电流源高频交流环节AC/AC变换器研究

提出了基于反激F1yback变换器的电流源高频交流环节AC/AC变换器电路结构与拓扑族。该电路结构由输入周波变换器、高频储能式变压器、输出周波变换器以及输入、输出周波变换器构成，能够将一种不稳定畸变的交流电变换成问频率稳定的正弦交流电压；该电路拓扑族包括单四象限功率开关式、推挽式、半桥式、全桥式等四种电路。以单四象限功率开关式电路拓扑为例，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，给出了变换器的外特性曲线、关键电路参数设计准则。原理试验结果证实了这类变换器新概念的正确性与先进性。     

电压源高频交流环节AC/AC变换器原理研究

首次提出了电压源高频交流环节AC/AC变换器电路拓扑族 ,这类电路拓扑由输入周波变换器、高频变压器、输出周波变换器构成。分析研究了这类变换器稳态原理与移相控制策略 ,绘出了变换器的外特性曲线。这类变换器具有电路拓扑简洁、两级功率变换 (LFAC/HFAC/LFAC)、双向功率流、高频电气隔离、网侧电流波形可得到改善、负载适应能力强等优点。PSPICE仿真波形充分证实了这类变换器的正确性和先进性。     

两种高频交流环节AC/AC变换器比较研究

新颖的高频交流环节AC/AC变换器,包括基于Forward变换器的电压源型和基于Flyback变换器的电流源型两种。首次对两种高频交流环节AC/AC变换器的电路结构与拓扑、控制策略、原理特性、关键电路参数设计准则、原理样机等进行了深入的比较研究,获得了重要研究结论。相对于电压源型,电流源型变换器具有电路拓扑更简洁、输入电压范围更宽、输出波形质量更高、可靠性更高、成本更低、变换效率略低和适用于小功率变换场合等特点。两种高频交流环节AC/AC变换器的比较研究,为实现新型电子变压器、正弦交流稳压器和交流调压器提供了关键的技术依据。     

单极性移相控制电压源高频交流环节AC/AC变换器研究

该文首次提出并深入研究了基于正激Forward变换器的单极性移相控制电压源高频交流环节AC／AC变换器。这类变换器由输入周波变换器、高频变压器、输出周波变换器、以及输入、输出滤波器构成。输入周波变换器将输入不稳定劣质的交流电压调制成双极性三态的高频交流电压，输出周波变换器将此高频交流电压解调成单极性三态SPWM波，经输出滤波后得到稳定优质的正弦交流电压。通过输入周波变换器右桥臂相对左桥臂的移相，让输出周波变换器功率开关在输入周波变换器输出的高频交流电压为零期间进行换流，并借助输出周波变换器换流重叠和输入电压极性选择，从而实现了变压器漏感能量和输出滤波电感电流的自然换流、输出周波变换器的ZVS开关。详细分析了这类变换器在1个高频开关周期内的12个工作模式及其等效电路，获得了变换器外特性曲线与关键电路参数设计准则。原理试验结果证实了这类变换器新概念，为实现新型电子变压器、正弦交流稳压器和交流调压器奠定了基础。     

A Pulsewidth Controlled AC-to-DC Converter to Improve Power Factor and Waveform of AC Line Current

As a method for improving power factor and waveform of ac line current drawn by an ac-to-dc converter a new pulsewidth controlled converter is proposed, its commutation mechanism is described, and experimental results are given which show a good power factor, a good waveform of the line current, and a wide adjustable range of dc output voltage.     

基于双管反激变换器的全桥式高频交流环节AC/AC变换器研究

提出了以双管反激变换器为基础的全桥式高频交流环节AC／AC变换器拓扑。该拓扑由输入周波变换器、高频储能式变压器、输出周波变换器以及输入、输出滤波器构成，能够将不稳定劣质的交流电变换成同频率稳定的优质正弦交流电压。分析研究了这种变换器的工作模式、稳态原理特性与电压瞬时值反馈控制策略，给出了变换器的外特性曲线以及变换器内阻对外特性的影响、关键电路参数设计准则。理论分析与原理试验表明，这种变换器具有高频电气隔离、电路拓扑简洁、两级功率变换(LFAC／HFAC／LFAC)、双向功率流、网侧功率因数较高、负载适应能力强、音频噪音小、负载短路时可靠性高、适合于高压输入小功率变换场合等特点。     

