三相零电流单开关降压型功率因数校正变换器的研究

发布时间：2018-12-14 19:42

【摘要】：电能的控制和变换技术使用日益广泛。传统的AC-DC变换器采用的是整流桥和母线电容的非线性组合,这使输入电流含有大量的谐波。大量的谐波污染了电网而且影响同一电网中用电设备的正常工作。在高功率等级的应用中,整流器一般使用三相PFC而软开关的三相PFC可以提升变换器的功率密度以及效率。本文首先介绍了功率因数校正技术的国内外研究现状以及三相PFC的拓扑结构和常用的控制策略。对三相单开关零电流Buck PFC在一个工作周期内的工作过程和工作波形进行了分析。其次分析了三相ZCS单开关Buck PFC的工作特性,通过仿真分析找到了合适的滞环电压控制上限电压和环内控制占空比,仿真结果说明滞环电压控制可以降低相电流的THD含量。对校正电容的三角形接法接行了探究并给出了结论。采用滞环电压控制和校正电容的三角形接法的结合进行了仿真分析。仿真结果显示该种组合可以有效的降低相电流的THD含量,THD含量低于5%。通过分析一个工作周期内各处的电压、电流波形特点,推导了变换器的效率。将器件的参数代入效率公式,在假定输入电压和负载不变化的情形下,利用Matlab工具绘制了占空比的变化和效率的关系,从而对变换器的效率和输出功率的选择提供指导。本文的最后设计了一台1.5kW的实验样机,并给出了主电路器件的选择和相应电路的设计。给出了 DSP控制程序的设计,并对一些重要的的子程序进行了说明。搭建了实验平台,实验结果表明:在额定输出功率时,开关工作在零电流开关,电网侧PF值接近于1,相电流THD含量为3.66%,低于5%,说明采用校正电容的三角形接法和滞环电压控制的结合可以优化THD。对变换器的效率进行了测试,给出了测试曲线,测试数据显示满功率时的效率为92.02%,根据推导的效率,变换器输出1.5kW功率时的效率为93.35%,效率测试值和计算值的误差在1%左右。对效率数据的误差以及满功率时功率的损耗进行了分析。测试了软启动功能,并对实验现象进行了分析。分析了样机的空载损耗。测试了负载突变时的相电流和输出电压的变化,相电流和输出电压的动态调整特性证明了程序设计的合理性。
[Abstract]:Electric power control and conversion technology is increasingly widely used. The traditional AC-DC converter uses a nonlinear combination of rectifier bridge and busbar capacitance, which makes the input current contain a lot of harmonics. A large number of harmonics pollute the power grid and affect the normal operation of the power equipment in the same power grid. In the application of high power level, the rectifier generally uses three-phase PFC while the soft-switching three-phase PFC can improve the power density and efficiency of the converter. This paper first introduces the research status of power factor correction technology at home and abroad, the topology structure and common control strategy of three-phase PFC. The working process and waveform of three phase single switch zero current Buck PFC in one working cycle are analyzed. Secondly, the working characteristics of three-phase ZCS single-switch Buck PFC are analyzed, and the suitable hysteretic voltage control upper limit voltage and the control duty cycle in the loop are found through the simulation analysis. The simulation results show that the hysteresis voltage control can reduce the THD content of the phase current. The triangle connection of the corrected capacitance is studied and the conclusion is given. The hysteretic voltage control and the triangulation method of correcting capacitance are used to simulate and analyze. The simulation results show that this combination can effectively reduce the THD content of phase current, and the THD content is lower than 5%. The efficiency of the converter is derived by analyzing the characteristics of voltage and current waveforms throughout a working cycle. Under the assumption that the input voltage and load do not change, the relation between duty cycle and efficiency is plotted by using Matlab tool, which provides guidance for the selection of converter efficiency and output power. At the end of this paper, an experimental prototype of 1.5kW is designed, and the selection of main circuit and the design of corresponding circuit are given. The design of DSP control program is given, and some important subprograms are described. The experimental results show that when the rated output power is rated, the switch operates on the zero current switch, the PF value of the grid side is close to 1, the THD content of the phase current is 3.66, which is lower than 5. It shows that the combination of triangle connection method and hysteresis voltage control can optimize THD.. The efficiency of the converter is tested and the test curve is given. The test data show that the efficiency of full power is 92. 02. According to the derived efficiency, the efficiency of output 1.5kW power of the converter is 93.35. The error between the efficiency test value and the calculation value is about 1%. The error of efficiency data and the loss of power at full power are analyzed. The soft start function is tested and the experimental phenomena are analyzed. The no-load loss of the prototype is analyzed. The variation of phase current and output voltage during the sudden change of load is tested. The dynamic adjustment of phase current and output voltage proves the rationality of the program design.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TM46

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