移相全桥ZVS变换器寄生振荡抑制方法的研究

发布时间：2019-01-04 06:57

【摘要】：移相全桥ZVS变换器在中大功率应用场合备受青睐，其中变压器漏感与功率管寄生电容的谐振实现了各开关管的零电压开关，变换器效率较高。可是其副边整流二极管存在寄生振荡、软开关范围窄、占空比丢失、环流损耗大等缺陷限制了变换器的进一步推广。特别是副边的寄生振荡问题不仅提高了整流装置的电压应力和导通损耗，同时给系统引入了严重的电磁干扰。本文针对实际场合中大功率变换应用系统，选取主电路拓扑为全桥变换器进行研究。论文首先对软开关全桥变换器进行了分类，详细介绍了移相ZVS全桥变换器的优缺点及其研究现状，指出寄生振荡产生的危害，确定本文研究重点是抑制全桥ZVS变换器副边寄生振荡的新方法。论文第二章，主要对移相全桥ZVS变换器副边寄生震荡机理进行研究，分别分析了超前臂和滞后臂的换流原理，并比较二者的不同，基于此不同之处提出利用超前环流思想抑制副边振荡的新对策。其次，提出了一种基于LCC辅助电路的新型ZVS全桥变换器。该变换器中，由于整流管提前换流，副边整流二极管上的寄生振荡得到有效的抑制，且副边不存在占空比的丢失，，同时利用LC辅助电路和滤波电感中的能量所有的功率管都可以在宽负载范围内实现软开关。本文分析了该变换器的工作原理，讨论了其主要的参数设计，并进行了实验验证。接着，本文根据上一新型变换器的缺陷，提出了一种改进型的ZVS全桥变换器。改进型全桥变换器中引入了辅助变压器，增大了换流电压幅值，大大加快了原边换流速度，副边寄生振荡抑制效果明显。此外，还引入了辅助耦合电感来拓宽超前管与滞后管的零电压开关范围。并且改进型变换器不存在环流时间，输出滤波电感纹波电流得到抑制，利于滤波器尺寸的缩小。本文详细分析了该变换器的工作原理，讨论了其参数设计原则，并搭建样机进行了实验验证。最后论文对研究内容进行了总结，并基于方案的不足之处给出了需进一步做的工作。
[Abstract]:Phase-shifted full-bridge ZVS converters are popular in medium and high power applications, in which the leakage inductance of transformers and the resonance of parasitic capacitors of power transistors realize the zero-voltage switching of each switch, and the converter is more efficient. However, the parasitic oscillation of the secondary side rectifier diode, the narrow range of soft switching, the loss of duty cycle and the large circulation loss limit the further development of the converter. Especially the parasitic oscillation of the secondary edge not only increases the voltage stress and the conduction loss of the rectifier but also introduces serious electromagnetic interference to the system. In this paper, the main circuit topology is selected as the full bridge converter for the practical application system of large power conversion. Firstly, the soft-switching full-bridge converter is classified, and the advantages and disadvantages of phase-shifted ZVS full-bridge converter are introduced in detail, and the harm of parasitic oscillation is pointed out. It is determined that the emphasis of this paper is to suppress the secondary parasitic oscillation of full-bridge ZVS converters. In the second chapter, the principle of secondary side parasitic oscillation of phase-shifted full-bridge ZVS converter is studied. The commutation principle of lead arm and hysteresis arm is analyzed, and the difference between them is compared. Based on these differences, a new strategy to suppress the secondary oscillation by using the idea of advanced circulation is proposed. Secondly, a novel ZVS full bridge converter based on LCC auxiliary circuit is proposed. In the converter, the parasitic oscillation on the secondary rectifier diode is effectively suppressed because of the rectifier in advance, and there is no duty cycle loss in the secondary side. At the same time, all the power transistors in the LC auxiliary circuit and the filter inductor can realize soft switching in a wide load range. In this paper, the principle of the converter is analyzed, and its main parameter design is discussed. Then, according to the defects of the new converter, an improved ZVS full bridge converter is proposed. An auxiliary transformer is introduced into the improved full-bridge converter, which increases the amplitude of commutation voltage, greatly speeds up the commutation speed of the original side, and reduces the parasitic oscillation of the auxiliary side obviously. In addition, an auxiliary coupling inductor is introduced to widen the range of zero voltage switches between lead and hysteresis transistors. And the improved converter has no circulation time, the output filter inductor ripple current is suppressed, and the filter size is reduced. In this paper, the working principle of the converter is analyzed in detail, and the design principle of its parameters is discussed. Finally, the research content is summarized, and the further work is given based on the shortcomings of the scheme.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM46

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