12V 120W开关电源设计_毕业设计论文.docx

天津职业技术师范大学Tianjin University of Technology and Education毕业设计12V120W开关电源二○一三年六月天津职业技术师范大学本科生毕业设计12V 120W开关电源设计12V 120W Switching power supply design2013年6月摘要本文介绍了一种电流控制型脉宽调制（PWM）控制器UC3843的特点和工作原理，并分析了其构成开关电源的整体电路结构和工作原理，最后提出了一种基于UC3843的反激式开关电源的设计方法。电路主要由整流滤波电路和反馈电路两部分组成，用到的两个主要芯片为UC3843、TL431，以UC3843作为控制核心器件，运用脉宽调制的基本原理，反馈电路以TL431和光电耦合器为核心。采用场效应管作为开关器件，其导通和截止速度很快，并且导通损耗小，这就为开关电源的高效性提供了保障。高频变压器的设计是电源设计中的核心工作。高频变压器的参数和制作工艺直接影响开关电源的性能，根据电源功率和开关电源工作频率，选用EC42型铁氧体磁芯，功率容量充分满足设计需要。同时，电路中辅以过压过流保护电路，为系统的安全工作提供保障。通过以上设计完成了12V 120W开关电源设计。关键词：电流控制型；PWM；反激式变换器；TL431；高频变压器；ABSTRACTIn this article,the features and principle of a current controlling mode pulse width modulation controller UC3843 and introduced. Then it analyzes the basic circuit and operating principle of switching power supply. At last, a kind of designing method of fly-back switching power supply based on UC3843 is presented. It is mainly composed of rectification filter circuit and feedback circuit, two main chip for the UC3843,TL431, with UC3843 as control core devices, by using the basic principle of pulse width modulation, feedback circuit TL431 and photoelectric coupler as the core. Using field effect tube as switching devices, the conduction and deadline fast, conduction loss is small, it can provide guarantee for the efficiency of switch power supply.The design of high-frequency transformer parameters and production process a direct impact on the performance of switching power supply, According to the working frequency of power supply power and switch power supply,chooseEC42 ferrite core, power capacity to fully meet the power capacity to fully meet the design need .At the same time, supplemented by over-voltage and over-current protection circuit in the circuit, while guarantees system of work safety. Through the above design completed the 12v,120w switching power supply design.Key Words：Current controlling mode； PWM；Flyback converter;TL431；High frequency transformer；目录1引言I2方案论证12.1 DC∕DC转换器的选择12.2PWM驱动电路开关器