【作者】 蔡凯；

【导师】 秦忆； 程善美；

【作者基本信息】 华中科技大学 ， 控制理论与控制工程， 2010， 博士

【摘要】 随着保护生态环境观念的深入人心,提高能源使用效率、减少能源资源消耗、促进使用可再生能源已成为当今世界各国谋求发展的重要共识。我国也适时提出了建设“资源节约型”社会、促进可持续发展的战略目标。将电力电子与自动控制等技术相结合,研制各种新型电力电子装置,构建绿色的电能使用环境,可以为实现这一发展目标提供强有力的支持。多电平变换器以其在高性能和大容量方面的突出优势已成为近年来国内外研究与应用的热点之一。多电平变换器包含独立直流单元型和单一直流单元型,以及混合型等多种拓扑结构。其中,单一直流单元类型中的二极管箝位型结构以其结构简单、成本较低等优点而得到最为广泛的研究和应用。多电平逆变器的通用调制策略是其研究领域中重要的课题,是实现多电平应用的基本保证,本文以其作为主要研究内容之一。本文分析了电力电子变换器数字控制的基本问题,从空间矢量意义和正弦调制波意义两个方面为任意电平或任意相的多电平逆变器建立了数学模型,对比传统的三、多电平调制策略,提出了新颖的基于二电平拓展的任意电平逆变器的控制策略和基于标量合成的任意电平、任意相系统的控制策略,并详细讨论了两种控制策略的工作机制、实现步骤和关键技术等问题。本文还对单相电路上的开关器件的工作机制进行了研究,依据运行特点将其分为二电平开关组、常开开关组、常断开关组,有效地解决了多电平PWM信号的扩展分配问题。二极管箝位型多电平逆变器以其结构简单、成本较低等优点而得到广泛的研究和应用,电容电压平衡问题是影响其安全运行和输出性能的关键问题,该问题的研究工作具有重要的理论和工程价值。本文首先讨论了三电平逆变器电容电压失衡原因和影响,对失衡特性深入地进行了解析推导,得到了电容电压瞬时波动、连续波动和最大波动等波动特性的分析结论,并将这些结论推广到更多电平逆变器中,为箝位型多电平逆变器的电气参数设计和电容电压平衡控制提供了指导。在失衡分析的基础上,本文针对载波通式中的自由度项,提出了两种新颖的三电平逆变器电容电压平衡控制策略——电容电压滞环变幅控制策略和电容电压滞环偏移控制策略。并在逆变器输出性能为首要控制目标这一思路的指导下,分析了严格刚性的电容电压平衡控制是存在弊端且不必要的,进一步提出了电容电压柔性平衡控制策略。在Matlab中搭建仿真模型中得到的仿真结果验证了分析结论和控制方法的正确性。依照模块化、最大化的思路,设计了基于DSP+CPLD架构的三电平逆变器实验平台。在实验平台上对本文所提出的空间矢量PWM通用控制策略和正弦PWM通用控制策略、三电平电容的失衡特性、以及滞环变幅、滞环偏移及电容电压柔性平衡控制策略等进行了实验研究。仿真和实验结果充分验证了本文理论研究工作的正确性。更多还原

【Abstract】 With the concept of protecting the environment going popular, to improve energy efficiency, to reduce resource consumption, and to promote the use of renewable energy have become an important consensus about human development in the world. China has also made timely strategic objectives of construction of resource-saving and sustainable development society. The power electronics and automatic control technology are combined to develop various new power electronic devices, which provides strong support to build a green environment of power energy usage.With its outstanding advantages in performance and capacity Multilevel Converter is one of the abroad hotspots in research and application these years. Multilevel structure contains single DC unit type and multi DC unit type, as well as mixed type. One of the single DC unit type, the Neutral Point Diode-Clamped multilevel structure is the most widely studied and applied due to its simple structure and low cost.Modulation strategy for multilevel inverter is an important issue in the related field, which is the basic guarantee for the application of multilevel technique, and is a major component of this paper. The basic problem in the digital control of power electronic converters is analyzes in this paper. The mathematic model for multilevel system with any phases and levels is built from the view of the space vector meaning and of the sinusoidal modulation meaning. Two novel strategy, Extended 2-level Space Vector Modulation and Scalar Level Synthesis Modulation are put forward, which are effective for multilevel system with arbitrary phase or level, and their working mechanism, implementation steps and key technology issues are discussed in detail. A study on the working mechanism of the switching device among single-phase bridge arm was conducted, and these switches are divided into three groups according their characteristics, two-level switch, normally turn-on switch, and normally turn-off switch, so as to solve effective the problem of multilevel PWM signal distribution.As diode-clamped multilevel system has been widely studied and applied owing to its simple structure and low cost, capacitor voltage balance is one of the key issues involving operation safety and output performance for this type. With general discussing about causes and impacts of imbalance of mid-point level in three-level system, a deep analysis is conducted on the imbalance characteristics, and the instantaneous fluctuation, continuous fluctuation and peek fluctuation is calculated as its results, finally these results are extended to more level multilevel system. This research gives guidance for design and control of the Clamped type Multilevel system. Based on analysis of the imbalance, two novel capacitor voltage balance strategies for three-level system, Hysteresis Zoom of Capacitor Voltage strategy and Hysteresis Shift of Capacitor Voltage strategy, are presented. Furthermore the Flexible Balance of Capacitor Voltage strategy is presented to enhance the output performance of the foregoing two strategies, obeying the rule that output performance lies above capacitor voltage balance. Simulation results on the model built in Matlab verify the analysis and schemes above.With the goal of achieving the structure modularity and maximum utility, a three-level inverter prototype is designed based on the DSP+CPLD platform. All proposed strategies and analysis, Extended 2-level Space Vector Modulation strategy, Scalar Level Synthesis Modulation strategy, three-level capacitor voltage imbalance of the mid-point, the proposed Hysteresis Zoom of Capacitor Voltage strategy, Hysteresis Shift of Capacitor Voltage strategy, as well as the Flexible Balance of Capacitor Voltage, are studied on Matlab simulation platform and the prototype platform. Simulation and experimental results fully verify the correctness of theoretical research in this paper.更多还原