相位裕量和幅值裕量算法.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,“,”,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,1,相对稳定性,稳定裕量,幅值裕量相角裕量,5.5,稳定裕量（度）,5.5.1,幅值裕量相角裕量,相角穿越频率,增益穿越频率,2,相位裕量,：,幅值裕量,表示系统在变到临界稳定时，系统的增益能增大多少。

系统稳定,系统不稳定,为负值,系统稳定,系统不稳定,为满足动态性能的要求，相角裕量在30,0,70,0,幅值裕量在515,dB,在增益穿越频率处，使系统达到临界稳定状态时所能接受的附加相位滞后角3,用开环,Bode,图判系统稳定：,1，若,L,(),穿越0,dB,线时，,(,c,)-180,0,，,则闭环系统稳定，否则不稳定2，若,(),穿越-180,0,线时，,L,(,g,)0，,则闭环系统稳定，否则不稳定L,(),幅频特性曲线,(),相频特性曲线,对数频率特性与系统的稳定性,4,稳定,不稳定,5,稳定裕量概念:只适合于开环稳定的系统实际中避免振荡的方法：(1)减小开环放大倍数,K,值,6,对数频率特性与系统的稳定性,+,-,(2)错开各环节的时间常数,7,例5.5,K,=5,和,k,=20,判系统的稳定性，求相角裕量和幅值裕量,(1)低频段:,1,k,=5,L,(1)=20,lg,5=14dB,-20dB/dec,k,=20,L,(1)=20,lg,20=26dB,-20dB/dec,(2)转折频率：,1,1 20dB/dec,2,10 20 dB/dec,8,14,dB,26,dB,w,s,/,rad,),(,w,f,度,0.1,1,10,-90,0,-180,0,-270,0,3.16,9,(3)计算相角裕量：求穿越0,dB,线的,c,和,(,c,),K,=5,-40,c1,1,14,dB,0,dB,系统稳定,66,0,12.6,0,10,K,=20,-40,c2,1,26,dB,0,dB,系统不稳定,77.4,0,24.1,0,11,(4)计算幅值裕量：,求穿越180,0,的,g,取,g,3.2,g,c1,c2,。