基于模块化多电平结构高压变频器控制系统研究

发布时间：2017-12-27 17:14

本文关键词：基于模块化多电平结构高压变频器控制系统研究　出处：《湖南大学》2015年硕士论文　论文类型：学位论文

【摘要】：能源问题已经成为一个全球性的重大问题,节能减排我国现阶段发展的一个重大方向。高压变频器是工业领域节能的重要手段,其所应用的多电平技术也已成为高压大功率传动领域的主流技术,主要有以下三种拓扑:二极管钳位型、飞跨电容型以及H桥功率单元级联型结构。目前,这几种结构的多电平技术虽然比较成熟,但仍存在不少问题,且对于高性能的高压变频器系统,其应用将受到限制。因此,本文提出将模块化多电平变流器(Modular Multilevel Converter,MMC)的拓扑结构应用到传动领域,构成新型的高性能高压变频系统。首先,本文对模块化多电平变换器的拓扑结构和工作原理做出基本介绍,对其适用在传动领域的基本特点进行分析,从整体上给出主拓扑图,包括与电网相连的MMC整流器、与交流异步电动机相连的MMC逆变器以及直流母线端,并重点介绍半桥型子模块结构的工作状态及运行方式,同时对在此基础上的几种电气模型进行比较分析。同时,对常用的调制策略进行介绍,并对启动时整流侧和逆变侧的预充电做出系统阐述。本文的控制整体分为两部分:整流侧的控制和逆变侧的控制。整流侧连接电网,起到实现单位输入功率因数控制、减少谐波污染和稳定直流侧母线电压的作用。因此,文章从MMC整流器出发,在模块化多电平电气模型的基础上进一步对MMC整流器建立数学模型,以此为依据,分析系统相间环流产生原因、存在方式和具体数学关系,表明环流的存在并不影响MMC外部特性,但会对增大桥臂损耗,并给出具体环流抑制措施。本文重点对电压均衡问题进行分析,基于载波移相调制策略阐述模块化多电平变流器电压平衡控制过程,并经过仿真验证其可行性,得到稳定的直流电压。最后,本文将MMC逆变器与异步电机结合,采用按转子磁链定向的矢量控制对电机进行调速。考虑到传动领域电机多数运行在低频工况,本文对MMC模型低频情况进行探讨,提出一种低频控制方案,并通过仿真验证理论分析的正确性和方法的可行性。
[Abstract]:Energy problem has become a major global problem, energy conservation and emission reduction of our country at the present stage of a major direction. High voltage inverter is an important means of energy saving in the industrial field. The multi-level technology has also become the mainstream technology in the field of high voltage and high power transmission. There are mainly three kinds of topology: diode clamp, fly capacitor and H bridge power unit cascaded structure. At present, the multilevel technology of these structures is quite mature, but there are still many problems, and the application of high-performance multilevel inverter system will be limited. Therefore, this paper proposes to apply the topology of Modular Multilevel Converter (MMC) to the transmission field, and form a new high-performance HV frequency conversion system. First of all, the topological structure and working principle of modular multilevel converter make the basic introduction, applicable to the basic characteristics in the field of transmission is analyzed, from a given main topology on the whole, including the MMC MMC rectifier inverter and AC asynchronous motor, and connected to the DC bus terminal connected to the grid, and focuses on working condition and operation mode of half bridge sub modules, and several electrical model on the basis of comparative analysis. At the same time, the commonly used modulation strategies are introduced, and the pre charging of the rectifier side and the inverter side is systematically expounded. The overall control of this paper is divided into two parts: control of the rectifier side and the control of the inverter side. The rectifier connects the power grid to realize the unit input power factor control, reduce the harmonic pollution and stabilize the DC bus voltage. Therefore, this article from the MMC rectifier of basic multilevel electrical model in the module on the further establishment of the mathematical model of MMC rectifier, on this basis, analysis of system phase existence and the mathematical relationship between the specific circulation causes, that circulation is the influence of the external characteristics of MMC, but will increase the leg loss, and give the specific measures to suppress circulation. This paper focuses on voltage balancing problem. Based on carrier phase shift modulation strategy, the voltage balance control process of modular multilevel converter is expounded, and its feasibility is verified through simulation, and a stable DC voltage is obtained. Finally, this paper combines the MMC inverter with the asynchronous motor, and uses the vector control of the rotor flux orientation to speed the motor. Considering that most of the motors in the transmission field operate at low frequency, this paper discusses the low frequency of the MMC model, proposes a low frequency control scheme, and verifies the correctness of the theoretical analysis and the feasibility of the method through simulation.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM921.51;TM46

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