半控型功率器件并联均流控制的非线性稳定运行机理

发布时间：2018-01-25 05:29

本文关键词： 晶闸管并联精确线性化非线性混沌　出处：《湘潭大学》2015年硕士论文　论文类型：学位论文

【摘要】：晶闸管器件具有耐压高、电流大等优点,在静止无功补偿、高压直流输电和高压变频调速等应用场合仍是主要采用的功率器件,且在很多场合需要采用晶闸管并联技术。现有晶闸管并联技术主要以阻感保护、阻容保护等方法为主,能够满足晶闸管并联的基本要求。然而,晶闸管是一个强的非线性元件,研究结果表明在不同驱动电压、工作频率和供电电压下会产生分岔及混沌行为,并使得晶闸管出现“电流细丝”现象,这将导致晶闸管因局部过流而损坏。因此,如何使晶闸管并联系统在局部和全局都保持良好的均流特性成为重要课题之一。本文以晶闸管器件为研究对象,建立非线性动力学模型,分析其分岔及混沌非线性行为,以期深入地探讨晶闸管并联系统非线性控制策略,为提高晶闸管并联系统的安全性与可靠性奠定研究基础。主要研究内容可论述如下:(1)分析了晶闸管器件的内部物理结构和工作机理,基于半导体物理理论建立晶闸管非线性动力学模型,重点研究了漂移区的动力学行为,推导了其双极扩散动力学方程。(2)基于晶闸管非线性动力学模型,系统分析了晶闸管外部电学特性与其内部物理量演化的相互联系,并在此基础上研究了晶闸管器件呈现的倍周期分岔及混沌等非线性现象。此外,探讨了晶闸管非线性现象对其并联电路工作特性的影响。研究结果表明,由于电路寄生参数和器件物理参数的差异,将会造成分岔或混沌行为而使得并联电路中晶闸管触发时刻的不同步,由此导致晶闸管间存在动态均流的问题,必然会影响到晶闸管的安全稳定运行。(3)为提高晶闸管并联系统的稳定性,本文基于状态反馈精确线性化方法从新的角度来解决晶闸管并联系统中存在的同步触发问题。首先,建立了晶闸管并联系统的非线性仿射模型,基于微分几何理论验证了该系统是否满足精确线性化的前提条件,再通过非线性坐标变换实现了晶闸管并联系统状态反馈精确线性化,并结合线性最优控制理论确定了状态反馈控制律,最后通过数值仿真证实了该控制方案的有效性,从而为晶闸管并联系统的同步触发控制提供了一种新思路。
[Abstract]:Thyristor devices have the advantages of high voltage resistance and high current. They are still the main power devices in static reactive power compensation, HVDC transmission and high voltage frequency conversion speed regulation and other applications. In many cases, the thyristor parallel technology is needed. The existing thyristor parallel technology mainly uses resistive protection, resistive and capacitive protection methods, which can meet the basic requirements of thyristor parallel connection. Thyristor is a strong nonlinear element. The research results show that bifurcation and chaos will occur under different driving voltage, working frequency and supply voltage, and the "current filaments" phenomenon will appear in the thyristor. This will lead to the damage of thyristor due to local overcurrent. Therefore, how to make the thyristor parallel system maintain good current-sharing characteristics both locally and globally has become one of the important topics. This paper takes thyristor devices as the research object. The nonlinear dynamic model is established to analyze the bifurcation and chaotic nonlinear behavior in order to discuss the nonlinear control strategy of thyristor parallel system. In order to improve the safety and reliability of thyristor parallel system, the main research contents can be described as follows: 1) the internal physical structure and working mechanism of thyristor devices are analyzed. Based on the semiconductor physics theory, the nonlinear dynamic model of thyristor is established. The dynamic behavior of drift region is studied, and its bipolar diffusion dynamic equation is derived. (2) based on the nonlinear dynamic model of thyristor. The relationship between the external electrical characteristics of thyristors and the evolution of their internal physical quantities is systematically analyzed, and the nonlinear phenomena such as periodic doubling bifurcation and chaos in thyristor devices are studied on this basis. The effect of thyristor nonlinearity on the performance of parallel circuit is discussed. The results show that the parasitic parameters of the circuit and the physical parameters of the device are different. It will cause bifurcation or chaos and make the thyristor trigger time in parallel circuit out of sync, which leads to the problem of dynamic current sharing between thyristors. In order to improve the stability of thyristor parallel system, it will affect the safe and stable operation of thyristor. In this paper, the synchronization trigger problem in thyristor parallel system is solved from a new angle based on the state feedback exact linearization method. Firstly, a nonlinear affine model of thyristor parallel system is established. Based on the differential geometry theory, it is verified that the system satisfies the precondition of accurate linearization, and the state feedback linearization of thyristor parallel system is realized by nonlinear coordinate transformation. Combined with the linear optimal control theory, the state feedback control law is determined. Finally, the effectiveness of the control scheme is verified by numerical simulation, which provides a new way for synchronous trigger control of thyristor parallel system.
【学位授予单位】：湘潭大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN34

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