The frequency response produced by bodeplot and freqresp for systems with delay is wrong. Here an example for a ZOH:
using ControlSystemsBase
using Plots
s = tf("s")
Ts = 0.1
bodeplot((1 - exp(-s*Ts))/s, hz=true)
The gain as s -> 0 should be 1.0, but it differs substantially. This happens for any value of Ts different from 1.0. Here the magnitude (blue) compared with the correct one red
The frequency response produced by
bodeplot
andfreqresp
for systems with delay is wrong. Here an example for a ZOH:The gain as
s
-> 0 should be 1.0, but it differs substantially. This happens for any value ofTs
different from 1.0. Here the magnitude (blue) compared with the correct onered