Section 4.1 Traditional Design Methods Practical PID Forms Ideal PID:Has a pure differentiator in it and therefore is not physically realizable An important method for realizing an improper transfer function:Introduce a low-pass transfer function to it Three practical forms: C(s)= ++） TDS C(s)=Kc(1+ TDs+1 Tis TEs+1 C(s)= TF5+1 Usually TF=0.1Tp in a PID 4口，+@，4定4=定0C Zhang.W.D..CRC Press.2011 Version 1.0 4/71Section 4.1 Traditional Design Methods Practical PID Forms Ideal PID: Has a pure differentiator in it and therefore is not physically realizable An important method for realizing an improper transfer function: Introduce a low-pass transfer function to it Three practical forms: C(s) = Kc  1 + 1 TIs + TDs TF s + 1 C(s) = Kc  1 + 1 TIs  TDs + 1 TF s + 1 C(s) = Kc  1 + 1 TIs + TDs  1 TF s + 1 Usually TF = 0.1TD in a PID Zhang, W.D., CRC Press, 2011 Version 1.0 4/71