[理工] [自控] 判斷系統穩不穩定
這是我自己想的一個題目
若考慮一個單位負迴授系統 其迴路轉移函數
G(s)=(s-1)/(s^2+2s+2) 請問這系統是否穩定?
想法1 : 由特性方程式△=s^2+3s+1=0,根據路斯準則得知系統是穩定的
想法2 : G(s)包含一個s=1的零點 由奈式路徑來看 s=1在路徑內 系統若要穩定 則奈
氏路徑內不得包含任何零點 故此系統是不穩定的
請問這兩個想法哪一個才是對的@@?
謝謝
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◆ From: 111.255.190.27
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若奈式路徑包圍△之a個零點和b個極點
則對應之奈式圖必定會圍繞(-1,0) N=a-b次
而當系統穩定時 將不包含△任何零點 亦即a=0
故N=-b
上面書是這樣說明的
那我的問題就是 本題a=1
所以對照於"當系統穩定時 將不包含△任何零點 亦即a=0"這句話時
就已經違反了
故系統是不穩定
請問哪裡有問題@@ 謝謝
※ 編輯: squallting 來自: 111.255.190.27 (02/21 22:26)
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判斷幾個零點和幾個極點不是從σ-jw平面上 在右半無限大圓內判斷的嗎?
本題s=1+j0的零點落在右半平面 故a=1
應該是這樣判斷的吧@@
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所以答案是不穩定 意思是這樣嗎?
※ 編輯: squallting 來自: 111.255.190.27 (02/21 23:34)
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ok 這句話我懂了 jack大我非常感謝你
我被書上他妹的給搞混了
原來是1+GH=0 包圍原點和 GH=-1 包圍-1的奈式準則不一樣
另外上面mp大和larry大也非常感謝
※ 編輯: squallting 來自: 111.255.190.27 (02/21 23:42)
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