Two‐switch flyback PWM DC‐DC converter in continuous‐conduction mode

The two‐switch flyback DC‐DC converter is an extended version of the conventional single‐switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single‐switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two‐switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed steady‐state analysis and design procedure of the diode‐clamped two‐switch flyback converter operated in continuous‐conduction mode (CCM). The power loss in each component of the two‐switch flyback converter is compared with those of the single‐switch flyback converters with and without RCD clamp, and is presented in a tabular form. The two‐switch flyback converter was bread‐boarded to validate the theoretical analysis. Experimental results from a 10 V/30 W, 100 kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright © 2010 John Wiley & Sons, Ltd.     

交错并联双管反激DC/DC变流器系统设计与实现

针对传统反激电路的一些不足,将交错并联技术用于双管反激电路中,具有工作频率高,输出纹波小,功率等级高等优点。本文分析了两路交错并联双管反激变流器的工作模式,采用开关平均法建立了电流断续模式(DCM)下的变流器小信号模型。详细论述了采用电流峰值控制和光耦隔离系统时,其反馈补偿回路的设计方法。最后通过一台100W实验样机,验证了工作模式分析和参数设计的正确性。     

反激式隔离型高增益DC/DC变换器

提出了一种反激式隔离型高增益DC/DC变换器.该变换器利用反激变压器的变比和开关电容来提高输出电压增益,满足输入输出的电气隔离.开关电容的引入,使得反激变压器副边绕组在开关管闭合时给倍压电容充电,在开关管断开时给负载供电,提高了变压器绕组的利用率,还解决了反激变换器输出二极管与漏感的谐振问题.由于变压器漏感的原因使得所...     

Two‐switch flyback PWM DC–DC converter in discontinuous‐conduction mode

The two‐switch flyback DC–DC converter is an extended version of the conventional single‐switch flyback converter. An additional switch and two clamping diodes serve as a simple, but an effective way to limit the switch overvoltages, which occur in the conventional single‐switch flyback converter due to the ringing of the resonant circuit formed by the transformer leakage inductance and the transistor output capacitance. The clamping diodes in the two‐switch flyback topology clamp the maximum voltage across each switch equal to the DC input voltage. This paper presents a detailed analysis and design procedure of the diode‐clamped two‐switch flyback converter operated in discontinuous‐conduction mode (DCM). A comparison of power losses of the two‐switch and the single‐switch flyback converters is given. The two‐switch flyback converter was bread‐boarded to validate the theoretical analysis. Experimental results from a 20‐V/30‐W, 100‐kHz laboratory prototype verified that the maximum switch voltage is limited to the DC input voltage. Copyright © 2010 John Wiley & Sons, Ltd.     

具有电压负反馈绕组的新型反激式单级功率因数校正变换器

提出一种具有电压负反馈绕组的新型反激式单级PFC变换拓扑。电压负反馈绕组的引入能够抑制中间储能电容电压,减小开关管的电压电流应力,解决了DCM PFC+ CCM DC/DC模式下轻载时,中间电容电压过高的问题,并且一部分输入功率将通过负反馈绕组直接传向负载,提高了变换器的效率。通过对电路工作模态和稳态的分析,可以得出该变换拓扑不仅具有较好的功率因数校正能力,还具有开关管电压应力低、效率高等优点。实验结果证明了该变换拓扑的优越性。     

全数字化双向DC/DC变换器的分析和设计

分析了电压和电流两种控制模式，基于电流模式提出一种具有恒压、恒流、恒功率控制等多种功能的控制器。详尽阐述了数字控制系统的采样速率、AD转换器位数、DPWM分辨率和开关频率的设计原则，提出了非同步采样检测方法。针对DC／DC变换器强的非线性、时变特性，提出一种新型变参数滞环PID调节器，改善系统稳定性。采用DSP-TMS320F243作为控制核心，设计了一台额定功率为5kW的双向DC／DC变换器装置。实验结果证明，系统性能优良，可有效用于电动汽车等领域。     

