du/dt avoiding in system
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Is there any possibility to solve
x = L*y*s + 2*y , without a du/dt block. ..
(x:output ; y:input)
Just e.g. integrators.
My system is very dynamic and du/dt would cause errors.
6 个评论
Walter Roberson
2015-6-28
What you posted looks like it only needs multiplication and addition, not integration or any du/dt block.
Marcel Büttner
2015-6-29
编辑：Marcel Büttner
2015-6-29
It looks like the following.
What I do not really know is how to prevent my system of errors, when I use the du/dt
Walter Roberson
2015-6-29
I think you were intending to attach an image?
Marcel Büttner
2015-6-29
Walter Roberson
2015-6-29
Under what circumstances would you get an error from the du/dt block?
Marcel Büttner
2015-6-29
采纳的回答
Two remarks here:
1. If you draw the Bode plot of the transfer function of the derivator, it looks like a line that ramps up with 20 dB/decade. In other words, for high frequencies it amplifies the signal (most likely it is a noise in this region). So, what you want is to avoid this phenomena, however keeping the derivator behavior for lower frequencies. In order to achieve this, replace your derivative block with a transfer function block:
where you have to choose tau sufficiently low. Notice that if tau = 0, then you end up with the derivator H(s) = s.
2. You say something about using integrators. This is possible if you solve your equation the other way around, namely you know x and want to calculate y. The dynamics of y is described by:
dy/dt = (1/L) (2y-x)
For this, you need to know the initial condition y(0) of your system, together with x(t). You code this equation in matlab or Simulink using an integrator block.
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