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1、课题六 三相异步电动机的制动控制线路,所谓制动,就是给电动机一个与转动方向相反的转矩使它迅速停转(或限制其转速)。制动的方法一般有两类:机械制动和电力制动。,一、机械制动 当电动机的定子绕组断电后,利用机械装置使电动机立即停转。,电磁抱闸制动器,MZD1系列交流单相制动电磁铁 TJ2系列闸瓦制动器,1线圈 2衔铁 3铁心 4弹簧 5闸轮 6杠杆 7闸瓦 8轴,电磁抱闸制动器结构示意图,电磁抱闸断电制动控制线路,L1L2L3,FU1,FU2,KM,KH,SB2,SB1,KM,YB,QS,KM,KH,M3,电磁抱闸断电制动控制线路,L1L2L3,FU1,FU2,KM,SB2,SB1,KM,YB,Q
2、S,KM,合上电源开关QS,KH,KH,M3,电磁抱闸断电制动控制线路,L1L2L3,FU1,FU2,KM,SB2,SB1,KM,YB,QS,KM,按下SB2KM线圈得电,KH,KH,M3,电磁抱闸断电制动控制线路,L1L2L3,FU1,FU2,KM,SB2,SB1,KM,YB,QS,KM,KM1自锁触头闭合,自锁,松开SB2电磁抱闸线圈YB得电,使抱闸的闸瓦与闸轮分开KM1主触头闭合,电动机起动运行,KH,KH,M3,电磁抱闸断电制动控制线路,L1L2L3,FU1,FU2,KM,SB2,SB1,KM,YB,QS,KM,停:按SB1,接触器KM失电释放电磁抱闸线圈YB也失电,在弹簧的作用下,闸
3、瓦与闸轮紧紧抱住,KH,KH,M3,思考,这个电路有什么问题?我们可以怎么避免?,二、电力制动 电动机产生一个和电动机实际旋转方向相反的电磁转矩,使电动机迅速停转。,(一)反接制动.反接制动原理在停车时,把电动机反接,则其定子旋转磁场便反向旋转,在转子上产生的电磁转矩亦随之变为反向,成为制动转矩。,单向启动反接制动控制,M3,L1L2L3,FU1,FU2,KM1,KM2,KH,SB1,KM1,SB2,KM2,KM1,KM2,KH,QS,KM1,n,KS,KM2,KS,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM1,SB2,QS,KM1,n,KS,KM2,KS,合上电
4、源开关QS,M3,KM1,KH,KM2,KH,KM1,KM2,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM1,SB2,KM1,KM2,QS,KM1,n,KS,KM2,KS,按下SB1KM1线圈得电,M3,KM1,KH,KM2,KH,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM1,SB2,KM1,KM2,QS,KM1,KS,KM2,KS,KM1自锁触头闭合,自锁,松开SB1KM1主触头闭合,电动机起动,运行在转速高到一定值时,KS闭合,M3,KM1,KH,KM2,KH,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM
5、1,SB2,KM1,KM2,QS,KM1,KM2,KS,停:按下SB2KM1失电释放KM2线圈得电,KM2主触头闭合,电动机串联电阻反接,反接制动KM2自锁触头闭合,M3,KM1,KH,KM2,KH,KS,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM1,SB2,KM1,KM2,QS,KM1,KM2,KS,停:松开SB2继续反接制动,M3,KM1,KH,KM2,KH,KS,单向启动反接制动控制,L1L2L3,FU1,FU2,KM2,SB1,KM1,SB2,KM1,KM2,QS,n,KM2,KS,当转速降低到一定值时,KS断开KM2线圈失电,各触头复位,M3,KM1,K
6、H,KM2,KH,KM1,KS,(二)能耗制动 电动机切断交流电源后,立即在定子线组的任意两相中通入直流电,利用转子感应电流受静止磁场的作用以达到制动目的。,M3,L1L2L3,KM1,KH,SB1,KM1,SB2,KM2,KM1,KM2,KH,KM1,KT,KM2,V,U,W,QS,FU1,FU2,KT,KT,单向启动能耗制动自动控制线路,KM2,电路组成分析,定子绕组直流电通路,KM2,V,KM2,L3,N,V,定子绕组直流电通路,L1L2L3,KM1,SB1,KM1,SB2,KM2,KM1,KM2,KM1,KT,KM2,QS,FU1,FU2,KT,KT,KM2,合上电源开关QS按下SB1
7、KM1线圈得电,单向启动能耗制动自动控制线路,KM2,V,M3,KH,KH,V,U,W,L1L2L3,KM1,SB1,KM1,SB2,KM2,KM1,KM2,KM1,KT,KM2,QS,FU1,FU2,KT,KT,KM2,KM1自锁触头闭合KM1主触头闭合KM1联锁触头分断,单向启动能耗制动自动控制线路,KM2,V,M3,KH,KH,V,U,W,L1L2L3,KM1,SB1,KM1,SB2,KM2,KM1,KM2,KM1,KT,KM2,KM2,V,QS,FU1,FU2,KT,KT,KM2,按下SB2KM1线圈失电KM1自锁触头分断KM1主触头分断KM1联锁触头闭合KM2线圈得电KT线圈得电,单
