H桥级联多电平逆变器相移SVPWM技术的研究

载波相移SPWM调制法是级联型逆变器的主流控制方法,其等效载波频率高、谐波特性好、功率单元之间输出功率平衡。而空间矢量法谐波特性好、电压利用率高、控制方法简单便于数字实现。文中针对H桥级联型多电平逆变器的结构特点,综合采用载波移相SPWM法和空间矢量法,并用一种新的空间矢量算法取代传统的方法。该算法中无需三角函数和无理数计算,计算过程非常简单,节约了计算时间,结果更为准确。最后通过系统仿真验证该算法的正确性和有效性。     

级联型多电平逆变器中多载波PWM控制方法的改进

级联型多电平逆变器由于其模块化结构、便于生产高度、更换容易等特点，受到电力电子工程技术人员的广泛关注。本文通过对于级联型多电平逆变器几种典型的控制方法的分析比较，提出了一种改进多载波PWM控制方法。该方法通过改变载波的幅值，使级联逆变器的各个逆变单元开关规律相同，并使所有的开关器件的损耗一致，有利于逆变单元的统一设计和可靠运行。     

一种简易交错级联式多电平逆变器

多电平变换器以其输出电能质量高、谐波失真小、电磁干扰小等优点受到了广泛的关注。然而,现有多电平逆变器存在器件数量较多和电压应力较大等缺点。对此,提出一种新型简易级联式多电平逆变器拓扑结构。首先,介绍了逆变器的拓扑结构,讨论了变换器的对称和非对称形式。然后,将该拓扑结构与级联H桥变换器进行了比较分析。结果显示,该拓扑结构减少了开关数量和门驱动器数量。同时,该拓扑的峰值反向电压低于传统CHB变换器。此外,模块化是该拓扑的另一个重要特征。最后搭建一台样机进行实验,证明了所提出电路的有效性和可行性。     

级联多电平逆变器

级联逆变器以其开关应力小、输出波形优、易于封装和扩展等性能，越来越广泛地应用于柔性交流输电、不停电电源及中高压变频调速等领域。本文详细介绍了目前级联多电平变换器常用拓扑结构、控制方法及它们的特点，最后就级联逆变器的功率平衡及共模电压抑制等问题进行了简要分析探讨。     

多电平逆变器主要控制策略综述

过出的十年中，多电平逆变器在中压大功率领域受到了广泛的关注。提出了各种各样的拓扑结构和控制策略，并广泛应用于各种场合。本文介绍了在多电平逆变器中重要的控制策略，包括载波调制、空间矢量、波形逼近和闭环调制等方法。     

二极管箝位型多电平逆变器载波PWM控制方法的研究

在分析二极管箝位型多电平逆变器不同的载波PWM控制方法的基础,提出了一种新型的载波PWM方法。为了验证所提出的PWM方法，对二极管箝位型五电平逆变器进行了仿真研究。仿真结果表明，该方法在低调制度下具有良好的谐波特性，同时可以提高调制度，增加直流电压利用率。     

混合型级联多电平逆变器的PAM调制和PWM调制

介绍了混合型级联多电平逆变器的PAM和PWM调制方法,在Matlab7．0中构建了基于这两种调制方法的多电平逆变器的仿真模型。仿真结果表明,混合型级联多电平逆变器能够有效减小谐波畸变率,改善输出电压波形。     

H桥级联型多电平逆变器调制策略对比分析

针对H桥级联型多电平逆变器,对比分析了传统的多电平PWM调制策略,指出其存在的输出电压谐波性能问题。提出一种改进的调制策略,不仅抑制了直流母线电压波动引起的低次谐波含量,而且有效地降低了高、次谐波含量。最后通过对比实验,验证了所提出方法的正确性与有效性。     

