基于三电平逆变器的异步电动机直接转矩控制-电力电子与电力传动专业论文.docx

中盅=摘要中文摘要 中盅=摘要 中文摘要 在高压大容量应用场合，多电平逆变电路具有显着的优势，比如输出谐波少、 开关频率低等。本文研究的对象正是基于三电平逆变器的异步电动机直接转矩控 制系统。直接转矩控制箢略以其优良的转矩控制特性，近年来受到了普遍的关注。 本文针对直接转矩控制算法在三电平逆变器供电异步电动机系统中的实现，进行 了理论分析、仿真研究以及实验验证。 在理解和掌握三电平逆变器和直接转矩控制基本原理的基础上，建立了异步 电动机和三电平逆变电路的数学模型，分析了直接转矩控制应用于三电平逆变系 统时可能存在的问题，提出了一种简单的电压矢量选择方案，实现了实时地调速 控制。 选用电压型磁键观测模型，并对低速时出现的磁链观测误差进行了{b偿，应 用MATLAB／SIMULINK软件对系统进行了仿真，验证了所提出方案的有效性。并在 现有实验平台的基础上，通过熟悉DSP算法，根据控制算法和硬件结构，编写了 控制程序，通过实验验证了所提出方案的可行性，实现了电机的稳定运行。 利用电机的全阶模型，构造以定子电流和定子磁链为状态变量的全阶磁链观 测器，利用此观测器直接观测出定子磁链，同时辨识电机定子电阻和转子速度。 全阶磁链观测器具有对电机参数变化和速度变化好的鲁棒性。仿真结果也表明了 全阶观测器方案的可行性。 关键词：三电平，异步电动机，直接转矩控制，磁链观测 AbsttactA Absttact A Direct Torque Control of Induction Motor based OH a Three．1evel Inverter Zbao Li(Power Electronics and Drives) Directed by Ge Qiongxuan Abstract In hi曲voltage and high power fields，multilevel inverter has significant advantages， such as less distorted output，lower switching frequency,etc．In this thesis，a direct torque control ofinduction motor based on a three level inverter is to be proposed． Direct Torque Control(DTC)has attracted popular interest because of its hi曲 performances．Theoretical analysis，simulations and experiments are made tO prove the validity of the proposed algorithm． By the analysis of a three level inverter and direct torque control，the mathematic models of both induction motor and three—level inverterre built．The problems existing in the system of direct torque control based on a three-level inverter studied． The voltage model flux estimator is adopted tO calculate the statol’flux，and flux compensation method is adopted to compensate the elror of flux estimator in low speed region．Some simulations have been made by the MATLAB／SIMULINK software package．The DSP TMS320F240 is used in the experiments．The results of both simulations and experiments have verified the proposed scheme． Based a full order model of jnduction motor,a full order flux observer iS deduced with stator current and statOr flux state variables tO observe stator flux directly and to