基于Multisim 11的品质因数计算与仿真分析

品质因数Q作为描述谐振电路性能的一项重要参数,直接影响谐振电路的通频带和选择性等指标,因此对品质因数进行研究有助于准确理解电路的谐振特性。Q值定义有多种不同的表述方法,也可以从不同的角度计算Q值。在此从研究Q的物理本质出发,分别就Q的能量定义、电路固有参数、复杂谐振电路端口等效和电路选频性能等方面综合剖析品质因数的不同计算方法,揭示了各种方法间的联系及电路的储能或频率选择特性。最后结合Multisim 11仿真软件对工程中常用的RL-C并联电路中功率、电压与电流等参量进行交流分析和参数扫描分析,通过实例计算与仿真验证了公式的正确性。     

RLC串联电路谐振特性的Multisim仿真

基于探索RLC串联电路谐振特性仿真实验技术的目的,采用Multisim10仿真软件对RLC串联电路谐振特性进行了仿真实验测试,给出了几种Multisim仿真实验方案,介绍了谐振频率、上限频率、下限频率及品质因数的测试和计算方法,讨论了电阻大小对品质因数的影响。结论是仿真实验可直观形象地描述RLC串联电路的谐振特性,将电路的硬件实验方式向多元化方式转移,利于培养知识综合、知识应用、知识迁移的能力,使电路分析更加灵活和直观。     

谈谈谐振电路的教学

根据作者的教学经验，从电磁振荡的角度讲解谐振的物理意义，以能量转换的观点给出串联谐振和并联谐振电路的品质因数Q值统一定义，是提高谐振电路教学质量的有效做法。     

基于频率响应法的RLC串联电路参数的测量

本文通过频率响应法给出了RLC串联电路参数的测量方法.频率响应与RLC串联电路参数之间呈现非线性关系,通过变量代换得到了线性拟合模型,从而简化了求解过程.基于Multisim的仿真计算结果和基于实际测量的计算结果表明,本文方法作为RLC串联电路参数的测量方法简单可行.     

RLC串联谐振电路的实验研究

从RLC串联谐振电路的方程分析出发,推导了电路在谐振状态下的谐振频率、通频带、品质因数和输入阻抗,并且基于Multisim 10仿真软件创建RLC串联谐振电路,利用其虚拟仪表和仿真分析,分别用测量及仿真分析的方法验证它的理论根据。其结果表明了仿真与理论分析的一致性,为仿真分析在电子电路设计中的运用提供了一种可行的研究方法。     

电路品质因数的计算

在电路课程教学中,电路的品质因数Q是一个十分重要的概念,它有助于对电路特性的描述。本文对品质因数的定义、各种定义间的相互关系以及品质因数的计算方法等进行了讨论,并对品质因数的教学给出了教学建议。本文的讨论对电路课程的教学具有一定的参考价值。     

关于RL与C并联电路阻抗的最大值

在谐振电路中,教材[1]讨论了线圈RL与电容器C并联电路的谐振问题,给出了谐振时电路的阻抗模值最大等结论,但容易使学生产生误解。实际上,如果通过调节电源频率使电路达到谐振,谐振时电路的阻抗模并不是最大值,一般教材对此没有给出阻抗模的最大值。本文通过推导,给出了RL与C并联电路阻抗模最大值的精确表达式及阻抗模达到最大时电路的频率。     

基于模拟电感的图示均衡器实现与MATLAB仿真

本文对RLC串联谐振回路图示均衡器的电路原理进行了研究及MATLAB仿真研究,推导出RLC串联谐振回路图示均衡器提升量与衰减量等重要设计计算公式。提出了一种模拟电感的设计电路并推导出模拟电感的设计计算公式,为将模拟电感应用于研制制作图示均衡器打下了理论基础。     

基于MATLAB的负阻抗变换器的特性及应用的研究

采用实验的方法研究负阻抗变换器的特性及其应用,存在数据处理量大、特性曲线绘制困难等问题,设计出基于MATLAB的仿真实验方案。与传统的实验方法相比,MATLAB利用群元素计算特性,把多个频率分量及相应的电压、电流、阻抗等都看作多元素的行数组,每一元素对应于一种频率分量的值,因为它们服从同样的方程,所以程序就特别简洁;直接绘制电压电流的相向图、电流的幅频特性和相频特性,且定量地分析电路的性质。应用MATLAB设计出RLC并联谐振电路,其谐振频率、品质因数、通频带等参数的测试比传统实验测试更精确。     

关于谐振电路中能量问题的讨论

在谐振电路中,一般学生会认为电源所提供的能量全部被电阻所吸收,能量的互换只是发生在电感和电容之间.本文以RL与C并联谐振电路为例,给出了电路谐振时电感和电容中所储存的总能量随时间的变化规律,其电感和电容所储存的总能量并不是恒定值,因此认为谐振电路中,能量的互换只是发生在电感和电容之间的观念是错误的.     

