small VAWT project

[kr3am3r]

Hello all, not going to bore you with an introduction about myself, i am new here and i have a problem with a school project.
I have to connect a VAWT to a hydrogen fuel cell, which will function as a battery. I will probably connect it to a LED or something as a feedback. I am going to use a DC motor to create the electricity.
I have already picked the type of paletes, they will be savonius of about 20 cm diameter and height.
My problem is that i don't really know how to control the current in the circuit. I was thinking of using a microprocessor, that will require me to program it and connect a comparator and sensor aswell.

Is there a simpler way to control it without using another power supply?

If i go with the microprocessor i will have to learn how to program it which will be a pain, thats why im trying to avoid doing this

[Flux]

I don't know anything about your fuel cell but it will have to be tiny for you to worry about excess power from a tiny Savonious.

If you do need some form of control then I suspect a simple dump regulator should do the job. I really think you are in the region where a simple transistor dump would do, I don't know how fuel cells behave with pwm and the same would apply with microprocessor control without chokes and filter capacitors.

Flux

[kr3am3r]

it is a small educational kit, i dont know if im allowed to post a link here.

[kr3am3r]

I wanted to edit my first post but i can't find any button.
I did not mention why i want to control the current and i am very sorry.
When the vawt works it should charge the battery, but when it does not, the LED gets the current from the battery. That is why i think need a microprocessor or if possible a simpler way of control, to make the battery the supply when the power from the vawt drops under a certain value. I am talking about values of 1-5 watts of course.

[Flux]

Thanks for completing the picture. As a young student I believe that you would almost certainly be expected to incorporate the microprocessor control you are at an age when you will have to learn the art sooner or later.

I was brought up in the analogue era and I am far too old to learn about processors. What you are wanting to do can be done with a couple of transistors and a few resistors but I suspect that would not be highly regarded as a modern student project. To do what you want with a processor is just a simple logic control, there is no need to worry about what I said about not knowing how fuel cells react to pwm.

Good luck
Flux

[kr3am3r]

I have one more question, i have a general ideea about how the circuit is going to work, and what logic processes the microprocessor will have to do.
What other components should the circuit have?

So far i have thought of a sensor and a comparator, but i can't think of something else. I am going to see what output the battery has once charged in case i need a transformer so it won't blow up the LED

[Flux]

You won't be able to use a conventional transformer with dc. I have no idea how many volts a single fuel will produce but it will be within the range of a single or perhaps 2 or 3 leds, you will need a stabilising ballast and for the low power you are using it could be a resistor. You may also look at constant current sources but I doubt that you will need to go that far.

Do not attempt to run a led direct without ballast, they are current driven devices.

Flux

[Bruce S]

Kr3am3r
IF at any time you have questions about adding a link, click on the to moderator and send us a note, if it truly is a website that sells educational items, we will normally just add it to your post for you.
To edit a post there is a time frame an 1 hour that allows you to add or spell-check and such.
It is small and very near the report to moderator, it looks like paper turned on its side and normally just above the IP address.
Hope this helps;
   

[Mary B]

Let me get this right, you are going to drive a small dc motor with the VAWT to produce electricity to run a hydrogen fuel cell. You want an led to verify output from the DC motor.

If that is correct you need to build the wind part and test it to see what the DC voltage output will be before I can answer a question on using an led because the dropping resister needed will be dependent on voltage... unless you use the MPU to sense that the wind part is generating voltage and use one of its outputs to turn on an led. Fairly simple programming for that part.

[electrondady1]

you are going to drive a small dc motor with the VAWT to produce electricity to run a hydrogen fuel cell. You want an led to verify output from the DC motor.
sweet

so if it gets 14 open volts at 60rpm and tops out around 140 volts (say under 200)
how do you surmise  the value  of the resister ?
 

[kr3am3r]

it will never reach 14 volts, i did some calculations and the maximum theoretical power i got out of it was about 4-5 Watts. I used this formula:


 P = .5 X air dens. X Area X V^3

Aparently i can get more if i find a good dc motor which has low rpm per volt but i don't think it will be by a lot

[Bruce S]

I think you are under estimating 4-5 watts.
At LED voltage (3.2Vdc) that's a whopping 1.6 amps! That's enough to run a whole string of LEDs, since they normally max out at 20milliamps.
Which educational website are you ordering this from?
The Mods will allow it if it's a known one, otherwise we can point you to a better one  .
I've actually done quite a lot of PEM studies in the past.

[kr3am3r]

this is the link : http://www.horizonfuelcell.com/#!junior-science-kits/c1dru

my set is the 3rd one, Solar Hydrogen Generation Set   FCJJ-16
im now trying to figure out what motor i need, i have been searching for some low rpm high volt but they are very expensive. A teacher of mine said he will order one for me if i find one and i am currently stumped. I found a 2000 rpm and 24vdc rated at 1.1A.  I'm not sure if this will do, I'll have to ask my teacher
Added link. I know this site very well.
Bruce S

[Bruce S]

You will not normally be able to get up to 2000RPM with a VAWT.
You need something in the 200 RPM range.

[electrondady1]

ok i checked out the kit


am i right in thinking the kit uses photo voltaic solar sells to create hydrogen through electrolysis?
and now you  want to create hydrogen with a vawt?
what about the little motor with the propeller?
what happens if you spin that ?
ed lenz has a vertical kit that would do the job
http://www.windstuffnow.com/main/3phase_turbine_kit.htm

[kr3am3r]

so you are saying i should look for a 200 rpm 12 vdc motor for my little vawt?
I don't know very well what power a motor can generate or how you can find that out.

[Bruce S]

Then you've come to the right place  .
Within these posts are all the information you'll need to know as much about wind & generation from it.
AS Electrondaddy1 stated: a good place to grab a decent starter VAWT kit would be Ed's.
Our daughter ordered one and built it for a science kit too while still in grade school.
It was well received and earned her high marks.
A word to the wise follow the directions! Read them , take a break, read them again ,,, then build it.
Once built which took our daughter a weekend, to build and understand what was going on.
It is still here and still 90% assembled ( it would still be out side, but a critic judge requested a tare-down for hidden batteries).
Best of luck!