solution

solution solution

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omg = 0.1:0.1:1000; num = [10,0];den = [1,20,100]; sys = tf(num,den); figure(1),bode(omg,sys);grid on; % using "bode" to get the Bode diagram Magnitude (dB) Phase (deg) 0 -20 -40 -60 90 45 0 -45 -90 10 -1 Asymptote: 10 0 j10ω H( jω) = ( jω + 10) 2 10 1 10 2 10 jω = ⋅ jω+ 10 jω+ 10 From the expression, we see the frequency response have: zero at jω = 0 , pole at jω =− 10 and pole at jω =− 10 . (1). Magnitude asymptote First consider the part 10 jω + 10 10 20log10 0 10 = . For high frequencies ( ω ω p 10 3 . For low frequencies ( ω ω p ), the dB-scale magnitude is 20log ), magnitude should be 10 10 , which jω is a straight line with the slope of -20dB and go through (10,0). The magnitude asymptote from 10 jω + 10 is a pair of straight lines with corner frequency at ω p = 10 ,

as shown (dashed line). Similarly, for part jω jω + 10 jω jω 20log ≈ 20log jω + 10 10 , 10 10 at low frequencies ( ω ω p ), which is a straight line with the slope of 20dB and go through (10,0). At high frequencies ( ω ω p asymptote from (dotted line). jω jω 20log ≈ 20log = 0 . So, the magnitude jω+ 10 jω ), 10 10 jω jω + 10 is also a pair of straight lines intersect at ω = ω p , as shown At last, applying compose the dashed line and dotted line to get the final magnitude asymptote, as shown (solid line). gain factor gain factor 0 -10 -20 -30 -40 10 -1 0 -10 -20 -30 -40 10 -1 (2). Phase asymptote The phase asymptote from ( ω ω 10 ) and p 10 0 10 0 10 jω + 10 10 1 ω 10 1 ω 10 2 10 2 10 3 10 3 contains three segments: 0 for low frequencies π − for high frequencies ( ω 10ω p ), and at frequencies around 2

as shown (dashed line).<br />

Similarly, for part<br />

jω<br />

jω<br />

+ 10<br />

jω jω<br />

20log ≈ 20log<br />

jω<br />

+ 10 10<br />

, 10 10<br />

at low frequencies<br />

( ω ω p ), which is a straight line with the slope of 20dB and go through (10,0). At high<br />

frequencies ( ω ω p<br />

asymptote from<br />

(dotted line).<br />

jω jω<br />

20log ≈ 20log = 0 . So, the magnitude<br />

jω+ 10 jω<br />

), 10 10<br />

jω<br />

jω<br />

+ 10<br />

is also a pair of straight lines intersect at ω = ω p , as shown<br />

At last, applying compose the dashed line and dotted line to get the final magnitude<br />

asymptote, as shown (solid line).<br />

gain factor<br />

gain factor<br />

0<br />

-10<br />

-20<br />

-30<br />

-40<br />

10 -1<br />

0<br />

-10<br />

-20<br />

-30<br />

-40<br />

10 -1<br />

(2). Phase asymptote<br />

The phase asymptote from<br />

( ω ω 10 ) and<br />

p<br />

10 0<br />

10 0<br />

10<br />

jω + 10<br />

10 1<br />

ω<br />

10 1<br />

ω<br />

10 2<br />

10 2<br />

10 3<br />

10 3<br />

contains three segments: 0 for low frequencies<br />

π<br />

− for high frequencies ( ω 10ω p ), and at frequencies around<br />

2

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