基于电容电压平衡的NPC三电平逆变器矢量控制的研究

发布时间：2018-06-08 19:59

本文选题：二极管箝位型 + 三电平逆变器　；参考：《河南科技大学》2014年硕士论文

【摘要】：随着我国工业的快速发展，多电平逆变器在高压大容量交流变频调速系统中的应用成为电力电子技术领域的研究热点。由于多电平逆变器相对于传统的两电平逆变器，具有输出电压谐波含量小、功率开关器件频率低等明显的优势，现已在电力系统和电力传动的高压大容量场合得到广泛的应用。本文以二极管箝位型（NPC）三电平逆变器的异步电机矢量控制系统为研究对象，针对矢量控制中的转子磁链观测进行理论研究，对三电平空间电压矢量调制（SVPWM）算法进行详细的分析和探讨，针对NPC三电平逆变器在运行过程存在的中点电位不平衡问题进行深入研究，并提出相应的解决方法。主要研究工作如下：对高压大容量交流调速系统进行简要概述，讨论多电平逆变器的研究现状，探讨多电平逆变器在变频调速系统的应用；分析NPC三电平逆变器的拓扑结构，建立其数学模型；阐述异步电机矢量控制的基本原理。针对NPC三电平逆变器采用的传统三电平SVPWM调制算法复杂，不利于实时控制的缺点，提出一种基于简化算法的三电平SVPWM调制算法，该算法通过对空间电压矢量的分解及平移，来计算基本电压矢量的作用时间和选择合适的开关输出状态，达到简化算法的目的。针对NPC三电平逆变器存在的中点电位不平衡的问题，分析中点电位波动的机理，提出一种基于gh坐标系的虚拟空间电压矢量(VSVPWM)准确补偿中点电位的控制策略，引入虚拟中矢量和电压调整系数，，对不同的正、负小矢量分配不同的调整系数，增加小矢量控制中点电位的平衡能力和灵活性；同时在gh坐标系下计算基本电压矢量的作用时间，简化算法的复杂性。针对上述理论研究，搭建Simulink仿真平台，利用MATLAB仿真软件对三电平简化SVPWM算法和中点电位补偿平衡控制策略进行仿真分析，验证所提算法的正确性。设计基于NPC三电平逆变器的异步电机矢量控制系统实验平台，搭建硬件电路。在以TMS320F2812为核心的DSP控制板上，编写软件程序，通过实验验证所提出的三电平简化SVPWM算法及中点电位补偿平衡控制策略的有效性与可行性。
[Abstract]:With the rapid development of industry in our country, the application of multilevel inverter in high voltage and large capacity AC frequency conversion speed regulation system has become a research hotspot in the field of power electronics technology. Compared with the traditional two-level inverter, multilevel inverter has the advantages of low output voltage harmonic content and low frequency of power switch devices. It has been widely used in high voltage and large capacity fields of power system and power transmission. In this paper, the vector control system of induction motor based on diode clamped three-level inverter is studied. The theory of rotor flux observation in vector control is studied, and the three-level space voltage vector modulation (SVPWM) algorithm is analyzed and discussed in detail. The neutral-point potential imbalance of NPC three-level inverter during operation is studied and the corresponding solutions are put forward. The main research work is as follows: briefly summarize the high voltage large capacity AC speed regulating system, discuss the research status of the multilevel inverter, discuss the application of the multilevel inverter in the frequency conversion speed regulation system, analyze the topology structure of NPC three-level inverter, The basic principle of vector control for induction motor is described. The traditional three-level SVPWM modulation algorithm used in NPC three-level inverter is complex, which is not conducive to real-time control. A three-level SVPWM modulation algorithm based on simplified algorithm is proposed. By decomposing and translating the space voltage vector, the working time of the basic voltage vector is calculated and the appropriate switching output state is selected. In order to simplify the algorithm, the mechanism of neutral-point potential fluctuation in NPC three-level inverter is analyzed. A control strategy for accurate compensation of midpoint potential by virtual space voltage vector VSVPWM based on gh coordinate system is proposed. Virtual middle vector and voltage adjustment coefficient are introduced to assign different adjustment coefficients to different positive and negative small vectors. Increasing the balance ability and flexibility of point potential in small vector control, calculating the action time of basic voltage vector in gh coordinate system, simplifying the complexity of the algorithm. In view of the above theoretical research, a Simulink simulation platform is built. The simulation analysis of three-level simplified SVPWM algorithm and neutral-point potential compensation balance control strategy is carried out by using MATLAB simulation software to verify the correctness of the proposed algorithm. An experimental platform for vector control system of asynchronous motor based on NPC three-level inverter is designed. Build the hardware circuit. On the DSP control board with TMS320F2812 as the core, the software program is written to verify the effectiveness and feasibility of the proposed three-level simplified SVPWM algorithm and the neutral-point potential compensation balance control strategy.
【学位授予单位】：河南科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM464

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