【作者】 贤燕华；

【导师】 冯久超；

【作者基本信息】 华南理工大学 ， 电路与系统， 2014， 博士

【摘要】 DC-DC开关变换器控制问题的研究是当前功率电子学研究的主要方向之一，通过对它的控制来改善变换器的输出电能质量。相比于传统的PWM控制，找到一种更有效控制方法来提高变换器的动态性能和稳态性能指标，是当前形势所需。本文致力于研究Hē控制和无源控制等鲁棒控制方法应用于DC-DC开关变换器的理论与技术。针对系统的干扰抑制问题和鲁棒镇定问题，通过建立变换器的确定模型和不确定模型，研究解决上述问题的鲁棒控制算法。具体内容如下：1．考虑电路输入端和输出端扰动以及外部噪声的影响，建立直流变换器的增广状态空间平均模型。应用Hē控制理论推导控制器算法来抑制干扰，以保证系统的鲁棒稳定性和动态响应性能。以boost变换器为例说明Hē控制器的计算过程，时域和频域的仿真结果表明该算法得到的控制器对干扰抑制的有效性。2.基于直流变换器的切换线性模型，提出了一种通过调节输入电压来稳定输出的鲁棒控制算法。通过建立直流变换器的扩张切换线性模型，应用线性矩阵不等式(LMI)性质和Hē控制理论，给出了该线性切换系统的Hē控制器存在的充分条件和设计方法的LMI形式。所得控制器使直流变换器闭环系统在任意切换策略下渐近稳定且具有Hē性能界。Buck和boost变换器的仿真结果显示了该控制器能有效抑制输出端干扰，鲁棒稳定性好；可用任意常数占空比切换变换器系统，在参数扰动时自动调节输入电压实现输出电压稳定在期望值上。3.以buck直流变换器为研究对象，推导了非线性鲁棒控制算法以达到减小干扰影响的目的。首先在buck变换器非线性模型的基础上，建立具有扰动的系统误差模型。然后根据无源性控制理论，得到Hē控制器及其参数约束条件，并理论分析了闭环控制系统的稳定性。最后对buck变换器元件参数扰动的情况进行数值模拟和电路仿真来验证该控制算法的正确性和有效性。4.考虑buck变换器中的多个参数存在不确定的情况，通过一阶泰勒近似的方法建立buck变换器的参数不确定模型，应用LMI和Hē控制理论，研究其输出反馈Hē控制算法。给出该不确定buck系统的输出反馈Hē控制器存在的充分条件和计算方法，所得控制器使得buck变换器闭环系统在多个参数小范围变化的情况下渐近稳定且对外部噪声的抑制具有最大Hē鲁棒性能界。5.为提高直流变换器对干扰及不确定因素的鲁棒性，提出了一种基于LMI的鲁棒PID控制算法。PID参数应用区域极点配置的方法来整定。将PID控制和Hē控制相结合，以LMI形式给出Hē PID控制器的可解性条件。所得的控制器使得闭环系统满足：闭环极点分布在指定区域内以获得期望的动态特性；对外部噪声的抑制具有最大Hē鲁棒性能界。此外，该控制算法也可应用于参数不确定的多胞型直流变换器系统。6.应用非线性系统无源化方法研究了Buck变换器的控制策略。基于Buck变换器的非线性误差模型，通过坐标变换得到与之反馈等价的系统。根据无源理论，对反馈等价系统施加适当反馈使之无源化，给出了闭环系统无源性证明，并构造Lyapunov函数保证闭环系统的渐近稳定性，进而得到Buck变换器的无源反馈控制律。设计了该无源控制器的Pspice仿真电路，仿真结果表明该无源控制的Buck变换器输出的稳定性可以得到有效控制，对负载扰动和输入电压扰动的鲁棒性好，且调整控制律中的可调系数可以改善系统的动态响应。更多还原

【Abstract】 The control problem of DC-DC switching converters is one of the main directions ofcurrent research in power electronics. By controlling converters, the quality of output powercan be improved. Compared to conventional PWM control, it is present requirement to find amore effective control method to improve dynamic performance and steady-state performanceof the converters.In this paper, the theories and technologies of robust control methods used in DC-DCswitching converters are researched, such as Hē control and passive control. To solve theinterference suppression problem and robust stabilization problem of the converters, somerobust control algorithms are studied by establishing certainty model and uncertainty model ofconverters. The main contents are as follows:First, to suppress perturbations of input, output and external noise for a DC-DC switchconverter, an Hē control algorithm is proposed based on the augmented average state-spacemodel of DC-DC converters. A robust controller, guaranteeing stability and the desiredclosed-loop dynamical response, is designed. As an example, boost converter is used toillustrate the design procedure of the controller. Simulation results in frequency domain andtime domain indicate that the controlled system has high immunity to perturbations.Second, a robust control algorithm by adjusting input voltage is studied based on theswitched linear model of DC-DC converters. The augmented switched linear model ofDC-DC converters is established. According to linear matrix inequality (LMI) and Hē controltheories, the sufficient condition of controller existence and the design method of Hēcontroller for the proposed switched system is derived in the form of linear matrix inequality.The obtained controller is such that the closed loop system is asymptotically stable underarbitrary switch conditions and has an Hē disturbance attenuation bound. The simulationresults for buck and boost converters are presented to show that the good robust stability canbe obtained with respect to the output disturbance. By adjusting the input voltage, the outputvoltage can be stabilized on the expected value with the parameters perturbation underarbitrary constant duty cycle.Third, to reduce the effect of disturbances, a nonlinear controller is designed for DC-DCbuck converter. Firstly, an error model with disturbances is built based on nonlinear model ofbuck converter. Then an Hē controller and its parameters are deduced based on the passivetheory. And the theoretical analysis is give to prove the stability of closed-loop control system.Finally, numerical simulation and circuit simulation are performed for the case of parametric perturbations of buck converter. The simulation results demonstrate the validity andeffectiveness of the proposed control strategy.Fourth，a parameter uncertainty model of buck converter with multiple uncertaintyparameters is built by method of first-order Taylor approximation. Based on the model, thesolvability condition for the existence of output feedback Hē controller is derived in the formof linear matrix inequality according to Hē control theory. The designed controller is such thatthe closed-loop system is asymptotically stable when several parameters change in a smallrange. And the closed-loop system has an Hē disturbance attenuation upper bound.Fifth，in order to improve the robustness of DC-DC converters with disturbances anduncertainties, an robust PID control algorithm based on linear matrix inequality is proposed.The PID parameters are tuned by regional pole assignment. The PID control is combined withHē control and solvability condition for the existence of Hē PID controller is derived in theform of LMI. The designed controller is such that the closed-loop system poles are assignedin a specific region in order to obtain anticipant dynamical characteristics, and the closed-loopsystem has an Hē disturbance attenuation upper bound. Further, the proposed algorithm isapplied to the DC-DC converters with polytopic uncertain parameters.Sixth，a passivity-based control strategy for DC-DC buck converter is proposed. Based onthe nonlinear error model of buck converter, a feedback equivalence system is obtained by theway of coordinate transformation. According to passive theory, the feedback equivalentsystem is to be passive by adding feedback appropriately. The proof of the passivity ofclosed-loop system is given. And a Lyapunov function is constructed to guarantee asymptoticstability of closed-loop system. Finally, a passive feedback control law for buck converter isderived. Simulate by designing control circuit in Pspice environment, and the simulativeresults show that the stability of output voltage is effectively controlled by the proposedcontrol method. The controller has very strong robustness for disturbance caused by loadchange and input voltage change. And the system dynamic response is improved by adjustingthe coefficient of the control law.更多还原