【作者】 钱峰；

【导师】 黄念慈；

【作者基本信息】 四川大学 ， 电力电子及电力传动， 2003， 硕士

【摘要】 BUCK型DC／DC变换器在电池供电的计算机，消费类产品等需多电源供电的电子系统中有着广泛的应用。小型化成为必然的要求。开关频率的提高使得变换器体积减小，如20KHz提高至1MHz，电源所用的DC／DC变换器体积只有原来的1／7。但随着开关频率的提高，硬开关的开关损耗增加，变换器的工作效率随之下降。而工作效率已是衡量高频DC／DC变换器品质的重要因素，如何在高频下获得高的工作效率成为研究方向之一。 对ZVT-PWM BUCK变换器而言，除了谐振参数对工作效率有很大的影响外，变换器输入输出电压和所带负载对工作效率都有影响。本文对一典型的ZVT-PWM BUCK变换器进行了深入的分析研究。计算出辅助回路各部分的损耗，以及辅助回路中各部分的损耗占输出功率的比例。根据计算公式和计算结果，分析了谐振电感，主开关并联电容和输入输出电压对变换器工作效率的影响，并且详细分析了辅助开关的关断损耗在带不同负载时对变换器工作效率的影响。找出了影响变换器工作效率的关键部分，并据此提出参数优化的方案和提高变换器工作效率的改进措施。设计了一新型ZVT-PWM BUCK变换器，并进行了实验和仿真验证，证实了所做的改进措施确实能够提高变换器的工作效率，验证了本文对辅助回路的损耗分析结果和所提出的参数优化的措施。最后为了适应大功率应用的场合，根据相同的原理对原有的一种两相ZVT-PWM BUCK变换器做出改进，提出一工作效率更高，并且适合于大功率应用的两相ZVT-PWM BUCK电路。更多还原

【Abstract】 The BUCK DC/DC converter is wildly used in the battery charged computers and consumption products. Minisize is required in these products. The improvement of the switching frequency can diminish the converter size. The DC/DC converter is just one seventh as before when the switching frequency is improved from 20KHz to 1MHz. But the switching loss is increased as the switching frequency is improved and so the converter efficiency is decreased. Because efficiency is a main aspect to evaluate the high frequency DC/DC converter, how can higher efficiency be obtained is the important aspect of research.To the ZVT-PWM soft-switching converter, not only the resonant parameters but the input and output voltage and the load can affect the converter efficiency. A detailed research of a typical ZVT-PWM BUCK converter is done in this paper. The loss of the different parts in the assistant circuit of the typical ZVT-PWM BUCK converter is calculated. The ratio of the loss of the different parts in the assistant circuit to the output power is calculated too. The influence of the resonant parameters and the input-output voltage to the converter efficiency is analyzed base the calculation. And the influence of the turn-off loss of the assistant switch to the efficiency of the typical ZVT-PWM BUCK converter is analyzed. The main aspects influence the efficiency are found out and the resonant parameters optimization schemes are brought forward. Due to the deficiency of the typical ZVT-PWM BUCK converter,the design of a new ZVT-PWM BUCK converter is described in this paper. The experimental results and simulation results all approved the improvement measurements can improve the converter efficiency. In the end of the paper, a improved two-phases ZVT-PWM BUCK circuit is brought forward base the same principle.更多还原