【作者】 李桃；

【导师】 张昆仑；

【作者基本信息】 西南交通大学 ， 电力电子与电力传动， 2008， 硕士

【摘要】 交流调速正逐步取代直流调速,在电气传动领域占据主导地位。无速度传感器直接转矩控制技术能够提高交流传动系统的简便性、廉价性和可靠性,得到了很大的发展。本文应用直接转矩控制理论,对无速度传感器直接转矩控制策略进行了深入研究,主要研究工作有: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中点电压波动的原因,为中点电压平衡控制提供了理论基础。分析了一种基于合成矢量的三电平异步电动机直接转矩控制(DTC)方法,不但有效地控制了三电平逆变器的中点电压,并抑制了输出电压的跳变;而且具有转矩输出高频脉动小,转子转速波动较小的优点。针对大功率电机控制中逆变器开关频率较低的情况,提出了在电机高速运行中采用十二边形磁链来近似圆形磁链的方式。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。分析了以定子电流、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,所采用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。更多还原

【Abstract】 Multilevel inverters are very suitable for high-voltage and high power conversion applications, for they have the advantages such as low voltage stresses for power devices and absence of voltage evenness of power devices compared with the topology of series connection. And the space voltage vector control of induction motors has been widely used in recent years because of its simple methods and high stable/transient performance.This thesis comprehensively describes the development future and the present development condition of multilevel inverter. And then present the development of direct torque control algorithms for induction motors fed by three-level diode-clamped inverter (neutral-point clamped, NPC) .On the basis of theory of direct torque control, this thesis system analyses the inherent property of three-level inner vectors. and introduced the application of fixing vector compound. Based on the way of keeping neutral point balancing and reducing the pulsation torque. Aimed at high power induction motor, this thesis brought forward a way to form 12-borders stator magnetic field, it can reduce the frequency of switch.This thesis adopted MRAS way to observe the speed of motor. then this control way can remove the speed sensors in motor drivers.Finally, this thesis simulates algorithm proposed with MATLAB.更多还原