电子与信息工程学院 本科毕业论文(设计)外 文 文 献 翻 译译文题目： Design of a Lead-Acid Battery Charging and Protecting IC in Photovoltaic System 学生姓名： 专 业： 电气工程及其自动化 指导教师： 2012年12月 湖北科技学院本科毕业论文（设计）：外文翻译Design of a Lead-Acid Battery Charging and Protecting IC in Photovoltaic SystemZENG De-you,LING Chao-dong,LI Guo-gang(Yuanshun IC Design R&D Center, Huaqiao University, Quanzhou 362021, China)Source: Microelectronic Device&Technology,June 20071.IntroductionSolar energy as an inexhaustible, inexhaustible source of energy more and more attention. Solar power has become popular in many countries and regions, solar lighting has also been put into use in many cities in China. As a key part of the solar lighting, battery charging and protection is particularly important. Sealed maintenance-free lead-acid battery has a sealed, leak-free, pollution-free, maintenance-free, low-cost, reliable power supply during the entire life of the battery voltage is stable and no maintenance, the need for uninterrupted for the various types of has wide application in power electronic equipment, and portable instrumentation. Appropriate float voltage, in normal use (to prevent over-discharge, overcharge, over-current), maintenance-free lead-acid battery float life of up to 12 16 years float voltage deviation of 5% shorten the life of 1/2. Thus, the charge has a major impact on this type of battery life. Photovoltaic, battery does not need regular maintenance, the correct charge and reasonable protection, can effectively extend battery life. Charging and protection IC is the separation of the occupied area and the peripheral circuit complexity. Currently, the market has not yet real, charged with the protection function is integrated on a single chip. For this problem, design a set of battery charging and protection functions in one IC is very necessary.2.System design and considerationsThe system mainly includes two parts: the battery charger module and the protection module. Of great significance for the battery as standby power use of the occasion, It can ensure that the external power supply to the battery-powered, but also in the battery overcharge, over-current and an external power supply is disconnected the battery is to put the state to provide protection, the charge and protection rolled into one to make the circuit to simplify and reduce valuable product waste of resources. Figure 1 is a specific application of this Ic in the photovoltaic power generation system, but also the source of this design.accumulatorDC loadcontroller Discharge controllerChargecontrollersolar battery arrayFigure1 Photovoltaic circuit system block diagram Maintenance-free lead-acid battery life is usually the cycle life and float life factors affecting the life of the battery charge rate, discharge rate, and float voltage. Some manufacturers said that if the overcharge protection circuit, the charging rate can be achieved even more than 2C (C is the rated capacity of the battery), battery manufacturers recommend charging rate of C/20 C/3. Battery voltage and temperature, the temperature is increased by 1 C, single cell battery voltage drops 4 mV, negative temperature coefficient of -4 mV / C means that the battery float voltage. Ordinary charger for the best working condition at 25 C; charge less than the ambient temperature of 0 C; at 45 C may shorten the battery life due to severe overcharge. To make the battery to extend the working life, have a certain understanding and analysis of the working status of the battery, in order to achieve the purpose of protection of the battery. Battery, there are four states: normal state, over-current state over the state of charge, over discharge state. However, due to the impact of the different discharge current over-capacity and lifetime of the battery is not the same, so the battery over discharge current detection should be treated separately. When the battery is charging the state a long time, would severely reduce the capacity of the battery and shorten battery life. When the battery is the time of discharge status exceeds the allotted time, the battery, the battery voltage is too low may not be able to recharge, making the battery life is lower. Based on the above, the charge on the life of maintenance-free lead-acid batteries have a significant impact, while the battery is always in good working condition, battery protection circuit must be able to detect the normal working condition of the battery and make the action the battery can never normal working state back to normal operation, in order to achieve the protection of the battery.3.Units modular design 3.1The charging moduleChip, charging module block diagram shown in Figure 2. The circuitry includes current limiting, current sensing comparator,