零階保持器

脈沖響應(yīng)

syms x? ?%? Sample Time = 1

fplot(heaviside(x)-heaviside(x-1), [-2, 2])

脈沖響應(yīng)的傳遞函數(shù)

s = tf('s');

G = (1-exp(-2*s))/s ;%? 采樣周期T=2s

bode(G)

w = 0:0.001:500;

T = 0.1;

G = T*sin(w*T/2).*exp(-1j*w*T/2)./(w*T/2);

plot(w,abs(G))

title("ZOH的相頻特性")

xlabel('w/(rad/s)')

ylabel('|G(jw)|')

figure

plot(w,angle(G))

title("ZOH的幅頻特性")

xlabel('w/(rad/s)')

ylabel('\angleG(jw)')

w = logspace(1,3,1000);

T = 0.1;

G = T*sin(w*T/2).*exp(-1j*w*T/2)./(w*T/2);

plot(w,[abs(G);angle(G)])

axis([0 1000 -5 0.2])

title('the Frequency Characteriistic of ZOH')

xlabel('w (rad/s)')

ylabel('Amplitude-Phase-frequency characteristic')?

w = logspace(1,3,1000);

T = 0.1; %sample time

G = T*sin(w*T/2).*exp(-1j*w*T/2)./(w*T/2);

figure % new figure

[hAx,hLine1,hLine2] = plotyy(w,abs(G),w,angle(G));

title('the Frequency Characteriistic of ZOH')

xlabel('w (rad/s)')

ylabel(hAx(1),'Amplitude-frequency characteristic') % left y-axis?

ylabel(hAx(2),'Phase-frequency characteristic') % right y-axis

由上可以總結(jié)：

零階保持器的相頻特性呈鋸齒狀，也被稱(chēng)為ZOH的開(kāi)關(guān)特性；另外，ZOH有許多小旁瓣，整體呈低通濾波

零階保持器的滯后特性