线径及匝数。最后讨论进一步提高开关变压器效率的办法。 相似文献
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彩色电视机大部分采用了开关电源电路,因为开关电源具有效率高、功耗低等特点,而开关电源变压器是开关电源的主要元件。1.开关电源变压器的测试方法(1)外观检查。开关电源变压器工作频率较高,为15625Hz,一般使用磁性材料来导磁,常见故障是绕组之间漏电或短路,使电视机无光栅、伴音。检查时首先应从外表来观察,是否有打火烧焦的痕迹,外表是否太脏,各引脚间是否有污物(有些开关电源变压器各引脚间距很小,如三洋83P机芯开关电源变压器),由于开关电源变压器是紧贴印刷电路板安装的,容易积灰,碰到气候或环境潮湿时易放电打火。 相似文献
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By means of exact conformal mapping method we have defined character of dependence of squares amounts of angular part of film
element on angled part dimension. We propose relations, approximating obtained dependence. Calculation results and experimental
researches of large-scale models are represented. 相似文献
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Moshrefzadeh R.S. Radcliffe M.D. Lee T.C. Mohapatra S.K. 《Lightwave Technology, Journal of》1992,10(4):420-425
The temperature dependence of refractive index of polymer films was determined for a number of slab waveguides by a grating coupling method. This dependence was examined as a function of parameters such as molecular weight and glass transition temperature of the polymer. Temperature-induced changes in N TE-N TM , N being the effective index, were studied systematically for different slab waveguide compositions. It is shown that with proper device design and choice of polymeric materials, thermal effects can be reduced 相似文献
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The article describes a model representation of radar probing data in form of a mixture of background and target samples, which is the sum of two random variables with very different parameters. For model development we research the behavior of the central moments of the distribution mix without assuming the distribution law form. An example it is described the detection of the signal at the output of compression system of chirp ionosonde. 相似文献
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解决IP网QoS问题是目前通信领域的研究热点之一.虽然研究已经取得了一定的进展,但人们对于IP 网QoS本身的含义及相关的问题还有着不同的理解.本文将从IP网QoS的定义入手讨论相关的一些问题以及解决IP网QoS问题所做的各种努力. 相似文献
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《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1968,56(6):1024-1032
Assuming that visual responses are due to the action of particles on the membrane of the visual cells, the stochastic variability of the response should be a function of the number of particles producing it. Quantitative predictions can be made with the aid of a model proposed in previous articles. It is found that responses produced in visual cells of Limulus by absorption of a single photon have the stochastic properties which would be expected if the response to one photon were brought about by 25 particles. It is concluded from this that the processes leading to visual responses produce multiplication of particles. The effects of temperature and of metabolic poisons suggest that these processes are of chemical nature. 相似文献
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近红外光谱技术在水果品质无损检测中应用的研究与现状 总被引:6,自引:0,他引:6
简单概述了我国水果产业的发展现状,着重阐述了国内外利用近红外光谱技术进行水果品质无损检测的最新研究进展,分析了当今研究中存在的问题,并对利用近红外光谱技术进行水果检测的前景进行了展望,提出了一些建议。 相似文献
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上市公司为了增强市场竞争力,不断扩大生产规模,追求规模经济,但是由于我国较低生产力水平、政府干预、体制等原因,上市公司的规模经济效果并不明显。同时,20世纪90年代以来,科学技术的日益发展,改变了企业发展的外部环境和条件,使得规模经济的实现方式发生了新的变化。在信息化时代下,规模经济理论需要进一步创新和拓展,企业按照新形势来选择合适的经济规模。 相似文献