一种新型ESD电压发生器的设计与调试

针对静电放电(Electro-static Discharge.简称ESD)对芯片造成损伤的现象,研究了静电放电发生的过程及产生的原因.首先阐述了几种常见的模拟静电放电过程的模型,然后利用彩色电视机的一体式行回扫变压器作为直流高压源、串联SCR作为高压开关,设计并制作出符合IEEE Std C62,38-1994标准的ESD人体模型实验发生仪器,并对ESD人体放电模型中的body/finger模型进行了实验模拟.最后给出放电电压为4kV时测量的ESD电流脉冲波形,并与理想放电波形进行对比,其结果验证了该方案的可行性和易操作性.     

An active‐clamping zero‐voltage‐switching flyback converter with integrated transformer

This paper proposes an active‐clamping flyback converter using an integrated transformer. The proposed converter is composed of two active‐clamp flyback converters. The presented converter can balance the total load current between secondary sides of two transformers so that the rectifier diode conduction loss is reduced. Also, the main switch of one converter is the auxiliary switch for the other converter, so that only two switches are required and both can achieve zero‐voltage‐switching operation. The two transformers are integrated into one magnetic core; therefore, the volume and copper loss of transformer can be reduced. Detailed analysis and design of this integrated magnetic active‐clamping flyback converter are described. Experimental results are recorded for a prototype converter with an AC input voltage ranging from 85 to 135 V, an output voltage of 24 V and an output current of 5 A, operating at a switching frequency of 100 kHz. Copyright © 2014 John Wiley & Sons, Ltd.     

基于模式切换的固态变压器多直流电压平衡控制方法

能源互联网通过固态变压器整合分布式可再生能源,但是容易出现不同H桥模块间电压失衡、直流变换效率低以及能耗高的问题。因此,研究基于模式切换的固态变压器多直流电压平衡控制方法,分析固态变压器中的负责能量传递的双移相桥隔离型双向直流变换器损耗分布情况,为直流变换器效率优化提供分析依据,通过移相控制模式和梯形电流控制模式间的合理切换控制,提高直流变换器效率,实现固态变压器中双向直流变换器全功率范围内的损耗最佳控制,在此基础上,通过单相任意单元数级联H桥固态变压器的SVPWM算法,解决变压器的模块级联H桥型固态变压器出现不同H桥模块间的均压问题,实现变压器多直流电压的平衡控制。结果表明,该方法对固态变压器多直流电压平衡后,使得变压器电网电流谐波小,固态变压器AC／DC的3H桥电容电压达到了平衡状态,固态变压器直流母线端口电压以及低压直流端口电压稳定,达到平衡状态。     

Non‐isolated single‐switch DC–DC converters with extended duty cycle for high step‐down voltage applications

Several new topologies of single‐switch non‐isolated DC–DC converters with wide conversion gain and reduced semiconductor voltage stress are proposed in this paper. Most of the proposed topologies are derived from the conventional inverse of SEPIC (Zeta) converter. The proposed topologies can operate with larger switch duty cycles compared with the existing single switch topologies, hence, making them well suitable for high step‐down voltage conversion applications. With extended duty cycle, the current stress in the active power switch is reduced, leading to a significant improvement of the system losses. Moreover, the active power switch in some of the proposed topologies is utilized much better compared to the conventional Zeta and quadratic‐buck converters. The principle of operation, theoretical analysis, and comparison of circuit performances with other step‐down converters are discussed regarding voltage and current stress and switch silicon utilization. Finally, simulation and experimental results for a design example of a 50 W/5 V at 42‐V input voltage operating at 50 kHz will be provided to evaluate the performance of the proposed converters. Copyright © 2014 John Wiley & Sons, Ltd.     

