ADSL变压器设计及传输特性测试分析

【作者】 蒋晓娜；

【导师】 兰中文；

【作者基本信息】 电子科技大学 ， 材料物理与化学， 2005， 硕士

【摘要】 随着网络的大面积拓扑,多样化的网络接入技术在日新月异地发生着变化。xDSL 技术被看作近年来最具发展前途和可行性的主流技术之一,xDSL 是以现有的入户铜绞线为介质基础,通过不同的调制方式提供不同的带宽,从而实现不同速度的网络用户接入技术。在xDSL 技术中ADSL 最适合目前我国的网络接入,因其成本低,且能够提供合适的带宽及网速。网络的发展为网络变压器发展提供了强有力的推动力,顺应器件发展趋势,网络变压器正在朝着小型化、高保真、高效率的方向发展。本文工作旨在设计出损耗和谐波失真小的小型ADSL 变压器,并对该变压器传输特性参数进行测试分析。通过对变压器传输特性进行分析,找出相应的影响因素,试图从变压器磁芯、匝数、线径、绕制方式等方面进行优化设计,从而提高变压器的传输特性。通过对变压器磁芯特性的分析研究可知:具有高μi、低ηB的磁芯材料是变压器进行高速率、高保真信号传输的前提;选择磁芯失真因子和形状失真因子小的磁芯是降低变压器谐波失真的重要方法;选择优化后的EPX(EPO)型磁芯制作的变压器比同等封装尺寸下EP 型变压器的谐波失真要低几个dB,或在变压器谐波失真未有太大改变的情况下缩小了变压器的封装尺寸;另外,通过开气隙可以使磁芯中B 和H 关系更趋于线性化,降低变压器的总谐波失真,延长信号传输距离,提高变压器的工作稳定性。在不同工作频段内,影响变压器传输特性的参数是不同的。通过优化绕组线径来降低绕组电阻是减小变压器中频损耗特性的重要方法;漏感和分布电容是影响变压器高频特性的关键参数,但漏感和分布电容是一个矛盾的统一体,需要对二者进行折衷处理。通过改变绕制方式(采用三明治结构)可以获得合适的漏感和分布电容。实验中选用优良的绝缘材料,可使变压器的电气绝缘性能得到提高。采用优化方法设计出了符合要求的ADSL 变压器。中频带插入损耗低于0.5dB,高频段插入损耗低于1.5dB,总谐波失真小于-82dB。更多还原

【Abstract】 With the development of networks, all kinds of access technologies of internet are changing quickly. xDSL have been considered the one of the technologies which have the good fortune and feasibility in recent years. xDSL systems are built upon the existing twisted-pair telephone subscriber loop plant and can provide different bandwidth by different modulation technologies, so different transmission rates are fulfilled. ADSL is one of the xDSL and is fit for the situation of our country, because the cost of ADSL is low, and furthermore, ADSL can provide moderate bandwidth and transmission rate. The development of networks has been the motive force of developing the network transformer. The tendency of the network transformer development is miniaturization, high fidelity, high efficiency. In this thesis, the aim is to design the ADSL transformer with low loss and harmonic distortion, and analyze the characteristic of transmission. By the analysis, we can find out the factors which influence the transmission characteristic and try to optimize design the transformer from the following factors: core, coil turns, diameter of the wire, the way of winding, etc. So the characteristic can be improved. From the above analysis, we can learn about that on the one hand the magnetic core with high μi and lowηB is the premise of the transformer which transmit the signals with high bit rate and high-fidelity, on the other hand selecting the low core distortion factor and shape distortion factor is an important way to reduce the distortion of the transformer. The optimized transformer of EPX (EPO) has less several dB in THD than the transformer of EP when they have the same package size. In addition, introducing air gap in the magnetism cores can make the B and H relationship tend towards the linearization, reduce the total harmonic distortion, extend the distance of information transmission, and enhance the stability of the transformer. In different working frequency bands, the factors which influence the insertion loss of the transformer are different. Reducing the resistance of the windings by optimizing the diameter of the winding wire is an important way to reduce the insertion loss in the mid-frequency band. The leakage inductance and the distributed更多还原