【作者】 谭智涵；

【导师】 夏长亮；

【作者基本信息】 天津大学 ， 电机与电器， 2012， 硕士

【摘要】 多电平逆变器是近年来中高压大功率电力电子应用领域的一个研究热点,它是一种通过改变电路自身拓扑结构来实现高压大功率输出的一种新型变换器,因而无需使用均压电路和升降压变压器。较传统两电平逆变器,由于输出电平数的增加,功率器件承受电压应力减小,开关动作频率降低,输出电压谐波成分减少,多电平逆变器在高压交流调速、柔性交流输配电技术等领域获得了越来越广泛的应用。本文选取常见的二极管箝位型三电平逆变器为研究对象,对其空间矢量调制技术及中点电位平衡控制方法进行了研究。对多电平逆变器各类拓扑结构进行分类,从电力电子电路基本单元的概念出发,以现有功率器件构造了基本开关单元,按照基本单元并-串及串-并的思想推导了各类拓扑结构。并对二极管箝位型三电平逆变器结构、运行原理和数学模型进行了详细讨论。PWM控制技术是多电平逆变器研究中的一个关键技术,其调制方法好坏对逆变器的输出性能有着至关重要的影响。本文对三电平空间矢量调制中扇区划分、基本矢量选择、作用时间计算及矢量优化等问题进行详细研究,在此基础上提出了一种三电平空间矢量调制简化算法,理论推导了该算法的正确性。控制中点电位平衡是保证二极管箝位型三电平逆变器正常工作的重要前提。本文简单介绍了二极管箝位型三电平逆变器中点电位不平衡的原因及不平衡所带来的危害,分析了各开关状态对中点电位的影响,并给出了一种通过重新分配正负小矢量作用时间平衡中点电位的控制方法。最后搭建MATLAB/SIMULINK仿真模型对三电平空间矢量简化调制算法及中点电位平衡控制方法进行了可行性验证,设计制作了一个以TMS320F2812和EP1C6Q240C8为控制核心的二极管箝位型三电平逆变器实验平台,进行了实验验证。更多还原

【Abstract】 Recently, multi-level inverters are the research focus in medium and/or high voltage high power applications. As a new type of converter, multi-level inverters provide high voltage high power output through changing the circuit topologies, without using voltage-sharing circuit and boost-buck transformer. Compared with the traditional two-level inverter, multi-level converters can output more voltage levels and have such advantages, the voltage across the power device is reduced, the switching frequency is lower, and the output voltage quality is better, so multi-level inverters are founding increased attention in high voltage drives and flexible AC transmission. The common neutral-point-clamped (NPC) three-level inverter is discussed in this paper, and the space vector modulation algorithm and neutral-point potential balancing control method are studied.In this paper, all kinds of multi-level inverter topologies are classified and the topologies are deduced from the parallel-series and series-parallel connections of the power electronics circuits basic cell, which is constituted by power devices. The topology, the operation principle and the switching mathematical model of the NPC three-level inverter are discussed in detail.PWM control strategy is a key technique to multi-level inverters, which can impact the output voltage quality. This paper studies the sector dividing, basic vector calculation, duration computing and vector optimization of three-level space vector modulation. A simplified modulation method is presented based on the previous analysis, and the validity of the proposed method is verified by the theoretical derivation.The neutral-point potential balancing control is the premise of NPC three-level inverter operations. This paper simply introduces the reasons of neutral-point potential unbalancing and the damages brought by the unbalancing in NPC three-level inverter. The effects on neutral-point potential produced by various switching states are analyzed, and a kind of neutral-point potential balancing control method by redistributing the duration of redundant vectors is discussed.The simulation analysis based on MATLAB/SIMULINK and the experiments verify the validity of the simplified modulation method and neutral-point potential balancing control strategy. An experimental setup of NPC three-level inverter including TMS320F2812 and EP1C6Q240C8 is used for the experimental verification.更多还原