导　　师： 谢运祥

学科专业： 080804

授予学位： 博士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 电力电子变换器是一类典型的开关非线性系统,现有的PI控制技术已经无法满足其高性能要求。随着非线性控制理论的不断发展,以及数字控制技术的成熟,将非线性控制理论应用于电力电子变换器的控制策略中,提高其性能,将具有重要的理论意义和实际价值。 近几年来,基于微分几何理论的反馈线性化非线性控制方法在电力电子变换器中的应用引起了国内外学者的关注。相关文献研究表明,该类控制方法比PI控制具有更良好的动、静态性能指标。目前该类控制方法大多数采用对状态反馈精确线性化后的线性系统进行最优控制设计的策略。但状态反馈精确线性化和最优控制理论都需要建立在被控对象的精确数学模型上,而获取被控对象的精确数学模型往往是困难的,因此目前电力电子变换器中基于状态反馈精确线性化的非线性控制方法对被控对象的数学模型具有较强的依赖性,不利于在工程应用中的推广。况且尚无理论表明线性化后的线性系统上的最优控制在对应的微分同胚的非线性系统上也是最优的。正是基于以上原因,本文不拘泥于性能最优的目标,尝试对线性化后的线性系统引入滑模变结构控制理论设计控制器,增强整个控制系统的鲁棒性,减弱对被控对象精确数学模型的依赖性,以期有利于基于状态反馈精确线性化的非线性控制方法在工程实际中的推广。 本文以DC-DC变换器的buck、boost和buck-boost三种基本拓扑为研究对象,提出了DC-DC变换器精确反馈线性化滑模变结构控制策略。首先采用状态空间平均法,分别对工作在CCM模式下的buck、boost和buck-boost变换器建立了适用于微分几何理论的仿射非线性模型。在此基础上,验证了实现状态反馈精确线性化的充要条件。然后根据不同拓扑结构,推导出坐标变换矩阵和状态反馈表达式,得到了DC-DC变换器状态反馈精确线性化模型。最后利用线性系统的滑模变结构控制理论,选取线性切换流形,利用指数趋近律求得变结构控制,设计了具有强鲁棒性的滑模变结构控制器。研究对比表明,所提出的精确反馈线性化滑模变结构控制策略具有良好的动态响应调节和稳态误差调节特性,同时克服了现有精确反馈线性化控制策略固有的对精确数学模型依赖性的缺点,表现出更强的鲁棒性,从而具有一般性理论和实际意义。 有源电力滤波器作为一类理想的谐波抑制装置,其控制策略是关键因素之一。目前大多数有源电力滤波器的控制策略都是采用电压外环和电流内环的双环结构。本文提出了一种基于精确反馈线性化的单相有源电力滤波器统一控制策略。在单相有源电力滤波器仿射非线性模型基础上,通过求解偏微分方程得到一个包含补偿电流变量和直流侧电压变量的输出函数,并推导出了其状态反馈精确线性化非线性控制律,将原非线性系统转换成微分同胚的二阶线性系统。选取适当的反馈系数设计控制器使输出函数渐进跟踪指令参考值,从而实现了电流和电压的统一控制。该方法的统一控制思想具有一般性意义,可拓展到其它电力电子变换器拓扑上。 对于功能及拓扑更为复杂的高阶电力电子变换器,本文以三相并联型有源电力滤波器为例,提出了一种基于状态反馈精确线性化的有源电力滤波器非线性控制方法。该方法采用电压外环、电流内环的双闭环控制结构。电压外环采用滑模变结构控制。电流内环采用状态反馈精确线性化方法将原非线性系统转换成微分同胚的线性系统,实现了三相并联型有源电力滤波器有功补偿电流和无功补偿电流的解耦控制。选取适当的反馈系数可确定交流侧指令电压,利用空间矢量脉宽调制/(SVPWM/)技术对所需的指令电压进行逼近。该控制方法结合了两者优点,既实现了三相有源电力滤波器有功补偿电流和无功补偿电流的解耦控制,又增强了系统的鲁棒性。 本文以三相并联型有源电力滤波器为研究对象,针对传统直接功率控制采用滞环比较器导致开关频率不固定的缺陷,提出了一种有源电力滤波器的预测直接功率控制策略。该方法是以有源电力滤波器交流侧输出的电压为被控量,利用电流、电压传感器采集到的信号,通过一定的预测算法计算出要使瞬时功率跟踪参考值有源电力滤波器交流侧应输出的交流电压,然后利用空间电压矢量脉宽调制/(SVPWM/)方法控制有源电力滤波器中的PWM变流器输出该电压。 在理论分析的基础上,结合产学研项目,将基于状态反馈精确线性化的新型控制策略应用于有源电力滤波器工业样机的研制,进行了大量仿真和实验,验证了本文所提出的新型非线性控制策略的正确性和可行性。 The power electronic converter is a typital switching nonlinear system. The existing classical PI control technique can not satisfy the demands on the high performance of power electronic converter. With the development of the nonlinear control theory and digital control technique, adopting the nonlinear control theory of power electronic control system can highly improve the control performance of the converter, which is a significant theory with practical values. Currently nonlinear control methods based on differential geometry theory have attracted the attention of scholars. Relevant literature shows that such control better than the PI control with static and dynamic performance. Currently most control method based on feedback linearization adopts the strategy which designs the optimal controller of linear system after feedback linearization. But the state feedback linearization and optimal control theory are needed to establish the accurate mathematical model of controlled object which is often difficult. So current nonlinear control method based on state feedback has a strong dependence on mathematical model of the controlled object and is not easy to promote in engineering applications. Moreover, there is no theory shows that the optimal control of linear systems is optimal in the corresponding diffeomorphism nonlinear system. It is for these reasons that this paper does not rigidly adhere to optinal performance and try to introduce sliding mode control theory to design the controller of linearized system using state feedback linearization. The strategy can enhance the robustness of control system and weaken the dependence of the accurate mathematical model. The control strategy based on feedback linearization is easy to promte in engineering applications. This paper proposes a novel sliding mode control strategy of DC-DC converters /(buck, boost and buck-boost/) based on state feedback exact linearization. Firstly using state space averging method, affine nonlinear model of DC-DC converter which works on CCM mode is established. It