General Treatment of Klystron Resonant Cavities

Klystron resonant cavities are treated for general cases and their equivalent circuits are theoretically determined, which allows a fairly accurate estimate of resonant properties. It is shown that a reentrant cavity is expressed as a low-frequency series LCR/sub se/ circuit or a shunt LCR/sub sh/ circuit, taking L as the inductance of a toroidal coil with one turn and with a cross section the same as the cavity, C as the gap capacitance plus the equivalent capacitance of the cavity, and R/sub se/ or R/sub sh/ as the equivalent series or shunt resistance of the cavity at resonance. The introduction of the equivalent cavity capacitance has proved to be very effective. The formulas derived here enable one to calculate the resonant frequency within an error of a few per cent and the shunt resistance and the Q within an error of several tenths of a per cent in most cases, and thus should prove to be very useful to the designer of microwave circuits.     

A new simplified model of the dynamics of the current-fed parallelresonant inverter

In this paper, the transient analysis of a current-fed parallel inverter, widely used in industrial applications (such as for the heating and melting of metals), is performed. A high-inductance smoothing inductor is usually connected in the input of the inverter and its load may be represented by a parallel resonant circuit characterized by high quality factor Q. To simplify the dynamic analysis of such an inverter, approximating it by a second-order switchless continuous dynamic link (i.e., RLC circuit) is suggested. The comparative analysis of the inverter and approximating circuit, whose parameters are properly chosen, shows the permissibility of such an approximation. It also shows how to assure desired aperiodic dynamic behavior. Then, by analyzing the approximating circuit, the expressions for inverter parameters are found. With these expressions, the values of a smoothing inductor, a compensating capacitance and a voltage factor, in order to ensure the aperiodic behavior of the inverter, can be calculated. The results of the proposed analysis were checked on laboratory and industrial prototypes of the above inverter. The theoretical and experimental results are in good agreement     

Experimental determination of finline post discontinuity parameters: application to stopband and lowpass filters

The shunt reactance of a finline post discontinuity is shown to be of resonant type. By using an experimental transmission procedure, we have determined accurately the parameters R, L and C of its equivalent circuit. These parameters, in the first approximation, can be considered as frequency-independent. Thus the use of the equivalent circuit in CAD is very easy. Applications to stopband and lowpass filters are described.     

Microwave circuit characteristics of bulk GaAs oscillators

The microwave circuit characteristics of bulk GaAs transit-time mode and limited space-charge accumulation (LSA) mode oscillators have been evaluated experimentally and theoretically. Experimental measurements were performed with a waveguide-coaxial microwave circuit having two experimental degrees of freedom in which the circuit radiation impedance at the device contacts was evaluated by a dyadic Green's function method. Experiments conducted in three rectangular waveguide circuits at fixed bias voltage have established that the LSA mode frequency tuning range is determined by the magnitude and variation of the circuit series inductive reactance XLrelative to the device low-field resistance R0. At a bias voltage which is twice threshold the tuning range is given by1/2.4leq X_{L}/R_{0}leq 2.4. No fixed, linear equivalent circuit characterizes the LSA mode. Analysis and experimental results indicate that the device impedance of small-signal transit-time mode oscillators changes from a passive parallel RC impedance well below threshold to an impedance just above threshold which can be approximated by a series RLC circuit. The series L and C decrease linearly with transit-time mode harmonic order number.     

波导阻抗带宽与缝隙导纳关系研究

本文从谐振阵等效网络出发,探索了缝隙波导谐振阵实现理想阻抗匹配的导纳特性,为波导谐振阵的超宽带设计提供了新思路.改进了波导并联缝隙的等效电路,首次实现缝隙导纳特性的单参数表征,创新提出了不同单元间距与单元数缝隙波导阵实现最大带宽的导纳特性分析方法,为波导缝隙阵带宽的优化设计提供了理论依据,建立了传统谐振阵非过载时的最大...     

Small signal equivalent circuit modeling of resonant converters

A general analytical procedure is presented for the equivalent circuit modeling of resonant converters, using the series and parallel resonant converters as examples. The switched tank elements of a resonant converter are modeled by a lumped parameter equivalent circuit. The tank element circuit model consists, in general, of discrete energy states, but may be approximated by a low-frequency continuous time model. These equivalent circuit models completely characterize the terminal behavior of the converters and are solvable for any transfer function or impedance of interest. With the approximate model it is possible to predict the lumped parameter poles and zeros, and to quickly determine the relevant DC gains of the output impedance and the control to output transfer function. Closed-form solutions are given for the equivalent circuit models of both converter examples. Experimental verification is presented for the control-to-output transfer functions of both series and parallel resonant converters, and good agreement between theoretical prediction and experimental measurement is obtained     

基于电压阀和电流阀模型的晶体管放大电路分析

依据已经提出的电压阀和电流阀两种非线性电路模型以及由电压阀和电流阀构造出的晶体管模型,进一步对各种晶体管放大电路进行了非线性模型等效,并在等效的模型电路基础上,研究晶体管放大电路的静态工作点计算方法、动态参数计算方法.该方法具有电路直观、概念清晰、分析计算准确等特点,而且能够判断出晶体管是否截止或饱和、动态工作范围大小等.