一种基于Buck/Boost电路的新型微逆变器功率解耦电路

针对微逆变器中存在的二次功率扰动问题,提出了一种新型四开关功率解耦电路。详细分析了基于Buck/Boost电路的新型功率解耦电路的4种工作模式,推导了采用脉冲能量调制控制策略原理,并对电路关键参数进行设计。该电路并联在逆变器交流输出侧,不仅能够明显抑制母线电压和直流输入侧电流中的二次纹波,而且可以将大电解电容替换成小容量长寿命的薄膜电容。最后,仿真实验验证了该拓扑的有效性和合理性。     

单相全桥离网逆变器输出侧功率解耦电路研究

单相逆变器输入电流低频纹波抑制是燃料电池及光伏电池发电系统亟需解决的问题.本文深入研究单相全桥离网逆变器输出侧功率解耦电路拓扑及其输入电流低频纹波抑制策略,给出控制参数、关键电路参数设计准则和实验波形.该电路拓扑中有源功率解耦电路位于全桥逆变器输出侧,与全桥逆变器共用输出滤波电感与电容,通过在输出滤波电容上叠加直流电压和低频偶次谐波电压实现逆变器功率解耦,使逆变器输出侧低频脉动功率在输出滤波电容与负载之间传递,阻断其向直流侧传递的路径.理论和实验结果验证了这种方法的有效性和可行性.     

一种基于混合Buck/Boost电路的两级式逆变器功率解耦方法研究

针对传统两级式逆变器由于输入输出功率不平衡所带来的二次功率扰动问题,提出了一种六开关的混合Buck/Boost电路,并联在逆变器交流输出侧进行功率解耦,从而抑制母线电压和直流侧电流中的二次纹波,并将大电解电容替换成小容量和长寿命的薄膜电容。混合Buck/Boost电路可以处理双向变化的脉动能量,通过脉冲能量调制法(Pulse Energy Modulation,PEM)计算每个开关周期的开关占空比,实现对脉动功率的解耦控制。分析了混合Buck/Boost电路的四种工作模式,推导了PEM控制原理。使用Matlab/Simulink平台搭建仿真模型进行验证,结果证明了方法的合理性和有效性。     

具有功率解耦能力的升降压逆变器

在单相光伏并网逆变器中,若要逆变器交流侧瞬时功率满足并网的需要,则在逆变器直流侧会产生不平衡脉动功率和二阶纹波电流,影响直流输入源利用率.为了减小直流侧的二次纹波,一般并联大容量的电解电容器,但电解电容器体积大且寿命较短.介绍了一种带有功率解耦电路的单相升降压逆变器,采用基于脉冲能量调制的有源功率解耦控制,将二阶纹波功率输送到薄膜电容,实现功率解耦.最后仿真验证了升降压逆变器功率解耦的有效性.     

基于功率解耦的单级隔离型微型逆变器研究

近年来,随着人们对新能源和环境问题的关注,清洁能源越来越多的受到重视,极大地推动了光伏逆变器的发展。微型逆变器以其即插即用、体积小、灵活安全等特点,在智能电网及户用场合得到广泛应用。然而,直流侧电解电容限制了微型逆变器的寿命和功率密度。提出了一种基于功率解耦的单级隔离型微型逆变器拓扑,该拓扑具有处理直流二次脉动功率的能力,直流母线侧可采用薄膜电容,进一步提高了系统寿命。详细分析了该新型拓扑的工作模态,并设计了100 W原理样机以验证其有效性。     

基于逆变器交流侧的四开关功率解耦技术研究

针对两级式单相逆变器常用大容量电解电容来缓冲其固有的二倍频脉动功率，大大降低其耐用性和可靠性这一问题，本文在保证变换器稳定运行的前提下提出了一种四开关功率解耦电路，对降低逆变器电容总容值具有实际工程意义。分析讨论解耦电路的工作原理，通过对4种不同的工作模式进行分析，从而确定解耦主电路各个开关管开关时序。在此基础上，设计了相应的脉冲能量调制策略以实现瞬时能量的精准补偿，提升了四开关功率解耦电路的解耦性能，改善了两级式逆变器交直流侧波形质量。该方案逆变电路与功率解耦电路相互独立，有利于传统设备的改造。最后，搭建了仿真模型和实验样机，仿真和实验结果验证了增加交流侧四开关功率解耦电路后，变换器只需几十μF的薄膜电容就能对二倍频脉动功率进行有效解耦。     

