三速电动机与控制线路演示幻灯片

1,三速电动机与控制线路,2,1.改变磁极对数p2.改变转差率s3.改变电源频率f1(变频调速),调速方法：,鼠笼电机,调压调速,滑差电机调速(电磁离合器调速),转子串电阻调速,转子串电势调速,变频机组,交直交变频,交交变频,3,改变定子的极对数，通常采用改变定子绕组联结的方法来实现。转子为笼型，由于各根导条电流的空间分布取决于气隙主磁场的分布，故笼型转子所产生磁动势的极对数与感生它的气隙磁场的极对数总是相等。也可以在电动机上安装两组独立的绕组，各个绕组联结法不同构成不同的极对数。,改变极对数p都是成倍的变化，转速也是成倍的变化，故为有级调速。,变极调速,变极调速是一种通过改变定子绕组极对数来实现转子转速调节的调速方式。在一定电源频率下，由于同步转速与极对数成反比，因此，改变定子绕组极对数便可以改变转子转速。,4,1变极原理,5,上图a、b、c分别为三相异步电动机变极前后定子绕组的接线图。其中，代表A相的半相绕组，代表A相的另一半相绕组。,结论:只要改变定子半相绕组的电流方向便可以实现极对数的改变。,为了确保定子、转子绕组极对数的同时改变以产生有效的电磁转矩，变极调速一般仅适用于鼠笼式异步电动机。,结论:对于三相异步电动机，为了确保变极前后转子的转向不变，变极的同时必须改变三相绕组的相序。这主要是极对数的改变会引起相序发生改变所致。,6,因为极对数为p时，如果A、B、C之间的相位关系为00，1200，2400，如图（a）所示；则在极对数为2p时，A、B、C之间的相位关系变为00，2400，4800（相当1200），如图（b）所示。显然，在极对数为p和2p下，A、B、C之间的相序相反，B、C两端应对调，以保证变速前后电动机的转向相同。,A,B,C,(a)P对极,(b)2P对极,A,B,C,7,(1)三相异步电动机Y/YY接变极调速的接线,(2)三相异步电动机/YY接变极调速的接线,变极接线方法,B,A,A,A,B,B,C,C,C,2p,p,p,B,A,A,A,B,B,C,C,C,2p,p,p,8,三速电动机定子绕组接线图,中速Y接法高速YY接法,三速电动机的两套定子绕组,低速接法,9,变极调速时容许输出,从充分利用电动机的角度出发，电动机在各种转速下的电流均为额定电流（每个支路的电路）。设电源电压UN不变，变极前后电动机的效率和功率因数不变。,容许输出时是指保持电流为额定值条件下，调速前、后电动机轴上输出的功率和转矩。,（1）Y/YY接变极调速,B,A,A,A,B,B,C,C,C,2p,p,p,10,为了确保电动机得到充分利用，每半相绕组中的电流应均为额定值，于是变极前后电动机的输出功率和输出转矩分别满足下列关系：,结论：Y/YY接变极调速属于恒转矩调速方式，适用于恒转矩负载。,从2pp，因电动机的转差率很小，认为nYY=2nY=2nS,11,（2）/YY接变极调速,B,A,A,A,B,B,C,C,C,2p,p,p,结论：/YY接变极调速属于近似恒功率调速方式，适用于恒功率负载。,12,3变极调速的机械特性,(1)YYY变极,2P（串联）p（并联），nsYnsYY=2nsY。N1N1/2，R，X(,)/4。sm不变，UN不变。,13,14,TmYY(TstYY)2TmY(TstY)。,15,nsYnmY=smYnsY=smnsY=smnsnsYYnmYY=smYYnsYY=smnsYY=sm2ns,Y,YY,16,(2)YY变极,2pp，ns2ns。N1N1/2，R，X(R，X)/4。sm不变，,17,18,TmYY(Tstyy)TmY(TstY)2/3。,19,ns,ns-nm=smnsnsYY-nmYY=smYYnsYY,20,小结,(1)调速方向YYY()：nY()YY：n(2)调速范围D=24,(3)调速的平滑性平滑性差。(4)调速的稳定性稳定性好。,21,形低速启动Y形中速运转过渡YY形高速运转,控制线路,22,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,按下SB3KT2线圈得电,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KH,KH,23,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KT2瞬时闭合触头闭合KT1线圈得电,KH,KH,24,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KT1瞬时闭合触头闭合KM1线圈得电,KH,KH,25,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KM1触头动作形低速启动松开SB3,KH,KH,26,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,经KT1整定时间KT1延时断开触头分断,KM1线圈失电KT1延时闭合触头闭合,KM2线圈得电,KH,KH,27,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KM2触头动作,电动机接成Y形,中速过渡,KH,KH,28,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,经KT2整定时间KT2延时断开触头分断,KM2线圈失电KT2延时闭合触头闭合,KM3,KM4线圈得电,KH,KH,29,L1L2L3,KM1,QS,FU1,FU2,KM2,KM1,低速,Y中速YY高速,KM3,KM3,KM2,KM3,KM1,KM1,KM2,SB4,KM1,KT2,SB2,SB3,SB1,U3,W1,V1,U1,V2,V4,U4,U2,W2,W4,KM4,KM4,KM4,KM2,KM3,KM4,KT1,KT2,KT1,KT1,KM2,KM3,KM2,KM3,KT2,KT1,KT2,KM3,KM4触头动作电动机YY形联接高速成运转KT1,KT2线圈失电触头复位,KH,KH,30,L1L2L3,KM1,QS,FU1,FU2,