电感器交流电感与磁芯等效电阻的数学拟合

利用铁氧体磁芯电感器的集中参数模型,以电感器交流电感和磁芯等效电阻的最小偏差为目标函数,结合最小二乘法,求解出电感器交流电感与频率、磁芯等效电阻与频率的解析表达式。利用拟合出的表达式求解电感器的等效串联电阻和电抗,比较计算结果和实测结果,证实了拟合方法的可行性,说明拟合所得电感器交流电感与频率、磁芯等效电阻与频率间的关系揭示了物理量之间的内在规律。     

带气隙铁氧体磁芯变压器模型及仿真分析

结合实际测得的铁氧体磁化曲线和损耗曲线,有利于提高变压器模型的仿真准确度。采用磁场分析软件Magnet分别对无气隙铁氧体磁芯变压器、有气隙铁氧体磁芯变压器和气隙-铁氧体等效材料磁芯变压器模型进行了仿真研究。对不同电压下三种模型的特性进行了分析与研究。仿真结果表明两种有气隙铁氧体模型均可对磁场分布进行有效计算。两种模型的建立为不同的需求提供了建模基础。     

一种提取EMI滤波器轭流圈集总参数的方法

采用等效并联电阻反映磁芯损耗,考虑其随频率变化的特性以及共模轭流圈寄生电容,给出了集总参数表示等效共模与差模模型.分析了等效并联电阻和模型电感随频率变化的趋势,并定性确定了它们在传导频率范围内与频率的线性关系,使得参数提取及模型仿真更为准确.讨论了共模轭流圈寄生电容在模型中的集总反应,首次提出了差共模模型中寄生电容存在两倍关系的假定,得到一种提取共模轭流圈集总参数更加简洁的方法,通过拟合计算曲线与实测曲线的比较证实了该方法的有效性.     

不同占空比下功率变换器磁芯损耗分析与建模

功率变换器中磁芯损耗与励磁波形密切相关。为了有效地评估和预测不同占空比的磁芯损耗,以铁氧体磁芯材料为研究对象,分析影响磁芯损耗的两个重要因素——交流磁通密度峰值和励磁频率,进一步研究磁芯损耗与磁通密度变化率的关系,引入矩形波励磁下磁通密度变化率波形系数的概念,在占空比为0.5时磁芯损耗模型的基础上,对不同占空比工况下磁芯损耗进行建模。最后,采用Origin数据统计分析软件对比了实验数据和所提出模型的计算结果,验证了模型的准确性。     

一种测量软磁铁氧体磁芯磁导率的方法

为了便于对共模扼流圈进行设计和仿真,需要准确掌握磁芯材料的磁导率.本文建立了一种电感高频等效模型,使用此模型在已知电感器实部和虚部的情况下测得两种软磁铁氧体磁芯的相对磁导率,最后通过此模型对插入损耗计算值与实际测量值的对比,证明其具有很高的准确性,并分析了误差产生的原因.由于此模型中的所有参数都用几何尺寸测量的方法得到,简单易行,有一定的工程利用价值.     

寄生参数效应的共模扼流圈集中参数建模

为分析传导EMI用共模扼流圈寄生参数的效应和预测EMI滤波器的高频特征,需要建立其寄生参数的模型,为此提出了基于阻抗测量实现共模扼流圈集中参数的建模方法,模型包括共模电感、漏感、绕组寄生电容等参数。基于阻抗测量,阐述求解寄生电容的基本原理;运用电路等效原理,将磁心的损耗等效为电阻的损耗,经适当简化,该电阻仅是频率的函数,将非线性的磁心损耗用一个与频率有关的电阻元件来等效,适合于电路的设计和仿真。最后通过样品实验,用所提出的方法建立了共模扼流圈的高频模型。     

电感集成式大容量高频变压器精细化设计方法

针对固态变压器用电感集成式大容量高频变压器进行优化设计,分析了高频变压器漏电感参数、磁芯高频损耗、绕组高频损耗以及温升的计算方法。在此基础上,利用自由参数扫描法建立了大容量高频变压器优化设计流程。按照最优设计方案制作了一台5kHz/10kW纳米晶磁芯高频变压器模型,并对其参数进行实验测试。将解析设计与有限元仿真和实验测量结果进行对比,结果表明模型漏电感、交流电阻和磁芯损耗的相对偏差分别为2.85%、1.49%和5.35%,验证了所提设计方法的有效性。     

