开关电源大学论文

毕业论文

反激式开关电源的开发

系别：电子信息系

专业名称：电子信息科学与技术学生姓名：

学号：

指导教师姓名、职称：

完成日期：2015年 4 月 1日

摘要

近年来，开关电源应用范围越来越广泛，它以体积小，携带轻便，能量利用率高，具有特别的绿色功能，使系统在空载的或在低负载的情况下工作在节能模式，从而被广泛的运用于航天航空领域、家电、通信、仪器仪表、工业控制、医疗设备等领域，随着电子技术发展使其越来越具有发展前景。

本次研究从经济上和实用性考虑，选择了众多开关电源里的一种类型——反激式开关电源。参数为AC220～110输入，DC13V 输出，最大输出电流达到1.5A，最大输出功率为14.5W。噪声系数小，两种输出电压以适合在不同国家中使用。系统由ST8853为核心的PWM 脉宽调制芯片，和结合完善的外围电路组成。系统主要由输入端设计，高频变压器，输出端，反馈电路，控制电路五部分组成，整个电路具有短路保护，防雷，隔离高压，防触电，短路检测，输出功率和电压自动调节等功能，其稳定性和安全性高。

系统工作原理: 交流电压输入,经直流滤波后，DC-DC 变压，整流输出，后级电路通过采样电阻后放大后耦合到线性光耦合器pc817,最后反馈到到st8853检测脚，芯片输出PWM控制信号控制大功率MOS管的开关，从而稳定调节输出电压。

关键词：反激式开关电源；高频变压器；st8853

ABSTRACT

In recent years, the switching power supply has got more and more wide application range, it has small volume, portable, high energy utilization, even has the special green pattern.It make the system in idle or work under low load condition in energy saving mode, which is widely used in aerospace field, home appliances, communications, instrumentation, industrial control, medical equipment and other fields, with the development of electronic technology to make it has the prospects for development.

The study from the economic and practical consideration, choose one type in a number of switch power supply--the flyback type switch power supply. Parameter is AC220 ~ 110 input, DC13V output, the maximum output current is 1.5 A, maximum output power is 14.5 W. Small noise coefficient, two kinds of output voltage to suit to be used in different countries. System by the PWM pulse width modulation chip ST8853 as the core, and combined with peripheral circuit. System is mainly composed of input terminal design, high frequency transformer, output, feedback circuit, control circuit of five parts, the whole circuit has the short circuit protection, lightning protection, isolation and high pressure, prevent to get an electric shock, short circuit detection, the output power and voltage automatic adjustment function, such as its high stability and safety.

The working principle of the system: the input AC voltage, DC filter, DC-DC transformer, rectifier circuit, through the sampling resistor after amplification coupled to the linear optical coupler PC817, finally feedback to st8853 feet, PWM chip output control signal to control the switch of high power MOS tube, in order to stabilize the output voltage regulation

Keywords: Flyback switching power supply; high frequency transformer; st8853

目录

1绪论 (1)

1.1研究背景 (1)

1.2开关电源的发展前景 (1)

1.3研究意义 (2)

1.4本课题要求及主要研究内容 (2)

2反激式开关电源的理论基础 (3)

2.1开关电源的概念 (3)

2.2反激式开关电源的原理 (3)

2.3正激式和反激式开关电源的区别 (3)

2.4反激式开关电源的优点 (4)

2.5反激式开关电源的缺点 (4)

3硬件系统的基本设计 (5)

3.1硬件系统的基本设计思路 (5)

3.2输入端的电压浪涌抑制设计和分析 (5)

3.2.1浪涌抑制器(压敏电阻)-7D471 (6)

3.3输入回路短路保护的设计和分析 (6)

3.3.1短路保护器件——保险管 (6)

3.4安规电容滤波电路的设计和分析 (7)

3.4.1安规电容 (8)

3.4.2安规电容与普通电容的区别 (8)

3.5共模电感组成的EMI抑制电路 (8)

3.5.1共模电感的理论知识 (9)

3.5.2共模电感和差模电感的区别 (9)

3.6前级整流滤波电路的设计和分析 (9)

3.6.1整流电路器件的选型 (10)

3.7隔离变压器的设计和分析 (10)

3.8输出端的滤波电路设计原理 (11)

3.8.1铁芯电感的滤波原理 (12)

3.8.2PI型滤波器 (12)

4核心电路设计原理和分析 (13)

4.1反馈电路的设计和分析 (13)

4.1.1TL431可控硅 (13)

4.1.2密勒补偿 (14)

4.1.3光耦隔离器PC817 (14)