I want to apply a time delay to a signal which is created from a pulse generator.

Pulse generator : T = 4e-05. I am using a powergui with discrete time and Sample time: 4e-07.

In order to succeed this i used the "Discrete variable time delay" block with sample time 4e-07 and the result is :

enter image description here

The first one is the original signal and the second one is the signal with the delay. As you can see there is problem in the seconde signal. One way to sovle this problem is to increase the Sample time but this with make my simulation very slow.

Do you have any suggestions ?

P.S. The delay time is an external signal with a variable value so I can not use the delay at the Pulse generator .

Thanks in advance.

  • \$\begingroup\$ Please be specific: what is the problem you see in the second signal? And why do you think it's a problem? \$\endgroup\$ – The Photon May 8 '17 at 0:05
  • \$\begingroup\$ If you observe in the second signal , there is a small difference in the shape of the pulse. I want to use these signals to feed the gates of IGBTs so it matters when the signal goes from "0" to "1" and from "1" to "0" . \$\endgroup\$ – Yiannis S. May 8 '17 at 1:32
  • \$\begingroup\$ Fast edges have high frequency content, even if a signal has a repetition frequency that's very low. If you want to model these signals, you have to sample the signal at 2x the highest frequency present in the signal (the Nyquist sampling rate). Or you have to accept this kind of sampling artifact \$\endgroup\$ – The Photon May 8 '17 at 3:43
  • \$\begingroup\$ If the MOSFET gate signal would have that shape, it will be fantastic. \$\endgroup\$ – Marko Buršič May 8 '17 at 6:45
  • \$\begingroup\$ I am concern about the Nyquist sampling rate , but if I increase the sampling time , this will make my simulation really slow. Is there another way to add a time delay to a signal in Simulink ? \$\endgroup\$ – Yiannis S. May 8 '17 at 12:59

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