摘要在单相两级式光伏逆变系统中，当逆变器稳定输出时，前级DC-DC变换器的输出功率是恒定的，后级DC-AC 变换器的输出功率却是以两倍工频脉动的，前后级的功率差需要大容值的母线电容来平衡，因此母线电容电压会有两倍工频的脉动。又因为前后级是相互独立的，所以母线电压的脉动会导致DC-DC变换器输入电流的两倍工频脉动，这会影响 MPPT 跟踪精度，恶化电磁干扰，减短光伏电池寿命等。本文通过研究单相两级式光伏并网逆变系统，理论推导了输入电流低频脉动的数学公式，并且比较现有的几种方案，提出了易于实现的基于直流母线电压反馈的输入电流低频脉动抑制的方法，在 Saber 软件上仿真验证了此方法的正确性，最后在光伏并网实验平台上设计了抑制输入电流脉动的方案。22535
毕业论文关键词 单相光伏逆变器 母线电压反馈 输入电流低频脉动
Title Study on inhibition of low frequency pulse of input
current on a single phase photovoltaic gird connected inverter
based on the DC bus voltage feedback
Abstract
In the single-phase two stages’ photovoltaic inverter system,when the
output inverter runs stably,the power of the front level of DC-DC converter
is constant,while the power of the back level of the DC-AC converter is
fluctuant at the frequency two times of grid frequency,then it needs a
bus capacitance of large capacity to balance the difference,so the voltage
of the bus capacitance will be fluctuant at the frequency two times of
the grid frequency.Pulsating DC bus voltage then leads to the two times
frequency ripple of input current of the inverter since the front and the
back level are independent,which will harmfully affect the MPPT accuracy,
the EMI of the inverter and shorten the photovoltaic battery’s
life.Through the researches on single-phase two stages’gridded connected
photovoltaic system,the mathematical model of input low frequency current
ripple theory and the comparison of several existing schemes,this paper
proposes an easy method to restrain the low frequency ripple of the input
current of the inverter based on the DC bus voltage feedback. It designs
a circuit to restrain the ripple of the input current on a grid connected
experimental platform and verify the validity of this method in the Saber
simulation software.
Keywords single phase photovoltaic inverter bus voltage feedback low frequency ripple of input current
目 次
1 绪论. 1
1.1 课题背景及其意义. 1
1.2 光伏技术的应用现状及发展方向. 2
1.3 输入电流低频脉动抑制的常用方案. 2
1.4 本章小结. 5
2 单相两级式光伏并网逆变器发电系统介绍. 6
2.1 两级式光伏并网逆变系统拓扑及原理. 6
2.2 光伏电池光电转换原理. 6
2.3 最大功率点跟踪( MPPT )原理与方法. 8
2.4 Boost变换器结构及原理 11
2.5 全桥逆变器（DC-AC 变换器）结构及原理 12
2.6 本章小结 14
3 输入电流低频脉动的理论推导 15
3.1 输入电流低频脉动的问题 15
3.2 功率传递对母线电压的影响 15
3.3 母线电压的脉动对输入侧电流的影响 17
3.4 本章小结 18
4 基于直流母线电压反馈的方法与设计 19
4.1 基于母线电容纹波 BPP V 的占空比补偿方法与设计. 19
4.2 基于母线电容纹波 BPP V 的占空比直接改变方法与设计. 21
4.3 基于母线电压反馈的控制方法与设计 22
4.4 本章小结 23 基于直流母线电压反馈的单相光伏并网逆变器输入电流低频脉动抑制研究:http://www.youerw.com/zidonghua/lunwen_15211.html