关于三相异步电动机的启动和制动问题研究毕业论文.doc

网络教育学院 专 科 生 毕 业 大 作 业 题 目： 关于三相异步电动机启动和制动问题的研究 学习中心： 河北唐山迁安奥鹏中心 层 次： 高中起点专科 专 业：电气工程学及其自动化 年 级： 2009 年 秋 季 学 号： 学 生： 指导教师： 完成日期： 2011 年 8 月 10日 内容摘要 三相异步电动机是水利、工矿、冶金、化工等轻重工业、农业生产中以电能转换为机械能的核心动力源，在其各个电力拖动领域中发挥着不可替代的主导作用。本文共分三章主要对三相异步电动机的启动问题、三相异步电动机的制动问题、电动机启动和制动分析总结、三相异步电动机的启动问题共分六节、相异步电动机的制动问题共分五节关于异步电动机的启动和制动的方式和特点以及适应场合作以阐述分析，同时以实例分析根据要求选择确定电动机启动方式，部分内容并以插图加以说明，但由于笔者水平所限难免偏波之处，望请指正。 关键词：三相异步电动机的直接启动、降压启动、机械制动、电气制动 目录 内容摘要·····························································I 前言·································································1 第一章三相异步电动机的启动问题·······································2 1.1异步电动机的启动要求··············································2 1.2异步电机固有的启动特性············································2 1.3直接启动··························································3 1.4笼型异步电动机的降压启动··········································3 1.5 绕线式转子异步电动机的启动····································10 1.6启动方法选择实例分析·············································12 第二章三相异步电动机的制动问题······································14 2.1制动作用及分类···················································14 2.2机械制动·························································14 2.3电气制动-反接制动·················································14 2.4电气制动-能耗制动·················································15 2.5电气制动-再生发电制动（回馈制动）··································16 第三章电动机启动和制动分析总结······································17 参考文献····························································18 前言 三相异步电动机基本工作原理是当三相定子绕组通入对称的三相正弦交流电时，在定转子气隙中就产生了一个旋转磁场。通过这个磁场把定子获得的能量传递给转子，在转子导条中产生了感应电动势即感应电流，与旋转磁场相互作用形成了电磁转矩，使转子沿着磁场方向转动，实现了拖动作用。在初始异步电动机投入电网时，电动机从静止状态一直加速到稳定运行的转速，这个过程就是