# Forum: Analog Circuits PID calculation boost converter

 Author: Nizar Sghaier (Company: issat kairouan) (issatkr) Posted on: 2015-06-02 11:23

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Peace, mercy and blessings of God:
when the input voltage equal to 1V and the output voltage equal to 5V.
Our goal was to maintain the output voltage of the boost converter
constante.Nous have used a simple P controller to achieve this goal. The
converter output voltage can be controlled by the PWM signal given to
the gate.
How to calculate the PID boost converter.
please help me

 Author: Joe F. (easylife) Posted on: 2015-06-02 15:26

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I would say, use a calculator. ;-)
Without knowledge of which boost converter you are using or how your
circuit looks like at the moment, it is very unlikely that somebody
could give you a more qualified answer.
Please provide more meaningful information.

 Author: Nizar Sghaier (Company: issat kairouan) (issatkr) Posted on: 2015-06-03 10:28
Attached files:

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please help me

 Author: IUnknown (Guest) Posted on: 2015-06-03 11:40

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Please don't use .docx, not all users can read this format. PDF would be
more suitable.

> document wrote:
> the switching frequency was 31150 kHz, thus Ts= 0.05 ms .

That does not work. Ill assume you use 31.15 kHz.

> document wrote:
> how to calculate the PID valueloop close

it's a control loop :)

First, let me ask you why you are using a microcontroller for
controlling? Should the code hang the microchip, or do something
unexpected, you're likely to burn your switching device. I would use an
externel analog circuit for that purpose. But enough of that.

The problem with P controllers is that they are not stable in a boost
converter, because the converter has an RHPZ (right half plane zero). A
PID controller can indeed deal with this problem.

First, to build your control loop, have a look at
http://www.ti.com/lit/ml/slup084/slup084.pdf
they use a flyback converter, but it's similar to a boost converter.

Now, when you have your transfer function, convert it to the z-domain,
so it can be implemented in code. This is described here:
http://lorien.ncl.ac.uk/ming/digicont/digimath/dpid1.htm

also, more information is needed, do you want to run in CCM, CRM or DCM?
(DCM is easy to control, but has more losses).

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