峰值电流模式非理想Boost变换器建模

应用能量守恒法建立了非理想Boost变换器的小信号模型,在该电路拓扑结构的基础上引入了峰值电流模式控制,并进一步推导出含有斜坡补偿的情况下电路等效功率级的精确模型,该模型具有更高的精度;然后以峰值电流模式Boost变换器为基础,针对该电路存在的缺点设计了电压控制器补偿网络,使得补偿后的系统具有更好的稳定性,并通过MATLAB软件仿真验证了该方案的优点和利用价值.     

基于推挽拓扑的输入并联输出串联直流变换器及其输出均压控制策略分析

在输出高电压场合,将较低的输入直流电压变换为较高的直流电压输出。输出端由于存在高压使得输出端器件承受较大的电压应力,存在变换器次级电压偏高、整流二极管电压应力大以及反向恢复时间长等问题。 基于此问题,提出以推挽变换器为基本单元,采用多个基本单元推挽变换器构成的输入串联输出并联变换器。为了确保该变换器系统的稳定可靠,从能量守恒的角度出发,分析了该变换器中各模块的输出均压之间的关系,给出了输出均压的实现条件。通过建立系统小信号模型,推导出系统的稳定条件,最后经试验验证了理论分析的正确性。     

CCM模式下非理想Buck变换器的建模与仿真

首先运用能量守恒原理将非理想型Buck变换器进行理想化转换;然后,就转换后的电路根据开关网络平均模型法建立平均变量模型,从而得到Buck变换器的大信号平均等效电路、直流等效电路和交流小信号等效电路,进而进行稳态和动态小信号特性分析;接着在此基础上,设计补偿网络,实现闭环控制;最后借助MATLAB软件进行仿真,与补偿前的仿真图形进行比较分析得出结论。     

谐振开关电容变换器的潜电路特性

潜电路是一种潜伏在系统中的路径或状态,仅在特定的条件下产生,使系统出现非期望的功能.本文以一个降压式谐振开关电容变换器为例,详细分析了潜电路出现时变换器的工作过程,利用电路能量守恒定理推导出变换器的潜电路特性以及潜电路发生条件.得到潜电路出现后,变换器的输出电压不再保持恒定,而是与电路参数、运行条件等密切相关,呈现出非预期特性的结论,并用实验结果加以证实.     

基于耦合电感高增益Buck-Boost变换器小信号建模

基于耦合电感的高增益变换器在新能源发电和直流微电网中均有良好的应用前景。论文在分析基于耦合电感的高增益升降压(Buck-Boost)变换器工作原理的基础上,采用开关流图法建立变换器的模型,详细推导了变换器的稳态模型和交流小信号模型;电力仿真(PSIM)软件对变换器小信号模型的仿真结果证明论文模型的正确性。论文结果对高增益DC/DC变换器控制回路的设计具有较高的参考价值。     

DC/DC变换器稳态建模的教学方法

本文介绍了一种为DC/DC变换器建立稳态模型,并利用稳态模型分析变换器的稳态工作特性的教学方法和研究思路。本方法所建模型既可以体现变换器的DC/DC变换功能,又可以包含变换器在稳态工作时的主要损耗。模型结构简单,运用简单的电路分析方法,就能够较为简便地得出直流变换器稳态工作时的主要电气特性。本文所介绍的建模方法是研究直流变换器稳态工作特性的有力工具,在教学研究中都具有较高的推广价值。     

Buck变换器的分数阶仿真模型与混沌分析

基于电感和电容本质上是分数阶的事实,基于分数阶微积分理论结合改进的Oustaloup分数阶微积分滤波器近似算法,在Matlab/Simulink下建立了电流连续模式下的电压控制型Buck变换器的分数阶数学仿真模型和对应的电路仿真模型,通过仿真验证了该模型的正确性。基于建立的分数阶数学仿真模型研究了很少有文献研究的以参考电压和比例放大系数作为混沌控制变量的Buck变换器的混沌行为,得到了分别以参考电压、比例放大系数为变量的Buck变换器的V-I混沌相图。此模型可以对电压控制型Buck变换器的所有能导致混沌行为的7种情况进行仿真分析,利用此模型仿真分析了Buck变换器的阶数对系统动态响应过程的影响。该模型的建立方法也适用于其他DC/DC变换器的分数阶模型的建立。     

