what is the Vref in power converters and MPPT

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Antonaros

Joined: 01 Sep 2009
Posts: 2
Location: UK

12 Oct 2009 22:36 what is the Vref in power converters and MPPT

Hello there to everyone.

I am a student and i have to design and alalyse a power converter for pv applications in matlab/simulink.
Until now i find already a lot of informations and i think i am in a good way, but i have a query, what is the Vref in power converters and in MPPT.
MPPT (maximum power point tracking)

Exactly what value i have to choose for the Vref?

If anybody knows can you please help with this.

Thanks in advance for your time.

Regards
A.K

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analog_match

Joined: 04 Nov 2008
Posts: 41
Location: USA

16 Oct 2009 15:21 what is the Vref in power converters and MPPT

I think the value of vref will depend on what Vout you want. If you are using voltage feedback, then you will sample the output with a resistor divider and your vref will be equal to this Vfb. Hope this answers your question.

Mr.Cool

Joined: 20 Jun 2001
Posts: 641
Helped: 24

17 Oct 2009 15:49 Re: what is the Vref in power converters and MPPT

wow.. you have much more to learn. i agree with previous poster.. if i were to guess, i think your Vref referes to your desired REFERENCE voltage.

typically this may be between 0 - 5V (unipolar). you set a desired Vref value, say 2.5V, and your controller works to drive the output to 50% of its rated operating condition.

Mr.Cool

Antonaros

Joined: 01 Sep 2009
Posts: 2
Location: UK

23 Oct 2009 21:07 Re: what is the Vref in power converters and MPPT

thanks a lot guys for your time to answer my question.

to give to understand better what i am trying to do is to design in Simulink a power converter for PV applications. ex. from 100Volts DC to 230Volts AC 50Hz grid connections.
Now this power converter most of cases comprise a DC/DC boost converter and a DC/AC bridge inverter.
In addition for the control method of both, DC/DC and DC/AC, a maximum power point tracker (MPPT) is used with combination of voltage mode control (VMC) or current mode control (CMC).

The Vref, where i am talking about, is the Vref in the MPPT algorithms and in the control methods.
For example in the P&O algorithm where is the classic and most in use algorithm at the final stages of the algorithm it says "Increase Vref" or "Decrease Vref" .
This is just one example of the Vref where i am talking about.

Thanks for your time.

Regards
A.K