摘要:各种电子设备都需要供电电源为其提供所需的电能，因此一旦某种原因出现供电中断，就会造成整个系统停机，其后果远远严重于电子设备的自身故障。为此，引入一种新型UPS是不间断电源(uninterruptible power system)的英文简称, 所谓不间断电源就是当交流电网（市电）输入发生异常或中断时，它可以继续向负载供电，并能够保证供电质量，使负载供电不受影响。这种供电装置称为不间断电源装置，简称UPS（Uninterruptible Power System）。本设计主要研究小功率UPS的工作原理及硬件设计，给出了不间断电源的不同工作方式及原理，经过比较论证、可行性和实用性分析，设计方案采用了UPS后备式工作状态，对非严格要求的供电场所提供较为可靠的不间断电源，防止突然断电而造成安全隐患或影响正常工作。该设计介绍了构成UPS的各部分的电路及所用到的主要芯片，重点完成了UPS系统的控制电路部分和逆变稳压电路部分，详细分析了其工作原理，画出了相应的电路框图和工作原理图，给出了元器件清单。控制电路部分主要采用集成化芯片LM339和常见芯片W7812、NE555，逆变电路主要采用集成化芯片TL494等。这样的电路优点是结构简单、检测维修方便、成本较低。这次设计还完成了实物制作，并通电调试，在一定程度上达到了设计的技术指标，能满足非严格要求的供电场所不间断供电的要求。可用于楼道上、房间里等一些对供电质量要求不高的场合，提供照明用电，减少停电带来的麻烦，提供一个安全、可靠的供电电源。
ABSTRACT:A variety of electronic devices are required for power supply to provide the required electric energy, so once a power interruption occurs, could cause the entire system shutdown, the consequence is far more serious in the electronic equipment's own fault. Therefore, the introduction of a new UPS uninterruptible power supply ( uninterruptible power system ) the English abbreviation, called uninterruptible power when AC power (electricity) input is abnormal or interruption, it can keep the power to the load, and can ensure the quality of power supply, so that the load of power supply is not affected. The power supply device called an uninterruptible power supply device, referred to as UPS ( Uninterruptible Power System ).The design of the main research small power UPS working principle and hardware design, gives the uninterruptible power supply to the different working mode and principle, through comparison, feasibility, practicability analysis, design adopts UPS backup type working state, the strict requirements of power supply place to provide more reliable uninterruptible power supply, preventing a sudden power failure potential safety hazards caused or affect the normal work. This design introduced the form UPS part of the electric circuit and the main chip, focus on the completion of the UPS system part of the control circuit and the inverter voltage circuit, a detailed analysis of its working principle, draw the corresponding circuit diagram and working principle diagram, gives the components list. Control circuit mainly adopts an integrated chip LM339 and NE555chip W7812, common, inverter circuit mainly adopts the integrated chip TL494. This circuit has the advantages of simple structure, convenient repair, low cost detection. This design also completed the physical production, and electrifying debugging, to a certain extent, has achieved the design technical indicators can meet the strict requirement, the power supply place uninterrupted power supply requirements. Can be used for building, room and some of the requirement of power supply quality is not high, to provide electricity for lighting, reduce power cut caused trouble, to provide a safe, reliable power supply.
Key words：Uninterruptible power supply; control circuit; the protection circuit; inverter powe