bode() yields wrong result

13 次查看（过去 30 天）
Pascal Warten
Pascal Warten 2021-12-18
评论： Star Strider 2021-12-20
Hello,
I would like to plot the Bode diagram of the following transfer function:
If I use the following code, I do not get appropriate results:
s = tf('s');
f1 = 0.99 * 18.88;
f2 = (1 + s / (2 * 3.1415 * 10.58)) / (1 + s / (s / (2 * 3.1415 * 26.74)));
f3 = (s / (2 * 3.1415 * 23.17)) / (1 + s / (2 * 3.1415 * 23.17));
f4 = (s / (2 * 3.1415 * 25.21)) / (1 + s / (2 * 3.1415 * 25.21));
f5 = 1 / (1 + s / (2 * 3.1415 * 48000));
bode(f1 * f2 * f3 * f4 * f5); grid on;
However, if I only plot one factor of the transfer function, it seems to work properly.
I would really appreaciate any help regarding this problem.
  4 个评论
显示 2更早的评论
Paul
Paul 2021-12-18
Ran in:
Most impportantly, correct the typo in f2 as indicated below by @Star Strider.
Also, bode() always works with frequencies in rad/TimeUnit. If you want to specify the frequency in Hz, you can do it manually.
s = tf('s');
f1 = 0.99 * 18.88;
f2 = (1 + s / (2 * 3.1415 * 10.58)) / (1 + s / (2 * 3.1415 * 26.74));
f3 = (s / (2 * 3.1415 * 23.17)) / (1 + s / (2 * 3.1415 * 23.17));
f4 = (s / (2 * 3.1415 * 25.21)) / (1 + s / (2 * 3.1415 * 25.21));
f5 = 1 / (1 + s / (2 * 3.1415 * 48000));
whz = logspace(0,6);
[m,p] = bode(f1 * f2 * f3 * f4 * f5,2*pi*whz);
semilogx(whz,db(squeeze(m)))
Or use bodeplot() to plot in Hz directly
opts = bodeoptions;
opts.FreqUnits = 'Hz';
bodeplot(f1*f2*f3*f4*f5,opts);
Pascal Warten
Pascal Warten 2021-12-20
Thank you for your tips regarding the specifications of the units.

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Star Strider
Star Strider 2021-12-18
Ran in:
There is a typographical error in ‘f2’ and correcting it produces the desired result —
s = tf('s');
f1 = 0.99 * 18.88;
f2 = (1 + s / (10.58)) / (1 + s / (26.74));
f3 = (s / (23.17)) / (1 + s / (23.17));
f4 = (s / (25.21)) / (1 + s / (25.21));
f5 = 1 / (1 + s / (48000));
figure
bode(f1 * f2 * f3 * f4 * f5, {0 5E+7*2*pi})
grid on;
.

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Get Started with Control System Toolbox 的更多信息

标签

产品


版本

R2020b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by