单相三电平SPWM整流器的研究与设计论文

摘要

随着电力电子器件、高精度高速运算芯片、实时仿真及控制等技术的飞速发展，各类电力电子装置正广泛地应用于交直流可调电源、电力供电系统、电气传动控制与电化学生产等领域，然而大多数的电力电子装置都是通过变流器与电网相连，总存在网侧功率因数低以及输入电流谐波成分高的问题。

为了减小谐波干扰对电网质量的危害，以及可能因此而引发的事故，1994年3月国家技术监督局颁布了国标GB/T 14549-1993《电能质量公用电网谐波》。抑制电力谐波提高功率因数的方法主要有两种，一种是装设专用的谐波补偿装置，该方法相应地带来了成本增加的问题；另一种是采用新型的高功率因数变流器。

PWM整流器作为高功率因数变流器的一个重要方向，在各种工业生产领域扮演着重要角色。它不仅要求中间直流环节的电压保持恒定，交流侧功率因数为1，还要求尽量减少电流谐波。

然而相对于两电平PWM整流电路，三电平PWM整流器的功率开关管所承受的关断电压为直流侧电压的一半，减少了功率开关管的电压强度，同时电平数的增加使入端电流更接近正弦波，在同样的的开关频率及控制方式下，其电流谐波总畸变率（THD）要远小于两电平PWM整流器。

因此，本毕业设计以单相三电平PWM整流器为研究对象, 首先介绍了课题的产生背景、研究概况及意义，阐述了PWM整流器的工作原理，并对其开关工作模态以及拓扑结构进行了分析；其次，在此基础上，建立了三电平整流器的系统数学模型，并对PWM控制技术进行总结，采用电压电流双闭环控制，利用MATLAB/Simulink进行了仿真实验。仿真结果表明，系统的工作情况与理论分析相符合，该系统不仅能使直流电压在一定围可调，而且使整流器交流侧电流谐波降低，实现了单位功率因数运行。

关键词：三电平整流功率因数校正 MATLAB仿真

ABSTRACT

With the rapid development of power electronic devices, high-precision

high-speed computing chip, real-time simulation and control technology, various types of power electronic devices are widely used in AC-DC adjustable power supply, power supply systems, electrical transmission control and electrochemical production etc, but most power electronic devices connected to the grid through the converter, there is always the low power factor and high harmonics problem of the input current.

In order to reduce the harm of grid-quality by the harmonic-interference, and the accident may resulted form it, the State Bureau of Technical Supervision issued a national standard GB/T 14549-1993 "harmonic power quality utility" in March 1994. There are two methods to improve power factor and inhibit power harmonic, one is the installation of a dedicated harmonic compensation devices, the method has brought a corresponding increase problem in the cost ; the other is using the new high power factor converter .

PWM rectifier ,as an important direction of high power factor converters, plays an important role in the various areas of industrial production. It not only requires the constant of middle- dc voltage, AC power factor is 1, also required to minimize the current harmonics.

However, in related to the two-level PWM rectifier, the DC side power switch turn-off voltages of three-level PWM rectifier are the half, so it reduce the power voltage- strength, and the increase of the level’s numbers makes the input-side current closer to the sine wave, and at the same switching frequency and control mode, the total current harmonic distortion (THD) is much smaller than the two-level rectifier.

Therefore, this graduating-design choose the single-phase three-level PWM rectifier as research object. First this paper introduces the background, research survey and significance of this research subject, explains the working principle of the PWM rectifier and analyzes its switching modes and topology; Secondly, on this basis, a system mathematical model of the three-level rectifier is built, then begin a MATLAB/simulink simulation experiment with the summary of PWM control techniques and the use of voltage and current double closed loop control. Simulation results show that the work of the system consistent with the theoretical analysis, this system not only enables the DC voltage is adjustable within a certain range, but also reduce the rectifier AC side current harmonics to achieve the unity power factor