软磁铁氧体高频复数磁导率的测量方法

叙述了一种配合Ｑ表进行铁氧体磁芯的高频磁导率和损耗值的测量方法。文中导出了测量方程,并给出测量结果。     

考虑集肤效应和邻近效应的变压器绕组谐波损耗计算及实验研究

基于国内外现有变压器谐波模型发展情况及其适用范围的局限性,以进一步精确量化变压器绕组谐波损耗为目的,建立了绕组谐波损耗模型。该模型综合考虑谐波情况下集肤效应、邻近效应对绕组的影响,基于电磁场原理分析绕组电阻参数畸变特性。进行了各次谐波电流下的绕组电阻测量实验,将实验测量值、传统模型计算值与该模型计算值进行对比,结果证明该模型提高了计算精度,使得变压器绕组损耗计算更加精确。最后基于实验测量值,建立了变压器绕组谐波电阻工程实用模型,对工程计算具有一定的指导价值。     

μs级脉冲激励下磁开关磁芯磁特性

为测试磁开关磁芯在μs级脉冲激励下的磁特性,设计并制作了基于没有附加磁芯复位电路的单级磁脉冲压缩系统,3块被测磁芯分别代表铁基非晶、Ni-Zn和Mn-Zn 3种软磁材料。磁芯的磁滞回线由测量所得的磁开关两端电压和电流数据经计算得到,由磁滞回线可知这3种软磁材料在μs脉冲激励下的各种特性参数。通过分析比较这些特性参数可知:铁基非晶磁芯具有最大的磁通跳变,同样的V-s积和匝数时,铁基非晶磁芯所需体积最小;Mn-Zn铁氧体磁芯具有最小的能量损耗,适合高重复频率下的应用;Ni-Zn铁氧体磁芯饱和后的相对磁导率最低,适用于较高压缩增益的磁压缩电路中。     

Modelling of battery‐powered boost DC–DC power LED driver with parasitics by multivariate power series expansion

This paper presents an analytic model of a battery‐powered boost DC–DC converter driving a power light emitting diode. The model is capable of taking into account parasitic components, including series resistances, parasitic capacitances and inductances. Unlike the standard approach to the converter modelling, the discussed model does not require any assumptions concerning current and voltage waveforms. It is based on power series expansion in normalized values of the parasitic components, leading to expressions comprising only physical parameters of the circuit. First‐order corrections are derived and illustrated in this paper. Copyright © 2014 John Wiley & Sons, Ltd.     

利用耦合电感改善EMI电源滤波器高频幅频特性的研究

高频开关电源的传导性电磁干扰EMI（ElectroMagnetic Interference）是电力电子装置应用的主要障碍之一,EMI电源滤波器能有效抑制其干扰传导。在高频状态下．EMI电源滤波器的电容器和电感器所带有的等效寄生参数会影响EMI高频性能,基于此提出了利用高频元器件的等效寄生参数间的互感耦合改善滤波器高频性能的措施,考虑了差模电感与电容器的寄生串联电感之间存在互感耦合以及2个串联支路的串联电感之间存在耦合电感2种情况。在分析带有寄生参数的差模等效电路的基础上,进行了仿真研究。结果表明,利用寄生参数的互感耦合使得EMI电源滤波器的高频性能有所改善。     

A Method for Determining Nonlinear Inductances of Electrical Equivalent Circuit for Three-Phase Induction Motor

Accurate values of the equivalent circuit parameters of three-phase induction motor are critical for its precise performance evaluation. Motor parameters, mainly the inductances obtained from conventional no-load and blocked rotor tests are constant parameters for all load conditions. However, due to inherent nature of the core material property, i.e., nonlinear B-H curve, the inductances do not remain constant in practical. This work proposes a method comprising simple tests using which all the motor nonlinear inductances can be determined. The motor mathematical model under the test conditions is also developed. The results obtained from equivalent circuit using the nonlinear inductances are validated with experimental results for two different motors and good agreement has been achieved. It is observed that the motor performances calculated using nonlinear inductances matches more closely to experimental results as compared to that using constant inductances.     

基于改进时域法的多端MMC-HVDC故障电流计算

为解决基于模块化多电平换流器 (modular multilevel converter,MMC) 的柔性直流输电 (high voltage direct current,HVDC) 故障电流解析计算精度不足的问题,提出一种计及远端站影响的多端MMC-HVDC故障电流改进时域求解法。首先,在分析故障后子模块电容放电路径的基础上,推导换流站等效电容值等系统参数,建立MMC-HVDC系统故障后网络等效模型。其次,将直流电网各换流站解耦,以故障后各支路电流近似解为初值,逐次修正计及远端站影响的多端MMC-HVDC线路等效电阻及等效电感,得到多端MMC-HVDC系统中各支路的故障电流值。最后,基于RT-LAB仿真平台搭建四端柔性直流电网模型,对故障电流计算值与详细电磁暂态仿真结果进行对比。结果表明,所提故障电流求解方法能够准确、有效地计算出多端MMC-HVDC短路故障后各支路电流值,最大误差小于5%。     

Modeling of a coil system considering frequency-dependent inductances and losses I. Analysis of the impedance matrix characteristics

