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毕业设计

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DZ095开关电源的应用——POS机的电源设计,毕业设计

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开关电源的应用 POS 机的电源设计 专业： 通信工程 学号： 1002592 姓名： 周少宏 指导教师： 林强、李伟 中文摘要 本文主要是通过分析并设计一款用于 POS 机的高效率、低功耗的开关电源适配器来介绍开关电源的优点，让更多人了解开关电源为什么能够逐渐取代线性稳压电源而得到广泛应用。该电源电路采用脉宽调制型（ PWM）、电流控制 模式、单端反激式工作原理，设计电路中还考虑了各种保护电路。该电源有效输入电压范围为 100V 240V，输出电压为 6.8V,误差范围在 2内，输出功率为 34W,效率高达 75以上 ，是一款高效率、低成本、微型化的小功率开关电源。 在开关电源轻型化、高效化的发展历程中，集成电路技术起了决定性的作用。近 20 年来，集成开关电源是沿着两个方向不断发展的：一个方向是，对开关电源的核心单元 控制电路的集成；另一个方面是，对中、小功率开关电源实现单片集成化，单片开关电源实际上是一种 AC/DC 电源变换器。 在介绍具体的设计电 路之前， 本文 先简单介绍了开关电源的发展历史及其工作原理，并与传统的线性稳压电源进行了比较。其次详细地对比介绍了不同的拓扑结构、调制方法、控制方式的不同特点。 然后第 3 章 详细介绍整个电路的设计思路、电路结构选择、器件选择、参数计算等一系列工作。限于篇幅，对一些辅助的电路，包括各种保护电路，如：过流、过压保护，欠压锁定电路， EMI 滤波电路 ,补偿网络 等等只做了简单的介绍。 本文除了完成原理分析和理论设计外 ， 还 得到了由本电源电路 图（附录 1）加工 而成的实物电源，并对实物电路进行测试，分析和总结。 在经过 调试过程中的对电路 结构 的 进一步修改后，电路的各项指标均达到或优于预定指标（各项指标值已附于文章最后），验证了作者的理论设计，实现了设计目标，是一次理论结合实践的大胆尝试。 关键词： 开关电源 ,脉宽调制 ,电流控制模式 ,反激变换器 ,高效率 ntsThe application of switching power supply The design of power supply for POS computer Abstract By analyzing and designing a high-efficiency low-power switching power supply used for the POS machine, this paper wants to tell us all about the advantages of the switching power supply, making more and more people to know why the switching power supply is going to replace the linear regulator gradually and becomes more and more popular in the power conversion arena today. The principle of this circuit is a current model control PWM flyback converter, and some protection circuits are also designed in this switching power supply. This circuit has a wide input voltage range of 100Vac to 240Vac to generate a output of 6.8Vdc,34W with error less than 2% and efficiency more than 75%, is a small-scale switching power supply of high-efficiency and low-cost. In the development of small-scale、 high-efficient switching power supply, the technology of integrated circuit take a decisive role. Over the past 20 years, the inte-grated switching power supply is developing in two directions: the first is the integra-tion of the core component-control circuit; the second is integration of the small and medium scale switching power supply in a integrated circuit. In fact, the single-chip switching power supply is a AC/DC power convertor. Before introducing the factual circuit, the author first introduces the development history and basic principle of the switching power supply in contrast to the linear reg-ulator. The different operating principles of different circuit topologies、 modulation mode and control model have been particularly analyzed after it. And then a series of tasks, such as design theory、 topologies selection、 components selection and pa-rameter calculation have been expounded in chapter3. Limited by the paper and time, some assistant circuits are simply introduced, for example, over current、 voltage protection circuit,under voltage locked circuit,EMI filter,compensation network and so on. Besides the principle analysis and theoretic design,the author obtains the real switching power supply processed according to the theoretic design circuit chart in the appendix1, then the author tests the power supply and analyzes the test result. Be-cause of the improvements of the real circuit during the test, the test result indicates that each target of the real power supply has achieved or better than the expecta-tion(the test results enclosed in the end of the paper), verifies the theoretic design and achieves