?is??3?cos(?t)?
?Im??i??2?sin(?t)??s??两相旋转坐标系中的电流
?isd??cos?sin???is??3?cos?sin???cos(?t)???Im??i????i?????sin?cos?2??s????sin?cos???sin(?t)? ?sq??3?cos?cos(?t)?sin?sin(?t)?3?cos(?t??)??Im??Im??2?cos?sin(?t)?sin?cos(?t)?2??sin(?t??)?当
d???1时，???1t，两相旋转坐标系中的电流 dt?3??isd?3?cos(?t??)??Im?
Im??i?????2?sin(?t??)2sq??????0??电流矢量幅值
is?isd?
3Im 26．4笼型异步电动机铭牌数据为：额定功率
PN?3kW，额定电压
UN?380V，额定电流
IN?6.9A，额定转速
，转子电阻
nN?1400r/min，额定频率
fN?50Hz，定子绕组Y联接。由实验测得定子电阻
Rs?1.85?Rr?2.658?，定子自感Ls?0.294H已折合到定子侧，系统的转动惯量
，转子自感
Lr?0.2898H，定、转子互感
Lm?0.2838H，转子参数
J?0.1284kg?m2，电机稳定运行在额定工作状态，试求：转子磁链?r和按转子磁链定向的定子
电流两个分量sm、st。
解：由异步电动机稳态模型得额定转差率
iisN?额定转差
n1?nN1500?14001??
n1150015?sN?sN?1?sN2?fN?电流矢量幅值
100?rad/s
1522is?ism?ist?3Im?3?6.9A 2由按转子磁链定向的动态模型得
Ldyr1=-yr+mismdtTrTrws=LmistTryr
稳定运行时，
dyr=0，故yr=Lmism， dtist=wsTryr100p0.2898=wsTrism=?ismLm152.6582.2835ism
22is?ism?ist?1?2.28352ism?2.493ism?3?6.9
解得
ism?3?6.9?4.79A
2.493ist=2.2835ism=2.2835?4.79=10.937A
转子磁链
yr=Lmism=0.2838?4.79=1.359Wb