I don't know your experience with control...
First you have to take the model of the system.
Termal system generaly are very slow,
a first order system should be enoght.
It will result in a second order system you
consider the resistence Tranfer Function.
In this case I think that just a PI controler is
necessary. The diferencial controler wont
contribute too much and will insert noise
problems.

The PI algorithm is something like this:

Loop any 10ms (SampleRate)
    Error = Temperature_Reference - Temperature_Read
    ProportionalValue = kc * Error
    IntegralValue = LastIntegralValue + ( ki * (Error + LastError) *
(SampleRate / 2))
    Output = ProportionalValue + IntegralValue
    SaveLastValues()
EndLoop
kc is the proportional gain and
ki the integral gain
The problem, that is not too much problem
is to calculate this.

I hope bein usefull

Augusto Marasca de Conto
augusto@automacao.eng.br



> He told us what he really needs:
>
> > In fact I need chocolate to reach 44 o C as quickly
> > as i can .... The point is not to pass this temperture border.
>
> This is a control-systems problem.  I'm not sure how I'd proceed
> but this sounds like a job for a PID algorithm.
>
> Barry
>
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