8、向启动能耗制动自动控制线路,M3,KH,KH,V,U,W,L1L2L3,KM1,SB1,KM1,SB2,KM2,KM1,KM2,KM1,KT,KM2,KM2,QS,FU1,FU2,KT,KT,KM2,KM2自锁触头闭合KM2主触头分断闭合电动机半波能耗制动KM2联锁触头分断KT瞬时闭合触头闭合松开SB2,单向启动能耗制动自动控制线路,V,M3,KH,KH,V,U,W,L1L2L3,KM1,SB1,KM1,SB2,KM2,KM1,KM2,KM1,KT,KM2,KM2,V,QS,FU1,FU2,KT,KT,KM2,KT延时断开触头延时分断KM2线圈失电KT线圈失电各触头复位,单向启动能耗制动自动控
9、制线路,M3,KH,KH,V,U,W,FU2,KH,SB1,KM1,SB2,KM1,KM2,KT,KT,KT,KM2,KM2,KM1,M3,L1L2L3,FU1,KM1,QS,FU3,VC,TC,KH,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,电路组成分析,FU2,SB1,KM1,SB2,KM1,KM2,KT,KT,KT,KM2,KM2,KM1,L1L2L3,FU1,KM1,QS,FU3,VC,TC,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,合上电源开关QS按下SB1KM1线圈得电,KH,M3,KH,FU2,SB1,KM1,SB2,KM1
10、,KM2,KT,KT,KT,KM2,KM2,KM1,L1L2L3,FU1,KM1,QS,FU3,VC,TC,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,KM1自锁触头闭合KM1主触头闭合KM1联锁触头分断松开SB1,KH,M3,KH,FU2,SB1,KM1,SB2,KM1,KM2,KT,KT,KT,KM2,KM2,KM1,L1L2L3,FU1,KM1,QS,FU3,VC,TC,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,按下SB1KM1线圈失电KM1自锁触头分断KM1主触头分断KM1联锁触头闭合KM2线圈得电KT线圈得电,KH,M3,KH,F
11、U2,SB1,KM1,SB2,KM1,KM2,KT,KT,KT,KM2,KM2,KM1,L1L2L3,FU1,KM1,QS,FU3,VC,TC,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,KM2自锁触头闭合KM2主触头分断闭合电动机半波能耗制动KM2联锁触头分断KT瞬时闭合触头闭合松开SB1,KH,M3,KH,FU2,SB1,KM1,SB2,KM1,KM2,KT,KT,KT,KM2,KM2,KM1,L1L2L3,FU1,KM1,QS,FU3,VC,TC,R,KM2,V,U,W,3,KM2,有变压器桥式整流能耗制动控制线路,KT延时断开触头延时分断KM2线圈失电KT线圈
12、失电各触头复位,KH,M3,KH,(三)电容制动,当电动机切断交流电源后,立即在电动机定子绕组的出线端接入电容器来迫使电动机迅速停转的方法叫电容制动。,电容制动原理,当旋转着的电动机断开交流电源时,转子内仍有剩磁。随着转子的惯性转动,形成一个随转子转动的旋转磁场。该磁场切割定子绕组产生感生电动势,并通过电容器回路形成感生电流,这个电流产生的磁场与转子绕组中的感生电流相互作用,产生一个与旋转方向相反的制动力矩,使电动机受制动迅速停转。,电容制动,M3,L1L2L3,FU1,FU2,KM1,KM2,KH,SB1,SB2,KM1,KM1,KM1,KM2,KH,U,V,W,QS,R,KM1,电路组成分
13、析,KT,KT,KM2,合上电源开关QS按下SB KM1线圈得电,电容制动,L1L2L3,FU1,FU2,KM1,KM2,SB1,SB2,KM1,KM1,KM1,KM2,U,V,W,QS,R,KM1,KT,KT,KM2,M3,KH,KH,电容制动,L1L2L3,FU1,FU2,KM1,KM2,SB1,SB2,KM1,KM1,KM1,KM2,U,V,W,QS,R,KM1,KT,KT,KM2,KM1自锁触头闭合KM1主触头闭合KM1联锁触头分断KM1辅助触头闭合KT线圈得电KT瞬时闭合延时断开触头闭合松开SB1,M3,KH,KH,电容制动,L1L2L3,FU1,FU2,KM1,KM2,SB1,SB
14、2,KM1,KM1,KM1,KM2,U,V,W,QS,R,KM1,按下SB2 KM1线圈失电KM1联锁触头闭合KM2线圈得电KM2主触头闭合KM2联锁触头分断电容制动开始,KT,KT,KM2,M3,KH,KH,电容制动,L1L2L3,FU1,FU2,KM1,KM2,SB1,SB2,KM1,KM1,KM1,KM2,U,V,W,QS,R,KM1,KT瞬时闭合延时断开触头延时分断KM2线圈失电各触头复位电容制动结束,KT,KT,KM2,M3,KH,KH,(四)再生发电制动,当起重机在高处开始下放重物时,电动机转速n小于同步转速n1,这时电动机处于电动运行状态,转子相对于旋转磁场切割磁感线的运动方向发生了改变,其转子电流和电磁转矩的方向都与电动运行时相反。,再生发电制动原理,