基于DSP的光伏MPPT控制器设计

发布时间：2018-05-23 10:22

本文选题：光伏发电 + 模糊控制　；参考：《东北石油大学》2017年硕士论文

【摘要】：近年来,光伏发电作为新兴的朝阳产业正在蓬勃发展。随着光伏发电的不断普及,相关的科研工作也在不断进展。整体发展方向正在从注重发电数量到发电质量和发电效率转变。由于光伏电池的输出特性具有较强的非线性特征,光伏电池的输出功率不仅与负载特性有关,外界环境(如光照强度、温度)同样会对其造成影响,这使得光伏系统的能量转换效率大大降低。针对以上问题,本文围绕最大功率点跟踪(MPPT)技术,设计出基于DSP的光伏MPPT控制器,通过时刻跟踪光伏电池的最大输出功率来提高太阳能利用效率。本文运用MATLAB/Simulink平台,首先,在数学模型的基础上搭建更利于工程应用的光伏电池模型,并分析了随外界环境变化的光伏特性规律。然后对光伏系统MPPT的实现机理进行阐述,在权衡各DC/DC电路优缺点后,选择Boost电路作为MPPT控制系统的主电路。在对当下热门的几种MPPT算法进行分析之后,将模糊控制引入到MPPT控制中,并提出了一种运用模糊控制来计算步长的变步长电导增量算法。该算法具有自动根据光照强度和温度的变化对步长进行调整的性质,当系统工作点距离最大功率点较远时采用大步长快速逼近最大功率点,随着工作点靠近最大功率点,匹配当前合适步长直至完成跟踪。借助模糊逻辑工具箱对算法进行了仿真,结果表明该算法可有效克服因步长选取引起的动态响应速度与稳态跟踪精度之间的矛盾,取得了较好的动态和稳态效果。接着,本文对系统的总体结构和控制方案进行了设计。采用TMS320F28035控制器作为控制芯片进行MPPT控制,并完成了包括电源电路,采样电路,驱动电路,保护电路在内的系统硬件电路的设计,利用CCS开发环境完成了主程序,AD采样,最大功率点跟踪和PWM生成等程序的编写。最后,对焊接的实物进行了软硬件的调试,由Lab VIEW搭建的上位机光伏数据采集和查询系统程序对控制器进行监测,结果表明所设计完成的MPPT控制器基本能够实现预期设想。
[Abstract]:In recent years, photovoltaic power generation as a new sunrise industry is booming. With the popularization of photovoltaic power generation, the related scientific research work is also making progress. The overall direction of development is changing from focusing on generating quantity to generating quality and generating efficiency. Because the output characteristics of photovoltaic cells have strong nonlinear characteristics, the output power of photovoltaic cells is related not only to the load characteristics, but also to the external environment (such as light intensity and temperature). This greatly reduces the energy conversion efficiency of photovoltaic systems. Aiming at the above problems, a photovoltaic MPPT controller based on DSP is designed around the maximum power point tracking (MPPT) technology, which can improve the efficiency of solar energy utilization by tracking the maximum output power of the photovoltaic cell at all times. In this paper, the MATLAB/Simulink platform is used. Firstly, based on the mathematical model, the photovoltaic cell model which is more suitable for engineering application is built, and the characteristics of photovoltaic cells changing with the external environment are analyzed. After weighing the advantages and disadvantages of each DC/DC circuit, the Boost circuit is selected as the main circuit of the MPPT control system. After analyzing several popular MPPT algorithms, this paper introduces fuzzy control into MPPT control, and proposes a variable step size increment algorithm which uses fuzzy control to calculate step size. The algorithm has the property of automatically adjusting the step size according to the change of illumination intensity and temperature. When the operating point of the system is far from the maximum power point, the maximum power point is approximated quickly by the large step size, with the working point approaching the maximum power point. Match the current appropriate step size until the tracking is completed. The algorithm is simulated by the fuzzy logic toolbox. The results show that the algorithm can effectively overcome the contradiction between the dynamic response speed and the steady-state tracking accuracy caused by the selection of step size, and achieve better dynamic and steady-state effects. Then, the overall structure and control scheme of the system are designed. The TMS320F28035 controller is used as the control chip to control MPPT, and the system hardware circuit including power supply circuit, sampling circuit, driving circuit and protection circuit is designed. The main program AD sampling is completed by using CCS development environment. Maximum power point tracking and PWM generation and other programs. Finally, the hardware and software of the welding object are debugged, and the PC photovoltaic data acquisition and query system program built by Lab VIEW is used to monitor the controller. The results show that the designed MPPT controller can basically realize the expected assumption.
【学位授予单位】：东北石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM615

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