拉普拉斯变换在线性动态电路分析上的应用

本文主要介绍如何利用拉普拉斯变换的方法来求解线性动态电路的响应,首先利用拉普拉斯变换将元器件的时域模型转化为S域模型,然后在S域中建立起联系输入输出的代数方程,求解该代数方程,得到系统的S域解,再做拉普拉斯反变换求出系统的时域解。     

有源含时RLC回路的量子化波函数

应用正则化变换结合路径积分方法,求解了电感、电阻、电容随时间变化情况下的有源含时ＲＬＣ回路的量子化波函数,并进一步研究了电路中电荷、电流的量子起伏。     

基于拉氏变换原理的三维磁化等离子 体电磁散射FDTD分析

 根据拉普拉斯变换(LT)原理,提出了一种新的分析色散介质的电磁特性的时域有限差分(FDTD)算法,称为电流密度拉普拉斯变换时域有限差分(CLT-FDTD)算法.利用磁化等离子体介质中的关于电流密度矢量与电场强度的本构方程,将其两边分别拉普拉斯变换,得到s域内的本构方程.最后进行逆拉普拉斯变换和指数差分,得到在时域里易于求解的FDTD迭代方程.通过该方法计算了非磁与磁化等离子体球的后向雷达散射截面(RCS),验证了该方法正确性与有效性.     

动态电路全时域响应的求解

在电路教材中对动态电路全响应的分析都是针对换路之后的电路模型列写电路方程,以换路结束的时刻为时间域的分析起点(一般为t=0+时刻),因此电路变量响应解的时间域为t≥0+.本文通过建立动态电路的全时域模型,采用时域分析法和傅里叶变换法求得电路响应的全时域解,为对电路进行进一步分析(如求电容电流、电感电压等)提供了方便.本文的讨论结果可供讲授电路课程的教师参考.     

求解场-路混合问题的时域积分方程法

研究了基于时域积分方程求解场-路混合问题的方法,其基础是“耦合电流”的思想,区域中的电路部分和电磁结构部分通过其连接处的耦合电流联系在一起,由此完善了传统的电流连续性方程.然后将TDIE方法与电路仿真方法——改进的节点分析法相结合,并通过广义基尔霍夫电压定律将电路中节点的电位与电磁结构上接口处的电位联系在一起.采用这种方法求解场-路混合问题,不需要生成端口模型,而直接求解场-路耦合方程.最后通过传输线算例证明了方法的正确性.     

对动态奇异电路的初始值问题的研究

在动态电路的时域分析中,若要解出描述电路的微分方程或状态方程,首先必须知道电路的初始状态。可是对含有纯电容回路和纯电感割集的奇异电路,在“换路”瞬间其初始值有可能发生跃变现象,不能用换路定则来求解。文章对此类电路中的初始值进行了详细的分析。通过深入探讨,给出了奇异电路中电容电压和电感电流初始值的确定方法,并给出了几个应用实例。     

脉冲放电回路电感的计算

脉冲功率技术广泛用于科学研究、军事、医学及工业等方面。脉冲放电电路为脉冲功率技术的主要研究对象,以高电压、大电流、高功率为特点。电路电感是脉冲放电电路的一个主要关注点,计算机仿真技术(CST)软件为快速计算电路电感提供了一种方法。根据导线间的磁场分布推导了导线电感的理论公式,分析了导线半径及导线间距对电感的影响;分析了基于脉冲放电电路电流波形迭代求解电路电感方法;最后利用CST建模计算了不同电路的电感。将CST计算电感与基于脉冲放电电路电流波形迭代求解的电感做对比,CST可用于辅助分析脉冲放电电路。     

BLT—FDTD 时频结合分析传输线瞬态响应

将频域BLT 方程与FDTD 方法结合起来对包含非均匀线缆的耦合传输线时域响应进行了分析。该方法将非均匀部分线缆从传输网络中独立出来,采用FDTD 离散进行时域分析,然后变换到频域与BLT 方程混合求解整个线缆网络的电压、电流响应。一方面避免了用单一的时域有限差分算法对传输网络进行整体离散时所带来的高计算量、高内存占用比问题;另一方面将非均匀线段当成节点处理,为频域方法求解含非均匀线的传输网络响应,提供了一种新的思路。仿真结果也表明了该方法的有效性。     

耦合腔慢波结构的特性分析

计算耦合腔慢波结构特性的方法很多,但是直接计算还比较困难,主要是因为耦合腔复杂形状造成的。等效电路方法是一个非常有效的、快速计算耦合腔色散特性和无损、有损耗情况下各个耦合腔电压、电流分布的方法。损耗是通过在电路中引入与电感串联的电阻。时域分析有利于单一频谱和所有频谱的瞬态分析和开启瞬态分析。     

基本电子电路

TN701 95030465指数号筒截止频率的设计/钱明哲/l电声技术一1995,(1)一26~27 指数号筒,就是横截面积依指数规律变化的号简.文中介绍了指数号筒截止频率的设计步骤及参数计算.图1参2(北)-用拉普拉斯变换分析动态网络/宋文玉,郭根生(山东师范大学)刀曲阜师范大学学报(自然科学版)一1994.20(4)一76~78 给出在完成电路的时域模型到复频域模型变换后,如何用拉普拉斯变换求解动态网络,图3参3(南)丁入701’95030466电压棋式与电流模式电路中的对偶原理及其应用/肖高标(湖南大学)II湖南大学学报一1994,21(6)一51~56 从节点电压KCL方程和回路电流…     

