精品毕业论文基于微机控制的三相异步电动机软启动器软硬件设计.doc

PAGE 1 摘 要 三相交流异步电动机具有结构简单、运行可靠和价格低廉等优点而被广泛应 用。但是异步电动机存在启动电流大，对电网和电动机本身产生严重影响.起动电流会加速电动机的绝缘老化，大大降低电动机的使用寿命，导致大量的能量被消耗；大的电流还会给电网带来不良影响，使电网电压波动。因此控制三相异步电动机起动过程中过大的电流，具有较重要的经济价值。本课题正是基于此目的，对三相异步电动机软起动器进行研究。 本文介绍了三相异步电动机软起动技术在国内外的发展状况及前景展望，对电动机的起动过程进行了理论分析，比较了常见的几种软起动方法的优劣，论述了三相异步电动机软起动器的几种常见运行方式的特点。其次，分析了三相感应电动机固有的起动特性以及单相交流调压电路带电感性负载时的特点。在此基础上总结了晶闸管三相交流调压电路的工作状态以及在不同触发角情况下各种工作状态之间的转换关系。 本文设计出了以80C196KC单片机为控制核心的软起动系统的硬件电路，包括主电路、触发驱动电路、同步信号电路、电流检测电路的分析与设计等；介绍了控制系统的软件设计，包括主程序、HIS.0中断服务程序、HSO中断服务程序、PI算法子程序等；并给出部分软件模块的流程图。 分析表明，软起动器能很好的消除电机起动中的电流冲击，达到了设计要求。论文最后对所做的工作进行了简单的总结与展望。 关键词：三相异步电动机，软起动，调压电路，80C196KC单片机。 Abstract The three-phase asynchronous motors are nowadays widely used in all types of industry applications due to their simple construction, high reliability and low price. However, the direct start of asynchronous motor can generate much high current, which will contaminate the power grid and injure the motor. High starting current will accelerate the motor’s aging process and lose lots of energy. The very high current will also affect the power network and make the power voltage fluctuant. Therefore, how to strict the starting current of three-phase asynchronous motors has very important economic value. The analysis on the soft starter of three-phase asynchronous motor is based on the purpose. The development and foreground of the soft start technique three-phase asynchronous motors is introduced in this paper. The theory of soft starting AC motors is deduced based on the analysis of the motor starting process. Several starting methods and some workings about soft starter age compared and analyzed. Then, inherent starting characteristics of three phases induction motor and the features of single phase AC adjusting voltage circuit with inductive load were analyzed, based on which the work states of thyristor three phases AC adjusting voltage circuit and the conversion of these work states due to different trigger angle were summarized. The hardware de