行波管高压电源中变压器的优化设计

研究了行波管高压电源中变压器的铁芯损耗、绕组损耗(铜损)和工作频率,主要通过理论推导和仿真对磁性元件的设计进行了优化分析,并用PC95材质PQ40/40磁芯设计了一种输出电压10kV、输出功率450 W的行波管高压电源变压器。变压器设计结果满足电源要求,实验结果验证了理论分析。     

一种测量反激变压器磁损的检测方法

阐述反激变换器中的变压器磁芯损耗一直是损耗分析和测量的难点。仿真软件没有考虑到Steinmetz参数会随频率增加而变化，而理论计算难以求解磁芯内部的磁感应强度分布。提出一种基于直流法磁损测试方法的改进型测试电路结构，使其能够对反激变换器在连续模式（CCM）和断续模式(DCM)下的变压器磁损进行测量。所提出的测试电路及方法具有简单、准确度高等优点。在损耗测量中，基于等效原则，得到测试电路固有损耗，从电路工作状态和器件温度两方面验证了测试电路工作状态的一致性，从而得到准确的待测磁元件的磁性损耗。测量反激变压器磁芯在CCM和DCM工作状态的损耗，与仿真结果和iWcSE模型进行了对比与分析，分析仿真和iWcSE模型与磁芯损耗实测值的误差。     

基于有限元法的高频开关电源变压器绕组损耗分析

应用有限元法对高频开关电源变压器绕组损耗进行分析,分别对单股粗导线构成的绕组和由多股细导线并绕构成的绕组进行仿真,得到其绝缘损耗、磁滞损耗、欧姆损耗以及能量分布等参数。仿真结果表明,虽然单股粗导线构成的绕组绝缘损耗较小,但是其磁滞损耗和欧姆损耗比由多股细导线并绕构成的绕组要大得多,导致整体绕组损耗要大于由多股细导线并绕构成的绕组。所以用多股细导线并绕来代替单股的粗导线,可以有效地减小高频变压器绕组损耗。     

埋磁芯多层印制电路板制作工艺探讨

文章主要针对埋磁芯多层PCB的制作工艺进行研究,通过嵌入磁芯层压定位技术、磁芯材料同心圆套钻技术、盲埋孔真空树脂塞孔、不对称铜厚分步蚀刻技术,实现了埋入磁芯多层印制板的研发生产;同时满足了客户在阻值、电感、磁芯损耗等方面的特种需求。     

高功率密度电源模块磁芯粘接的工艺可靠性

新型高功率密度电源模块采用芯片塑封的工艺方式,实现磁芯、元器件、印制板(PCB)和塑封料的一体式封装.磁芯设计采用绕组内置在印制板内部,并采用扁平磁芯装配的方式实现磁芯的电气功能.由于磁芯材料、粘接材料和印制板之间的材料性能不匹配,环境试验中产生的粘接内应力过大会直接造成磁芯材料产生裂纹甚至断裂失效,严重影响了电源产品...     

同步电机励磁电源高频变压器的设计

针对晶闸管相控整流式同步电机励磁装置的问题,提出了一种新型的同步电机励磁电源。对新型励磁电源所用高频变压器的设计进行了详细阐述,着重从高频变压器的磁芯材料选择、绕组计算与布局、温升校验分析等方面进行讨论。与传统的晶闸管励磁电源相比,新型同步电机励磁电源的性能得到很大提高,使用简便可靠,是一种较好的同步电机励磁选择方案。     

平面高压脉冲变压器的设计

介绍了一种小型新颖的叠片式高压脉冲变压器。采用PCB工艺制作变压器绕组，使绕组和磁芯结合紧密。这种变压器具有体积小、重量轻、低漏感以及交流电阻小的特性，为小型化平面化高压变压器设计提供了技术和经验。     

高频变压器铜损的三维模拟仿真与分析

对高频变压器建立三维电磁分析模型,采用有限元法对变压器铜损进行数值求解.模拟分析次级绕组段间距、初级绕组以及磁芯漏磁对次级绕组损耗的影响,并引入了矩形导线和圆导线之间的等效因子.分析表明,在考虑次级绕组段间距、初级绕组以及磁芯漏磁后,高频变压器次级铜损为246.086W,大于Dowell模型的理论计算值107.500W,这为变压器的优化设计提供了参考.     

