基于J-A磁滞理论的变压器谐波损耗研究

文中提出了一种考虑铁芯铁磁磁滞的变压器电磁暂态模型,仿真研究了谐波存在时变压器的损耗。基于目前工程中应用较为广泛的Jiles-Atherton铁磁磁滞原理建立铁芯磁滞磁化曲线模块,通过设置适合的参数计算得到了与实际测量值较为吻合的B-H曲线;通过分析单相三绕组变压器铁芯绕组结构及其电路模型,得到其电磁暂态计算模型。最后,利用该模型对电力变压器的谐波损耗进行仿真和实验研究,证明了模型的有效性和实用性。     

高Q值平面螺旋电感的多电流路径结构设计

通过将平面螺旋电感器中的单股宽导线分成并联的多条细导线而在电感中形成多电流路径结构,可以降低电感的高频损耗并提高其品质因数(Q值)。利用HFSS电磁仿真软件对具有多电流路径结构的螺旋电感进行了设计与优化。结果表明,在尺寸不变的情况下,采用了多电流路径结构的平面螺旋电感的Q值提高了80%以上,这为高Q值小型平面螺旋电感的研制提供了思路。     

分布电容对高频高压变压器性能的影响及其控制措施

高频高压变压器的微小分布电容对变压器的性能和带有变压器的高频高压电源的性能有着重要影响,分布电容会加大变压器的损耗,降低了变换器的功率因数和效率。文中分析了高频高压变压器匝间电容和层间电容的大小对高频高压变压器的电压分布和可靠性的影响,指出减小层间分布电容和降低单层电压对变压器的可靠运行的重要意义。通过对不同绕组结构型式下的层间分布电容大小的分析和比较,指出采用＂Z＂型绕法和＂∠＂型绕法能够进一步减小高频高压变压器的层间分布电容,同时降低了变压器的绝缘要求,大幅改善高频高压变压器的电压分布,提高了变压器的绝缘耐压水平和可靠性。     

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.     

小功率电源变压器的绕制（三）——练习绕线

比起音频变压器来,普通小功率电源变压器的结构比较简单,生产工艺技术也并不复杂,通常也是把导线有规则地绕成线包,处理好绕组的端子引出和电气绝缘,并将线包装在铁心之内,经过浸渍烘干就行了。只是变压器的一些绕组工作在高电压下,又受其铁心窗口体积限制,线包绕制和绝缘处理的自由性不大,并且变压器的可拆性和可修性都不好。因此,也就对它的绕制工艺、电气绝缘和线包的几何尺寸有严格的要求,一些关键的工艺也来不得半点马虎大意。     

高频变压器绕组涡流损耗等效因子分析

针对平面磁性元件,利用Dowell模型和有限元方法对绕组涡流损耗等效因子Δ进行研究。分别对单股、多股圆导线和其等截面积正方形导线进行仿真分析,得到当圆导线直径为2~6个集肤深度时,涡流损耗减小显著;当圆导线直径大于6个集肤深度时,涡流损耗趋于平稳。圆导线直径为2~6个集肤深度时,等效因子的值较为理想;圆导线直径大于6个集肤深度时,其值偏低。为了提高设计的精确性应尽量选择直径少于6个集肤深度的圆导线。     

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。     

IT/AV设备中的绝缘绕组线测试

正引言绝缘绕组线是一种具有绝缘层的导线,主要用来绕制电子产品的变压器、电感器、电动机等安全关键件的绕组或者线圈,是整机安全评估中需要重点考核的部件。GB 4943.1-2011《信息技术设备安全第1部分:通用要求》和GB 8898-2011《音频、视频及类似电子设备安全要求》规定,绝缘绕组线在使用时除了要满足相关的结构要求外,还要满足抗电强度、柔韧性和附着力、热冲击、弯曲后抗电强度的保持等要求。     

平面螺旋线圈回扫变压器

介绍一种由多层平面螺旋线圈和印刷线路连接板构成绕组的新颖回扫变压器。平面线圈绕组由薄膜螺旋线圈和双面印刷线路连接板以及KAPTON绝缘片层叠加而成。简介样品装配工艺,并提出进一步优化结构的措施。     

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。     

A New Type of VF Repeater for Two-Wire Transmission Loops

Power loss at voice frequencies in two-wire telephone lines is presently overcome by employing electronic repeaters which produce bidirectional amplification without undue interaction between the outgoing and incoming paths. This isolation between the directional gain elements is achieved by employing balanced transformer windings or negative impedance transformations. Both methods rely heavily on complex line matching circuits to minimize the chance of instability or "singing." This paper describes a simple repeater that achieves bidirectional amplification while using conventional 1:1 line transformers. The obtainable return loss against fixed terminal impedances is only limited by the quality of these transformers. The new device reproduces the action of a hybrid transformer using very simple electronic circuitry and has a potentially wide application both in two-wire systems and in two to four wire conversions.     

