文档介绍：毕业设计[论文]
题目: 电网故障下两电平PWM整流器的研究仿真
学院: 电气与信息工程学院
专业: 电气工程及其自动化
姓名:
学号:
指导老师: 赵张飞
完成时间: 5月25日
摘要
PWM整流器相比传统的不控整流和相控整流,能实现输入单位功率因数,正弦化的输入电流,稳定的直流电压。然而在电网电压不平衡时,电网电压中的负序电压分量导致整流器的直流电流出现二次谐波,使得直流侧电压也产生二次谐波,严重影响PWM整流器的性能。如何抑制不平衡电网电压下产生的二次谐波电流,提高PWM整流器性能足本文的重点研究内容。
本文分析了传统整流器存在的问题,阐述了三相电压型PWM整流器的基本作原理,建立了其三相静止坐标系下的基本数学模型和两相旋转坐标系下的数学模型。根据控制系统设计的需要,建立了采用占空比描述的低频数学模型。分析了PWM整流器的基本电流控制方法,讨论其在平衡时和不平衡时的控制策略,阐述了PWM整流器的空间矢量调制策略,及其PWM整流器的输入滤波器的选犁原则。
在MATLABT下进行电网电压平衡时的PWM整流器的仿真实验,验证了直接电流控制的可行性。并且进行了电网电压不平衡时的PWM整流器的双电流控制仿真,验证了双电流控制在抑制二次谐波方面的可行性以及输入滤波器选型的基本原则的正确性。最后阐述了PWM整流器所需的硬件设计,并完成了三相PWM整流器在平衡条件下的物理实验,实验结果验证了论文提出的控制策略的正确性。
关键词 PWM整流器,不平衡电压,抑制谐波电流,仿真
Abstract
Recent years, power electronic devices have been used wildly used in various industrial applications as essential modules. A large part of these facilities posed of diodes or thyristors, which bring severe harmonics pollution to the power grid. The "green "converter of power has e the study key point of power electronic technology. Among the methods of harmonic restraining, the technology of using PWM rectifier, which can modulate the grid power factor, emplement the bidirectional transmission of power and improve the power quality actively has gotten in-depth study and development. This paper studied on the control strategy of rectifier based on the structure of the structure of three phase PWM rectifier.
The working principle and mathematic model of PWM rectifier is the base of rectifier's control. This paper analyzed the working principle of PWM rectifier at every work state, and built the AC mathematic model of PWM rectifier based on the switching function and duty ratio.
The efficient control of PWM rectifier is the key technology of improving grid quality. This paper analyzed the two control strategy of hysteresis current control and feed-forward decoupled current control, and designed the parameter of the controller, and settled the theory base of the PWM rectifier's control.
A three-phase VSR simulati