JFET高精度可变电阻器的设计及其应用

根据JFET线性区漏源之间沟道电阻受栅源电压控制的机理,推导JFET电流公式,对可变电阻的性能进行了分析。通过PSpice软件仿真了JFTT压控可变电阻,提出了改善JFET可变电阻非线性及扩展电阻动态范围的方法。结合单片机和D/A转换器,利用该方法设计了程控JFET可变电阻,其阻值范围为75.703~141.004Ω,分辨率低于0.025Ω,满足了自动气象站信号模拟器温度通道所需电阻阻值范围80.305~130.894Ω及分辨率低于0.03Ω的要求,为数据采集器温度通道的检定提供标准的可变电阻信号。     

基于OrCAD/PSpice9的电路优化设计

提出了基于OrCAD/PSpice9的电路优化设计方法,介绍了OrCAD/PSpice9的特点,通过实例借助于计算机来完成数据处理、模拟评价、设计验证等工序,实现电子系统或电子产品的整个或大部分设计过程,并说明了基于OrCAD/PSpice9环境下的电路优化设计过程。     

基于PSpice的MAXIM集成IC的接口仿真分析

Spice I/O宏模型有助于理解系统中可能存在的信号反射和阻抗匹配问题。对于大多数Maxim的高频/光纤通信IC是通过利用电流模式逻辑(CML)、正射极耦合逻辑(PECL)或低电压差分信号(LVDS)输入、输出电路来传输数据的。因此可通过PSpice语言建立IC的电路模型,用理想的受控电压源和电流源替代有源电路元件。并使用spice宏模型仿真,以检验电路芯片接口设计的性能。     

EAST-NBI抑制极电源IGBT串联技术的研究

中性束注入器(Neutral Beam Injector,NBI)是东方超环(Experimental Advanced Superconducting Tokamak,EAST)核聚变实验装置辅助加热的重要组成部分。目前NBI离子源引出系统采用四电极结构,即加速电极、梯度电极、抑制电极和地电极。抑制极电源是为其中的抑制电极提供负电位的高压直流电源。根据抑制极电源输出特性的要求,输出端采用串联绝缘栅双极型晶体管(Insulated Gate Bipolar Transistor,IGBT)作为调制开关。为研究IGBT串联技术对均压效果和抑制极电源输出特性的影响,采用PSpice软件对IGBT开关进行了建模,并进行了不同电路参数下的仿真。仿真表明:一定条件下,电阻电容二极管(Resistance Capacitance Diode,RCD)缓冲电路中电容参数对动态均压效果和电源关断特性具有决定性影响,缓冲电阻影响电容的放电时间及放电电流峰值。最后给出了相应的实验测试结果。该研究结果可以明确缓冲电路参数与均压效果以及抑制极电源开关特性之间的定量关系,为抑制极电源开关特性的进一步优化及其与加速极电源的特性匹配提供数据指导,对于NBI离子源的安全稳定运行具有重要意义。     

可用于片上集成的绝对值电路

系统中绝对值电路含悬浮二极管,阻碍了片上集成.为此,另辟蹊径用运放构成无二极管绝对值电路.PSpice仿真表明,运放OPA365构成的无二极管绝对值电路与理想电路输出电压的幅值误差较小,最大仅为0.7%;在零电平附近的幅值误差<12 mV,相位误差可略.因此,内部结构合理的轨到轨运放构成无二极管绝对值电路,其幅值误差可望<0.7%.其片上集成后,可用于笔者"AC-AC变换" 项目及电气测量.     

DC–AC switching converter modelings of a PV grid-connected system under islanding phenomena

Nonlinear modeling of a dc–ac full-bridge switching converter PV grid-connected system under islanding phenomena is proposed. It is a model that can be easily derived by using simple analytical techniques. A state-space averaging technique (no linearization) and voltage source inverter with current control are performed as “large-signal modeling” that is used to analyze the dynamic response of load voltage under 3 different resistive loads: 125%, 100% and 25% of inverter output and RLC when the grid system is disconnected as well as a step change of load. The nonlinear equation from the proposed modeling is handled by MATLAB/SIMULINK. The results of the proposed model are compared with experiments and PSpice simulation which shows good agreement among them. Moreover, it is found that the proposed model consumes much less computation time than PSpice and does not encounter any convergence problem.     

Equivalent circuit elements for PSpice simulation of PEM stacks at pulse load

The PEFC stack in a commercial power system was operated with room air and pure hydrogen. After the system reached a steady temperature, an ac impedance test was conducted on the fuel cell power system. The impedance data were real-time response generated by the ac sinusoidal excitation. Data for a single PEM stack and PEM stacks operating in parallel and series were collected with or without an embedded system controller board and electronic devices. The equivalent circuit model with three time constants and the non-linear least square fitting program (NLLS) were applied for fitting the stack impedance spectrum. The Levenberg–Marquardt algorithm utilized in the NLLS fitting process automatically adjusted the parameter values of the physical elements in the model to find the best fit result. From the preliminary results, data interpretation and the equivalent circuit model identified the physical elements, the related electrochemical processes, and the phenomenon inside the fuel cells or stacks. Losses from ohmic conduction, anode activation, cathode activation, and mass transfer were separated and analyzed. Further PSpice simulation curves using these equivalent circuit elements demonstrate good agreement with the pulse testing data measured from the PEFC power system.     

一种高频动态磁滞回线的PSpice电路模型研究

根据Jiles-Atherton铁磁磁滞理论和Hammerstein结构宏模型提出了一种高频动态磁滞回线的PSpice电路模型.将二阶低通滤波器插入Jiles-Atherton数学模型的等效PSpice电路中,追踪磁滞回线随频率的变化,近似地模拟高频动态磁滞回线.经实验论证,用该PSpice电路模型仿真所得磁滞回线与实...     

OrCAD PSpice在模拟电子技术教学应用中的实践

讨论了传统模拟电子技术教学和实验设计的现状,以双极性结型晶体共射极放大器为例子,对OrCAD PSpice仿真技术在模拟教学中的应用进行了探讨。基于OrCAD PSpice仿真技术在很多方面能弥补传统教学的不足,指出先进的模拟电路仿真技术对于模拟电子教学具有重要意义。     

计算机仿真在科研与实验教学中的应用

本文分析了计算机仿真技术在教学、科研、产品设计与制造等方面的应用。介绍了专业电力电子电路仿真软件PSpice,以Cuk变换器为例详细分析了瞬态响应的各种情况。分析了开发仿真性实验的必要性。最后给出了结论。