need more power

[newind]

Ok, so i built this little savonius turbine with a PMG that i got online. I've connected it to a SMA windyboy 700 and am making power. Very little power... Actually i psyched it even worked. Granted the barrel diameter is about 2'. As soon as the unit sees load, or i program the power curve of the inverter to draw more power, it becomes very unstable. essentially the turbine sees more load, and starts to stall. Then the inverter de-rates and allows the unit to spin back up. So my question is this. How do i get more power? Or should I say more torque? and dont say go HAWT, i'm kinda into making this thing work.

Thanks

[wdyasq]

"How do i get more power? Or should I say more torque? and dont say go HAWT, i'm kinda into making this thing work."

The same way you get milk from a chicken......

Many have tried to make a successful VAWT. Few have succeeded.

Find a successful VAWT design and copy that is my best advice...

Ron

[TheCasualTraveler]

How do i get more power?

Larger swept area

Good bearings

Perfect balance

Properly matched alternator

Higher tower

MPPT

 

[Flux]

The Savonious needs to be large to produce much power. You don't give a lot in the way of details but yours doesn't seem to be large so if you are getting 50 plus Watts then you are probably on the right lines.

All you can do is make it bigger and site it in the best possible position. These big clumsy things are usually sited at or near ground level where there is little useful wind. There seems to be some mistaken belief that there is real wind energy at ground level but HAWTs can't use it effectively. I have never seen any VAWT manage to do better under these conditions, I have come to the conclusion that there is no real wind energy at ground level unless on a completely open site with no trees or buildings.

When you make it larger you will need to increase the alternator speed to be able to get more from the alternator. I suspect the Windyboy curves may not completely suit a VAWT but I am sure your issue is that it is just too small.

Flux

[newind]

Yes, I agree there is no real power at ground level. Dually noted... I'm guessing its too small as well, and will start working on a larger diameter. As to the alternator speed, I may look to gear it. I think i'll start at a 2:1 ratio and see what that gets me as well. Am a little nervous about taking large steps which I'm assuming will only increase the torque requirements and the potential of stall.

Thanks for the unbiased input. I know i'm going against the conventional HAWT thought but I just cant help myself. Having fun too.

Thanks,

-k

[Bruce S]

newind;

 I'll ask the question

Got pictures of your setup?

It really is true pics can tell us tons more than most words can. IS your 2 footer 2' high or 2' wide?

If the unit is becoming unstable, please explain in greater detail "unstable" is it wobbly type off balance? If erratic during loads and sputters then I'm fully with Flux on this. Not enough useful wind OR not enough windswept area.

You could instead of making them bigger, addon a 2nd set but 90D offset; that should allow you to keep the gearing out of the equation a bit.

Gearing has it's own problems, even if it does help with RPM issues.

Best of Luck!! On bring on the pics ( properly sized of course)

Bruce S

[newind]

Ah... excellent questions! Unfortunately no pics as of yet. I will say 2' high, and just about 22" in dia. Spinning, its perfect. Balanced and stable. Unloaded the thing is a dream to see run. Loaded... well that another story. "erratic during loads and sputters" would be an excellent way to put it. I am pretty comfortable with the amount of wind, when i have it, so I'm thinking it's just too small as well.

Busy week for me, so not sure how much time i'll be able to spend on it, but i'll try to keep ya posted, and work on those picts too.

As to gearing, is it just the additional torque requirements or is it more than that. I'm naively thinking that a 2:1 would be pretty straight forward. After of course i make it bigger.

Anyway, thanks for the well wishes, and i'll report back when its bigger.

-k  

[hvirtane]

It sounds like your load is too big and errant, too.

You could try adding a resistor on the line.

Try starting to charge directly batteries and try with resistors, how much load the turbine can stand.

- hv

[electrondady1]

it's sweeping less than 4 sq. ft.(like mine)

if it's direct drive  double you swept area by stacking a second set of vanes.

if its a pulley or whatever,

 quadruple the swept area with  another savonius spinning in the opposite direction

hey,just keep making it bigger and bigger until the authorities come.

always be polite and keep your hands in site !