【作者】 宋文祥；

【导师】 陈国呈；

【作者基本信息】 上海大学 ， 电力电子与电力传动， 2006， 博士

【摘要】 基于多电平变换器的高压大容量交流调速技术是当今电力电子与电力传动领域的研究热点之一。本文对二极管箝位型三电平逆变器的空间电压矢量调制技术进行了全面研究，并以异步电机为负载研究和探讨了异步电机直接转矩控制及其无速度传感器控制技术，建立起一套三电平逆变器实验平台，进行了大量的实验研究。本文绪论部分针对国内外高压大容量多电平变换技术和交流传动控制技术作了简要综述，着重分析了多电平拓扑结构的发展和研究现状，讨论了交流调速的发展和直接转矩控制技术的特点，指出本文选题的目的和意义。论文详细论述了三电平逆变器空间电压矢量调制的工作原理和实现方法，提出了首发矢量全部采用正小矢量或负小矢量的空间电压矢量调制算法，这是一种八段对称式SVPWM，实际上是一种单极性的脉宽调制方法。考虑到对冗余矢量的不同处理方式，提出了一种准双极性SVPWM方法，通过对冗余矢量的不同处理，其调制方式更有利于抑制中点电压的波动。深入分析了中点电压波动的原因，建立起平均中点电流模型，为中点电压平衡控制提供了理论基础。基于空间矢量调制与三角载波调制两类调制方法的本质联系和准双极性调制方法，提出了两种中点电压平衡控制的方法，该方法只需电容电压和负载三相电流信息，控制算法简便易行，有利于计算机数字控制实现。分析了三电平逆变器在高调制深度下中点电压平衡控制效果差的原因，提出了一种将中矢量由冗余小矢量合成的空间矢量调制方法。理论分析和仿真研究结果表明，这种基于矢量合成的空间矢量调制方法在一个采样周期中对中点电流的平均效果为零，对中点电压不构成影响，可以有效抑制中点电压的波动，尤其是在高调制深度下。深入阐述了三电平逆变器直接转矩控制的主要问题及虚拟合成矢量控制方法，详细讨论了三电平逆变器直接转矩控制中的矢量选择方案。在此基础上，将基于PI调节思想的感应电机DTC控制策略引入到三电平逆变器的控制中。这种基于PI调节的直接转矩控制方法具有便于中点电位控制、转矩响应快、转矩脉动低等优点。研究了基于异步电机数学模型直接推导的定子磁链估算方法，并对其估算性能进行了深入分析。提出了以定子电流、定子磁链为状态变量构成异步电机全阶状态观测器的方案，系统地给出了这种全阶状态观测器的设计方法。并根据李雅普诺夫稳定性原理推导了基于自适应全阶观测器的速度辨识算法，所提出的全阶观测器方案在准确观测电机磁链的同时可实现高性能的无速度传感器运行。以TMS320LF2407A DSP为控制核心，研制了一套三电平逆变器实验装置。在此装置上完成了三电平逆变器的相关实验研究，实验装置运行稳定可靠。大量的仿真和实验结果证明了本文的研究思想和控制策略是正确的。更多还原

【Abstract】 The high-voltage high-power AC motors variable speed techniques based on multilevel converter have become one of research hot points now in the field of power electronics and power drives. Space vector pulse width modulation (SVPWM) method of a three-level neutral-point-clamped (NPC) inverter is studied comprehensively in this dissertation. Then, direct torque control (DTC) and speed sensor-less methods of induction motor, which is driven by a three-level NPC inverter, are studied and explored further, also, a three-level inverter prototype system is built and a lot of experimental results are obtained based on this prototype.The high-voltage high-power multilevel converter and AC motors drive techniques are summarized compendiously for domestic and overseas studies in the prolegomenon of this dissertation. The evolution and research status of multilevel converter topologies are analyzed, the development of AC variable speed techniques and the characteristic of DTC are discussed, also, the aim and significance for the research are demonstrated.In this dissertation, SVPWM pattern and implement method have been addressed comprehensively for three-level NPC inverter. In order to avoid the abrupt change of output voltage vectors during the process of desired vector changing from one section to another, a novel space vector modulation (SVM) algorithm is proposed where positive or negative small vectors are adopted as first active vector, which is virtually a kind of scalar unipolar modulation pattern. Besides, based on the particular disposition of all the redundant voltage vectors, a SVPWM approach called semi-bipolar PWM pattern is present. The harmonic performance of this modulation strategy not only has better output voltage and current waveforms (lower harmonic and lower EMI) than the popular eight-stage centered PWM strategy but also evidently favors the neutral-point voltage balance control.The author investigates the variation mechanism of neutral point (NP), establishes the neutral point current model, therefore, the theory base is built for the balancing control of neutral point potential. Moreover, based on the inherent correlation between carrier-based PWM and SVPWM for three-level inverter and on the semi-bipolar PWM pattern, two control techniques of NP potential variation are proposed, only requiring the information of dc-link capacitor voltages and three-phase load currents, which is convenient to apply and is compatible of digital computer realization.The characteristics of the balancing control of NP potential for a three-level NPC inverter at high modulation depth are analyzed, and based on the analysis, a novel space vector modulation pattern where a middle vectors are synthesized by redundant small vectors is proposed. Theoretical analysis and simulation results indicate that the proposed SVPWM method vector synthesizing concept based can make the average NP current zero, and do not influence the NP potential within every sample period. Thus, the NP potential variation can be restrained effectively, especially at high modulation depth.The main problem of direct toque control of a three-level inverter and control technique virtual synthesizing vectors based are demonstrated in detail, also, the method of vector selection is discussed materially. Then DTC strategy of induction motor based on PI regulating concept is utilized in control method of the three-level inverter, which contains such characteristics as convenient NP variation control, fast torque response and lower torque ripple.The estimation methods of stator flux linkage based on mathematic model of induction motor are studied, and the performance of these estimation methods is analyzed in details. The design method of a full-order state observer, in which the state variables are stator current and stator flux linkage, is present systematically. Based on a adaptive full-order observer, speed estimation method is deduced according to Liapunov stability theorem. With the proposed full-order observer, the flux linkage of motor can be accurately observed and high performance can be achieved without shaft encoder.Based on microprocessor TMS320LF2407A, a three-level inverter prototype is built and correlative experimental researches are implemented by this prototype. The three-level inverter prototype system can work reliably in the whole experimental process. The simulation and experimental results validate the control strategies proposed in this dissertation更多还原