基于模块化多电平结构高压变频器的研究

发布时间：2018-04-08 22:32

本文选题：模块化多电平变流器　切入点：直流母线电压平衡策略　出处：《湖南大学》2014年硕士论文

【摘要】：现今，多电平技术逐渐成为中高压大功率传动的主流技术。在现有的技术下，人们已经能较为有成效的实现高性能的大功率中高压传动。但是仍然存在不少问题，二极管钳位型和飞跨电容型多电平变流器大都只有三电平五点平的产品难以满足国内6KV、10KV甚至更高的电压等级要求。级联型高压变频器虽然通过一定数目单元子模块的级联可达到任意等级的电压，但是由于其没有公共的直流母线不能方便的进行能量的双向流动，所以很难被应用于需要四象限运行的高性能高压变频器系统。如果级联型高压变频器要应用于高性能的传动系统则需要对级联单元的不可控整流替换为可控的PWM整流器，这大大增加系统的复杂性，同时仍然不能避免主电路前端的工频变压器将电网电压调整至合适的电压值。基于以上原因，本文在查阅了国内外大量的文献的基础上提出了一种新型的基于模块化多电平变流器(Modular Multilevel Converter，MMC)的高性能的高压变频器系统，该方案在国外和国内研究的人较少，具有创新性和前瞻性。模块化多电平变流器是近年来兴起的一种多电平结构，该结构与级联型多电平变流器结构相似，都是通过一定的模块级联而来，不同的是模块化多电平子模块能量来自直流母线，故采用背靠背结构就能形成可四象限运行的高压变频器系统。本文从以下几个方面阐述该新型高压变频器系统。 1）本文介绍了模块化多电平的拓扑结构以及基本的工作原理，其中包括半桥型模块化多电平结构和全桥型模块化多电平结构，并详细探讨了半桥以及全桥结构的各种工作状态。而后介绍了模块化多电平变流器的调制算法。 2）引入了模块化多电平的电气模型，，在模块化多电平电气模型的基础上进一步建立其数学模型，从数学模型出发，提出了一种模块化多电平变流器直流母线电压平衡的策略。 3）为了获得一种高性能的高压变频器系统方案，本文将PWM整流算法以及感应电机的矢量控制算法与模块化多电平变流器进行了融合。 4）结合本文所提出的新型高性能高压变频器系统方案，搭建了相应的MATLAB仿真模型，对模块化多电平的基本调制算法、电压平衡策略、PWM整流控制策略以及感应电机的控制策略进行了仿真。仿真结果表明该方案的在理论上的可行性。
[Abstract]:Nowadays, multi-level technology has gradually become the mainstream technology of medium-high-voltage high-power transmission.In the existing technology, people have been able to achieve high-power high-power and high-voltage transmission.However, there are still many problems. Most of the multilevel converters with diode clamping and flying capacitance have only three level and five point flat. It is difficult to meet the domestic requirement of 6kV 10KV or higher voltage grade.Although cascaded high voltage converter can reach any level of voltage through the cascade of a certain number of unit submodules, it can not easily carry out the two-way flow of energy without a common DC bus.Therefore, it is difficult to be applied to high performance high voltage inverter system which needs four quadrant operation.If the cascaded high voltage converter is to be applied to the high performance transmission system, it needs to replace the uncontrollable rectifier of the cascade unit with the controllable PWM rectifier, which greatly increases the complexity of the system.At the same time, the power frequency transformer at the front end of the main circuit can not avoid adjusting the grid voltage to the appropriate voltage value.Based on the above reasons, this paper presents a new high voltage converter system based on modular multilevel converter Modular Multilevel converter MMC, which is based on a large number of literatures at home and abroad.Innovative and forward-looking.Modular multilevel converter is a kind of multilevel structure developed in recent years. It is similar to cascaded multilevel converter structure and is cascaded by certain modules.The difference is that the energy of the modularized multilevel sub-module comes from the DC bus, so a four-quadrant high voltage inverter system can be formed by using the back-to-back structure.This paper describes the new high-voltage inverter system from the following aspects.1) this paper introduces the topology and basic working principle of modularized multilevel, including half-bridge modularized multilevel structure and full-bridge modularized multilevel structure, and discusses the various working states of half-bridge and full-bridge structure in detail.Then the modulation algorithm of modularized multilevel converter is introduced.2) the modular multilevel electrical model is introduced, and the mathematical model is further established on the basis of modularized multilevel electrical model. Based on the mathematical model, a strategy of DC bus voltage balance for modularized multilevel converter is proposed.3) in order to obtain a high performance high voltage inverter system, this paper combines the PWM rectifier algorithm and the vector control algorithm of induction motor with the modular multilevel converter.4) combined with the new high voltage frequency converter system scheme proposed in this paper, the corresponding MATLAB simulation model is built, and the modularized multilevel basic modulation algorithm is proposed.Voltage balance strategy, PWM rectifier control strategy and induction motor control strategy are simulated.The simulation results show that the scheme is feasible in theory.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

【参考文献】