Simulation and Modeling of Common Mode EMI Noise in Planar Transformers

The transformer is the key circuit component of the common-mode noise current when an isolated converter is working.The highfrequency characteristics of the transformer have an important influence on the common-mode noise of the converter.Traditionally,the measurement method is used for transformer modeling,and a single lumped device is used to establish the transformer model,which cannot be predicted in the transformer design stage.Based on the transformer common-mode noise transmission mechanism,this paper derives the transformer common-mode equivalent capacitance under ideal conditions.According to the principle of experimental measurement of the network analyzer,the electromagnetic field finite element simulation software three-dimensional(3D)modeling and simulation method is used to obtain the two-port parameters of the transformer,extract the high-frequency parameters of the transformer,and establish its electromagnetic compatibility equivalent circuit model.Finally,an experimental prototype is used to verify the correctness of the model by comparing the experimental measurement results with the simulation prediction results.

Analysis of output voltage on a planar insulating core transformer

Output voltage is an important performance characteristic of planar insulating core transformer (PICT).In PICT magnetic cores are insulated from their neighboring magnetic cores by solid insulating materials.Solid insulating materials can increase leakage flux.This results in a low generated voltage in secondary coils,especially on the upper stages.Connecting flux compensation capacitors to secondary coils can compensate the flux loss.Design equations to calculate the flux compensation capacitors value and relevant simulation by CST and Protel software were presented.Simulation results of an actual PICT showed that output voltage increased by 19% after being connected to flux compensation capacitors and the voltage on every stage was equally distributed.Results of simulation were consistent with the following experimental test,which revealed that flux compensation capacitors were effective.

Asymptotic analysis on bright solitons and breather solutions of a generalized higher-order nonlinear Schrödinger equation in an optical fiber or a planar waveguide

We study a generalized higher-order nonlinear Schr¨odinger equation in an optical fiber or a planar waveguide.We obtain the Lax pair and N-fold Darboux transformation(DT)with N being a positive integer.Based on Lax pair obtained by us,we derive the infinitely-many conservation laws.We give the bright one-,two-,and N-soliton solutions,and the first-,second-,and Nth-order breather solutions based on the N-fold DT.We conclude that the velocities of the bright solitons are influenced by the distributed gain function,g(z),and variable coefficients in equation,h1(z),p1(z),r1(z),and s1(z)via the asymptotic analysis,where z represents the propagation variable or spatial coordinate.We also graphically observe that:the velocities of the first-and second-order breathers will be affected by h1(z),p1(z),r1(z),and s1(z),and the background wave depends on g(z).

Magnetic flux leakage analysis and compensation of high-frequency planar insulated core transformer

A novel high-frequency and high power density planar insulated core transformer(PICT) applied to high voltage DC generator is introduced. PICT's operating principle and fundamental configuration are described,and preliminary experimental results in self-designed PICT apparatus are presented. Emphatically, magnetic leakage flux(MFL) giving rise to the output voltage drop is analyzed in detail both theoretically and by finite element method(FEM). Showing good consistency with experimental result, FEM simulation is considered to be practicable in physical design of PICT. To cancel out leakage inductance and improve the voltage uniformity,compensation capacitor is adopted and experimental verification is also presented. All shows satisfactory results.

STATE TRANSFORMATION PROCESSES FOR FREE-FLOATING THREE-LINK PLANAR ROBOTS

The transformation process of an m-DOF free-floating robot from one staticstate to a different static state has m degrees of freedom. The proposed approach of thesetransformations utilizes a series of single-DOF transformation processes as an alternative to them-DOF transformation process. Two static state transformation processes are studied in detail.First, a single-DOF transformation process is established using a newly defined concept, referred toas transformation planning, and the definite integral of conservation of angular momentum. Second,the governing equation of the single-DOF transformation process is established using the dynamicequations of motion of the robot. This allows the joint torques to be computed to effect the statetransformation. Finally, an extension of the single-DOF transformation process is proposed to extendthe application of this proposed transformation methodology to create a transformation net whichallows the reconfiguration of a robot from one state to many other possible states.

高变比LLC型矩阵式谐振变换器的效率优化

在高压输入、低压大电流输出的应用场合,LLC谐振变换器在变压器和整流管上产生巨大损耗,不能有效凸显LLC谐振变换器高效率的特点。针对此问题,这里通过采用矩阵式平面变压器、同步整流控制策略等措施极大降低了LLC谐振变换器的损耗,变换器的效率得到了显著提升。同时进行了同步整流效率和暂态稳定性的实验验证。

一类平面解析系统强退化奇点的可积性

利用正规型理论研究一类平面解析系统强退化奇点的可积性问题。首先证明,任意一个可微系统,在可微同胚的变量变换以及时间尺度变换下,可积性保持不变。其次,对于二次齐次的微分系统,可以通过仿射变换及时间尺度变换化为4种标准形;针对其中的一种标准形,结合正规型理论,利用主系统是哈密尔顿的,且所对应的哈密尔顿函数的分解式是单因式的形式微分系统可积的充要条件,给出了相应的非线性系统可积的条件。该结果为研究平面系统的相图和局部定性结构提供了理论依据。

