单级功率因数校正AC/DC变换器

详细分析了一种单级功率因数校正ＡＣ／ＤＣ变换器,通过增加变压器绕组反馈直流总线电压,以抑制输入高压、轻载情况下过高的直流总线电压。在交流输入电压为１８０￣２５０Ｖ、输出为４８Ｖ／１００Ｗ情况下,直流总线电压被控制在４００Ｖ以下。输入电流谐波满足ＩＥＣ１０００－３－２ Ｃｌａｓｓ Ｄ要求,效率为８５％,功率因数达０．９１。     

直流调制单级功率因数校正交-交变流器

功率因数校正是产生或吸收无功功率力图达到功率因数等于1.单级交-交变流器被广泛应用在各工业领域.传统的交-交变流器采用电压调制法,全谐畸变高,功率因数低,功率转换效率差.本文介绍全新直流调制方法,由直流变流技术实现.直流调制单级功率因数校正交-交变流器有效地改进了功率因数,使之达到0.999,功率转换效率达到97.8%.实验结果证实了设计和计算的正确性.     

高功率因数三相单管Boost PFC变换器

三相单管Boost功率因数校正(power factor correction,PFC)变换器具有开关管零电流开通、二极管无反向恢复、开关频率恒定、控制简单、成本低等优点,适用于中低功率场合。但在工频周期内占空比恒定,尤其在输入电压较高时,输入电流谐波含量较大、功率因数(power factor,PF)相对较低。分析三相单管Boost PFC变换器的PF值。在此基础上,提出变占空比控制的方法,从而降低输入电流谐波、提高PF值。为了简化电路实现,进一步给出一种拟合占空比的方法。与定占空比控制相比,所提方法还具有输出电压纹波小和效率高等优点。完成一台3kW的原理样机,进行实验验证,实验结果验证了理论分析和参数设计的正确性。     

改进的单级功率因数校正AC/DC变换器拓扑的研究

单级功率因数校正(简称单级PFC)由于控制电路简单、成本低、功率密度高在中小功率场合得到了广泛的应用。但是单级PFC中存在一些问题,如储能电容电压随输入电压和负载的变化而变化,在输入高压或轻载时,电容电压可能达到上千伏,变换器的效率低,开关损耗大等缺点。介绍了几种改进的拓扑结构来解决这些问题。     

单级不间断高功率因数交-直变换器的研究

在论述单级不间断AC/DC变换器研究现状的基础上,提出了单级、单级组合式、单级并联式不间断高功率因数AC/DC变换器拓扑;分析研究了这类变换器的3种工作模式;给出了原理试验结果。这类变换器实现了不间断供电、功率因数校正、输出直流电压的稳定与调节,具有拓扑简洁,变换效率高,功率密度高,不间断供电,功率因数高,蓄电池与交流电网电气隔离等优点,在计算机、通信、医疗等电子设备中有广泛的应用前景。     

双级矩阵变换器输入功率因数可调的载波调制策略

载波调制方法的出现简化了双级矩阵变换器的控制,使用传统载波调制方法时在高调制区时会产生窄脉冲,且设定输入功率因数角较大时会有安全隐患。先对传统载波调制方法的窄脉冲现象进行研究,通过对调制函数的修正一定程度上避免了窄脉冲的产生,并在此基础上解决输入功率因数角较大时直流母线可能出现负压的问题,从而输入功率因数角不再受传统调制方法下有关调节范围的限制。实验结果证明了所提方案的正确性及可行性。     

单级组合式不间断高功率因数AC/DC变换器研究

提出了一类基于Boost-Flyback变换器的单级组合式不间断高功率因数AC/DC变换器电路结构与拓扑族。这类变换器由二极管整流桥和具有功率因数校正、不间断供电、输出电压快速调节等功能的Boost-Flyback变换器构成，可以将1种交流电压变换成所需要的输出直流电压。分析研究了这类变换器的3种工作模式(正常工作模式、后备工作模式、充电工作模式)、稳态原理特性、控制策略和关键电路参数设计准则，并给出了原理试验结果。这类变换器具有单级功率变换、不间断供电、网侧功率因数高、蓄电池与电网或负载高频电气隔离、输出电压调节速度快、体积重量小、成本低等优点。     

分布式供电系统中负载变换器的输入阻抗分析

直流分布式供电系统由多个子系统组合而成,子系统之间的相互作用容易导致系统稳定程度和动态性能降低,甚至于不稳定。通常,恒功率负载具有的负阻抗输入特性是导致级联系统不稳定的主要原因。该文针对直流变换器在恒功率负载的情况下,以分布式供电系统中负载变换器的输入阻抗作为标准化研究的对象。该文以分布式供电系统中常见的同步整流Buck变换器为例,详细分析了变换器的输入阻抗随功率等级、开关频率和控制方式变化时的规律。并进一步通过实验验证了理论分析的正确性。实验结果为将来制定出Buck类DC-DC模块的输入阻抗的标准打下基础。     

Power Converters for Feeding Asynchronous Traction Motors of Single-Phase AC Vehicles

Asynchronous induction motors are very well suited to powerful traction drives. For electric locomotives and motor coaches with single-phase supply, a power conversion on the vehicle is necessary. Three different types of static power converters for this application are described. Indirect ac converters with direct voltage link have been developed successfully in the past. For indirect ac converters with direct current link some problems are discussed. At last a self-commutated direct ac converter with suppressed dc link is presented.     

能量因数及功率直流变换器建模

直流变换器的数学模型是自20世纪40年代以来伴随直流变换科技发展的历史性问题.传统数学模型成功描述了基础变换器,但无效于高阶复杂结构变换器.研究新方法对直流变换器建模势在必行.     