具有功率解耦功能的光伏并网微逆变器

为了解决光伏并网微逆变器直流侧引入的二倍工频扰动问题,传统解决方案是在太阳能板两侧并入大容量的电解电容来平抑扰动,但电解电容的使用寿命过短,导致整个光伏系统的使用寿命受限。为此提出了一种新型的功率解耦电路拓扑,实现了以寿命长、容值小的解耦电容替代电解电容,在完成功率解耦的同时也有效延长了微逆变器系统的整体寿命。最后通过仿真验证了该新型解耦电路的可行性。     

基于电压定向直接功率控制的光伏并网逆变器

将基于电压定向直接功率控制用于光伏并网逆变器的控制策略,引入电网电压和瞬时功率的估算概念,并将并网逆变器输出的瞬时有功功率和无功功率作为被控量进行功率的直接闭环控制。系统无需检测输入变压器二次侧的电网电压,省去了电网电压传感器,从而不仅克服了电流控制方案的不足问题,还降低了成本,而且系统具有鲁棒性好、控制结构简单等优点。分析了电压定向直接功率控制的原理,设计了并网逆变器的具体参数,并给出了仿真和实验结果。     

基于复合虚拟阻抗的混合储能系统功率分频协调与谐波电流抑制策略

混合储能系统在传统下垂控制下不能根据蓄电池和超级电容各自的储能特点和动态响应进行功率合理分配,同时单相逆变器负荷的存在导致前级变换器和输入源产生二次谐波电流,这将缩短系统的使用寿命,破坏系统稳定运行。针对以上问题,该文提出一种基于复合虚拟阻抗的功率分频协调与低频谐波电流抑制策略。在复合虚拟阻抗作用下,系统等效输出阻抗在低频段和高频段分别由蓄电池侧和超级电容侧阻抗主导,此时蓄电池提供系统功率波动的低频分量,抑制直流母线电压波动以稳定系统能量供需平衡,超级电容快速吸收系统功率波动的高频分量,提高系统的动态响应。在此基础上分析了复合虚拟阻抗使电感支路在二倍频时呈现高阻抗,非二倍频时呈现低阻抗,从而抑制二次谐波电流。最后,通过实验验证所提方法的有效性。     

微逆变器交流侧泛Buck-boost功率解耦技术研究

针对微逆变器二倍频功率扰动问题,提出了一种交流侧泛Buck-boost功率解耦技术。设计的四种能实现能量双向流动的解耦电路均并联在逆变器交流侧,不同拓扑都可等效工作在Buck、Boost或Buck-boost的模式中。从拓扑结构、工作模式及解耦性能三方面分析了设计的四个解耦电路,以及每种拓扑抑制二次谐波的能力。讨论了脉冲能量缓冲的计算方法。仿真结果表明,三模态六开关Buck-boost功率解耦电路抑制电压二次谐波效果最优,单模态六开关Buck-boost功率解耦电路抑制电流二次谐波效果最优。泛Buck-boost功率解耦技术可以在不依赖母线大电压情况下,大幅降低解耦电容容值,实现无电解电容,提高微逆变器可靠性并延长其使用寿命。     

低压微网中永磁风力发电系统逆变器控制策略研究

在低压微网中,以永磁风力发电并网系统的逆变器为研究对象,主要研究了风力发电系统在并网和离网两种模式下系统逆变器的控制策略。对于系统处于并网和离网情况下,逆变器的电流内环采用瞬时反馈电容电流控制,有效解决了因LCL滤波器引起的系统不稳定控制问题。针对两种不同模式下,本文对并网模式下系统的逆变器控制采用瞬时功率外环、瞬时电容电流PIR内环控制;离网模式下采用负载电压为外环、瞬时电容电流PIR控制为内环的双闭环控制。经过仿真分析,外环瞬时有功无功控制实现了风力发电并网系统逆变器给定功率控制,在系统输出功率发生变化的情况下,电流具有快速精确的动态跟踪性能,实现了系统功率解耦控制,保证了系统输出高质量电能,有效验证了本文控制策略的可行性。     

