【作者】 彭国庆；

【导师】 欧阳红林；

【作者基本信息】 湖南大学 ， 控制理论与控制工程， 2004， 硕士

【摘要】 异步电动机直接转矩控制(DTC)变频调速技术是继矢量控制变频调速技术之后发展起来的一种新型变频调速技术。它以其新颖的控制思想，简洁明了的系统结构，优良的静、动态性能得到了迅速的发展。 本文首先简要地介绍了直接转矩控制的原理和基本结构，对异步电机的三种磁链模型进行了仿真对比，并在电压-转速(u-n)磁链模型中引入PI调节器对由于定子压降而造成的磁链失真进行动态补偿，获得了良好的磁链和转矩响应。文中详细地分析了电压型逆变器以及其空间电压矢量与异步电机的电磁转矩、定子磁链之间的关系以及相互影响，在此基础上构建了基于两电平逆变器异步电机直接转矩控制系统，对直接转矩控制理论以及其性能进行了仿真分析和验证。 文章从增加电压空间矢量的数目，改善磁链轨迹着手，提出将直接转矩控制技术应用于多电平逆变器的控制中，并重点以三电平逆变器为例对其进行了分析论证，提出了一种将三电平逆变器的中间电压矢量应用于直接转矩控制以改善电机在低速运转时受定子压降影响大而产生的磁链模型失真、转矩波动大的缺点的控制策略。根据这种思想，制定了用于控制三电平逆变器的开关状态选择表，并在MATLAB下对其工作性能进行了仿真和对比。实践证明该方案是一种减小转矩波动、削弱低速运转时的弱磁效应，同时有效地降低主控器件的开关频率的一种控制策略。文中也对多电平逆变器的电压空间矢量以及其控制进行了分析和说明，提出了一种将直接转矩控制技术应用于悬浮电容五电平逆变器控制的一种实现方案，并以简化电压查找表为思路，提出将不同电平的电压空间矢量根据电机转速分解成几个简单的电压查找表的方法，文中还以表格的形式给出了五电平逆变器电压空间矢量与相应的开关状态之间的对应关系。 文章最后提出了将数字信号处理器(DSP)应用于三电平逆变器直接转矩控制系统的一种实现方案，给出了控制系统的硬件框架以及部分控制程序的软件流程图。更多还原

【Abstract】 Direct Torque Control (DTC) is a new developing AC motor speed control strategy with simple structure and easy implementation but high performance. In this paper the basic theory of DTC is introduced briefly, and three kind of flux-models of induction motor are constructed in MATLAB. The simulation results show that the u-n model with PI regulator to compensate voltage drop caused by the resistance of stator is much better in performance than other models. A kind of simulation model of direct torque control system is established use this u-n model, the results show that the conventional DTC has some drawbacks such as large ripple in low speed region and switch frequency variation according to the change of motor parameters and motor speed. Because the tight relations among the voltage vector, stator flux linkage and torque, we proposed a new kind of control strategy based on three-level inverter. Take the advantage of more voltage vector is available, we tried to used the inter-mediate voltage to replace the traditional selector and found that the demagnetization problem is resolved when the motor running in low speed region. Further study about the multi-level inverter is proposed in the following chapters. The voltage vector selecting rules are listed out in the form of tables, also a kind of application scheme of DTC based on the Flying Capacitor Five-level inverter is presented.In the last part, the hardware design of real-time DTC system driven by three-level inverter is proposed based on DSP (TMS320F240), the central control circuit and PWM signal generation circuit are described in detail, and also parts of the main program flow charts of the control system are given out.更多还原