PWM开关DC-DC变换器的低频波动

为了揭示PWM开关变换器输出电压出现低频波动的规律，基于电感电流和输出电压包络的波动频率远低于变换器的开关频率的假设，建立了变换器中电感电流和输出电压包络的微分方程，并在s域进行分析，得出了变换器的闭环输出—输入电压传递函数，采用胡尔维茨稳定判据得出了变换器的稳定条件，分析结果表明：反馈环节的滞后是造成变换器输出电压出现低频波动的原因。采用零极点分析的方法确定了变换器低频波动的频率，利用变换器拓扑结构的约束关系，得出了变换器低频波动的幅值。采用SPICE仿真和实验的方法验证了理论分析结果的正确性。     

光伏发电接入直流配电网DC-DC变换器的仿真研究

光伏发出的电压较小且不稳定,不能直接接入配电网,需要通过相应的控制装置来实现电压的升高和稳定。为此,设计了升压型DC-DC变换器,采用全控型器件绝缘栅双极型晶体管(insulated gate bipolar transistor,IGBT)的控制电路,将最大功率点跟踪控制器的输出作为脉冲宽度调制(pulse w idth modulation,PWM)控制器的输入,PWM控制器输出占空比不同的矩形波控制IGBT的导通时间,从而实现变换器升压和稳压的功能。仿真结果表明,所设计的DC-DC变换器实现了光伏发电的升压和稳压,验证了所提控制方法的有效性和可行性。     

推挽型隔离DC-DC变换器软开关条件分析

电流型隔离DC-DC变换器具有电流脉动小的优点,有利于延长储能系统锂电池的使用寿命;同时,减小开关损耗是提高功率变换效率的关键技术之一.因此该文讨论利用电流型推挽隔离DC-DC变换器开关管的寄生电容进行谐振,满足开关管的软开关条件.首先分析变换器的增益特性和工作模态;其次基于变换器的等效电路模型,详细分析推挽型隔离DC-DC变换器的软开关瞬态过程,推导出变换器全部开关管软开关条件的参量表达式;最后通过仿真和实验结果验证了软开关条件的正确性.     

三管推挽双向DC-DC变换器电流应力优化控制*

为提高三管推挽双向全桥变换器运行效率,提出了一种峰值电流应力优化控制策略。首先,分析了TPBFC变换器扩展移相控制(Extended Phase shift Control,EPS)下的基本运行模态,推导了系统传输功率与峰值电流应力表达式。进一步,采用拉格朗日函数构建了变换器传输功率与峰值电流应力的约束模型,推导了各运行模态下满足峰值电流应力最小的移相比组合。在搭建的500 W样机上的实验表明,采用所提出的方法使变换器峰值效率提升了2%。     

高升压增益软开关DC-DC变换器

在软开关Boost变换器基础上,通过引入Flyback单元,提出了一种高升压增益软开关DC-DC变换器,进一步提高了变换器的电压增益,避免了高占空比,减小了开关管电压应力。因此,可选取低电压等级低导通电阻MOSFET以降低变换器的成本,提高变换器的效率。在开关管关断期间,漏感能量向负载传递,有效利用了漏感能量,且无需额外的吸收电路。此外,变换器实现了开关管的零电压(ZVS)导通和二极管的零电流(ZCS)关断,进而消除了开关管的开通损耗和二极管的反向恢复损耗。研究了高升压增益软开关DC-DC变换器电路的工作特性和占空比丢失的主要原因,分析了该变换器的元器件应力及电路损耗。设计了一台160W的实验样机,实验结果验证了理论分析的正确性。     

输出功率300W的12V-220V DC-DC变换器的实现

鉴于推挽逆变-全桥整流的DC-DC变换器具有磁芯利用率高、高效节能等优点,非常适合用来设计车载直流电源。详细分析和设计了一种额定输出功率300W的12V-220V DC-DC变换器,包括推挽升压工作原理、变压器初级无源无损吸收电路设计、高频开关变压器设计和基于CA3524的模拟控制电路设计,最后进行实验测试,给出了实测波形和不同输入电压和不同输出功率条件下整机效率曲线,总结出一些规律,并给予解释。实验结果表明,推挽逆变-全桥整流的DC-DC变换器各项指标良好,在输入端为低电压大电流场合具有明显优势,如车载电源。     

大功率DC-DC变换器的设计

针对DC-DC变换器应用于大功率输出储能系统的场景,提出应用基于降压-升压电路的多级交错并联拓扑结构.针对多台DC-DC变换器并联运行的场景,提出应用下垂控制技术.在此基础上,设计了大功率DC-DC变换器.通过测试验证,所设计的大功率DC-DC变换器满足大功率输出的要求.     

