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摘要研究了应用于光伏发电系统中的隔离型DC-DC变换器，分析了全桥变换器的工作原理和存在的一些问题，采用了一种基于Boost变换器和移相全桥ZVS DC-DC变换器的组合式前级隔离型 DC-DC变换器，将MPPT控制和全桥变换环节的四个开关管的控制有效解耦。简要介绍了MPPT技术的发展，对常用的三种MPPT技术的原理和存在的问题进行了分析和比较，并选择扰动观察法作为MPPT控制技术。 设计了总体方案， 对主电路中各元器件的参数进行了设计，包括对滤波电容、谐振电感、高频变压器和输出滤波器的设计。基于IR2110对Boost升压环节的驱动进行了设计，基于UC3875对全桥DC-DC变换环节的控制和驱动进行了设计。基于 LPC2131 对控制软件进行了设计。在硬件设计的基础上，在matlab的Simulink模块中进行了光伏发电系统的建模、仿真和分析。以移相全桥电路为核心搭建了原理样机。实验结果表明，所搭建的原理样机能够按照要求工作。 31386
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毕业论文关键词 光伏发电 MPPT 组合式变换 移相全桥 UC3875
Title Design of Isolated DC-DC converter in Small PV System
Abstract Pre-isolated DC-DC converter applied for PV system is studied in this paper. Based on the analysis of the principle of full-bridge converter and some existing problems of the converter, a type of combination of circuit topology based on Boost converter and phase-shifted full-bridge ZVS DC-DC converter is adopted. Thus the contradiction of MPPT controller and the control for four switches of full-bridge converter is solved. Development of MPPT technology is briefly introduced and the most common three types of MPPT technology are analyzed and compared, what’s more, perturbation and observation method is chosen as the MPPT technology in this paper. Parameters of various components in the main circuit is devised, including input filter capacitor, resonant inductor, high frequency transformer, and output filter. Besides, drive circuits for Boost converter basing on IR2110 and for full-bridge DC-DC converter basing on UC3875 are designed. On the basis of hardware design, modeling, simulation and analysis is carried out in the Simulink model in matlab. A prototype of phase-shifted full-bridge converter is built in the end. The result of experiment indicates the prototype constructed can work as required.
Keywords PV power generation MPPT combined conversion phase-shifted full-bridge UC3875
目次
1绪论..1
1.1课题背景和意义..1
1.2光伏发电现状.1
1.3光伏发电系统简介2
1.4光伏发电系统中的DC-DC变换器3
1.5本文主要研究内容3
2隔离型DC-DC变换器5
2.1移相全桥ZVSDC-DC变换器.6
2.1.1移相全桥ZVSDC-DC变换器的工作原理6
2.1.2移相全桥ZVSDC-DC变换器软开关的实现10
2.1.3移相全桥ZVSDC-DC变换器存在的问题..11
2.2含Boost升压环节的全桥变换器..11
2.3本章小结.13
3最大功率点跟踪技术..14
3.1光伏电池的工作原理14
3.2光伏电池的工程模型14
3.3最大功率点跟踪技术17
3.3.1固定电压法..17
3.3.2扰动观察法..18
3.3.3电导增量法..19
3.4MPPT技术比较与选择..20
3.5本章小结.20
4系统硬件设计..21
4.1总体设计方案21
4.2功率开关管和二极管的选择21
4.3Boost环节设计.23
4.3.1Boost环节电感设计.23
4.3.2Boost环节电容设计.24
4.4全桥DC-DC变换环节设计..24
4.4.1高频变压器设计.24
4.4.2谐振电感设计26
4.4.3滤波电感设计26
4.4.4滤波电容设计27
4.5输入滤波电容设计..27
4.6驱动电路设计27
4.6.1Boost环节驱动设计.27
4.6.2全桥DC-DC变换环节控制和驱动设计.29