新型三电平交流斩波电路的输出频谱结构分析

关于多电平变换器的研究已经有十几年了，但是多电平技术在交流电能变换当中的应用尚不多见。三电平交流斩波电路是一种用于高压电能变换的新型电路拓扑。它允许使用低电压等级的器件完成高压电能变换，并采用较多的电平数去逼近所希望的波形，使输出电压或电流的质量大大提高，谐波含量减少。文中对三电平斩波电路的输出电压频谱进行了一般性的讨论，得到了普适的结论。这一结论同样可分析普通的交流斩波电路的输出频谱结构。通过实验验证了电路的工作原理。     

A New Concept for Improving the Performance of Phase-Controlled Converters

High-power phase-controlled converters suffer from several fundamental disadvantages. They inject current hannonics into the input ac mains due to their nonlinear characteristics, thereby distort the supply voltage waveform, and demand ractive power from the associated ac power systems at retarded firing angles; also the output voltage is not smooth dc but contains superimposed harmonic ripples. A novel sequential control technique is suggested, which, when applied to more than one converter in cascade, substantially overcomes these disadvantages. The method consists of specifying the proportions of the maximum power to be handled by the individual converters and incorporating a sequence controller, the function of which is to ensure that at any output voltage the converter supplying the minimum power operates over the ful range of thyristor firing angles. The firing angles of other converters are restricted to values corresponding to their ratings. A generalized method of optimizing the performance of sequentially controlled cascaded converters is presented, and the economic viability of the proposed scheme is examined. It is shown that the effective ratings of thyristors in the proposed scheme are greatly reduced. The method should offer improved converter performance in variable speed dc drives, solid-state slip-energy recovery systems, or high-voltage dc transmission systems.     

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     

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。     

A single-phase p-type ac–ac converter with reduced components count and high boost factor

This paper proposes a new single-phase direct step-up ac–ac converter by modifying the p-type impedance source. It provides a high boost factor as well as high efficiency, while only six parts are required to design it, involving just two bidirectional power switches. A safe commutation method has been applied to power switches to make the converter snubber-free and high efficient. Input and output harmonic filters are no longer required since input and output currents variate continuously with small ripple and low total harmonic distortion (THD). The proposed topology only modulates the output voltage amplitude, not the phase and frequency, so the output frequency is identical to the input frequency and constant. Thus, it can be utilized in step-up conversion applications, like inductive power transmission from low ac voltage sources. Input and output have the same ground, which is a good protective feature. In this paper, the operating principle of the converter is demonstrated. Experimental results have been represented to evaluate the performance of the converter. For this purpose, an experimental prototype has been fabricated. Results are investigated and compared with other previous step-up ac–ac converters. Results confirm the theory, operating principle, and performance of the converter.     

Buck变换器的多频率矩阵模型及其在分布式供电系统中的应用

电力电子变换器是频域内典型的单输入多输出系统,当输入某一频率的扰动信号时,变换器各状态变量既包含扰动频率分量,也包含与扰动相关的边带频率成分。在包含多个电力电子变换器的分布式供电系统中,一个变换器的开关纹波为另一个变换器的扰动,这种相互作用在某些情况下可能会导致母线电压差频振荡从而影响系统电能质量。然而,传统小信号模型以单个变换器的分析和设计为背景提出,主要用于描述变换器的低频特性。由于这些模型忽略了开关变换器的很多固有特性,因此不能准确地分析上述变换器之间在开关频率附近的相互作用。为此,提出了一种新的矩阵小信号模型并以Buck变换器为例进行了详细的说明。该模型可以准确地描述变换器的单输入多输出特性,并解释分布式供电系统中电力电子变换器相互作用导致的母线电压差频振荡现象。对比结果表明,传统的平均小信号模型和多频率小信号模型都是所提出的矩阵模型在不同情况下的近似。仿真和实验结果证明了所提模型的准确性和有效性。     

电力电子化电力系统的调频挑战与多层级协调控制框架

电力电子接口装备在源、网、荷的深度应用推进了电力系统的电力电子化进程。净负荷波动增加、同步惯性减小、有功平衡能力削弱,对系统频率稳定的冲击初现端倪。电力电子接口电源的输出功率不响应系统频率变化、输入能量不可控、控制器高度异构,难以纳入传统交流同步系统的有功频率调整框架,而未来的电力系统需要在越来越少同步发电机容量背景下维持有功平衡,问题更加凸显。从电压源型换流器可定制性出发,提出了电力电子化下对电力系统有功频率多层级协调控制的新框架：在接口层面,重建输出功率与系统频率的耦合关系,虚拟同步机的惯性响应与一次调频特性;在单机层面,协调电力电子电源内部储能元件释能和输入能量来提供调频能量,优化虚拟参数实现机网协调,降低频率二次跌落风险;在多机层面,统筹改善频率动态特性的装置和长期频率恢复装置的配合;在系统层面,借助柔性直流输电换流站的下垂策略,重建直流互联的多同步系统间跨区频率支援。     

