Buck补偿DCM Flyback PFC变换器研究

发布时间：2019-01-25 21:15

【摘要】：为减小AC/DC变换器等电子设备给电网带来的谐波污染,功率因数校正技术(Power Factor Correction, PFC)得到了广泛应用。工作于不连续导电模式(Discontinuous Conducting Mode, DCM)的Flyback PFC变换器具有效率高、成本低、结构简单、功率因数高、输入-输出电气隔离等优点而得到广泛应用。传统单级Flyback PFC变换器存在二倍工频纹波、负载瞬态响应慢等缺点,限制其应用范围。本文以DCM Flyback PFC变换器为例,研究了引入Buck变换器补偿二倍工频纹波,以消除DCM Flyback PFC变换器输出的二倍工频纹波的技术。论文研究了Buck补偿DCM Flyback PFC变换器的工作原理、主要工作波形和控制策略,建立了变换器的等效模型,分析了其直流稳态和交流小信号特性；研究了实现低输出电压纹波的条件；且对比了本文所研究的变换器、单级DCMFlyback PFC变换器和DCM Flyback PFC变换器级联Buck变换器三种变换器之间的效率；此外还推导了Flyback PFC变换器和Buck变换器工作于DCM模态下临界电感。以理论分析为基础,搭建一台48V/50W的实验样机。论文介绍了恒压式电压型控制Buck补偿DCM Flyback PFC变换器设计步骤；详细分析了变压器的设计和控制环路的设计以及参数的选取；介绍了实验中功率电路等具体使用参数；通过实验,验证理论分析的正确性。实验结果表明：Buck补偿DCM Flyback PFC变换器不仅实现输出电压低纹波,且具有快速的负载瞬态响应速度。通过改变控制策略,实现Buck补偿DCM Flyback PFC变换器的恒流输出。论文介绍了恒流式Buck补偿DCM Flyback PFC变换器工作原理和主要工作波形；详细研究了其控制策略；推导了变换器实现低输出电流纹波控制器应满足的条件；详细介绍了变换器恒流输出时控制器的设计。最后研制了一台0.7A/50W的实验样机。通过实验样机,验证了理论分析的正确性和Buck补偿DCM FlybackPFC输出二倍工频纹波的可行性。
[Abstract]:In order to reduce harmonic pollution caused by electronic devices such as AC/DC converters, power factor correction (Power Factor Correction, PFC) technology has been widely used. The Flyback PFC converter operating in discontinuous conductive mode (Discontinuous Conducting Mode, DCM) is widely used because of its advantages of high efficiency, low cost, simple structure, high power factor and electrical isolation between input and output. The traditional single-stage Flyback PFC converter has the shortcomings of double power frequency ripple and slow transient response of load, which limits its application scope. Taking DCM Flyback PFC converter as an example, this paper studies the technique of introducing Buck converter to compensate double power frequency ripple in order to eliminate the double power frequency ripple output from DCM Flyback PFC converter. In this paper, the working principle, main working waveform and control strategy of Buck compensated DCM Flyback PFC converter are studied, the equivalent model of converter is established, the characteristics of DC steady state and AC small signal are analyzed, the condition of realizing low output voltage ripple is studied. The efficiency of the three converters, single stage DCMFlyback PFC converter and DCM Flyback PFC cascade Buck converter, are compared, and the critical inductance of Flyback PFC converter and Buck converter working in DCM mode is deduced. Based on theoretical analysis, an experimental prototype of 48V/50W is built. This paper introduces the design steps of Buck compensated DCM Flyback PFC converter with constant voltage mode control, analyzes the design of transformer, the design of control loop and the selection of parameters in detail, and introduces the power circuit in the experiment. The correctness of the theoretical analysis is verified by experiments. The experimental results show that the Buck compensated DCM Flyback PFC converter not only achieves low ripple output voltage, but also has a fast load transient response speed. By changing the control strategy, Buck compensates the constant current output of DCM Flyback PFC converter. This paper introduces the working principle and main working waveform of constant current Buck compensated DCM Flyback PFC converter, studies its control strategy in detail, deduces the conditions that the converter should satisfy to realize the low output current ripple controller. The design of constant current output controller of converter is introduced in detail. Finally, an experimental prototype of 0.7A/50W is developed. The correctness of the theoretical analysis and the feasibility of Buck compensating DCM FlybackPFC output double power frequency ripple are verified by the experimental prototype.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TM46

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