数字式恒流电源的讨论摘 要本设计以 AVR 单片机为核心，通过 A/D、D/A 转换、DC/DC 变换与 PID 算法利用 PWM 技术实现了高精度的，电流输出围为 20mA～2000mA 的数控直流电流源。该电流源具有电流可预置，50mA 步进。本系统采纳单闭环负反馈 PID(比例、积分、微分)算法控制，缩短上升时间，减小超调量，减小了输出电流的偏差。系统采纳中文 LCD 提供显示支持，可同时显示设定值，实际值以与其他相关信息。我们自行设计了15V、+12V 和 5V 电源为系统供电。关键字：数控恒流源 AVR PWM PID DC/DC 转换AbstractThe paper expounds the design of the numerical controlled constant-Current source.The system core is AVR.The A/D,D/A,DC/DC converts and the specific arithmetic is used to carry out high precision and the current output range from 20mA to 2000mA.The source realizes that the output current can be set, 50mA adjusted step by step.This system adoption list shuts the wreath negative feedback PID( proportion, integral calculus, differential calculus) calculate way control, shortening to rise time, let up super adjust the quantity, let up to output the deviation of the electric current.LCD with Chinese characters is used to display part of this system, which can show the initial value at the same time, actual value etc.We by ourselves designed the 15 Vs, 12V and 5V power supplies to be the system power supplies.Keywords:DC Power AV PWM PID DC/DC conversion目 录第一章绪论- 1 -1.1 恒流源简介- 1 -1.1.1 恒流源的定义- 1 -1.1.2 恒流源的分类- 1 -1.1.3 恒流源的应用- 1 -1.1.4 恒流电源的进展过程- 5 -1.2 国外进展现状与趋势- 5 -1.3 课题的意义和目的- 7 -1.4 本文所作的主要工作- 7 -第二章理论分析与可行性方案论证- 8 -2.1 恒流电源工作特性分析- 8 -2.2 开关电源几种电路类型- 9 -2.2.1 降压型（Buck）变换器- 9 -2.2.2 升压型（Boost）变换器- 11 -2.2.3 极性反转升降压（Buck—Boost）变换器- 12 -2.2.4 Cuk 变换器- 14 -2.3 PWM 的工作原...
