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。     

基于能量守恒平均模型的开关变换器建模

文中介绍了一种常用的开关变换器建模方法——能量守恒平均法,依据能量守恒平均原理,建立连续模式下Buck变换器的直流和小信号模型,并给出开环传递函数。仿真分析表明,该模型能够准确描述变换器的频域特性,验证了理论推导的有效性。     

基于有效占空比的ZVZCS全桥变换器建模与仿真

分析了零电压-零电流开关(ZVZCS)全桥脉宽调制(PWM)变换器的工作原理,引入变压器副边电压有效占空比的概念并考虑电路元件的寄生参数,在Buck变换器的PWM开关等效模型的基础上,建立了ZVZCS全桥软开关变换器的小信号等效模型,该方法通用于任何可以计算出有效占空比的全桥变换器.通过对小信号传递函数的幅频和相频特性...     

CCM模式Boost开关变换器的非线性建模和仿真

在开关元件平均模型法的思想基础上,提出了一种工作在连续电感电流模式下的DC-DCBoost(升压)变换器模型。考虑开关电阻、电感电阻及纹波寄生参数的影响,推导出理想与非理想传递函数。对其开环传递函数进行仿真和比较后可以发现考虑电感纹波的模型与实际更加接近,精度更高。     

连续导电模式下单电感多输出变换器的分析与设计

介绍了共模峰值电流型控制输入半桥(主级环路),差模电压型控制输出半桥(次级环路)的BUCK型SIDO(Single Inductor Dual Output)变换器的工作原理.利用开关元件平均法,建立了BUCK型SIDO功率级的小信号模型.并根据峰值电流控制模式、电压型控制模式的工作原理,建立了SIDO控制环路的小信号模型,最终得到连续导通模式下整个系统的小信号模型.在0.18 μm CMOS工艺下完成了SIDO变换器的电路设计,利用Spectre中的PAC (PeriodicAC)分析对所建的小信号模型进行了验证,并对SIDO变换器的性能进行了仿真验证.     

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.     

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。     

基于开关流图法Cuk型DC/DC变换器小信号建模

Cuk变换器具有输入与输出电流纹波低、能量双向流动等优点,在新能源发电和直流微网中具有良好的应用前景。在分析变换器工作原理的基础上,分别建立导通和截止状态的开关流图;引入以乘法器描述的开关支路模型,推导变换器在整个开关周期的开关流图;对开关支路施加扰动,提取变换器的小信号模型,并应用梅森公式计算变换器的传递函数。采用PSIM软件对变换器小信号模型进行仿真,结果证明了模型的正确性,本文方法对高阶开关变换器建模具有较高的参考价值。     

峰值电流模式的移相半桥三电平DC/DC变换器闭环系统建模研究

半桥三电平变换器拓扑解决了PFC技术带来的功率管应力过高问题,非常适合于大功率高压输出场合,峰值电流模式采用电压外环,电流内环的双环控制,是开关电源闭环系统最实用的控制模式.对移相半桥三电平DC/DC变换器进行了小信号建模分析;建立了峰值电流内环和电压外环的小信号传递函数,在此基础上给出了峰值电流模式的移相半桥三电平变换器闭环系统结构图,推导出相关闭环传递函数;给出了补偿网络参数设计步骤;对建立的双闭环系统模型进行了MATLAB仿真,结果表明经过补偿后的闭环系统具有满意的性能指标.     

带CLC滤波的反激变换器小信号建模与控制研究

为满足大型激光陀螺仪(ring laser gyroscope, RLG)中激光器激励源输出高精度、高稳定度的要求,针对单端反激变换器输出性能较差的问题,本文在传统反激变换器的输出端增加电感、电容元件,构成了输出带电容-电感-电容(capacitor inductor capacitor, CLC)滤波的单端反激变换器。在此基础上,采用开关元件平均模型法确定该变换器的静态工作点,建立电流连续模式(continuous conduction mode, CCM)下的四阶小信号模型;推导出相关传递函数,并引入相位超前校正环节以提高系统的稳定性;借助MATLAB软件构建比例-积分-微分(proportion-integral-differential, PID)控制的系统模型,完成了对带CLC滤波的反激变换器的分析与验证。结果表明,利用小信号建模理论建立的变换器模型是合理的,对激光器激励源的优化设计有参考意义。     

Interpreting small signal behavior of the synchronous buck converter at light load

The pulse-width-modulation (PWM) buck converter with synchronous rectifiers operating at light load is usually modeled by its continuous conduction mode (CCM) model. However, the actual power-stage small-signal control-to-output response shows a different behavior from what the traditional CCM model predicts, specifically, more damping around the double-pole frequency, instead of more resonance. This paper presents a modified small-signal light-load model for a synchronous buck converter. The developed model accurately predicts the actual small-signal behavior of a PWM converter at light load. The derived averaged switch model for light load can also be used for the small-signal models of the other basic PWM converters operating in CCM at light load.     

