Exercice 3 2 H(p)= -------- p(p+2) 2 H(jw)= ---------- jw(jw+2) Module : 2 |H(jw)| = ------------------ w(2^2 + w^2)^1/2 Argument : phi(H)=-90-arctg(w/2) Marge phase initiale:delta phi i |H|=1 -> w(2^2 + w^2)^1/2 = 2 pour w = 1 -> ...=sqrt(5)>2 pour w = 0.5 -> ...= ...<2 pour w = 0.9 -> ...= 2 => wc = 0.9 rad/s phi(H)=-90 * tg^-1(0.9/2)= -114deg delta phi i = -180+114 = -66deg ///////// Reglage : pour w = 3 et deltaf = -60deg phi(H)=-90-tg^-1(3/2) = -146deg -180 = phi(H)+deltaf+phi(cor) -180 = -146 - 60 + phi(cor) phi(cor) = 26deg 1+sin(phimax) => a = --------------- 1-sin(phimax) 1+sin(30) = ----------- = 3 1-sin(30) wx = 3 = 1/T*sqrt(a) => T = 1/3*sqrt(3) = 0.2 |H|w=3 = 2/3 * 1/(2^2 + 3^2) = 2/3 * 1/sqrt(13) = 0.18 (1+jawt) C(jw)= K * ---------- (1+jwt) sqrt(1+(3*0.2*3)^2) |C|w=3 = K * -------------------- sqrt(1+(3*0.2)^2) = K * 1.76 puisque |H|w=3 * |C|w=3 = 1 on peut poser 0.18*1.76*K=1 K=3.16 /////////////////////////////// E(p)= Ref(p) / 1+Bo(p) E(t)t->00 = (p*ε(p))p=0 =0.15 Bo(p)= C(p)*H(p) (1+aTp) 2 = K * ------- * ------ (1+Tp) p(p+2) E(t)t->00 = 2/2K = 1/K=0.15 => K=6 Remarque : On a trouve K=3 par avance de phase et il faut k=6 pour la précision