【作者】 马伟；

【导师】 王明渝；

【作者基本信息】 重庆大学 ， 电气工程， 2011， 博士

【摘要】 功率变换器是典型的非线性系统,会表现出非线性系统特有的分岔和混沌等现象。由于这些非线性现象会使得变换器的正常运行受到影响,破坏其安全工作,所以要深入分析这些非线性现象发生的原因,认识它们的特点。过去二十多年的研究主要集中于各种线性控制的功率变换器中的非线性动力学行为,而对非线性控制的功率变换器中的非线性动力学行为则知之甚少。由于非线性控制和线性控制的本质不同,非线性控制功率变换器会表现出不同于线性控制功率变换器的动力学行为,对它们的研究有着重要的理论价值。在功率变换器的非线性控制方法中,单周期控制是一种应用非常广泛的方法,本文研究多种单周期控制功率变换器的非线性动力学行为。单周期控制Buck和Boost变换器是两种最基本的变换器拓扑结构。建立了单周期控制Buck变换器的采样数据模型,通过对其进行分析指出,在参考电压小于输入电压的情况下,此变换器会稳定运行。通过对单周期控制Boost变换器采样数据模型的分析,研究了参考电压和负载电阻变化时变换器可能出现的分岔现象;通过对此变换器平均模型的分析,确认了上述分岔现象;基于平均模型,提出了采用washout滤波器消除分岔的方法,对于washout滤波器中的两个新引入的参数,使用Routh-Hurwitz准则进行选取。仿真和实验验证了所提方法的有效性。建立了单周期控制Cuk变换器的采样数据模型,分析了参考电压和负载电阻变化时,在此变换器的输入级中出现的分岔现象;提出了采用washout滤波器的方法来稳定变换器,利用输入级电容电压作为washout滤波器的输入消除了分岔。建立了采用washout滤波器的单周期控制Cuk变换器的采样数据模型,分析了washout滤波器中参数对变换器稳定性的影响。利用采样数据模型,讨论了washout滤波器在功率变换器分岔控制中的基本特点。研究了单周期控制Boost功率因数校正(PFC)变换器的慢时标分岔现象。利用双平均方法和谐波平衡法建立了描述单周期控制Boost PFC变换器动力学行为的直流分量模型﹑一次和二次谐波分量模型。通过对这些模型平衡点的分析和合理的假设,根据信号传递函数,得到了此变换器电路参数的稳定工作范围近似表达式。分析了主要电路参数的稳定工作范围。提出了采用washout滤波器控制平均电流模式控制Boost PFC变换器中的慢时标倍周期分岔。在平均电流模式控制Boost PFC预调节器平均模型的基础上,根据双平均方法和谐波平衡法建立了平均电流模式控制Boost PFC预调节器的直流分量模型﹑一次和二次谐波分量模型,在合理假设的条件下,一次谐波模型的稳定性可以用一个线性系统来判定,为了控制慢时标倍周期分岔,就要采用washout滤波器使这个线性系统稳定。研究了washout滤波器参数的选取方法,分析了电路参数变化时变换器的响应。建立了平均电流模式控制两级Boost PFC变换器的平均模型,讨论了washout滤波器方法中参数的选取方法。对Boost PFC预调节器和两级Boost PFC变换器采用washout滤波器进行慢时标分岔控制的特点进行了比较。分析了单周期控制Cuk PFC变换器的慢时标分岔现象,讨论了其双平均模型的特点,在平均模型的基础上,通过谐波平衡法得到了各变量周期平衡解的近似表达式,应用Floquet理论分析了主要电路参数对此变换器运行的影响。更多还原

【Abstract】 Power converters are highly nonlinear systems, which means they may exhibit nonlinear phenomena, such as bifurcation and chaos. The nonlinear phenomena jeopardize performance of the converters, so it is necessary to thoroughly analyze these phenomena. Over the last two decades, many works have been done to study the nonlinear dynamics in traditional linear controlled power converters. Little is known about nonlinear dynamics in nonlinear controlled power converters, which may exhibit nonlinear dynamics different from linear controlled converters, due to the different control methods. Therefore, study of nonlinear dynamics in nonlinear controlled power converters is important. One-cycle control is one of the most widely used nonlinear control methods, and this dissertation focuses on nonlinear dynamics in several basic One-cycle controlled power converters.One-cycle controlled Buck converter and Boost converter are two basic topologies. In this dissertation, sampled-data model of One-cycle controlled Buck converter is derived. Analysis of the model indicates that, when the reference voltage is less than the input voltage, the One-cycle controlled Buck converter is always stable. In One-cycle controlled Boost converter, bifurcation due to variation of the reference voltage and the load resistance is analyzed by using the sampled-data model. Averaged model of the One-cycle controlled Boost converter is derived to confirm the result from the analysis of the sampled-data model. Based on the averaged model, a washout filter is proposed to control the bifurcation in the One-cycle controlled Boost converter. Routh-Hurwitz criterion is applied to select the parameters of the washout filter. The sampled-data model of the One-cycle controlled Cuk converter is derived, and the bifurcation in the input stage of the converter under variations of the reference voltage and the load resistor is analyzed using the model. A washout filter is proposed to control the bifurcation in the input stage by taking the input capacitor voltage as its input. The sampled-data model of the One-cycle controlled Cuk converter with the washout filter is derived. The effect of the parameters of the washout filter on the stability of the converter is analyzed. The characteristics of the washout filter aided method used in power converters are discussed by using the sampled model.Slow-scale bifurcation in the One-cycle controlled Boost Power Factor Correction (PFC) converter is studied. The averaged model of the converter is derived through the first averaging, which averages all state variables within one switching cycle. After adopting the second averaging and harmonic balance method, the DC component model, the first- and the second-order harmonic component averaged model are derived to describe the dynamics of the converter. The equilibria of these models are calculated. Based on the signal transfer function, the stability boundaries of the circuit parameters are derived. The stability boundaries of some main parameters are discussed.A washout filter is proposed to control the slow-scale bifurcation in the average current mode controlled Boost PFC. Two cases of the Boost PFC are studied, i.e., the Boost pre-regulator and the complete two-stage Boost PFC. The DC component model, the first- and the second-order harmonic component averaged model are derived from the averaged model of the Boost pre-regulator to study its dynamics. After reasonable assumption of the steady state of the DC component and the second-order harmonic component, the dynamics of the converter is decided by a linear system. A washout filter may be used to stabilize the linear system. The effect of circuit parameters of the washout filter on the dynamics of the converter is studied in detail. The response under variation of parameters in the converter is analyzed. The average model of the complete two-stage Boost PFC converter is derived, and the DC component model, the first- and the second-order harmonic component averaged model are derived from the averaged model to study the effect of the washout filter aided method. A comparison between the effects of the washout filter method on the two cases is given.Slow-scale bifurcation in the One-cycle controlled Cuk PFC converter is analyzed. Based on the average model, the approximate resolution of the state variables is obtained by adopting harmonic balance method. The stability boundaries of some circuit parameters are presented and are discussed.更多还原