用耦合模原理分析RLC串联电路

用两个状态变量构造的复数状态变量叫做耦合模.以耦合模为变量对电路或系统进行分析的方法叫耦合模分析.本文以RLC串联电路零输入响应和正弦稳态响应为例,介绍了耦合模原理在电路分析中的应用,包括耦合模的定义与性质,耦合模方程的列写与求解,耦合模方程的简化,以及用耦合模计算的元件储能和电路储能等.用数值计算方法给出了这些响应的波形,它们和用传统电路理论获得的波形完全一致.耦合模原理在分析模式耦合系统,并着眼于能量的传递时,具有特殊的用途,例如无线电能传输系统.     

压电振动能量收集电路的设计与实验研究

压电材料可将机械振动能转换为电能,但其产生的电能较小且具有交流特性,有必要建立储能电路将压电振动产生的电能储存起来并输出稳定的直流电。根据压电构造方程,建立压电振动能量收集系统的耦合场数学模型,对输出电压和最大输出功率进行数值模拟。设计与制作了一种以电容为储能介质的储能电路,通过电压比较器和电压调节器来保证稳定的直流输出。实验结果表明该储能电路能提供稳定的2.24V的直流输出电压,储能效率最高可达66.3%,并分析其能耗及误差产生的原因。     

叠加定理在求解交流负载线中的应用

图解法常用于分析波形失真问题和估算最大不失真输出电压,其中交流负载线的求解和作图又是该方法的核心。为此,应用叠加定理对交流负载线方程的求解进行了探讨,证明了直接耦合放大电路的直流负载线和交流负载线相同、阻容耦合放大电路的直流负载线和交流负载线不同;提出了应用解析法计算最大不失真电压幅值、分析波形失真。与目前广泛采用由戴维宁定理求解交流负载线的方法相比,得出了由叠加定理求解交流负载线的三个优点。     

电路分析教材的编写思路

为编写《电路分析》教材,研究了电路课程教学内容的分类和排序。用结构图表说明三组电路方程贯穿全书,而且主要分析对象为线性非时变电路。当电路作为系统来分析时,必然涉及基本激励信号,用到系统函数和系统响应。     

蔡氏电路的等效电路设计及其应用

针对蔡氏电路中电感的误差与蔡氏二极管复杂的缺陷,设计了一种蔡氏电路的等效电路。对电路参数表示的蔡氏电路方程用数学语言方程进行归一化设计,对归一化的状态方程的变量重新组合,根据组合后的方程设计出各模块电路,按照方程各状态变量的对应关系将各模块联结起来并优化,设计出了一种无感能产生二涡卷蔡氏混沌吸引子的等效电路。用反馈型驱动-响应式同步混沌保密通信制式对等效电路进行研究,结果表明保密通信很好。由此证实了该方法的可行性。     

IGBT串联技术在固态刚管调制器中的应用

介绍了一种固态刚管调制器的方案和原理,该调制器使用6只1.2 kV/200 A绝缘栅双极型晶体管串联作为放电开关,讨论了刚管调制器设计的难点和解决方法.设计中采用脉冲顶部补偿电路以减小储能电容值,避免使用撬帮电路;详细分析了均压电路的计算方法,并从关断缓冲电路角度讨论了吸收电容计算,依据绝缘栅双极型晶体管伏安特性曲线选取合适的电容值.结合具体课题,给出了相关的试验波形,肯定了固态刚管调制器在工程上的价值.     

含全耦合电感电路的求解

分析动态电路既可以应用拉普拉斯变换方法,也可采用时域分析方法。通过分析含全耦合电感电路,得出流入耦合电感的电流有可能发生跃变的结论,该电流不是电路的状态变量。对含全耦合电感电路的求解以拉普拉斯变换方法为宜。如果采用时域分析方法,则应采用含全耦合电感电路的等效电路来求解。上述分析结果可供讲授电路理论的教师参考。     

降低电路方程数目算法的研究

用改进节点法列解电路方程时，其方程数目较多，本文叙述了一种简化电路方程的算法，它能使电路方程数目减到最少，从而减少内存，计算省时，虽然它是一种通用方法，但特别适用于微型计算机分析电路的频域、时域响应。     