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     

A leakage-inductance-based ZVS two-inductor boost converter with integrated magnetics

A two-inductor boost converter topology has conduction loss and transformer utilization advantages in converting low-voltage higher current inputs to high output voltages. In this letter, a new zero-voltage switching (ZVS) two-inductor boost converter with integrated magnetics is proposed. In the new topology, the two current source inductors, a resonant inductor and a two-winding transformer, are integrated into one single magnetic core with three windings. Two windings simultaneously perform the functions of the current source inductors and the transformer primary. The transformer leakage inductance forms the resonant inductance. This leads to a much more compact converter design with a significant reduction in the number of core and winding components. A theoretical analysis establishes the operating point of the ZVS converter. Both of the theoretical and experimental waveforms, including flux waveforms for the legs of the integrated core structure, are presented at the end of the letter.     

The relationship between size and power dissipation in a 1-10 MHztransformer

The trade-off between size and power dissipation in the design of low-profile 1-10 MHz transformers with planar spiral windings is considered. For a fixed power loss and number of conductor layers, the transformer with the smallest possible footprint can be designed by a trade-off of core and copper loss. The relationship between the marginal reduction of the transformer footprint and the associated marginal increase in power dissipation and/or number of conductor layers for the design of the smallest possible transformer is discussed     

A new compact model for monolithic transformers in silicon-based RFICs

A new compact model for monolithic transformers on silicon substrates is presented. The new lumped-element equivalent circuit model employs transformer loops to represent skin and proximity effects including eddy current loss in the windings of the transformer. In addition to the self-resistances and self-inductances of the windings, the effects of the frequency-dependent mutual resistance and mutual inductance are included in the model. The new compact model has been applied to a stacked transformer on a 10-/spl Omega//spl middot/cm CMOS substrate. The extracted circuit model shows very good agreement with data obtained by full-wave electromagnetic simulation and measurement over the frequency range of 0.1-10GHz.     

Computationally efficient winding loss calculation with multiplewindings, arbitrary waveforms, and two-dimensional or three-dimensionalfield geometry

The squared-field-derivative method for calculating eddy-current (proximity-effect) losses in round-wire or litz-wire transformer and inductor windings is derived. The method is capable of analyzing losses due to two-dimensional and three-dimensional field effects in multiple windings with arbitrary waveforms in each winding. It uses a simple set of numerical magnetostatic field calculations, which require orders of magnitude less computation time than numerical eddy-current solutions, to derive a frequency-independent matrix describing the transformer or inductor. This is combined with a second, independently calculated matrix, based on derivatives of winding currents, to compute total AC loss. Experiments confirm the accuracy of the method     

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%     

单级反激式PFC连续模式下电流有效值计算

单级反激式连续工作模式下功率因数校正电路的输入电压在半个工频周期内呈正弦变化。变压器绕组中的电流是一系列梯形脉冲,并且脉冲宽度以及电流的变化率都随着输入电压的瞬时值变化。依据有效值定义推导出了变压器原副边电流有效值的解析解;在相同的假设条件下,利用积分得出了电流有效值数值计算公式。解析解和数值解分析对比结果表明,两种计算结果具有很好的一致性。通过实验验证,用这种方法设计的变压器在同样温升的前提下,变压器体积大大减小。     

A high-density 1 kW resonant power converter with a transient boostfunction

A series/parallel resonant DC-DC converter with secondary-side resonance and a novel input boosting feature is described. In order to greatly reduce the conduction loss (factor of four) due to circulating currents in the resonant components, the boost circuit, which requires no additional active switches, operates only when needed during transient input voltage dips. This reduces the effective input voltage range over which the converter must operate and allows optimization at the steady-state input voltage. The converter employs highly efficient resonant inductors and novel Z-folded thin flex circuit transformer windings to meet a density of greater than 50 W/in³ with an efficiency approaching 95%. The DC-DC converter was developed for use as a 270 to 50 V line converter for distributed power applications