Two‐loop power‐flow control of grid‐connected microgrid based on equivalent‐input‐disturbance approach

This study employed the equivalent‐input‐disturbance (EID) approach to devise a two‐loop power‐flow control system that controls the output current of an inverter so as to regulate the flow of active and reactive power between a distributed generation unit and a utility grid. It actively eliminates disturbances that degrade the power quality of a microgrid. The pq theory and an all‐pass filter are employed to generate an instantaneous reference current for the control system based on the prescribed active and reactive power of a utility grid terminal. The inner loop consists of a disturbance compensator and a state observer. The disturbance compensator uses information acquired from the state observer to estimate disturbances, such as drops and harmonics in the grid voltage, and compensates for them by incorporating the equivalent input disturbance into the control law. The outer loop consists of a resonance‐based internal model and a state‐feedback controller, which enables the output current of inverter to track the instantaneous reference current. The small‐gain theorem ensures the stability of the system. The system improves the power quality and guarantees that the flow of active and reactive power from the grid and inverter has low harmonic distortion. Simulations demonstrated the effectiveness of the system. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

无电解电容永磁电机高功率因数控制策略

无电解电容驱动系统常采用体积小，寿命长的薄膜电容贮存网侧输入能量，但该拓扑结构易引起网侧输入功率和逆变器侧输出功率耦合的问题。针对无电解电容驱动电路中由于功率耦合导致的网侧谐波含量多和功率因数降低的问题，提出了一种基于二阶广义积分锁相环和比例积分谐振控制器的带相位补偿的逆变器输出功率控制策略以改善网侧电流品质。首先，通过分析无电解电容驱动系统的电路拓扑结构，明确无电解电容驱动系统高功率因数条件；其次，利用二阶广义积分锁相环获取网侧电压的相位与幅值信息，并利用基尔霍夫电流定律计算逆变器输出功率相位补偿角；然后，建立了基于比例积分谐振控制器的逆变器输出功率控制回路，将逆变器输出功率调节接近理想值。最后，对比实验结果验证了所提方案的有效性。     

A High‐Efficiency Single‐Phase Utility Interactive Inverter with an Active Power Decoupling Function and its Control Method

The present paper introduces a single‐phase utility interactive inverter with a power decoupling function. In a conventional single‐phase inverter, power pulsation at twice the grid frequency appears in the input power. Hence, electrolytic capacitors having large capacitances have been connected to the DC input terminal to stabilize the input DC‐bus voltage. Because the lifetime of the electrolytic capacitor is relatively shorter than that of another component, the lifetime of the inverter is affected by the capacitor. In order to prevent such a problem, a novel single‐phase inverter circuit with an active power decoupling function is introduced. The pulsating power on the input DC‐bus line and the pulsated energy on the input DC capacitor is transferred to the energy in a small film capacitor. Hence, the extension of the inverter lifetime can be expected by substituting a small film capacitor for the large electrolytic capacitors. In addition, the loss in the power decoupling circuit is very small; hence, the reduction in the overall conversion efficiency of the inverter can be minimized. The effectiveness of the proposed method is verified using a 300 W experimental setup.     

