适合中小功率的高效隔离型升压变换器研究

发布时间：2018-08-01 11:37

【摘要】：隔离型升压电源作为一种可以实现直流升压功能的变换器,将在新能源以及航空航天等相关领域发挥重要作用。目前,针对隔离型升压电源的研究主要集中在如何提高升压比、如何提高效率以及如何提高变换器的功率密度三个方面。本文对隔离型升压变换器的研究现状进行了分析,并对常用的升压方式进行了介绍。通过对典型的隔离型升压变换器进行对比,说明了有源箝位正反激在拓扑结构、开关管应力、效率等方面的优势。正反激变换器工作时存在三种模式:连续模式、临界连续模式以及断续模式,文章详细分析了三种模式的工作原理,并对临界连续模式的实现方式进行了介绍。有源箝位电路通常存在两种驱动方式:互补驱动、非互补驱动。通过对有源箝位电路的驱动方式进行分析研究,本文最终采用导通时间短,箝位电路环流小,有利于软开关实现的非互补驱动方式。正反激变换器的传统控制方式主要有三种:关断时间控制、定频控制以及准谐振控制。本文对上述三种控制方式进行分析,通过结合此三种控制方式的优点,提出了一种新型混合控制方式,提高了变换器在整个负载范围内的效率。新型混合控制设计变换器重载工作于临界连续模式,实现主功率开关管的软开关;轻载工作于关断时间控制的断续模式,降低轻载频率;极轻载时工作于定频控制的断续模式,保持较低频率的驱动输出。变压器的交流阻抗与变压器的绕法以及绕线选型有直接的关系,本文通过对变压器集肤效应以及邻近效应的分析,确定采用三明治绕法,将原边绕组拆分为多层并联,实现与副边绕组的夹绕。根据给定的设计指标,本文给出了正反激变换器的参数设计结果,并搭建了300W样机平台。通过实验,验证了新型混合控制的可行性以及设计思想的正确性,采用新型混合控制,变换器能够在全输入、全负载范围内实现功率开关管的软开关,变换器整机CEC峰值效率为97.66%,CEC标称平均效率为97.29%,CEC加权效率为97.19%。
[Abstract]:As a kind of converter which can realize DC boost, isolated booster power supply will play an important role in new energy sources, aerospace and other related fields. At present, the research of isolated booster power supply mainly focuses on how to improve the boost ratio, how to improve the efficiency and how to improve the power density of the converter. In this paper, the research status of isolated boost converter is analyzed, and the usual booster mode is introduced. Through the comparison of typical isolated boost converters, the advantages of active clamp forward and flyback excitation in topology, switch stress, efficiency and so on are illustrated. There are three modes in forward and flyback converter: continuous mode, critical continuous mode and intermittent mode. The working principle of the three modes is analyzed in detail, and the realization mode of critical continuous mode is introduced. There are usually two driving modes in active clamp circuits: complementary drive and non-complementary drive. Through the analysis of the driving mode of active clamp circuit, this paper finally adopts the non-complementary driving mode which is beneficial to the realization of soft switch because of the short on-on time and the small circulation of clamping circuit. There are three traditional control methods of forward and flyback converter: turn-off time control, fixed frequency control and quasi resonant control. In this paper, the three control methods mentioned above are analyzed, and a new hybrid control mode is proposed by combining the advantages of the three control modes, which improves the efficiency of the converter in the whole load range. The new hybrid control design converter works in critical continuous mode to realize soft switch of main power switch, light load works in intermittent mode of turn-off time control to reduce light load frequency, and very light load works in intermittent mode of constant frequency control. Maintain lower frequency drive output. The AC impedance of the transformer is directly related to the winding method of the transformer and the selection of the winding wire. Through the analysis of the skin effect and proximity effect of the transformer, the sandwich winding method is adopted to split the original side winding into multi-layer parallel connection. Realize the clamp winding with the secondary side winding. According to the given design index, the design results of the forward and flyback converter parameters are given, and the 300W prototype platform is built. Through experiments, the feasibility of the new hybrid control and the correctness of the design idea are verified. With the new hybrid control, the converter can realize the soft switch of the power switch in the full input and full load range. The CEC peak efficiency of the converter is 97.66 and the nominal average efficiency is 97.29 and the weighted efficiency is 97.19.
【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】：2016
【分类号】：TM46

【参考文献】