交错并联Buck中耦合电感的设计

针对开关电源系统对功率密度等级不断提高的要求,为进一步发挥交错并联技术的优势,本文以减小输出电流纹波和改善动态特性为目标,对大占空比条件下交错并联Buck电路中的耦合电感进行了详细分析和计算。通过软件仿真验证,得出了耦合系数和占空比对电路性能的具体影响,耦合系数的取值应尽量接近-1,从而为耦合电感的设计提供了理论依据。     

A resetting algorithm for transient analysis of coupledtransmission line circuits

The numerical inversion of the Laplace transform has been used as an important tool for time domain analysis of high speed VLSI interconnects modeled by transmission line networks. In this paper, a resetting algorithm based on the numerical inversion of Laplace transform with Pade approximation is described. The initial conditions of coupled transmission lines required by the resetting algorithm are also derived. The new method results in substantial improvement of the accuracy of the numerical inversion of Laplace transform for solving transmission line networks with long transients. The new method also bridges the gap between two types of circuit simulation techniques, i.e., the numerical inversion of Laplace transform and the numerical integration     

介观耗散耦合电感电路的量子涨落

从有源耗散耦合电感电路的经典运运方程出发,通过三个么正交换实现了哈密顿量的正则变换,给出了相应的变换矩阵,计算了真空态下介观电路中电荷和电流的量子涨落。     

Sinusoidal current-controlled oscillator

A sinusoidal oscillator whose frequency is linearly related to an input control current is described. A variable inductor is realised using a fixed inductor and a variable-gain current-controlled current source. The variable inductor is then used in an LC oscillator circuit. Linear frequency variation with control current is obtained in a temperature-independent manner by using a function generator. Frequency variation over a range of 1:3 is obtainable, with a linearity of better than 1%.     

Lossless Inductor Current Sensing Method With Improved Frequency Response

The lossless inductor current sensing method is well-known and is frequently applied in the measurement of output current in DC-DC converters due to its low cost and simplicity. This technique uses a low-pass filter that is matched to the inductance (L) and winding resistance to compensate for induced voltages due to the inductor. However, the waveform fidelity above the corner frequency of the inductor is generally poor due to large production tolerances and thermal drift. In this letter, we propose the use of a coupled sense winding, which increases the corner frequency of the sensing circuit by more than two orders of magnitude. We show, as an example, that for a 3.85 muH inductor the corner frequency of the measurement circuit can be increased from 36 Hz using the conventional approach to 5.8 kHz using the coupled sense winding method. Above the new corner frequency, a low-pass filter is still required but may now be constructed using a smaller capacitor and with improved high-frequency response.     

Single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor

A single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor is proposed. The proposed power-factor-correction circuit can achieve unity power factor and ripple-free input current using a coupled inductor. A saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. The proposed ballast has high energy efficiency, low cost, and high reliability compared to the conventional high-power-factor electronic ballasts. Experimental results obtained on a 30-W fluorescent lamp is discussed.     

A new approach to the modeling of converters for SPICE simulation

An approach to the modeling of DC-DC converters for SPICE simulation is developed in which the average current in the energy-storage inductor is first simulated in a SPICE subcircuit for both the continuous and discontinuous modes of operation. The inductor current is then weighted and redistributed to related branches of the circuit to simulate the average input and output currents of the converter. Based on this technique, various converter models, including that of the Cuk converter with coupled inductors, which are valid for both continuous and discontinuous modes of operation, are developed     

Fast computer-aided simulation of switching power regulators basedon progressive analysis of the switches' state

A new method for time-domain analysis of power electronics circuits is developed based on the following principles: (a) at each instant, the switching topology is a linear time-invariant circuit; (b) at each instant, the voltage across a capacitor and the current through an inductor have a certain value, like an independent voltage- or current source, respectively; (c) generally, no switching relationship between the externally and internally controlled switches may be assumed; (d) prior knowledge of the internally controlled switches' operation is not available; and (e) the switching action may change the response of the circuit immediately after the switching moment, implying that some constraints may be in violation of the presumed switches' states. The algorithm is based on solving a system of algebraical modified nodal equations at each integration step. The number of systems to be solved equals the number of topologies the converter goes through in a cycle. This feature, and the fact that no solutions of time-differential equations or Laplace transform inverses are required, cause the algorithm to be a fast one. At each step, the presumed state of all the switches is checked, and if some constraints are violated, the program looks for another valid topology. An example, with parasitic effects taken into account, is presented; the experimental results, as well as the simulation results obtained by using other available algorithms, confirmed the accuracy of the results achieved with the presented approach     

SPICE transient analysis errors estimated in frequency space

Comparison of the circuit simulator SPICE numerical integrator Z transform with the original system Laplace transform reveals that the trapezoidal method causes only frequency wrapping, while the Gear method generates frequency and amplitude errors. A universal expression for the magnitude of the Gear method error is derived. The theoretical analysis is tested by an example     

Improved power flow control for contactless moving sensor applications

An improved power flow control method for contactless moving sensor applications is proposed. The method allows the design of a system where sensors with different power ratings or a wide range of load variations can be implemented. A phase-controlled variable inductor is used to tune the resonant circuit of the power pickups of an inductively coupled power transfer (ICPT) system according to the actual power requirements of the sensors, thereby, helping to reduce the power losses without affecting the maximum power transfer capacity. Soft switching is achieved in the variable inductor control, and the effect of the equivalent tuning parameters on the power flow is analyzed theoretically. Simulation results show that a significant improvement of the existing controllers is achieved at no load or very lightly loaded conditions.