一种基于双环控制的S-FB-ZVS-PWM变换器研究

提出采用三端PWM开关模型法建立PS-FB-ZVS-PWM变换器的平均电路小信号模型。分析并推导出PS-FBZVS-PWM变换器的传递函数,设计了电流内环功率外环的双环控制算法,并分析了基于双环控制的开环传递函数幅频和相频特性,最后通过PSIM仿真软件搭建了变换器的仿真模型。实验结果验证了基于双环控制的PS-FB-ZVS-PWM变换器可以很好地实现对输出功率的控制。     

基于动态相量法的PWM DC/DC变换器的建模与分析方法

文章从动态相量的概念以及基本性质出发,推导了动态相量法应用于PWM DC/DC变换器建模与分析的数学方法。首先介绍了纹波的计算方法,引入了选择模式分析法对PWM DC/DC变换器动态相量模型进行简化,建立了小信号模型,并以PWM BUCK/BOOST双向DC/DC变换器为例,用MATLAB软件建立了PWM DC/DC变换器的动态相量模型,将之与时域仿真模型进行了比较,验证了该方法的有效性。     

平均电流控制型PFC Boost变换器中的低频分岔现象研究

在设计和分析平均电流控制型功率因数校正(PFC)Boost变换器时,通常假设其工作在电流连续模式下,而采用电流连续模式下的平均模型分析变换器的动力学特性.而实际的变换器可能工作在电流断续状态,当变换器负载较小时,电流断续状态更加明显.因此,采用电流连续状态下的平均模型无法准确描述变换器的特性,尤其是混沌和分岔现象.本文采用考虑电流断续工作状态的状态空间模型,对PFC变换器中的低频分岔现象进行了分析,得到了低频分岔图,使该变换器由倍周期分岔到达混沌的路径更加清楚,使人们可以更全面理解这种变换器的动力学行为.并从分岔的角度分析了变换器的稳定性.其结果表明,变换器的输出电容和负载对变换器的稳定性具有很强的影响.通过给出的参数分岔图和二维参数与稳定性的映射图,为更好地设计变换器提供了指导.仿真分析结果和实验结果表明了本文所提方法的合理性和结果正确性.     

Conservation principles for plasmas and relativistic electron beams

Many useful conservation theorems are derived for relativistic electron beams and anisotropic plasmas. All these theorems are valid for confined-flow and irrotational-flow devices, and cold, collisionless plasmas. All the theorems are derived in a similar way, and a generalization of this method, using linear operators, is given. Among the power theorems discussed are: Tonks' theorem, the instantaneous and sinusoidal small-signal theorems, the energy theorem, a large-disturbance theorem, the Manley-Rowe formulas, an ac power theorem, and a cross-correlation theorem. Contributions to power and energy from surface waves are included. Allowing for relativistic flow and writing all equations in the laboratory frame does not significantly complicate the theorems, and in fact clarifies them somewhat. Many simple applications are discussed, although not in detail. Among these are: small-signal energy, power, and passivity; energy velocity in electron beam and plasma wave-guides; and a conservation theorem for multiple electron beams and electron beam-plasma interactions.     

Modeling and small-signal analysis of controlled on-time boostpower-factor-correction circuit

A large-signal average model for the controlled on-time boost power-factor-correction (PFC) circuit is developed and subsequently linearized, resulting in a small-signal model for the PFC circuit. AC analyses are performed using the small-signal model, revealing new results on the small-signal dynamics of the PFC circuit. The analysis results and model predictions are confirmed with experimental measurements on a 200-W prototype PFC circuit     

Implementation of a DSP-controlled photovoltaic system with peakpower tracking

Photovoltaic systems normally use a maximum power point tracking (MPPT) technique to continuously deliver the highest possible power to the load when variations in the insulation and temperature occur. It overcomes the problem of mismatch between the solar arrays and the given load. A simple method of tracking the maximum power points (MPPs) and forcing the system to operate close to these points is presented. The principle of energy conservation is used to derive the large- and small-signal model and transfer function. By using the proposed model, the drawbacks of the state-space-averaging method can be overcome. The TI320C25 digital signal processor (DSP) was used to implement the proposed MPPT controller, which controls the DC/DC converter in the photovoltaic system. Simulations and experimental results show excellent performance     

Effect of carrier injection into MESFET substrates : comparison of MESFET on a semi-insulating buffer,MESFET on a P substrate,and substrate-less MESFET