偏振模色散对波分复用系统性能影响的仿真分析

基于多波长光波在双折射光纤中传输的非线性耦合方程，用分步傅立叶变换求耦合方程的数值解，仿真分析了偏振模色散对波分复用系统脉冲波形的影响，并进一步仿真分析了输入功率、啁啾系数、占空比不同时，偏振模色散对系统性能的影响。     

传输线端接复杂电路的电磁耦合时域分析方法

该文基于时域有限差分(FDTD)方法和传输线方程,结合Ngspice软件,提出一种高效的时域混合算法,能够快速模拟空间电磁场作用传输线端接复杂电路的电磁耦合问题。该算法的优势在于实现了空间电磁场辐射与端接复杂电路瞬态响应的协同计算,且避免了对传输线和复杂电路结构的直接建模。首先,将复杂电路通过传输线的特性阻抗进行等效,采用FDTD方法结合传输线方程,求解得到特性阻抗上的入射电流响应。然后,在每个时间步上,将该电流引入复杂电路作为激励源,联合电路模型建立网表文件。最后,使用Ngspice软件读取网表文件,并仿真得到电路各元件上的瞬态响应。通过相应计算实例的数值模拟,与电磁场仿真软件CST的计算结果以及耗用内存和时间进行对比,验证了算法的正确性和高效性。     

Design and experiment of wireless power transfer systems via electromagnetic field near-zone region

This paper presents the fundamental principle, circuit implementation and measurement of wireless power transfer (WPT) technology through both Colpitts and Hartley oscillation prototype circuits. The Colpitts and Hartley oscillation prototypes are used to convert DC voltages into AC ones. Meanwhile, both half- and full-wave rectification circuits are designed correspondingly for AC/DC voltage conversion. In addition, the orientation and distance effects between the transmitting and receiving coils are investigated. The self-inductance, mutual-inductance and coupling coefficient for the coupled inductors are extracted as a function of distance and frequency by using an equivalent T-circuit network and a derived Z-parameter matrix. The proposed WPT systems operate at around 3.6 MHz and the transferred voltage is measured at the WPT receiving terminal. The measured results indicate that the two proposed WPT systems can operate properly for potential short-distance applications.     

A unified approach for the coupled-mode analysis of nonlinearoptical couplers

A unified approach for the coupled-mode analysis of nonlinear optical couplers is proposed. This approach is basically an extension of the work of [Haus, vol. 5, p. 16, 1987] to include optical nonlinearity. After the nonlinear coupled-mode theory is established, various basis functions are used as trial fields to derive coupled-mode equations. It is found that two published coupled-mode theories can in fact be deduced from the proposed one with individual linear or nonlinear waveguide modes serving as trial fields, thus making the coupled-mode equations from variational principle and reciprocity theorem equivalent. Coupled-mode equations based on system modes are also presented. Furthermore, analytical and/or numerical methods for solving coupled-mode equations are included. More research and discussion can be conducted based on the knowledge addressed in this paper     

Asymmetric Coupled Transmission Lines in an Inhomogeneous Medium

Terminal characteristic parameters for a uniform coupled-line four-port for the general case of an asymmetric, inhomogeneous system are derived in this paper. The parameters (impedance, admittance, etc.) are derived in terms of two independent modes that propagate in two uniformly coupled propagating systems. The four-port parameters derived are of the same form as those obtained for the symmetric case resulting in similar port equivalent circuits for various circuit configurations considered by Zysman and Johnson. The results obtained should be quite useful in designing asymmetric coupled-line circuits in an inhomogeneous medium for various known applications.     

