毕业设计--开机预偏置电压问题研究

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1、 毕业设计（论文）说明书 共 40 页 第 1 页摘要 随着社会的发展以及人们生活水平的提高，市场对电子产品的需求越来越大，由于所有的电子产品都需要有电源对其供电，电源的性能和安全可靠性就显得至关重要。电源的高效率、低功耗、小体积、高可靠性已经成为大势所趋，在这种情况下，对电子产品电源安全性能的考虑是必要的。当电路由于各种原因出现反向电流时，若反向电流过大，不仅可能烧坏元器件，也可能对负载正常运行造成影响和安全隐患，甚至威胁人们的财产和生命安全。由此可见，对变换器反向电流的研究从各个角度来说都是很有价值的。 本文主要阐述的是 DC-DC 变换器开机过程 中的反向电流问题，对于 DC-DC 变换

2、器来说，当主电路开关管占空比很小，且输出有一定预偏置电压时，可能导致输出电流反向累积，逐渐增大。在基本理论知识的基础上，为了防止过大的反向电流对负载正常运行造成的影响和安全隐患，本文在电路中增加了脉冲阻止电路，使电路在检测到电流反向时阻止续流开关管的导通脉冲传递至续流开关管，以阻止续流开关管导通，从而使反向电流无法通过续流开关管形成通路，即无法持续增大，从而达到有效遏制反向电流的目的。 关键词 ： 直流 -直流变换器 反向电流 脉冲阻止 预偏置 毕业设计（论文）说明书 共 40 页 第 2 页 Abstract As the society develops and peoples stand

3、ard of living improves, more and more electronic products are needed in the markets. Due to the demand of sources to power electronic products, its crucial to possess a high function and reliability for a power supply. To realize the demand of the public, sources of high efficiency, low power loss,

4、small volume as well as high reliability have represented the general trend, so its necessary to lucubrate its safety performance. If by any chance, there be a reverse current and the current be large, this may ruin devices or trigger safe trouble, and even throw a threat to peoples safety of life.

5、From all of these, we can see, its of great value to research the reverse current. As for the DC-DC converter, with a dinky duty ratio and pre-bias voltage, the circuit can own an increasing reverse output current. Elaborated on the basic theoretical knowledge, to prevent the reverse current increas

6、ing problem, when reverse current detected, a pulse blocking circuit is introduced to prevent the freewheel triode from conducting, so as to stop the loop of the reverse current, so the current will be unable to become bigger, that is the purpose to curb the reverse current problem. Keywords: DC-DC converter reverse current pulse block pre-bias