非对称H桥五电平逆变器及其通用调制策略

非对称H桥五电平逆变器所用功率开关较少,具有较高的性价比。对该类拓扑的结构进行分析,提出一种通用的调制策略,对三种五电平非对称H桥均适用。最后通过电容箝位型五电平非对称H桥实验平台,验证了所提调制方法的正确性与有效性。     

一种级联H桥多电平变频器改进型载波移相PWM调制策略

级联Ｈ桥多电平变频器已经广泛应用于光伏发电、电机调速等领域，但由于各单元独立直流电源参数差异，导致各单元直流电压不均衡， 在单元直流电压不均衡时，传统载波移相ＰＷＭ调制策略存在输出电压低频边带谐波无法消除的问题，从而影响输出电能质量，对传统载波移相ＰＷＭ调制策略下变频器输出电压进行了傅里叶分析，研究了一种可变移相角的改进型载波移相ＰＷＭ调制策略，根据不同工况实时改变移相角，从而消除输出电压的低频边带谐波，有效提高输出电能质量，最后，通过样机实验验证了改进型调制策略的有效性。     

分布式电源并网逆变器控制策略与仿真研究

逆变技术的发展是随着电力电子技术、微电子技术和现代控制理论的发展而发展.针对光伏并网过程中的直流升压、SPWM波形产生、同步锁相、逆变并网动态过程、研究了基于电网特点的FIR数字滤波、交流采样和稳定直流母线电压的数字PID控制器等技术提出了基于改进MPPT算法的控制策略并进行Simulink动态仿真.     

基于模糊控制的光伏并网逆变器MPPT控制研究

最大功率点跟踪控制的目的是为了将光伏阵列发出的最大能量实时地提供给负载,使光伏发电系统的能量利用率达到最大。在光伏阵列产生电能的应用中,有许多不确定因素,如太阳光照强度、光伏阵列温度的变化、负载的变化、光伏阵列输出特性的非线性,则建立模型分析光伏阵列输出最大功率要考虑很多的因素。从模糊控制技术的分析中知道,模糊控制不需要对被控对象建立精确的数学模型,是一种相对简单的智能控制方法,对处理非线性问题有很好的效果。因此,用模糊控制法来实现MPPT可以得到比较好的效果。本文基于此研究了光伏阵列的非线性功率输出特性,建立了基于Matlab simulink/Power system的光伏阵列仿真模型,对基于模糊控制采用扰动观察法进行光伏发电最大功率点跟踪进行了仿真验证。     

光伏并网逆变器控制和仿真

为了达到提高光伏逆变器的容量和性能目的,采用并联型注入变换技术。根据逆变器结构以及光伏发电阵电流源输出的特点,选用工频隔离型光伏并网逆变器结构,并在仿真软件PSCAD中搭建光伏电池和逆变器模型,最后通过仿真与实验验证了理论的正确性和控制策略的可行性。     

Economical design of H-bridge multilevel inverter drive controlled by modified fast algorithm

Traditional cascaded multilevel inverter needs n DC voltage sources to give 2n + 1 levels. As number of levels increased, the amount of switching devices, their proper related drive circuits and their controllers and other components are also increased excessively, making the inverter more complex and costly. A simple and low cost single-phase cascade multilevel inverter with no transformers can be implemented using only single-DC source with n-1 DC sources represented by capacitors and with reduced switches. So, current inverter hardware cost can be reduced abruptly as compared with conventional one.When the number of DC sources is increased, inverter output has higher harmonic content characterized by their transcendental equations that become more complicated and required more time to be solved. New technique is exhibited to find the inverter switching angles by executing modified fast recursive algorithm providing an on-line precise solution for the Harmonic Elimination (HE) problem. The suggested optimized algorithm technique have been used to find optimum switching angles necessary to eliminate any number of lowest order harmonics and maintain the desired fundamental voltage for driving an AC motor. Simulation results of cascade 7-level inverter with single-DC source under the optimized HE stepped waveform technique is used to eliminate the 3rd and 5th harmonics. Prototype design for the proposed inverter loaded by single-phase fan motor is built.     