AC Adjustable-Speed Drives with Electronic Power Converters?the Early Days

Some of the early electronic power converters utilized mercury-arc rectifiers such as thyratrons and ignitrons. Their use in an-ac adjustable-speed drive began about 50 years ago. The first commercial application in the United States was made to an induced draft fan at the Logan station. This drive was in service for about 25 years. The early history of ac adjustable-speed drives which employed electronic power conversion is reviewed.     

交流斩波型无功补偿器的输入滤波器设计

为了使交流斩波型无功补偿器输出正弦的无功补偿电流,针对交流斩波器谐波次数较高的特点,采用二阶LC滤波器达到滤除高次谐波的目的。提出1种交流斩波电路输入滤波器的改进设计方法,根据系统的无功功率补偿等级,确定电容器参数,从无功补偿能力和补偿电流THD 2个角度,设计电感参数,与通过LC滤波器截止频率确定的补偿范围取交集限定LC参数,使滤波器兼顾无功补偿和滤除高频谐波的能力。仿真和实验结果验证了该优化方法的可行性和有效性。     

DC to DC Converters with High-Frequency AC Link

The properties of a dual thyristor are advantageously used for the development of very high-efficiency dc-dc converters. A new device named ``dual thyristor' having static and dynamic characteristics dual to that of a thyristor has been recently reported. The development aspects of a dual thyristor based high-efficiency dc-dc converter with an intermediate ac link using a high-frequency inverter is described. The output voltage is regulated by varying the frequency of operation of the inverter. In spite of the relatively high-frequency operating range of this device between 30 kHz and 100 kHz, high efficiency of operation of the converter is obtained due to the use of lossless snubbers. Further, the selfprotective nature of the device against overcurrents enables a high reliability of operation of the dc-dc converter.     

一种新型充电泵高功率因数AC/AC变换器

提出一种新型充电泵高功率因数AC/AC变换器拓扑结构。该变换器具有电路结构简单和采用PFM控制方式的特点。文中分析了电路的工作过程及取得高功率因数的条件 ,给出了电路参数设计指导 ,并通过实验证实了理论分析的正确性。达到了不用专用控制芯片实现高功率因数的目的     

Energy Factor and Mathematical Modeling for Power DC／DC Converters

Mathematical modelling for power DC/DC converters is a historical problem accompanying DC/DC conversion technology since 1940‘s. The traditional mathematical modelling is not available for complex structure converters since the differential equation order increases very high. We have to search other way to establish mathematical modelling for power DC/DC converters. We have theoretically defined a new concept - Energy Factor (EF) in this paper and researched the relations between EF and the mathematical modelling for power DC/DC converters. EF is a new concept in power DC/DC conversion technology, which thoroughly differs from the traditional concepts such as power factor (PF), power transfer efficiency (η), total harmonic distortion (THD) and ripple factor (RF). EF and the subsequential EFV (and EFVD ) can illustrate the system stability, reference response and interference recovery. This investigation is very helpful for system design and DC/DC converters characteristics foreseeing. Two DC/DC converters: Buck converter and Super-Lift Luo-Converter.as the samples are analysed in this paper to demonstrate the applications of EF, EFV (and EFVD ), PE,SE, VE (and VED ), time constant τ and damping time constant τd.     

An AC-to-DC Converter with Improved Input Power Factor and High Power Density

A novel single-phase switch-mode rectifier (SMR) structure is proposed and analyzed. The proposed converter structure employs a synchronous front-end rectifier (SFER) stage which provides high-quality input characteristics with small input filtering. Consequently the proposed converter structure exhibits high power density and has low implementation cost.     

矩阵变换器输入功率因数可调时的换流控制策略

矩阵变换器的电压型两步换流策略具有换流过程快,开关损耗小,不受运行工况影响,控制系统结构简单等优点。针对该方法在输入电压换区间时易发生短路的现象,一些文献提出了一种带有过渡区间的电压型两步换流策略,较好地解决了矩阵变换器在较大功率输出条件下的换流问题,但是该方法只适用于输入功率因数为1附近的情况,当输入功率因数变化较大时,系统仍会发生短路问题。为此,本文在具体分析换流过程的基础上,提出了适用于输入功率因数可调时的换流方法,在过渡区间内通过判断电压的相对大小,使用换序法将大压差电压调整至调制顺序的中间,避免了换流时可能出现的短路现象,进一步完善电压型两步换流策略。最后,仿真和实验结果表明本文所提出的改进策略是正确可行的。     

灯丝稳流电源AC/AC变换器的设计与研制

介绍了一种新型灯丝稳流电源的关键设计和计算,采用并联交错单端正激变换器电路拓扑结构,它由输入整流、逆变及输出换向以及输入、输出滤波器构成。分析研究了这类变换器工作模式、稳态原理与电压瞬时值反馈控制策略。原理试验结果证实了这类变换器的正确性和先进性。     

一种新颖的高功率因数AC/DC变换器

提出了一种新颖的高频电荷泵功率因数校正AC/DC变换器 ,详细论述了该电路的工作原理 ,对电路的参数设计进行了讨论 ;最后对该变换器电路进行了仿真和试验。研究结果表明 :该电路的功率因数高 ,谐波含量小 ,是一种结构简单、性能优良的变换器。     

Forward Single-Stage Power Factor Correction AC/DC Converter

1 InroductionPower Factor Correction (PFC)is the capacity of generat-ing or absorbing the reactive power to a load without the use ofthe supply.The major industrial loads have an inductive powerfactor,so that the current tends to go beyond the power is us…