Capacitorless Solid-state Power Filter for Single-phase DC-AC Converters

Converters rely on passive filtering as a crucial element due to the high-frequency operational characteristics of power electronics.Traditional filtering methods involve a dual inductor-capacitor(LC)cell or an inductor-capacitor-inductor(LCL)T-circuit.However,capacitors are susceptible to wear-out mechanisms and failure modes.Nevertheless,the necessity for monitoring and regular replacement adds to an elevated cost of ownership for such systems.The utilization of an active output power filter can be used to diminish the dimensions of the LC filter and the electrolytic dc-link capacitor,even though the inclusion of capacitors remains an indispensable part of the system.This paper introduces capacitorless solid-state power filter(SSPF)for single-phase dc-ac converters.The proposed configuration is capable of generating a sinusoidal ac voltage without relying on capacitors.The proposed filter,composed of a planar transformer and an H-bridge converter operating at high frequency,injects voltage harmonics to attain a sinusoidal output voltage.The design parameters of the planar transformer are incorporated,and the impact of magnetizing and leakage inductances on the operation of the SSPF is illustrated.Theoretical analysis,supported by simulation and experimental results,are provided for a design example for a single-phase system.The total harmonic distortion observed in the output voltage is well below the IEEE 519 standard.The system operation is experimentally tested under both steady-state and dynamic conditions.A comparison with existing technology is presented,demonstrating that the proposed topology reduces the passive components used for filtering.

一种宽输入范围高效率宇航二次电源的设计

提出一种宽输入电压、高效率100 W宇航二次电源的设计方法。输入电压范围达到20 V~50 V,可覆盖星上28 V母线、42 V母线电压范围。峰值效率达到90%以上,具有体积小、功率密度高的特点。采用单端反激电路拓扑,通过加入斜坡补偿技术,使得反激变换器的占空比工作在60%以上,拓宽了输入电压范围。同时采用平面变压器技术,降低变压器漏感,提高效率并减小尺寸。

三维扫描技术支持下的震后隧道断面变形分析

三维激光扫描技术已被广泛应用于隧道变形检测,但存在点云数据量大、断面提取效率低、不同类型的隧道变形检测算法通用性差等问题。本文提出了一种切割隧道断面局部范围点云的快速搜索算法,首先为点云数据建立八叉树索引,降低算法复杂度,简化搜索流程,给定查询点坐标、切割厚度、偏距,定义搜索范围平面多边形,并基于八叉树索引节点多边形相交判断,进行隧道断面的快速定位与提取;然后对隧道设计断面轮廓线进行等分,完成基于激光点云测量的任意形状隧道变形数值计算;最后以受地震影响的兰新客专大梁隧道为例,对扫描设站精度进行统计,完成隧道断面提取与变形检测分析,并给出了不同里程区间的偏移规律,为震后修复设计提供了数据支撑。

本安技术用可靠隔离平面变压器的一种新型评定方法研究

传统漆包线绕制变压器用作本质安全可靠隔离器件时,存在评定方法不足的问题,因此引出将平面变压器用作可靠隔离器件的思路,并针对平面变压器的特点,提出一种采用计算分析代替型式试验的新型评定方法,同时给出隔离间距的判定方法。理论分析表明,该种新型评定方法可用于判断平面变压器的可靠隔离性能。

LiDAR点云数据坐标转换关键技术研究

LiDAR技术近年来日趋成熟,在各行业得到了广泛应用。LAS文件格式标准,为LiDAR点云数据交换提供了便利。为实现点云数据的坐标转换,本文基于LASlib库和坐标转换模型,实现了LAS文件的坐标转换,并利用工程项目验证了其正确性。同时,针对不同坐标转换模型的坐标转换效率进行了分析,对LAS文件的坐标转换具有指导意义。

平面变压器绕组损耗改进二维混合计算方法

高频下绕组损耗的快速计算方法对平面变压器精细化设计和优化有着至关重要的作用。对于垂直方向与水平方向同时存在交叉换位结构的平面变压器,其绕组损耗无法通过一维解析模型计算得到。为解决这一适用性问题,该文提出一种改进二维混合计算模型,从涡流场求解角度对绕组损耗进行计算。该模型将高度方向磁场强度考虑在内,在磁准静态假设以及二维假设基础上,以电流密度与磁场强度为变量对电磁场边值问题进行完全表述,并通过矩量法将电磁场边值问题转化为线性方程组求解问题。通过该文方法所建立线性方程组系数矩阵具有阶数较低,且不随剖分节点、单元数增加而增加的优点,达到确保一定计算精度的前提下有效节约计算成本的目标。搭建原副边匝数比为2:2的交叉结构平面变压器实验模型,对该文方法的有效性进行验证。