Switch fault detection and diagnosis in space vector modulated cascaded H-bridge multilevel inverter

This article investigates the development and online implementation of the power switch open-circuit fault detection and diagnosis in symmetric cascaded H-bridge multilevel inverter. A mathematical modelling technique is presented to understand the effect of the fault on the bridge voltages and output voltage. The modelled values of the output voltage, simulation results and experimental results indicate that the fault diagnostic methods based on the output voltage as the diagnostic feature have certain ambiguity in identifying the fault switch, since the output voltage waveform and its features remain the same for a group of switches under the fault condition. In order to overcome this, fault detection and diagnosis method based on the mean values of the bridge voltages is proposed in this article, which identifies the faulty switch pair and H-bridge in which the fault has occurred. Further, this method has been experimentally validated on a five-level space vector modulated symmetric cascaded H-bridge multilevel inverter.     

具有APF功能的光伏发电并网系统的逆变器控制

为了实现光伏并网发电,同时补偿电网中的谐波,提出了三相光伏并网发电与有源滤波统一控制的方案。文章首先给出一种具有有源滤波(APF)功能的光伏并网发电系统;然后提出PID与模糊神经网络相结合的APF控制策略,其中PID控制器用于保证逆变器电流控制系统的渐近稳定,模糊神经网络控制器用来改善系统的动态性能。最后,利用Matlab/Simulink对系统进行了仿真,验证了系统的可行性。     

双级式光伏并网逆变器Boost控制算法研究

介绍了户用型光伏并网发电的优点。指出在双级式并网逆变器的Boost电路中,控制算法应当完成升压控制和最大功率追踪（MaximumPowerPointTracking,MPPT）,对这两种控制策略进行了详细研究。此外,对MPPT应用时的两个实际问题最大功率限制输出以及逆运行也进行了讨论。最后在Simulink中建立了仿真模型,仿真结果表明Boost控制算法具有可行性。     

双级式光伏并网逆变器Boost控制算法研究

介绍了户用型光伏并网发电的优点。指出在双级式并网逆变器的Boost电路中,控制算法应当完成升压控制和最大功率追踪(Maximum Power Point Tracking,MPPT),对这两种控制策略进行了详细研究。此外,对MPPT应用时的两个实际问题最大功率限制输出以及逆运行也进行了讨论。最后在Simulink中建立了仿真模型,仿真结果表明Boost控制算法具有可行性。     

Reduction in controlled power switches for a single-phase novel multilevel inverter

Multilevel inverter (MLI) generates stepped voltage with appropriate switching combination of power devices, thus restraining the requirement of filter circuit for an efficient power conversion. MLIs are attracting due to some of the major features like economic cost, installation space, bulkiness, complexity along with its enormous applications in industries like cement factory, ceramic industry, aerospace applications etc. In this paper, a single-phase generalised inverter based on five different algorithms is proposed that uses the minimum of overall power components. The presented topology can be used in low and medium voltage applications. To verify the simulation results obtained by MATLAB/Simulink, DS1103 controller is used to generate the corresponding experimental results by developing a prototype model in the laboratory. Nevertheless, a comparative assessment for the different required components of the proposed topology is carried out with some recently developed topologies. Reduction in power switches, driver circuits and DC voltage sources reduces the size, cost, complexity and enhances the overall performance. In addition, level per switch ratio is added in this paper to decide the effectiveness of the proposed topology.     

Unified power flow controller using the cascade multilevel inverter

Power flow control is important in power systems and recently becomes more urgent because of the deregulation and 2003 blackout. This paper presents a novel configuration of unified power flow controller. The proposed configuration has several unique features and advantages over the conventional configuration. As a result, cascade multilevel inverter can be used in the new configuration to lower the cost, volume, and increase the reliability of the system. Analysis and simulation results will be presented.