基于非关联开关电容Cuk变换器的单相PFC电路

基于非关联开关电容ＣｕｋＤＣ－ＤＣ变换器,本文提出一种新的功率因子校正（ＰＦＣ）电路－非关联ＳＣ－ＣｕｋＰＦＣ电路。和普通ＰＦＣ Ｃｕｋ电路相比,该电路不需要变压器也可以实现大的输入输出电压变化,即使电路工作在较大的开关导通比。提出电路的输入电感工作在不连续导电模式（ＤＣＭ）,而输出电感工作在连续导电模式（ＣＣＭ）。本文对提出的ＰＦＣ电路的工作原理进行了详细分析。实验结果证实了文中的理论分析。     

一种交错并联反激式三电平DC-DC变换器

本文在传统反激变换器基础上,引入三电平技术,并针对传统反激三电平DC-DC变换器电源两端并联的分压电容不均压的问题,提出了一种交错并联反激式三电平DC-DC变换器。该变换器具有电路拓扑简洁,输出只需电容滤波,减小输出滤波器,提高了变换器功率密度等优点。深入分析了该变换器的工作原理及工作过程,推导了其输入输出关系,和传统的反激两电平变换器相比,可以得出该并联交错三电平反激变换器能减小输出电容,降低功率开关管电压应力等结论。最后设计了闭环控制策略,并基于saber对电路进行仿真,验证了该拓扑的正确性和输出电容小、功率开关管电压应力低等特点。     

一种高效率低输入纹波电流的光伏并网微逆变器

针对传统光伏系统存在热斑、整体效率低等问题,提出了一种高效率、低输入电流纹波的隔离型单相两级式光伏并网微逆变器。该微逆变器由前级DC/DC升压环节和后级逆变环节组成。DC/DC变换器采用有源钳位和倍压整流电路,使变压器原边开关管及副边整流二极管实现软开关,分析了其稳态下的工作原理并给出了变换器关键波形曲线;后级逆变环节应用软件锁相、脉宽调制等技术实现了逆变并网。提出了一种低成本的在中间母线电压环中加入扰动环节的方法,抑制了两级式逆变器直流输入侧存在的两倍交流输出频率的电流纹波。研制了一台220 W光伏微逆变器样机并进行了测试,实验结果证明了理论分析的可行性。     

一种新型并联型零电流全桥DC/DC变换器

提出了一种新型的含并联辅助电路的零电流转换(ZCT)全桥DC/DC变换器拓扑结构。该变换器采用脉宽调制(PWM),通过在原边增加一个由电容和电感构成的并联有源辅助电路,在开关管状态发生变化时,控制辅助电路的谐振电流,实现了主开关管和辅助开关管的零电流开关(ZCS),也实现了输出整流二极管的软换流,使整流二极管承受的电压相对较低,即为输出电压,特别适合于开关器件为IGBT的高电压大功率场合,消除了IGBT拖尾电流引起的开关损耗,改善了电路性能。分析了变换器的工作原理及零电流开关的实现条件,给出了主电路拓扑结构和谐振网络相关参数设计。根据所选取的参数对主电路进行了仿真研究,结果验证了电路分析的正确性和可行性。     

Pulse current regenerative resonant snubber‐assisted two‐switch flyback‐type ZVS PWM DC‐DC converter

In this paper, a two‐switch high‐frequency flyback transformer‐type zero voltage soft‐switching PWM DC‐DC converter using IGBTs is proposed. Effective applications for this power converter can be found in auxiliary power supplies of rolling stock transportation and electric vehicles. This power converter is basically composed of two active power switches and a flyback high‐frequency transformer. In addition to these, two passive lossless snubbers with power regeneration loops for energy recovery, consisting of a three‐winding auxiliary high‐frequency transformer, auxiliary capacitors and diodes are introduced to achieve zero voltage soft switching from light to full load conditions. Furthermore, this power converter has some advantages such as low cost circuit configuration, simple control scheme, and high efficiency. Its operating principle is described and to determine circuit parameters, some practical design considerations are discussed. The effectiveness of the proposed power converter is evaluated and compared with the hard switching PWM DC‐DC converter from an experimental point of view, and the comparative electromagnetic conduction and radiation noise characteristics of both DC‐DC power converter circuits are also depicted. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 74–81, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20081     

