②两业x大 §5.6开环对数频率特性和射域指标(4) (1)二阶系统 G(S) K=On,/25 On s(+250n) S(S+25Qn) G()= 2+(2n) ∠G(o)=-90- arctan 25a s2+22o,s+ G(j@) 2+(25an)2 P[a+45a 1-0=02+450,o-am=0 45+1-25 r=180+(a)=90-arctan S 20 arctan 25n§5.6 开环对数频率特性和时域指标(4) 1 2 v K wn (1) 二阶系统 ( 2 ) ( ) 2 n n s s G s w w 2 2 2 (2 ) ( ) n n G j w w w w w n G j w w w 2 ( ) 90 arctan 1 (2 ) ( ) 2 2 2 c c n n c G j w w w w w 2 2 2 2 4 [ 4 ] wc wc wn wn 4 0 4 2 2 2 4 wc wn wc wn wc wn 4 2 4 1 2 180 ( ) j wc 2 2 2 2 ( ) n n n s s s w w w n c w w 2 90 arctan c n w 2w arctan