一款峰值电流控制模式的Buck型DC-DC变换器设计及稳定性分析

发布时间：2018-02-25 02:11

本文关键词： Buck 峰值电流控制小信号模型稳定性 Ridley　出处：《电子科技大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着各种电源技术的发展,开关电源作为一种新型的绿色电源,其具有效率高、体积小的特点,同时由于其具有的多种拓扑结构,使其能满足各种不同的工作要求,是得其在实际生活中应用的越来越广泛。作为开关电源的重要特性,其稳定的工作特性是其应对各种复杂工作情况的保证。因此,对开关电源稳定性的研究凸显出越来越重要的特性。本文设计了一款峰值电流控制模式的单片式Buck型DC-DC变换器,其输入电压范围可从6 V变化到32 V,最大的负载电流可以达到4.5 A,稳定5 V的输出电压,其工作频率为500 kHz,同时具有同步功能,能够通过外部时钟改变系统的工作频率,最高可以达到1 MHz。为开关电源的工作特性建模是研究其稳定性的重要基础。本文首先研究了开关电源的主要建模方法,这其中包括基本建模法、状态空间平均法和开关平均法。在这些基本建模方法的基础上,本文针对峰值电流控制模式的开关电源模型进行了详细的阐述,介绍了三种常用的峰值电流控制模式的开关电源等效模型,其中有Ridley的模型,科罗拉多大学电力电子中心(CoPEC)的模型和Bryant的模型,并对各种模型的建模思想、建模过程及最终具体的模型进行了详细的介绍,为设计BUCK型DC-DC变换器奠定理论基础。本文详细介绍了整体系统的拓扑结构和工作原理及外围元器件的选择原则,并完成了系统中一些关键模块的设计,包括电感电流采样电路、误差放大器、振荡器、同步模块和功率管驱动电路的设计,详细分析了电路的工作原理,并在所选取的工艺的基础上进行了仿真验证。同时,针对本文的设计,通过采用Ridley的模型,对本设计的稳定性进行了分析,得到系统重要的环路传递函数,分析其零极点特性并进行了环路补偿,保证了系统环路的稳定性。最后,基于BJT工艺,对本设计的系统进行了总体仿真,验证了其在各种输入电压及负载情况下的系统工作特性,并对仿真结果进行了分析,最终系统能够满足设计指标要求。
[Abstract]:With the development of various power supply technologies, switching power supply, as a new type of green power supply, has the characteristics of high efficiency and small volume. As an important characteristic of switching power supply, its stable working characteristic is the guarantee to deal with all kinds of complex working conditions. The study of switching power supply stability highlights more and more important characteristics. In this paper, a single-chip Buck DC-DC converter with peak-current control mode is designed. The input voltage range can be changed from 6 V to 32 V, the maximum load current can reach 4.5 A. the output voltage is stable at 5 V, and its operating frequency is 500 kHz. At the same time, it has the function of synchronization and can change the operating frequency of the system through the external clock. It is an important foundation to study the stability of switching power supply. In this paper, the main modeling methods of switching power supply, including the basic modeling method, are studied. State space averaging method and switching average method. On the basis of these basic modeling methods, the switching power supply model of peak current control mode is described in detail in this paper. In this paper, three kinds of switching power equivalent models of peak current control mode are introduced, including Ridley model, Bryant model and power electronics center model of the University of Colorado. The modeling process and the final concrete model are introduced in detail, which lays a theoretical foundation for the design of BUCK type DC-DC converter. This paper introduces in detail the topological structure and working principle of the whole system and the selection principle of peripheral components. Some key modules of the system are designed, including inductance current sampling circuit, error amplifier, oscillator, synchronous module and power tube drive circuit. The working principle of the circuit is analyzed in detail. At the same time, according to the design of this paper, the stability of the design is analyzed by using Ridley model, and the important loop transfer function of the system is obtained. The zero-pole characteristic is analyzed and the loop compensation is carried out to ensure the stability of the system loop. Finally, based on the BJT process, the overall simulation of the system is carried out. The characteristics of the system under various input voltages and loads are verified, and the simulation results are analyzed. Finally, the system can meet the design requirements.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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