The carrier injection from the active-layer of the submicron-gate-lengthMesfet into the buffer-layer, or substrate in general, is studied by means of a two-dimensional computer simulation in which the energy conservation equation is simultaneously solved with the carrier conservation equation and Poisson’s equation. The mobility, electron temperature and energy relaxation time are treated as energy dependent parameters. This model is capable of simulating the non-stationary conditions associated with the submicron-gate-length devices. The effect of the carrier injection on the I-V characteristics as well as on the small-signal parameters is investigated by simulating twoMesfet structures; the first is aMesfet on a perfect buffer-layer while the second is a symmetricalMesfet which has no substrate. It is found out that the drain current is increased by the carrier injection, whereas the transconductance is reduced due to the increase of the device dynamic range. TheMesfet with an interfacial potential barrier is also simulated. It exhibits characteristics intermediate between those of the other two devices.     

磁约束放电CO激光模型的研究

建立了磁约束放电 CO激光的模型。在该模型下分析、计算了 CO气体放电系统电子的能量分布函数 ;CO分子的电子碰撞激发速率 ,CO分子各振动态的布居数分布和对应的小信号激光增益系数。研究表明 ,由于磁场的加入 ,在对应 CO分子振动态电子碰撞激发截面的能量范围内电子数有较大的增加。CO分子的电子碰撞激发速率提高。CO分子各振动能级均获得更大的布居数和激光小信号增益。     

TOM3 capacitance model: linking large- and small-signal MESFETmodels in SPICE

Improved accuracy in the modeled gate capacitance of GaAs metal-semiconductor field-effect transistors (MESFET's) is obtained in SPICE using conservation of charge in an implanted layer. The gate junction creates a natural partition between mobile and fixed channel charges. Relating the gate charge to the channel current creates gate capacitances dependent upon the channel current derivatives linking the small-signal model to the large-signal equations. Results are illustrated using a depletion-mode MESFET     

Small-signal and transient analysis of a full-bridge, zero-current-switched PWM converter using an average model

This paper presents a detailed small-signal and transient analysis of a full bridge zero-current-switched (FB-ZCS) PWM converter designed for high voltage, high power applications using an average model. The development shows the model follows directly from the converter's steady-state analysis and is produced by inspection of the converter's instantaneous waveforms. The method used in model development can be extended to other topologies that are not easily modeled by conventional methods. The derived model is implemented in a PSPICE subcircuit and used to produce the small-signal and transient characteristics of the converter. Results obtained in the analysis of the high voltage and high power design example are validated by comparison to the actual, switched-circuit simulations.     

Electrodynamics of rotating relativistic electron beams

On the basis of the Minkowski formulation, this paper discusses the basic laws governing the small-signal fields propagated along an electron beam which is rotating around its axis with constant angular frequency of rotation and drifting in the axial direction at constant relativistic velocity. In the first preliminary section are described the dc conditions for getting a stable relativistic electron beam in the presence of neutralizing ions with arbitrary number density and externally applied static magnetic field. Then, after a brief discussion of the ac-field equations, the constitutive relations for small-signal fields are obtained in both the laboratory frame, which is assumed to be an inertial frame, and the rest frame of the electron beam, which is not an inertial but a rotating frame. The rotating relativistic electron beam is found to be a nonuniformly moving dispersive medium or, more specifically, an inhomogeneous bianisotropic medium with space and time dispersion. With the use of the constitutive relations derived above, the following sections consider the energy and momentum for the small-signal fields, and their conservation relations, together with their transformation laws between the laboratory frame and the rest frame of the electron beam. Our discussion includes, as the special cases, all the important cases of an ion-neutralized or axially confined beam and the Brillouin beam.     

Equivalent circuit models for resonant and PWM switches

The nonlinear switching mechanism in pulsewidth-modulated (PWM) and quasi-resonant converters is that of a three-terminal switching device which consists only of an active and a passive switch. An equivalent circuit model of this switching device describing the perturbations in the average terminal voltages and current is obtained. Through the use of this circuit model the analysis of pulsewidth modulated and quasiresonant converters becomes analogous to transistor circuit analysis where the transistor is replaced by its equivalent circuit model. The conversion ratio characteristics of various resonant converters and their relationship to a single function, called the quasi-resonant function, is easily obtained using the circuit model for the three-terminal switching device. The small-signal response of quasi-resonant converters to perturbations in the switching frequency and input voltage is determined by replacing the three-terminal switching device by its small-signal equivalent circuit model