基于准谐振技术的宽电压范围双管反激电源设计

设计了一种基于变频控制芯片L6565D的宽电压范围双管反激电源,其输入电压范围为200～1 000 V,作为系统的辅助电源应用于光伏电站中;L6565D通过采集输入电压的变化情况实现不同电压段的电流环限流点的调节,同时利用检测变压器磁复位状态来控制两个开关管工作于谷底导通模式,实现软开关功能。其准谐振工作模式降低了开关管开通损耗,改善了电磁兼容EMC(electromagnetic compatibility),提高了整机效率,节约了成本。目前该款电源已经成功应用到光伏系统中,取得了良好的效果。     

反激变压器漏感和分布电容的影响分析

针对反激变压器工作在高频情况下寄生参数不可忽略的事实,详细分析了变压器漏感和分布电容给反激变换器带来的影响。首先,分析了理想变压器情况下电流断续模式反激变换器的工作过程;其次,分析了理想变压器中只加入漏感、只加入分布电容、同时加入漏感和分布电容3种情况下寄生参数对反激变换器工作过程的影响;最后,设计了一台反激变换器实验样机对寄生参数的影响进行了验证。实验结果表明,漏感会在开关管关断瞬间的漏源电压上产生一个电压尖峰,分布电容会在开关管开通瞬间的漏极电流上产生一个电流尖峰,同时开关管截止期间漏感和分布电容之间以及励磁电感和分布电容之间产生的谐振会在开关管的漏源电压上叠加相应的振荡。     

反激变换器的漏感影响分析及钳位电路参数设计

反激变换器中,开关管关断时漏感瞬时续流产生电压尖峰,对开关器件会有较大影响,通常使用RCD箝位电路来吸收该尖峰。在对变压器T型模型的分析基础上,通过理论分析,揭示出除了原边漏感之外,副边漏感会同时影响到开关管漏源电压的大小,进而影响RCD箝位电路能量的吸收,并提出了一种新的RCD参数计算思路。通过仿真与实验,验证了该设计的正确性与有效性。     

A novel single‐stage AC–DC converter with quasi‐resonant zero‐voltage‐switching for high power factor and high efficient applications

A new single‐stage‐isolated ac–dc converter that can guarantee both high efficiency and high power factor is proposed. It is based on a new dc–dc topology that has prominent conversion ratio similar to that of boost topology so that it is adequate to deal with the universal ac input. In addition, since it utilizes the transformer more than others based on the general flyback topology, the size of whole power system can be reduced due to the reduced transformer. Moreover, the voltage stresses on the secondary rectifiers can be clamped to the output voltage by adopting the capacitive output filter and clamp diode, and the turn‐off loss in the main switch can be reduced by utilizing the resonance. Furthermore, since this converter operates at the boundary conduction mode, the line input current can be shaped as the waveform of a line voltage automatically and the quasi‐resonant zero‐voltage switching can be obtained. Consequently, it features higher efficiency, lower voltage stress, and smaller sized transformer than other topologies. A 100 W prototype has been built and tested as the validation of the proposed topology. Copyright © 2010 John Wiley & Sons, Ltd.     

Performance comparison of input current ripple reduction methods in UPS applications with hybrid PEM fuel cell/supercapacitor power sources

An uninterruptible power supply (UPS) system with different input current ripple reduction methods is proposed, and a comparison research has been conducted about these methods. The proposed UPS system consists of a 63-cell 300 W proton exchange membrane (PEM) fuel cell stack, two 16-cell supercapacitors (SCs) in series, a high-efficiency push–pull DC/DC converter and a half-bridge DC/AC inverter. Besides that the traditional push–pull DC/DC converter has inherent advantages of low input-current stress and high voltage conversion ratio, the SCs, LC filter, and an active clamp circuit are employed to reduce the input current ripples in the UPS system. First, the input current ripple generation and performance without an external component are analyzed and modeled in the PEM fuel cell. Then the input current ripple reduction methods mentioned above are proposed and operated in the designed UPS system. Finally, the experimental results show that the input current ripple can be further reduced by using different current ripple reduction approaches, and the active compensation method has better performance than the passive compensation method. The input current ripple is less than 5% of the rated input current.