高升压比DC-DC变换器的研究

随着电力需求的不断增长,高升压比DC-DC变换器的需求也不断增大。提出了一种新型的高升压比DC-DC变换器,该变换器基于两个围绕LC电路的全桥结构使其工作在增幅谐振状态,实现电容电压导数为正,以此来达到升压的目的,而不需要变压器的参与。详细介绍了该变换器的拓扑结构,分析了该变换器的工作原理,对该变换器建立了数学模型,并给出了变换器的设计步骤,最后在Matlab/Simulink平台上搭建了仿真模型。仿真结果表明:所提出的升压DC-DC变换器将4 kV升压到80 kV,升压比达20,因此具有很高的升压比。     

基于DSP控制的ZVZCS型DC-DC变换器设计

本文设计了一款全桥ZVZCS型DC—DC变换器,给出了变换主电路的关键元器件的选型。该变换器以TMS320F2812为核心控制芯片,实现了电压电流双闭环调节控制,且具有输出过流、过压、以及功率管过热保护功能。仿真结果验证了ZVZCS的软开关工作模式。     

数字控制DC-DC变换器改进离散迭代建模和稳定性分析

离散迭代模型是一种能精确描述数字控制变换器特性的工具,然而传统的离散模型通常计算复杂而且不够直观,不利于控制器的设计。该文对离散迭代模型进行合理近似,推导出数字控制DC-DC变换器在前沿和后沿调制下的二阶全局等效电路模型,解决了传统模型直观性和精确性之间的矛盾。该模型可以反映具有不同脉冲宽度调制方法的DC-DC变换器的稳态和动态行为。在等效电路的基础上,分析了数字控制的特性,推导出了z域传递函数,从而得到了不同调制方式下控制-输出的频率响应,并且分析了两种调制方式对系统稳定性的影响。此外,等效电路模型可以准确地跟踪详细开关电路的工作波形,并且对系统参数变化时系统的稳定边界做出精确预测。最后,搭建了DC-DC变换器的样机,验证了模型和理论分析的有效性。     

Motor performance investigation of an indirect matrix converter with a reactor‐free boost converter

This paper describes a three‐phase power converter which utilizes the neutral point of an induction motor and demonstrates the performance of the motor using the proposed method under various operating conditions. Several motor test results, such as the speed–torque characteristic, the torque impact, and the acceleration–deceleration characteristic, are included to confirm the performance of the induction motor. The structure of the proposed circuit consists primarily of an AC/AC converter [indirect matrix converter (IMC)] and a boost converter connected to the neutral point of the induction motor. In addition, this paper also proposes a method to reduce the ripple found in the battery current. Several experimental results show that the motor works well, and even the leakage inductance is utilized in the boost converter. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于LLC谐振变换器的直流电源控制系统设计

基于LLC谐振变换器的直流电源,具有输出电压范围宽、效率高、体积小等优点,因此受到了青睐。首先分析了三电平半桥LLC谐振变换器的数学模型。在此基础上,设计了以数字信号处理器(DSP)为控制器的脉冲频率调制(PFM)控制系统。针对DSP处理器在闭环调频过程中易出现周期值和比较值装载时间不一致、导致电路出现异常振荡的问题,提出了特定区域内赋周期值和比较值的方法。最后,通过实验证明了该方法的有效性。     

家庭太阳能光伏系统中前级直流变换器的研究与设计

本文首先提出了家庭太阳能光伏系统的组成结构,详细分析了半桥型DC/DC变换器的工作原理;分析了电压控制型脉宽调制芯片SG3525的内部结构及其控制特性,并设计了基于SG3525的系统控制电路,实现了系统的电压电流双闭环控制。最后,通过实验对本系统提出的设计方案进行了验证。     

