他励直流电动机串电阻启动的设计

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1、课程设计名称：电机与拖动课程设计题目：他励直流电动机串电阻启动专业：电气工程及其自动化班级：12-2班姓名：闫伟学号：1205040222辽宁工程技术大学课程设计成绩评定表学期2013－2014学年第二学期姓名专业班级课程名称电机与拖动论文题目评定标准评定指标分值得分知识创新性20理论正确性20内容难易性15结合实际性10知识掌握程度15书写规范性10工作量10总成绩100评语：任课教师李国华时间2014年7月5日备注课程设计任务书一、设计题目他励直流电动机串电阻启动的设计二、设计任务一台他励直流电动机，已知参数如下Pan=200kw；U

2、an=440v；Ian=497A；nN=1500r/min；Ra=0.076Ω；WW采用分级启动，启动电流最大不超过2IaN,，求各段电阻值，并且求出切除电阻时的瞬时转速和电动势，并作出机械特性曲线，对启动特性进行分析。三、设计计划第1天查阅资料，熟悉所选题目；第2天根据基本原理进行方案分析；第3天整理思路，按步骤进行设计；第4天整理设计说明书；第5天准备答辩；四、设计要求1、设计工作量为按要求完成设计说明书一份。2、设计必须根据进度计划按期完成。3、设计说明书必须经指导教师审查签字方可答辩。指导教师：王继强刘春喜李国华教研室主任：李洪珠

3、时间：2014年7月5日摘要他励直流电动机启动时由于电枢感应电动势Ea=CeΦn=0，最初启动电流Is=U/Ra，若直接启动，由于Ra很小，Ist会十几倍甚至几十倍于额定电流，无法换向，同时也会过热，因此不能直接启动。要限制启动电流Ist的大小可以有两种方法:降低电枢电压和电枢回路串接附加电阻。本文仅以他励直流电动机的串电阻启动为主题进行详细的阐述。在实际中，如果能够做到适当选用各级启动电阻，那么串电阻启动由于其启动设备简单、经济和可靠，同时可以做到平滑启动，因而得到广泛应用。但对于不同类型和规格的直流电动机，对启动电阻的级数要求也不尽相

4、同。关键词：他励直流电动机；启动电流；串电阻启动目录第一章直流电动机················································11.1直流电动机的工作原理·······································11.2直流电动机的分类···········································11.3他励直流电动机的工作原理···································2第二章他励直流电动机的启动·················

5、·····················32.1他励直流电动机串电阻启动···································32.1.1启动过程分析···········································32.1.2起动电阻的计算·········································42.2直流电动机电枢串电阻启动设计方案···························52.2.1选择启动电流和切换电流···························

6、···52.2.2启动、切换电流比β······································52.2.3启动时电枢电路的总电阻Ram······························62.2.4启动级数m··············································62.2.5重新计算β，校验I2······································62.2.6各级总电阻的计算·······································62

7、.2.7各级启动电阻的计算·····································62.3多级启动的规律·············································72.3.1不同加速级的机电常数···································72.3.2不同加速级的起始转速与稳定转速·························72.3.3启动级数的选取·········································7第三章结论·········

8、·············································8第四章心得体会···········································