MPPT for wind turbine

[Burnit0017]

https://www.youtube.com/watch?v=0TE38SOdf64&feature=player_embedded

Hi, I was so inspired by the video’s results, I decide to try a build a simple MPPT for a wind turbine. I have limited knowledge of subject and will appreciate any help received.

I found a article in Power Electronics Technology_ June 2006 “Buck-Converter Design Demystified” https://www.electro-tech-online.com...0Converter20Design20Demystified20606PET25.pdf

The article provides methods for selecting component values for a basic step down converter circuit and I plan on using it as a guide to develop the MPPT. Comments welcome.

 

[ronv]

I guess the first questions would be what are your current and voltage and RPM targets? Alternator specs.? The thing that struck me as odd about the video was that the alternator had 23 ohms resistance. I guest they got there looking for 1 volt per RPM, but the high resistance means power in the alternator not the batteries or whatever. I don't know anything about it but I would think you might get a better match to start with between the load and the alternator.

 

[Burnit0017]

MPPT for VAWT, concept drawing

Hi, I have a working system. I fabricated the PMA and VAWT. I have it configured using a bridge rectifier to the battery bank and a dump load controller monitors the batteries to protect from over charging.

Because I fabricated the PMA with inputs and outputs on each stator I am able to connect the coils to form
a 3 phase Star with 12 coils per phase. When the PMA, permanent magnet alternator, is connected to a 12 volt deep cell battery using a bridge rectifier, the voltage is locked at the voltage level of the battery and as the turbine RPM increases the bridge rectifier output current increases and over time the battery voltage increase until the dump load control diverts the current. So it acts a current source.

When the PMA is not connected to a battery bank and has no load it spins freely and the measured voltage can be very high depending on the RPM. With no load I can spin it manually and measure 60 Vdc.

Because the PMA will act differently with different loads I am having difficulty developing a algorithm for MPPT controller and determining values needed to design MPPT circuit.

I do know the PMA is capable of 30 amps max output.

MPPT circuit parameters:
V in = 15 to 60 Vdc
I out max = 15 amps
V out = 13.5 Vdc

Because I am charging 12 volt deep cell batteries I do not know if regulation of the output is important.

I am planning on fabricating a simple buck circuit with a fixed oscillator and use the PMA at fixed RPM for V in of the MPPT and using a 12 volt deep cell for a load to determine if there is a increase in the amp output can be measured.

This is a first attempt and I still reviewing MPPT strategies.
This is a new project so the values and circuit can change. The objective is to improve turbine performance and increase current output.
Thank you any help received. Comments welcome

 

[Burnit0017]

MPPT concept drawing

 

[ronv]

Ahh, I think I understand the concept now. The resistance of the windings is pretty high so you can get a useful voltage at a low RPM. The problem with this is that when the current is high a lot of power is "burned" in the windings. The buck converter lets the voltage from the generator go high then lowers it with the buck converter. Thus the IR drop is reduced in the generator Kind of like high tension lines. So I would think a simple algorithm would be to maximize the voltage from the generator while maximizing the current into the batteries by varying the output from the buck converter. The maximum product is the sweet spot. I would think with the micro you could just move back and forth to see which way to go so it would continuously optimize. I think I would buy a regulator chip. You might want to include the battery charge management in the same system since you will have all the hooks by the time your done. This seems like a really good idea. Keep in mind I don't know much about these things. Maybe someone with more experience can confirm my thinking.

 

[Burnit0017]

Hi, I was wondering how other projects where reporting such high wattage outputs.
Using the buck converter method is how they are doing it. The buck converter isolates the PMA from the battery bank and stepping down the voltage increases the amp output and improves turbine performance. It is a great idea.

Is there a reason why a N channel can not replace the P channel fet in the circuit?
Comments welcome?

 

[alec_t]

Is there a reason why a N channel can not replace the P channel fet in the circuit?

No. Obviously the drive for the FET would be different and depend on whether the FET was high-side or low-side.

 

[ronv]

Something like this might be better than trying to do a discrete design.

https://www.electro-tech-online.com/custompdfs/2012/01/3703fb.pdf

Do you know your coil resistance by any chance? It would be interesting to see how big the improvement is.