Buck型DC-DC变换器的滑模控制研究

发布时间：2019-03-04 21:31

【摘要】：DC-DC开关变换器是一种时变非线性开关电路,其建模、控制器设计和性能分析一直是功率电子学领域的热点问题。在众多非线性控制策略中,滑模控制的DC-DC开关变换器具有快速的瞬态特性和良好的鲁棒性,其控制器算法的研究具有重要的理论意义和实际应用价值。本文以DC-DC开关变换器中Buck电路为研究对象,设计有效的滑模控制策略。本文的主要研究工作包括：首先,根据Buck电路建立其数学模型；其次,研究Buck开关变换器采用传统滑模方法的控制器设计和参数选择,并分析其控制作用下的系统性能;再次,针对传统滑模控制存在的问题,研究面向性能的改进型滑模控制算法,主要包括终端滑模控制算法和自适应滑模控制算法；最后基于构建的FPGA实验平台对Buck开关变换器的传统滑模控制算法进行验证。本文的主要内容如下： (1)介绍DC-DC变换器中Buck电路的工作原理,对Buck电路在开关导通和断开两种不同状态进行分析,利用基尔霍夫电压、电流定律对系统的状态进行数学描述。采用多种方式对Buck电路进行数学建模。 (2)在介绍滑模控制算法的基础上,将滑模变结构控制引入到DC-DC开关变换器控制器设计中。针对Buck电路数学模型,利用变结构控制理论,设计合理的滑模面以及滑模控制器参数,并分析滑模面的收敛性。 (3)针对传统滑模控制收敛时间长,负载电阻与标称值存在偏差的问题,设计了终端滑模控制和自适应滑模控制。传统滑模控制可以通过选取合适的参数值使其动态响应加快,但无论如何选取,其状态跟踪误差都将无限时间收敛。终端滑模控制通过改进滑模面的设计形式,使得状态跟踪误差收敛时间有限；此外由于Buck开关变换器的负载电阻实际值与标称值存在偏差,造成实际滑模面的选取并非最优,自适应滑模控制通过计算电阻电流和输出电压,实时地获取最优滑模面。 (4)搭建实验平台,验证了所提滑模控制算法的优越性。采用NI9683板卡、NI sbRIO-9606板卡和Buck电路评估板搭建实验平台,通过LabView语言实现控制算法,以验证滑模控制算法的有效性。同时编写PID控制算法作为比较,验证滑模变结构控制的优越性。通过仿真和实验平台的结果进一步证实了本文研究的滑模变结构控制在控制Buck开关变换器所表现出来的优势。两种面向性能的滑模算法也都具有较好的控制效果,有助于开关电源的性能优化和设计效率的提高。
[Abstract]:DC-DC switching converter is a time-varying nonlinear switching circuit. Its modeling, controller design and performance analysis have always been hot issues in the field of power electronics. Among many nonlinear control strategies, sliding mode controlled DC-DC switching converter has fast transient characteristics and good robustness. The research of its controller algorithm has important theoretical significance and practical application value. In this paper, an effective sliding mode control strategy is designed for Buck circuit in DC-DC switching converter. The main research work of this paper is as follows: firstly, the mathematical model of Buck circuit is established; Secondly, the controller design and parameter selection of the Buck switching converter using the traditional sliding mode method are studied, and the system performance under the control action is analyzed. Thirdly, aiming at the problems existing in the traditional sliding mode control, the performance-oriented improved sliding mode control algorithm, including terminal sliding mode control algorithm and adaptive sliding mode control algorithm, is studied. Finally, the traditional sliding mode control algorithm of Buck switching converter is verified based on the constructed FPGA experimental platform. The main contents of this paper are as follows: (1) the working principle of Buck circuit in DC-DC converter is introduced, and the Buck circuit is analyzed in two different states: on-off and off-off, using Kirchhoff voltage, The state of the system is described mathematically by the law of current. Mathematical modeling of Buck circuit is carried out in many ways. (2) on the basis of introducing sliding mode control algorithm, sliding mode variable structure control is introduced into the controller design of DC-DC switching converter. According to the mathematical model of Buck circuit, the reasonable sliding mode surface and sliding mode controller parameters are designed by using variable structure control theory, and the convergence of sliding mode surface is analyzed. (3) the terminal sliding mode control and adaptive sliding mode control are designed to solve the problem of long convergence time of traditional sliding mode control and deviation between load resistance and nominal value. Traditional sliding mode control can speed up its dynamic response by selecting appropriate parameter values, but its state tracking error will converge infinitely in any case. By improving the design form of sliding mode surface, the convergence time of state tracking error is limited. In addition, due to the deviation between the actual value and the nominal value of the load resistance of the Buck switching converter, the selection of the actual sliding mode surface is not optimal. The adaptive sliding mode control obtains the optimal sliding mode surface in real time by calculating the resistance current and output voltage. (4) the advantages of the proposed sliding mode control algorithm are verified by building an experimental platform. NI9683 board, NI sbRIO-9606 board and Buck circuit evaluation board are used to build the experimental platform. The control algorithm is realized by LabView language to verify the effectiveness of the sliding mode control algorithm. At the same time, the advantages of sliding mode variable structure control are verified by programming PID control algorithm as a comparison. The results of simulation and experiment further confirm the advantages of the sliding mode variable structure control in the control of Buck switching converter. The two performance-oriented sliding mode algorithms also have better control effect, which is helpful to the performance optimization and design efficiency improvement of switching power supply.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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