浅谈开关电源中的平面变压器

与传统变压器相比较,使用平面变压器可以提高开关电源的功率密度,减小开关电源中磁性元件的体积。因此,近年来平面变压器被广泛地研究。文章介绍了平面变压器的结构,将平面变压器与传统变压器进行比较,分析综述了平面变压器在当今开关电源发展应用的优势和前景,并进一步说明了平面变压器中绕组间距选择,绕组交叉技术及PCB绕组设计等要点。     

浅谈绕组结构对介质损耗测量的影响

绝缘元件在电力设备中得到广泛的使用。绝缘水平的好坏直接影响着电力设备是否可以正常运行。但是,绕组的结构对绝缘元件的绝缘水平将会产生一定的影响。因此,本文针对绕组结构对介质损耗测量的影响进行了一定的讨论与分析。本文首先介绍了绕组的基本结构,然后,给出了变压器绕组介损的现场测量情况。最后,以实例针对介质损耗的测量影响情况进行了分析与阐述,并根据试验结果进行了绕组结构对介质损耗测量的影响情况的讨论。     

The Effect of Windings on ADSL Transformer Insertion Losses

Insertion loss （IL） is one of the important parameters of asymmetrical digital subscriber loop （ADSL） transformers. In different frequency bands, the factors that affect insertion loss are different. Windings mainly affect insertion loss in mid and high frequency bands. The effects of winding ways, winding wire diameter and winding turns on insertion loss were discussed. The presented experiment shows that the insertion loss of an ADSL transformer could be under 0.4 dB in mid frequency band when the winding is 30 turns, in which the ADSL transformer satisfies the requirement of total harmonic distortion （THD）. Our experiments also show that the sandwich winding structure is better than the side by side winding structure and the twisted-pair winding structure, and the increase of winding diameter is one means to reduce insertion losses of an ADSL transformer in mid frequency band.     

高频反激变压器绕组模型优化设计

反激变换器中高频变压器是核心部件,其效率直接关系到变换器的效率,因此优化设计高频变压器就成为提高效率的关键。通过对反激变压器绕组采用不同结构时所带来不同的涡流损耗和漏感进行分析,得到本文所设计绕组结构二维模型。利用有限元分析软件进行数值仿真,获得的数据证明此模型是可行的。制作出实验样机对其进行实验比较,验证了所设计的高频变压器绕组结构合理,漏感小,效率高,输出的电压的谐波含量低。     

Design issues for the transformer in a low-voltage power supplywith high efficiency and high power density

Circuit model, design feasibility, and design tradeoffs are investigated for the transformer in 1.5-5 V power supplies with high efficiency and high power density. The transformer is constructed from a single or a matrix of pot cores and from interleaved planar windings. It has been determined theoretically and verified experimentally that such a transformer is realizable as long as the loss constraint is not severe (e.g. less than 0.5 W transformer loss per 100 W output). The primary source of loss is the winding, not the core, in 1.5 V/turn design. Measures to reduce the transformer height tend to increase transformer loss or volume     

Finite-element analysis of copper loss in 1-10 MHz transformers

Issues related to the copper loss in the planar windings of 1-1 MHz power transformers are discussed. The relationship between current distribution, copper loss, and core geometry is investigated with the aid of finite-element analysis. Magnetizing current proximity effects are shown to cause excessive copper loss in a simple sandwich transformer, a structure formed by sandwiching the planar winding between two plates of magnetic material. Three alternative transformer structures that reduce this problem are compared. These alternative structures are: the cofired transformer, the slotted gapped transformer, and the slotted ungapped transformer. It is concluded that a slotted transformer design should be used if the magnetizing current is relatively large. Both a slotted gapped and a slotted ungapped design relies strongly on the exact permeability of the material and may suffer from higher core losses because all of the energy is stored in the magnetic material, rather than in an air gap. In either case, the depth of the slot should be About 40% of its width     

Modeling of losses in a sandwiched-winding matrix transformer

This paper assesses the suitability of the sandwiched-winding matrix HF power transformer for low-profile applications from the loss standpoint. Finite-element simulations and experiments suggest that the core loss can be adequately characterized by approximating the matrix transformer as a collection of identical uncoupled elements. Thus, a matrix transformer with a large number of elements may have higher core loss than a conventional (tall) transformer, and more core loss than winding loss. Eddy-current analysis reveals that the interconnects which parallel the elements incur a significant fraction of the winding loss. Thus, load distribution is recommended to eliminate the paralleling interconnects in matrix transformers     

A low-profile power converter using printed-circuit board (PCB)power transformer with ferrite polymer composite

A new design of low-cost and low-profile power transformer is presented in this paper. The manufacturing cost of a power transformer can be reduced using the proposed printed-circuit board (PCB) transformer. The transformer windings are etched on the opposite sides of a double-sided PCB. Self-adhesive ferrite polymer composite (FPC) sheets are stuck on the two PCB surfaces to shield the magnetic flux induced from the transformer windings. The PCB transformer does not require manual winding and bobbin. A power converter prototype employing the PCB transformer has been implemented. The technique of choosing the optimum switching frequency of the power converter using the PCB transformer is addressed in this paper. The maximum power delivered from the prototype is 94 W. The maximum efficiency of the power converter is 83.5%     

光纤光栅测温系统在变压器绕组温度在线监测中的应用

介绍了变压器绕组热点温度在线监测的重要性,对目前测量变压器绕组热点温度的几种测量方法进行了分析和比较,在此基础上提出将光纤光栅温度传感器粘贴在绕组表面进行测温的方法,并得出了具体的实验数据.