 A general equivalent circuit for the modeling of a system of magnetically coupled coils including the losses is presented. This equivalent circuit includes two parts: a subsystem of primary branches whose terminals correspond with those of the real coils, and a secondary network which allows the representation of frequency-dependent inductances and resistances. An analysis of the equations of the proposed circuit is carried out and an expression of the frequency-dependent impedance matrix as seen by the primary coils is determined. The properties of the mathematical expression are analyzed. The proposed equivalent circuit allows representing the dependence of inductances and resistances on the frequency. The expression of the impedance is the starting point for the synthesis of an equivalent circuit, which is carried out in a separate article. Received: 25 May 2001/Accepted: 25 June 2001     

Influence of skin effect on the series resistance of millimeter-wave IMPATT devices

An attempt is made in this paper to study the influence of skin depth on the parasitic series resistance of millimeter-wave IMPATT devices based on Silicon. The method is based on the concept of depletion width modulation of the device under large-signal condition. A large-signal simulation model based on non-sinusoidal voltage excitation is used for this study. The electric field snap-shots of 35 GHz Single-Drift Region (SDR) and 94 GHz Double-Drift Region (DDR) IMPATT devices are first obtained from which the series resistances are estimated by incorporating the effect of skin depth in the modeling and simulation. The series resistances of these devices are also obtained by neglecting the effect of skin depth. The values of series resistances obtained from the simulation are compared with the corresponding experimentally reported values. It is observed that the series resistance estimated by including the skin effect is in closer agreement with the experimental values as compared to that without including the same. Thus the skin effect plays an important role for determining the series resistance of IMPATT devices at millimeter-wave frequency bands.     

基于约束最小二乘法的变压器三相漏感辨识算法

对于变压器保护,当前提出的功率差动原理、磁通特性识别法、等值电路参数鉴别法及基于变压器的回路方程法等都要求预知原副边各相的绕组电阻和漏感参数。文中提出一种三相漏感的辨识方法,不需改变三角形侧的电流互感器配置,只通过测量空载合闸瞬时的线电压和线电流,利用约束最小二乘法进行2次辨识后,就能够快速、准确地辨识出原副边绕组漏感。通过EMTP仿真和变压器动模试验,表明该算法能够正确辨识各相漏感,误差很小,具有较好的应用价值。     

构成平面EMI滤波器元件电磁参数的提取

平面型电磁干扰(electromagnetic interference,EMI)滤波器因其易于进行磁集成、寄生参数小、抗电磁干扰强等优点在航空领域具有很好的应用前景。论文提出一种以"圆环型"结构为基础的EMI共模、差模模块,其中,前者通过将"电感和电容"(LC单元)集成于一体构成,后者利用前者泄漏的磁场而形成的漏感和一个独立的差模电容器构成。提取这些模块单位长度的电磁参数是分析各模块甚至整个滤波器特性的基础。论文建立LC单元的轴对称静电场模型,提取各线匝之间的部分电容;建立LC单元线匝系统的时谐磁场模型,在计及线匝导体集肤效应、邻近效应、磁芯损耗的基础上,提取了各线匝电感、电阻;建立LC单元形成漏感的时谐场模型,并提取该漏感,该漏感即为差模电感;差模电容可以直接采用平行板的近似表达式求得。结合适当的边界条件,利用所建立模块的分布参数模型对其阻抗的频率特性进行了测试,验证了提取参数方法的正确性和数值的准确性。     

Calculation of self and mutual inductances and 3-D magnetic fields of chokes with air gaps in core

Contents  This work deals with the analysis of 3-D magnetic field in electric choke (reactor) with two windings. The analysis is related to the solutions of Laplace's and Poisson's equation by the Finite Element Method. The package OPERA-3d has been used. The self and mutual inductances of windings, which are connected in series aiding as well as in series opposing, have been determined. The calculation results of magnetic flux density components and the inductances are compared with the measured values. Received: 14 August 2000     

Line inductance measurement by using commutation time in line commutated converters

Finding line inductance using wiring diagrams of the network is usually difficult or even impossible. In general, line inductance has to be measured in a simple nondisruptive way without service interruption. Several line inductance measurement techniques have been suggested previously, but they suffer from a number of limitations. In this paper, a novel line inductance measurement technique that uses the current commutation in a line-commutated converter is proposed. An expression for the line inductance as a function of phase-to-phase voltage, utility angle frequency, load current, triggering angle α and commutation time is procured. The line inductance is calculated by recording the commutating current waveforms by means of an accurate oscilloscope and measuring the other required values. Because of its simplicity, diode converter is employed in the experimental circuit when α = 0. The experiment is repeated for the case in which the phase inductances are different, and these phase inductances are calculated. To verify the performance of the proposed line inductance measurement technique, the known inductances are added in series to the line phase inductances. The results obtained show that the line inductance can be measured by the proposed measurement method precisely below 6% error. Finally, the error sources that may be encountered when the proposed method is applied are discussed.