基于高开关频率精确模型的峰值电流型BUCK电源的补偿设计

针对工作在高开关频率的连续导电模式的峰值电流型BUCK电压源,建立了包含功率管导通电阻和寄生参数的精确小信号模型,设计一个新颖的电压环路的补偿模块,优化了瞬态响应。补偿模块仅增加一个极点,消除输出电容寄生电阻引入的零点。在此补偿模块基础上,分析了输出电压Vo对参考电压Vref的传递函数的频率响应,和补偿模块直流增益之间的关系,得出了补偿模块的最佳增益,使得输出电压对参考电压Vref的瞬态响应既快速又没有过冲和振荡,并且在Spice电路仿真中得到验证。     

Implementation of zero current switch turn-ON based buck-boost-buck type rectifier for low power applications

A single-stage single-switch AC–DC integrated converter is proposed in this paper, as a tight DC voltage regulator with unity input power factor for the fundamental component of the input current. Proposed converter is formed by the integration of buck-boost configuration with a buck converter operated by a single switch. The buck-boost section of the proposed configuration is operated in current discontinuous conduction mode (DCM) to get unity input power factor at the supply terminals and the buck section is operated up to boundary current conduction mode (BCM). The features acquired by the converter operating in complete discontinuous conduction mode (DCM) are unity input power factor, zero-current turn-ON for the Switch, fast and good DC output voltage regulation with extensive conversion range and low voltage stress on the switch. Additionally, the intermediate capacitor voltage stress is independent of converter load variations and so the switch also is subjected to constant peak voltage stress. A comprehensive study is carried out to obtain the necessary design equations. A design model is implemented using simulation and hardware. The results confirm the performance of the proposed configuration.     

基于电路平均模型的ZVS移相全桥的小信号与暂态分析

介绍了ZVS移相全桥变换器的电路平均模型,在Simetrix仿真软件环境下实现了该电路平均模型,并做了小信号与暂态仿真分析。仿真实践证明,使用电路平均模型,仿真用时明显减少。文章最后给出了小信号和暂态仿真结果。     

Fractional order Buck–Boost converter in CCM: modelling,analysis and simulations

In this paper, the modelling, analysis and the power electronics simulator (PSIM) simulations of the fractional order Buck–Boost converter operating in continuous conduction mode (CCM) operation are investigated. Based on the three-terminal switch device method, the average circuit model of the fractional order Buck–Boost converter is established, and the corresponding DC equivalent circuit model and AC small signal equivalent circuit model are presented. And then, the equilibrium point and the transfer functions are derived. It is found that the equilibrium point is not influenced by the inductor’s or the capacitor’s order, but both these orders are included in the derived transfer functions. Finally, the comparisons between the theoretical analysis and the PSIM simulations are given for confirmation.     

A general unified large signal model for current programmedDC-to-DC converters

A general and unified large signal averaged circuit model for current programmed DC-to-DC converters is proposed. In the averaged circuit model, the active switch is modeled by a current source, with its value equal to the averaged current flowing through it, and the diode is modeled hy the voltage source, with its value equal to the averaged voltage across it. The averaged circuit model has the same topology as the switching converter. The large signal averaged circuit model for current programmed buck, boost, buck-boost and Cuk converters are proposed, from which the large signal characteristics can be obtained. The steady-state and small signal transfer functions of the current programmed DC-to-DC converters can all be derived from their large signal averaged circuit models. The large signal characteristics of the current programmed buck converter are studied by both the phase plane trajectory and the time domain analysis. Experimental prototypes for a current programmed buck converter, with and without an input filter, are breadboarded to verify the analysis     

PWM-switch modeling of DC-DC converters

The introduced PWM-switch modeling method is a simple method for modeling pulse-width-modulated (PWM) DC-DC converters operating in the continuous conduction mode. The main advantage of this method is its versatility and simple implementation compared to other methods. The basic idea is the replacement of the switches in the converter by their time-averaged models. These switch models have been developed in such a way that the converter model provides the same results as the state-space-averaging technique but not including nonlinear effects. Simple rules for determination of the switch models are obtained. The resulting model is a time-averaged equivalent circuit model where all branch currents and node voltages correspond to their averaged values of the corresponding original currents and voltages. The model also includes parasitics, second-order effects and nonlinearities, and can be implemented in any circuit-oriented simulation tool. The same model is used for the simulation of the steady-state and the transient behavior     

Analysis of RCD snubber based non-ideal Z-source inverter using average modelling approaches

ABSTRACT

Z-Source inverters (ZSIs) are one of the most promising single-stage power converters in modern industrial applications. However, these ZSIs exhibit non-minimum phase behaviour as a result of right half-plane (RHP) zero in the converter transfer functions and impose a constraint on the controller design. A detailed mathematical model of the converter plays a crucial role in the design of an efficient control strategy. This paper presents a detailed mathematical model of non-ideal ZSI using averaged modelling approaches and its comparisons are summarised. The pole-zero and step response plots reveals the impact of parasitic elements and parameter variations on system steady-state and dynamic performance. Finally, the effects are outlined, which gives a basic guideline to the designers in the converter performance optimisation such as the feedback control bandwidth, damping factor, resonant frequency, and overshoot/undershoot in the desired output. The sensitivity function is defined for a voltage gain of ZSI with respect to system parasitic elements and snubber parameters. In order to validate the theoretical analysis of converter dynamics, a laboratory prototype model of 50 watts ZSI is developed. Further, a hardware implimentation of PID-based capacitor voltage control is shown to check the effectiveness of the derived transfer functions on closed-loop performance.