输入并联输出串联AC/AC变换器的研究

传统两电平AC/AC变换器的开关管电压应力高,输出电压和输入电流谐波含量较高。针对此问题,基于多模块串并联组合变换器的相关技术,提出了一种输入并联输出串联(IPOS)电流源高频交流环节AC/AC变换器。为保证该变换器的正常工作,研究并提出了一种均压控制策略。此控制策略实现了该变换器在4种工作模式下的输出均压和输入均流。实验结果验证了该变换器的工作原理和控制策略的正确性,该变换器适用于较低输入电压和较高输出电压交流电能变换场合。     

AC/DC/AC PWM converter with reduced energy storage in the DC link

The paper introduces the family of quasi-direct converters, i.e., forced-commutated AC/DC/AC power converters including small energy storage devices in the DC link. In particular, the case of the three-phase to three-phase quasi-direct power converter is considered. Since energy storage minimization calls for instantaneous input/output power balance, a proper control strategy is needed. The paper describes a simple and effective control technique which also provides high-power factor and small distortion of the supply currents. After a discussion of the general properties of quasi-direct power converters, design criteria of both power and control sections are given, and experimental results of a 2-kVA prototype are reported     

Three-Phase AC/DC PWM Converter with Sinusoidal AC Currents and Minimum Filter Requirements

A pulsewidth modulation (PWM) control technique suitable for fully controlled three-phase ac/dc converters is analyzed, which gives sinusoidal input currents and ideally smoothed dc voltage. The technique allows four-quadrant operation and full-range control of the input power factor. An extension to a simplified converter scheme, capable of one-quadrant operation, is also considered. Operation of the converter is analyzed under both ideal and actual conditions. Control implementation and design criteria are discussed and experimental results are reported.     

The High-Frequency Base Converter?A New Approach to Static High-Power Conversion

A new approach to high-power conversion in which two naturally commutated converters (cycloconverters) are used in tandem, each with its input connected to a (passive) high-frequency (HF) source (``base') is presented. The arrangement approximates an ideal converter; its ``input' and ``output' frequency can be equal or different, and the power factor at both external terminals can be maintained at unity or any other value. Potential utility applications in which the HF base converter functions as an asynchronous intertie between two ac power systems and as a tie between a dc transmission line and a weak ac system are discussed, and technical and economic comparisons with conventional approaches are given.     

分布式供电系统中源变换器输出阻抗的研究

随着功率电子变换技术的发展,构建大型电力电子供电系统越来越多地采用模块集成的方式。美国海军提出的电力电子积木的概念对模块级的系统集成做出了很大贡献。该文提出一种新颖的系统集成的观点,即从系统级的高度将分布式供电系统中的源变换器的输出阻抗和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移相全桥DC-DC变换器为例,对输出阻抗进行了模型验证,并详细分析了输出阻抗的特点。为了便于将来制定出Buck类DC-DC模块的输出阻抗的标准,通过实验揭示了移相全桥DC-DC变换器的输出阻抗随功率等级、开关频率和控制方式变化时的规律。     

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.     

Features of traction electric equipment of prospective electric rolling stock

On the main railways in Russia, two types of current in the contact wire are used: dc voltage of 3 kV and ac voltage of 25 kV with a frequency of 50 Hz. Therefore, prospective electric rolling stock should have double the power. Improving the capacity and structural speed of locomotives is based on the use of asynchronous traction motors (ATDs) with a squirrel-cage rotor allowing increasing the tractive force and the weight of the train and the capacity and speed of cargo delivery, increasing reliability and reducing life cycle costs, and increasing service life. Electrical equipment for such rolling stock should be used when working from either contact system, dc or ac. In this article, the scheme of power circuits is considered using the example of a module of a traction drive in one bogie of dual-system electric locomotives. It is proposed to use the secondary winding of the traction transformer as a choke of the input filter when powered from a dc contact system. Regulation of operation modes of asynchronous traction motors is carried out from static semiconductor converters with a two-tier structure. Input transducers provide the exchange of electric energy between the contact system and the intermediate link of dc voltage, and the output converters regulate the traction motors by changing the magnitude and frequency of voltage on the stator windings of ATD depending on the speed of the locomotive and its operating mode. 4QS input converters and output converters are autonomous voltage inverters of the intermediate ac: in the case of single-phase input and output, they are three-phase. The basic ratios are given to determine voltages and currents of 4QS converters, to determine the variable component of a rectified current 4QS converter, and to formulate requirements for a resonant L₂C₂ filter configured for a frequency of 100 Hz. Expressions are given for determining the ratio of the input power of the converter, as well as recommendations for determining the basic parameters of electrical equipment.