BUCK型PFC电路功率因数提升方案研究与电路设计

发布时间：2018-03-16 23:21

本文选题：功率因数校正　切入点：降压型变换器　出处：《天津大学》2014年硕士论文　论文类型：学位论文

【摘要】：功率因数(Power Factor)定义了有功功率在视在功率中所占的比例。电流中谐波含量越大,功率因数越低。在电路中采用有源功率因数校正技术能够使输入电流波形接近正弦波并且与输入电压同相位,进而达到功率因数校正的目的。功率因数校正电路只有三种基本结构,所有的结构都是基于这三种基本结构所进行相应的变化。这三种结构分别是:降压型(Buck)、升压型(Boost)、降压升压型(Buck-Boost)。相对于其他两种类型的变换器,Buck型变换器具有其不可替代的优点,但是由于其输入电流存在固有的交越失真(Cross-over Distortion),也称为输入电流死区,其功率因数总是不能达到满足各种工业标准要求的水平,因而限制了这种结构在实际中的应用。如果能够采用某种方法使Buck型功率因数变换器的输入电流死区得到一定程度上的抑制或者补充,那么在这种特定控制方式下的改进型功率因数变换器的应用范围将大大拓展。本文基于传统Buck型变换器基本拓扑结构,提出了两种改进的降压型功率因数变换器的结构。这两种结构能够在输入电流交越失真阶段补充电流,使输入电流准正弦,从而能够在保持传统Buck型变换器优点的基础上克服其固有的缺陷。在此基础上,本文针对这两种改进的变换器结构提出了两种控制方案。本文所阐述的结构相对于传统Buck型电路在输出端增加一个MOS开关,通过控制两个MOS开关的不同开关状态,使电路在交越失真阶段转换为Buck-Boost型拓扑结构,从而使电流失真得到克服。对于控制电路,通过使用额外的电压比较器判定发生交越失真的时间节点,从而实现对电路结构变换的控制。论文中采用临界导通控制方式,单级变换器结构设计的PAB(pulse assisting buck)变换器与MTB(multiple topology buck)变换器克服了传统Buck型变换器的输入电流死区,大大提升了Buck型变换器的性能。本文设计的两种结构适用于中等功率水平的单级PFC变换器,并采用SIMPLIS进行验证。其中,PAB变换器在输入220V,50Hz的条件下,其功率因数为98.74%,电源效率为97.21%。MTB变换器在输入电压90V~264V范围内的功率因数范围为96.74%~99.70%。结果表明这两种改进型的功率因数变换器确实能够大幅提高传统Buck型变换器的功率因数,并改善了谐波条件,使变换器能够满足各种国际标准的指标要求。
[Abstract]:Power Factor Power Factor defines the proportion of active power in apparent power. The lower the power factor is, the more active power factor correction technology is used in the circuit to make the input current waveform close to sine wave and the same phase as the input voltage. Thus achieving the purpose of power factor correction. There are only three basic structures of the power factor correction circuit. All the structures are based on the corresponding changes of these three basic structures, which are: buck, booster boost, and boost Buck-Boost.Compared with the other two types of converter, the Buck converter has its irreplaceable advantages. However, due to the inherent cross-over distortion of the input current, also known as the dead zone of the input current, its power factor can not always meet the requirements of various industrial standards. Therefore, the application of this kind of structure in practice is limited. If some method can be used to suppress or supplement the dead time of input current of Buck type power factor converter to a certain extent, Then the application range of the improved power factor converter under this particular control mode will be greatly expanded. This paper is based on the basic topology of the traditional Buck converter. Two improved step-down power factor converter structures are proposed, which can replenish the input current during the phase of cross-distortion and make the input current quasi-sinusoidal. Therefore, it can overcome the inherent defects on the basis of maintaining the advantages of traditional Buck converters. In this paper, two control schemes are proposed for these two improved converters. Compared with the traditional Buck circuit, the structure described in this paper adds a MOS switch at the output end, and controls the different switching states of the two MOS switches. The current distortion can be overcome by converting the circuit to Buck-Boost topology in the phase of cross-over distortion. For the control circuit, the time node in which the cross-over distortion occurs is determined by the use of additional voltage comparator. In this paper, the PAB(pulse assisting converter and MTB(multiple topology converter designed by single stage converter structure overcome the dead time of input current of the traditional Buck converter. The performance of Buck converter is greatly improved. The two structures designed in this paper are suitable for single-stage PFC converter with medium power level and verified by SIMPLIS. The power factor of the converter is 98.744.The power efficiency of the converter is 97.21.MTB converter has a power factor range of 96.7474 / 99.70V within the input voltage of 90V / 264V. the results show that the two improved power factor converters can greatly improve the power factor of the traditional Buck converter. The harmonic condition is improved so that the converter can meet the requirements of various international standards.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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