基于混杂自动机模型的DC-DC变换器的控制方法研究

发布时间：2018-05-03 04:13

本文选题：DC-DC变换器 + 混杂自动机模型　；参考：《华南理工大学》2014年硕士论文

【摘要】：DC DC变换器在本质上是一类典型的混杂动态系统，同时包含连续和离散两个子系统。混杂自动机模型是混杂系统的一个简单的形式化模型，能直观、简便的描述混杂系统的连续和离散特性。本文主要进行了以下几个方面的研究：一、介绍了混杂系统的定义、特点及其研究内容，重点阐述了混杂自动机模型。然后针对三种基本的DC DC变换器：Buck、Boost和Buck boost变换器，分别建立了其混杂自动机模型。二、在此混杂自动机模型的基础上，研究了DC DC变换器的基本控制方法：峰值电流控制、平均电流控制、电流滞环控制、预测占空比控制。根据电路理论，这些基本控制方法可以简化为简单的边界选取问题：其中，峰值电流控制，选取电感的峰值电流与恒定的开关周期作为边界条件；平均电流控制，选取合适的锯齿波与电感电流进行比较作为边界条件；电流滞环控制，通过设置一定环宽，选取电感电流的上限值和下限值作为边界条件；预测占空比控制，根据预测的占空比大小，选取开关管的导通时间以及恒定的开关周期作为边界条件。三、提出了一种基于混杂自动机模型的DC DC变换器的CCMDCM统一控制方法。根据能量守恒定律，分别计算出CCM与DCM模式中电感的峰值电流、周期内开关管的关断时间以及临界电阻值，首先根据临界电阻值判断DC DC变换器的具体工作模式，然后选取对应模式的电感电流峰值与开关管关断时间为边界条件。该方法在宽负载范围内，能使DC DC变换器同时稳定工作于CCM和DCM模式，且不受占空比的限制，稳态时的开关频率恒定。最后，，运用MATLAB/stateflow对该控制算法进行仿真，仿真结果验证了本方法具有算法简单、动态响应快、稳态精度高等优点。混杂自动机模型是包含连续时间和离散事件动态系统的模型，未对离散事件动态特性作任何近似处理，因此能够准确的描述DC DC变换器的动态过程。基于混杂自动机模型的控制把DC DC变换器的连续过程和离散切换过程进行统一的控制，具有重要的理论和现实意义，能进一步推广到其他的电力电子变换器中。
[Abstract]:DC / DC converter is a kind of typical hybrid dynamic system, which consists of two subsystems: continuous and discrete. Hybrid automata model is a simple formal model of hybrid systems. It can describe the continuous and discrete characteristics of hybrid systems intuitively and easily. This article mainly carries on the following aspects research: Firstly, the definition, characteristics and research contents of hybrid system are introduced, and the hybrid automata model is emphasized. Then, the hybrid automata models of three basic DC-DC converters, the Buck boost converter and the one of the two converters, are established respectively. Secondly, based on the hybrid automaton model, the basic control methods of DC / DC converter are studied: peak current control, average current control, current hysteresis control, predictive duty cycle control. According to the circuit theory, these basic control methods can be simplified as simple boundary selection problems: the peak current control, the peak current of inductor and the constant switching period are selected as boundary conditions; Choosing suitable sawtooth wave and inductor current as boundary condition; current hysteresis control, selecting the upper and lower limit value of inductance current as boundary condition by setting a certain loop width; predictive duty cycle control, According to the predicted duty cycle, the switching time and the constant switching period are selected as the boundary conditions. Thirdly, a CCMDCM unified control method for DC / DC converters based on hybrid automata model is proposed. According to the law of conservation of energy, the peak current of inductor in CCM and DCM mode, the switching off time and critical resistance of switch in the period are calculated, respectively. Firstly, the concrete working mode of DC / DC converter is judged according to the critical resistance. Then the peak inductance current of the corresponding mode and the switch off time are selected as the boundary conditions. The method can make DC / DC converters work stably in both CCM and DCM modes in a wide load range, and the switching frequency is constant in steady state without the limitation of duty cycle. Finally, the control algorithm is simulated by MATLAB/stateflow. The simulation results show that the method has the advantages of simple algorithm, fast dynamic response and high steady-state precision. Hybrid automata model is a dynamic system model with continuous time and discrete events. It can accurately describe the dynamic process of DC / DC converters without any approximate treatment of the dynamic characteristics of discrete events. The control based on hybrid automata model unifies the continuous and discrete switching processes of DC / DC converters, which has important theoretical and practical significance and can be extended to other power electronic converters.
【学位授予单位】：华南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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