is testified that the model is satisfied the condition of state feedback exact linearization in theory. Secondly according to different topologies, the nonlinear coordinate change matrix and state variable feedback equations are derived. Then the exact feedback linearization model is obtained. Finally using linear system sliding mode control theory, the sliding mode controller is designed by selecting linear sliding surface and exponent reaching law. The research result shows that the exact feedback linearization sliding mode control method is superior to the customer control method in the dynamic response performance and steady-stage error regulating characteristics. At the same time, the method overcomes the inherent disadvantage of dependence on the model accuracy of existing feedback linearization control method and shows the stronger robustness. So it is a generality theory with practical significance. Active power filter as an ideal harmonic suppress device, its control strategy is one of the key factors. Currently active power filter control strategies are based on double-loop structure including current inner loop and voltage outer loop. A unified control method based on exact feedback linearization is presented for single-phase active power filter in this paper. First, the output function which contains compensation current and DC side voltage variables is obtained by solving the partial differential equation. Then, in order to transferring the nonlinear system into diffeomorphisms second-order linear system, the nonlinear state feedback control law is derived. Third, the controller which forces the output function asymptotically track the reference output is designed by selecting appropriate feedback coefficients. So it is come true that unified controlling of compensation current and DC side voltage. Unified control theory of this method has a general sense and can be extended to other power electronic converter topology. For more complex functions and topology power electronic converters, this paper presents a novel nonlinear control method based on state feedback linearization for three-phase active power filter. The method adopts double-loop structure including current inner loop and voltage outer loop. Voltage outer controller is designed using sliding mode control theory. Current inner controller transforms original nonlinear system into diffeomorphism linear system using state feedback exact linearization method and realized decouple control of active and reactive compensation currents. The command voltage can be exactly obtained which should be output from AC side of APF by selecting appropriate feedback coefficients. The command voltage is approached using SVPWM method. The control method combines the advantages of both, realized the decouple control of active compensation current and reactive compensation current, and enhance the robustness of the control system. In order to overcome switching frequency fluctuation shortcoming of traditional direct power control method, this paper presents a predictive direct power control method for three-phase shunt active power filter. The method looks active power filter AC side output voltage as control object. It gathers the votage and current signal from transducer and calculates the voltage that active power AC side should output to make instantaneous power tracking the reference value through a certain prediction algorithm. Then the voltage is output from PWM converter of active power filter using SVPWM method. On the base of theory analysis, the state feedback linearization nonlinear control method is applied to design active power filter industry prototype which connects with production and research projects. Extensive simulation and experiment are carried out to validate correctness and feasibility of presented novel nonlinear control stratege.

关 键 词： 变换器 有源电力滤波器 精确反馈线性化 滑模变结构控制 统一控制 非线性复合控制

分 类 号： [TM46]

领　　域： [电气工程]