摘 要

地球上的常规能源储量是有限度的，多年来，人类已经过度开采了许多化石能源，由此产生了世界性的能源危机。各国为了应对能源危机及环境污染问题，开始大力投资开发新的清洁能源。在目前已知的新能源中，太阳能因其清洁环保，使用安全，以及其取之不尽用之不竭等特点，成为了人们重点开发新能源。就大趋势来看，大力发展光伏发电技术，对于改善能源结构和能源安全体系具有重大意义。

众所周知，光照、温度等环境条件的变化是非常迅速的，而光伏电池的工作状态大大受制于环境的变化。当光伏电池工作在不均匀光照条件下时，光伏阵列出现发电效率降低，局部温度过高甚至热斑现象。而作为实现光伏发电系统最大功率点跟踪（Maximum Power Point Tracking, MPPT）控制的主要执行机构，光伏系统DC/DC电路是光伏发电系统不可或缺的重要环节。因此设计高效稳定的DC/DC电路及其控制方法，进而当光伏发电系统所处的工作环境发生变化时，可以迅速而准确地驱动系统工作于所处环境下的最大功率点，对于光伏系统的稳定高效运行至关重要。最大功率点跟踪的最终目的是实时根据环境的变化而改变系统工作状态，使系统可以一直工作于当时环境条件下的最大功率点，进而实现太阳能利用效率的最大化。因此，建立高效的光伏系统DC/DC电路结构，并研究有效的控制算法实现电路控制，对于提升光伏系统应对外界环境的变化能力，实现系统高效的MPPT控制具有重要意义。

本此实验旨在设计一个合理有效的光伏系统DC/DC电路，以解决由于环境因素变化导致的光伏阵列工作效率下降的问题。本文首先就光伏发电系统的基本原理及构造进行介绍，然后深入探讨光伏电池的分类及它们各自的优缺点，其次对光伏发电系统最大功率点跟踪技术展开讨论简述其概念，并列举了当下主要的最大功率点跟踪方法。最后根据光伏发电系统的基本原理，在 MATLAB/Siumlink 平台设计仿真实验，通过调节光照强度、环境温度等不同的参数进行仿真实验，从而得出对光伏系统最大功率点构成影响的主要因素。在此基础上，针对某一特定规模的光伏系统，在MATLAB/Simulink仿真平台下搭建光伏阵列仿真模型，设计其DC/DC电路，并研究其基于比例-积分（PI）控制及脉宽调制（PWM）的电路控制方法。在仿真平台下开展相关实验，验证所设计电路及其控制方法的有效性并得出结论。实验结果表明，本文所设计的DC/DC电路及其控制方法对提高在遮光条件下工作的光伏发电系统的输出功率具有显著效果。因此，本文所设计电路及其控制方法是有效可行的。

关键词：太阳能；光伏发电；不均匀光照；最大功率点跟踪，DC/DC电路

Abstract

The conventional energy reserves on the earth are limited. Over the years, human beings have over exploited many fossil energy resources, resulting in a worldwide energy crisis. In order to deal with the energy crisis and environmental pollution, countries began to invest heavily in the development of new clean energy. Among the known new energy sources, solar energy has become the focus of the development of new energy because of its clean and environmental protection, use safety, and its inexhaustible characteristics. In terms of the general trend, vigorously developing photovoltaic power generation technology is of great significance for improving energy structure and energy security system.

As we all know, the change of environmental conditions such as light and temperature is very rapid, and the working state of photovoltaic cells is greatly subject to the change of environment. When the photovoltaic cells work under the condition of uneven illumination, the generation efficiency of the photovoltaic array will be reduced, and the local temperature will be too high or even hot spots. As the main actuator of MPPT control, DC / DC circuit is an indispensable part of photovoltaic power generation system. Therefore, the design of efficient and stable DC / DC circuit and its control method, and then when the working environment of photovoltaic power generation system changes, it can quickly and accurately drive the system to work at the maximum power point under the environment, which is essential for the stable and efficient operation of photovoltaic system. The ultimate purpose of maximum power point tracking is to change the working state of the system according to the change of the environment in real time, so that the system can always work at the maximum power point under the environmental conditions at that time, and then realize the maximum utilization efficiency of solar energy. Therefore, it is of great significance to establish an efficient DC / DC circuit structure of photovoltaic system and to study effective control algorithm to achieve circuit control, so as to improve the ability of photovoltaic system to cope with changes in the external environment and to achieve efficient MPPT control of the system.

The purpose of this experiment is to design a reasonable and effective photovoltaic system DC / DC circuit, to solve the problem of photovoltaic array efficiency degradation caused by environmental factors. This paper first introduces the basic principle and structure of photovoltaic power generation system, then discusses the classification of photovoltaic cells and their advantages and disadvantages, then discusses the concept of maximum power point tracking technology of photovoltaic power generation system, and lists the main maximum power point tracking methods at present. Finally, according to the basic principle of photovoltaic power generation system, the simulation experiment is designed in Matlab / siumlink platform, and the simulation experiment is carried out by adjusting different parameters such as light intensity, environmental temperature and so on, so as to obtain the main factors affecting the maximum power point of photovoltaic system. On this basis, aiming at a certain scale photovoltaic system, a photovoltaic array simulation model is built on MATLAB / Simulink simulation platform, and its DC / DC circuit is designed, and its circuit control method based on proportional integral (PI) control and pulse width modulation (PWM) is studied. Experiments are carried out on the simulation platform to verify the effectiveness of the designed circuit and its control method. The experimental results show that the DC / DC circuit and its control method designed in this paper have significant effect on improving the output power of photovoltaic power generation system under the condition of shading. Therefore, the circuit and control method designed in this paper are effective and feasible.

Key words： solar energy; photovoltaic power generation; uneven illumination; maximum power point tracking, DC / DC circuit

目录

摘 要 I

Abstract II

目录 2

第1章 绪论 1

1.1 研究光伏发电技术的意义 1

1.2 国内外研究现状 2

1.2.1光伏产业概况 2

1.2.2 光伏发电系统的最大功率点 5

1.3 本文研究内容 7

第2章 光伏发电系统工作原理 8

2.1 光伏电池结构与工作原理 8

2.1.1 光伏电池的发电原理 8