An asynchronous pulse width modulator for DC-DC buck converter

This paper presents an asynchronous pulse width modulation (APWM) approach for the analysis of a new class of the switched mode power supply (SMPS). The proposed APWM significantly simplified the mathematical analysis by utilizing a binary comparator (BAPWM) and a distinctive delay cell instead of hysteretic comparator. By this way, the mathematical analysis can be extended to study the behavior of high-order self-oscillating modulators in terms of key parameters such as the harmonic distortion and the stability. The performance of the proposed BAPWM is deeply analyzed for different orders of loop filters (here up to third order) in both time and frequency domain. To verify the effectiveness of the proposed analytical derivations, the BAPWMs are employed in a classic synchronous DC-DC buck converter and its closed loop performance, in terms of stability, has been investigated. Then the converter is designed and simulated in 130-nm CMOS technology to convert input voltage of 5 to 3.3 V with maximum load current of 1 A, using Spectre simulator. From the post-layout simulation results, the peak efficiency conversion efficiency for 3.3 V output voltage is higher than 89%.     

一种双PWM变换器新改进型直接功率控制策略*

为了解决双PWM变换器常规直接功率控制的电压外环响应速度慢的问题,提高控制系统跟踪性能,首先,设计了一种新型开关矢量表,在某些扇区由原来的一个矢量控制变为两个矢量控制,从而改善有功功率和无功功率的变化程度在不同扇区影响的差异性,增强灵敏程度和实时性;其次,提出电机侧功率向前反馈的控制策略,增设反馈网络,提高响应速度,确保功率给定,改变了常规电压外环缓慢的调整过程。并在功率波形、突加负载的响应速度、电网电流、谐波等方面,与常规直接功率控制进行了实验对比。实验结果表明,本文设计的控制系统能在负载变化时实现快速跟踪响应并恢复和保持稳态,验证了该策略的有效性。     

A new parallel ZVS converter with less power switches and low current stress components

A new direct current (DC)/DC converter with parallel circuits is presented for medium voltage and power applications. There are five pulse‐width modulation circuits in the proposed converter to reduce current stress at low voltage side for high output current applications. These five circuits share the same power switches in order to reduce switch counts. To reduce the converter size, conduction loss, and voltage stress of power semiconductors, the series connections of power metal‐oxide‐semiconductor field‐effect transistor (MOSFET) with high switching frequency instead of insulated gate bipolar transistor (IGBT) with low switching frequency are adopted. Thus, the voltage stress of MOSFETs is clamped at half of input voltage. The switched capacitor circuit is adopted to balance input split capacitor voltages. Asymmetric pulse‐width modulation scheme is adopted to generate the necessary switching signals of MOSFETs and regulate output voltage. Based on the resonant behavior at the transition interval of power switches, all MOSFETs are turned on under zero voltage switching from 50% load to 100% load. The circuit configuration, operation principle, converter performance, and design example are discussed in detail. Finally, experimental verifications with a 1.92 kW prototype are provided to verify the performance of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

Snubberless boost full-bridge converters: Analysis of soft switching performance and limitations

This paper analyses current-fed (current source) isolated dc-dc converters that are proposed for various renewable energy and dc microgrid applications, such as photovoltaic, fuel cell, or energy storage systems. The analysis addresses current-fed (boost) full-bridge converters that achieve clamping and soft switching without dedicated external auxiliary circuits, such as snubbers or clamps. Such converters have certain limitations that can lead to degraded performance and feasibility due to high circulating energy or low silicone utilization at some operating points. The current study reveals these limitations, highlighting advantages and drawbacks of selected snubberless converters at different operating conditions. The relation between the rms input current and the isolation transformer primary current as well as the cumulative rms current of primary semiconductors is used as figure of merit for converter characterization. This approach can be extended and applied to other topology types and used as a universal tool for performance assessment of snubberless converters without auxiliary circuits for particular operating conditions in various systems.     

基于TL494芯片的高效DC/DC变换器的研究与设计

本文针对一种新型的DC/DC变换器拓扑结构,采用电流控制型脉宽调制芯片TL494构成了变换器的控制电路。TL494芯片功能强,工作频率高,通过外扩简单的硬件电路即可实现输出电压电流的双闭环控制。实验结果表明,该系统效率高,动态性能较好。     

极低电压数字控制DC/DC变换器仿真研究及实现

数字化控制是开关电源的发展趋势.以同步整流的Buck电路为例,首先对电路进行了建模和设计,然后详细论述了数字控制中应注意的问题,并提出了定点仿真的概念,利用Matlab/Simulink进行了仿真.仿真结果表明,该数字控制Buck变换器具有良好的动态响应性能和稳态输出.最后,通过实验给予了验证.