Power factor improvement of single‐phase diode rectifier circuit by field‐weakening of inverter‐driven IPM motor

This paper proposes a novel inverter drive system to improve the input power factor of single‐phase diode rectifier. Conventional rectifiers need a high‐frequency switching device and a reactor to improve the input power factor. However, the proposed power converter does not need the switching device, electrolytic capacitor, or reactor. By making many ripples across the DC‐bus voltage, the input power factor can be improved. The proposed system consists of only a single‐phase diode rectifier, small film capacitor, three‐phase inverter, and motor. The proposed system adopts an interior permanent magnet (IPM) synchronous motor. The IPM motor is well known as a high‐efficiency motor and can realize field weakening. The basic ideas of the inverter control method are based on the following operations: the inverter's controlled synchronous with the DC‐bus ripple voltage by field‐weakening method, and direct active power feeding from the source side to the motor without smoothing the DC‐bus voltage. This paper describes that the proposed method can obtain an input power factor of 97.3% by experimental tests, and realizes the goals of small size and long life of the system. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(2): 66–73, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20047     

Development of a long‐life three‐phase flywheel UPS using an electrolytic capacitorless converter/inverter

A long‐life three‐phase flywheel (FW) uninterruptible power supply (UPS) using an electrolytic capacitorless converter/inverter and a transformerless isolating system rating of 200 V and 5 kW–1min is described. The UPS has the following characteristics: (1) electrolytic capacitorless converter/inverter configuration for long life and smaller size (2) transformerless isolating system to realize small size and correct weight (3) batteryless system for maintenance‐free long life of about 20 years The electrolytic capacitorless converter/inverter has a small‐film capacitor value of 1/50 times of a conventional one. The converter/inverter is controlled by a current and voltage follow‐up method using PWM control. Charging and discharging abilities of the FW energy is achieved only by controlling the instantaneous slip frequency of the induction machine. The UPS has obtained excellent test results, such as an input power factor of 99.8%, a small output voltage distortion of 1.03%, and 93.8% efficiency at full load. © 1999 Scripta Technica, Electr Eng Jpn, 127(3): 25–32, 1999     

光伏并网逆变器自抗扰二自由度内模控制策略

针对逆变器内环采用传统的一自由度内模控制无法兼顾系统跟随性和抗干扰的局限性,同时由于系统在同步旋转坐标系下不能实现彻底解耦、控制器设计依赖系统参数过强的问题,提出一种新型双闭环控制策略。其中,内环采用基于合成矢量的二自由度内模控制,既解决了系统因输入电感值不能实现彻底解耦的问题,又能保证并网电流同时具有较强的跟随性和抗干扰性;外环在基于瞬时功率平衡的思想上采用不依赖精确模型且强鲁棒性的自抗扰控制技术来保持直流侧电压的稳定,二者结合实现对并网逆变器的综合控制。仿真结果表明,所提控制策略比基于自抗扰的传统内模控制具有更好的动态、静态性能和抗干扰能力,以及更低的并网电流谐波含量。     

基于IMC多机传动系统的控制策略研究

针对传统交直交变换器多机传动系统中间直流环节存在大电感或大电容而使其体积大,笨重等的问题,采用了一种新颖的基于间接矩阵变换器IMC的多机传动系统电路拓扑。其结构紧凑,体积小,重量轻;整流级采用两段式PWM调制策略,可获得单位功率因数的正弦输入电流,多个逆变级均采用空间矢量调制,实现各个逆变级的独立控制,获得不同频率和幅值的正弦电压。在这种调制策略的基础上,分析了零矢量重叠PWM分布方式对输入输出性能的影响,它可以实现整流级电路的零电流换流,减少了逆变级的开关次数,极大地降低了开关损耗,提高了变换器的效率。仿真结果表明:采用零矢量重叠的调制策略可以减少输出电压电流的谐波含量,能够有效改善传动系统的动态和稳态性能。     

光伏并网微型逆变器中功率解耦技术概述

在光伏并网微型逆变器中,输出功率含有两倍工频的功率脉动,而光伏组件根据MPPT算法控制输出为恒定的功率,这两者的瞬时功率不平衡通常由并联在光伏组件两端的大电解电容来解决。然而电解电容寿命有限,远低于光伏组件的寿命要求,成为影响微型逆变器寿命和稳定性的决定性因素。回顾了国内外应用于光伏并网微型逆变器中的功率解耦技术,进行分类介绍并列举了不同的电路拓扑及控制方法,最后对其进行比较并指出各种方法的优缺点。