Contra-directional coupling in grating-assisted guided-wave devices

Contradirectional power coupling in grating-assisted guided-wave devices is studied by applying a vector nonorthogonal coupled-mode formulation. The coupled-mode equations are solved by a transfer matrix method. All the space-harmonics generated by the periodic grating are considered. The coupling can be understood in terms of the interference among the normal modes of coupled waveguides with a grating perturbation. Phase-matching grating periods for maximum reflections are equal to the beat lengths between the two normal modes involved in the coupling process. The reflections are built up constructively (Bragg reflection), resulting in stopbands in the spectral response. The expressions for the grating periods are obtained and compared with those derived from conventional phase-matching conditions     

Broadside coupled strip inset dielectric guide and its directionalcoupler application

A theoretical and numerical method is presented for the analysis of broadside-coupled strip inset dielectric guide. The method of analysis is based on an integral equation formulation and Galerkin's procedure. Besides propagation constants for two fundamental and higher order modes, the characteristic impedances for the two fundamental modes are calculated using the total propagating power and the longitudinal strip currents. The propagation characteristics of the two fundamental modes are then used to compute 4-port circuit parameters that are essential for accurate analysis and design of coupled line circuits. The effects of various structural parameters on the S-parameters are investigated and it is found that this broadside coupled strip IDG structure is useful for the realization of the directional couplers. Examples of strong and weak directional couplers are given. Furthermore, the propagation constants and S-parameters of coaxially excited coupled strips are measured, and are in good agreement with the theoretical analysis     

Generalized coupled interconnect transfer function and high-speedsignal simulations

A new expression for the coupled interconnect system transfer function has been derived under general linear generator and uncoupled load conditions, i.e., without any restrictions in circuit load impedance. High-speed-signals on coupled interconnects have been simulated using this transfer function. The simulation uses generalized interconnect circuit model parameters in which all line parameters are frequency dependent. The validity of the interconnect circuit parameters was confirmed previously using s-parameter measurements. High-speed signal simulation using this novel interconnect transfer function has been verified with time-domain measurements using an HP54121T high-speed sampling oscilloscope. This work accurately predicts coupled interconnect circuit responses. With this transfer function, signal integrity problems of high-performance VLSI circuits can be predicted in the design stage     

Obtaining the equations of motion for parametrically coupled oscillators or waves

When the equations of motion for any parametric system are written in terms of an appropriate set of normal modes, these equations have a general coupled-mode form which depends on the number of frequency components present and on the order of nonlinearity considered, but not on any other details of the specific system considered. This paper presents a simple procedure, based on a Hamiltonian approach, for obtaining the most general set of parametric coupled-mode equations for any number of frequency components and any order of nonlinearity. The procedure applies to parametrically coupled normal modes which grow in time, or to parametrically coupled waves which grow in distance and/or in time. The general equations obtained in this way are useful for pedagogic purposes and for general discussions of parametric interactions; for checking or even for bypassing detailed derivations on specific physical systems; and for proving the Manley-Rowe relations, which emerge very directly from the resulting general equations.     

可集成互感耦合电路的实现

在分析互感耦合电路端口电压和电流关系的基础上提出了一种新的互感耦合电路的系统设计方法,并以CCCII和CCDDCC为有源器件实现了具体电路。提出的电路仅有4个有源器件,2个接地电容和2个接地电阻,能够实现初、次级电感L1,L2和互感M(或-M)。初、次级电感和互感能够通过调节有源器件CCDDCC的偏置电流和电阻RM实现独立可调。作为应用和验证设计的正确性,将提出的互感耦合电路应用到双调谐回路。     

Power exchange in tapered optical couplers

The power exchange between nonparallel optical waveguides or tapered couplers is analyzed by the coupled-mode theory based on local modes of the individual waveguides (local waveguide modes). A self-consistent nonorthogonal coupled-mode formulation is presented and transformed into an orthogonal form which is equivalent to the coupled-mode equations for the local modes of the coupled waveguides (local array modes). The coupled-mode equations are then solved numerically and the effect of the taper on the power exchange between the two guides is studied     

基于LTC3863的负电压电路设计

现代电子系统中不少电路需要负电压作为供电或控制,而传统使用变压器电路的方法具有体积大效率低的缺点。分析了负电压产生的原理,结合工程实际应用提出一种基于LTC3863的负电压电路设计方法,并对电路中主要器件参数进行分析和计算。仿真及试验结果验证表明,该电路具有转换效率高、体积小等特点,可以在各种嵌入式及手持终端设备中广泛使用。