基于傅立叶变换频移特性的平面近场测试方法

为了满足快速和无相测试现场天线的需求,文中提出了一种基于傅立叶变换频移特性的平面近场测试方法。该方法采用多探头技术,利用各个通道的移相,达到天线角域的移动,实现了任意指向角信号的采集,具有测试快速、使用便捷的特点,特别适用于天线的大规模生产测试和现场测试等。对一个标准喇叭天线进行了平面近场扫描测量,对比了用传统近场数据处理插值方式得到的和用频移性质得到的天线远场方向图(E面)。实验显示,该方法具有与传统近场测试方法相同的效果,能有效地测试天线方向图。

基于GaN的高效率、高功率密度ACF变换器的设计

高效高功率密度是减小开关电源尺寸的关键。有源箝位反激(ACF)变换器结构简单、可实现软开关控制,是中小功率隔离型DC/DC变换器提升高效高功率密度的主流解决方案。此处通过对ACF变换器工作原理及其软开关过程的详细分析,在优化设计参数的基础上,使初级开关管与箝位开关管采用集成门极驱动器与氮化镓(GaN)的功率IC,再结合次级同步整流(SR)技术及平面变压器设计方案,设计了一款155 V输入,28 V/150 W的电源模块,模块整体功率密度达8.7 W/cm3,峰值效率可以达到94.37%。测试结果验证了设计方案的高效率与高功率密度。

柔性叉指电极折叠特性的仿真建模与试验研究

柔性叉指电极以其稳定性好、灵敏度高、制作方便等优点成为柔性电容传感器的重要研究方向,也逐渐在可穿戴领域得到应用及发展。在不同的触觉信号作用下,柔性叉指电极可产生不同的电容输出值,通过平面映射及保角变换法得到柔性叉指电极在不同折叠情况下的计算式。运用COMSOL Multiphysics有限元软件建立柔性叉指电极传感器的仿真模型,详细分析了折叠角度及折叠位置对传感特性的影响,并通过试验研究进一步验证仿真结果的可行性。仿真及试验结果表明:当折叠角度θ≤90°时,对电容输出信号的影响较大;而折叠位置对电容的影响相对有限。该研究成果对柔性叉指电极在智能可穿戴领域的应用具有创新性的参考价值,为柔性叉指电容传感器提供了更广阔的发展前景。

坐标变换下平面解析系统单值轨道的不变性

为了研究平面解析系统在何种坐标变换下单值轨道具有不变性,首先给出平面解析系统的轨线沿固定方向进入奇点的两个定义,并证明了它们是等价的;其次引入判别轨线沿固定方向进入奇点的一个充要条件,得到平面解析系统在非正则变换下系统轨道可以具有不同的单值性;最后通过对平面解析系统做正则变换,证明了变换前后的系统轨线具有相同的单值性。该结果对研究平面解析系统单值轨道的不变性具有参考价值。

MapGIS影像镶嵌融合控制点获取的一种有效方法

Mapgis的msi影像要方便应用,镶嵌融合校正必不可少。采集足够多的镶嵌融合控制点使得影像校正更加精细。传统采集控制点需要先产生控制点参照文件,然后在Mapgis图像处理、图像分析系统中的影像文件窗口与控制点参照文件窗口中交互采集,窗口切换、平移、缩放,对于采集大量的控制点时,很是费时费力。具有公里网格的栅格地图,常通过公里网格的理论坐标进行影像校正。本研究主要探讨这类影像的镶嵌融合控制点的一种有效获取方法,以改善镶嵌融合控制点的采集体验,提高采集效率。

基于ADP1071-2的高效率超薄反激变换器

平面变压器具有漏感低、转换效率高、散热性能好等优点,非常适用于超薄开关电源的设计。氮化镓器件(GaN)与Si器件相比,具有开关速度高、通态电阻低等优势,可进一步提高电源转换效率。以ADP1071-2为控制芯片,应用PCB平面变压器和GaN晶体管,设计了一台3.3 V/10 A的高效率超薄反激变换器,给出主电路参数详细设计方法,以此为依据研制了实验样机,验证了理论分析的正确性和参数设计的合理性。

应用于AHB非对称半桥拓扑的平面变压器设计

变压器是开关电源系统中的关键器件,其体积大小占整个电源系统的20%~30%。变压器的能量损耗较大,通常为电源系统总能量损耗的30%左右。平面变压器作为一种新型变压器,因其具有体积小、电流密度大、漏感低、功率密度高、散热性优、参数重复性优、生产一致性高等优点,受到电源行业的广泛关注。因此,平面变压器的设计对于实现开关电源系统的小型化和轻量化至关重要。文章主要针对应用于非对称半桥拓扑(Asymmetrical Half-Bridge,AHB)的平面变压器设计展开研究。