More Power From Wind Generators

[s4w2099]

Hello guys, this is my implementation of Flux's idea for a boost converter for windmills. This one does as he explains in his diaries. It has a potentiometer to set the cutin speed and has another one to set the output current limit while under boost.

I made this one small it can only deliver about 125Watts max when used at 24V. It works great for two system voltages, 12 and 24V. The output diode can handle up to 16A continuous MAX so after boost this is the current limit that it can handle.

For full explanation of how this device works please visit:

http://s4wsbox.com/?q=node/32

Note, this will not collect power if it is not already available in the wind, no magic here. The power curve from this booster should always be below the propeller power curve to avoid stall.

If anyone is interested in one of this boards please contact me. Ill order the parts and put it together. Ill ship only to USA, Canada and UK.

Schematics are free for personal and educational purposes. In case anyone decides to put it together here they are: HERE

I link outside of the forum because the image is too large to post here. Enjoy it.

[dbcollen]

is it capable of being modified for 48 volts?

Dustin

[s4w2099]

I have not tested it for anything higher. The reason why it would not work at 48V is because of the 7812 V reg. It can only take up to 37Vdc in. The output caps are only 50Vdc and the inductance would have to be increased. it would certainly work but those modifications must be made. I will be working on a 48V version soon, not much to change at all but I would not advertise this one as capable of handling it because I have not tested it myself at such voltage.

[Flux]

Nice work, it puts my untidy prototype to shame.

You are wise to offer the whole thing with a proven layout, that is half the battle as a bad layout will kill the mosfet.

48V is a problem with power supply and I haven't done anything at 48V. Even at 28v nominal on one of my machines I run close to the regulator limit. I have a simple resistor/zener shunt limiter clamping at 35v to protect the supply. It doesn't zener except in high winds so the shunt current is no issue.  This would be wasteful at 48V.

Flux

[ghurd]

Nice to see it coming together!

I didn't notice any plumes of smoke from down you way. :-)

G-

[BigBreaker]

There was a debate a while back about boost versus buck.

It seems to me that buck is better since the stator and transmission cables operate at higher voltage.  The buck convertor reduces the voltage to battery level.

The converse is that boost is active only in low power situations, so the electronics do not need to handle big currents.  That's because low wind, low current situations are the ones with low voltages and are also quite common.

[s4w2099]

Yes, Layout is critical. Ill be giving a tutorial soon on how to properly choose an inductor value and material for a certain switching frequency.

The layout basically consists of two ground planes on the bottom of the board. The POWER ground and the logic ground should be separate from each other and only joined at a SINGLE point. By putting the mosfet and the mosfet driver in the same ground plane (power ground) it allows proper turn offs of the mosfet as well as better turn ons.

The logic ground is separated and joined by a little track. This is a good idea because when switching high current the mosfet will pull ground up possibly disturbing the logic's reference voltages etc. This single point of connection is like a small value resistor.

Using SMD components I could achieve small track runs. The whole circuitry is under 1sq inches and has a part count of 53. The board is about 2x3 inches because there is nothing I could do about the inductor, capacitors and the bulky hall effect current sensor.

[s4w2099]

I think you were looking the wrong way :-)

[Boondocker]

On your website it stated that 300 watts maximum when not boosting. Does that mean pass through watts?  If there are two sets of rectifiers, main and boost, in the installation. When the alternator achieves battery voltage wouldn't the amperage by-pass the boost converter via the main rectifiers?  Therefore, allowing the system to handle more than the 300 watts in higher winds.

[s4w2099]

Yes, when not boosting the total current delivered by the windmill is shared between the main rectifier and the boost converter output diode. What I meant to say is that the power going through it should not go over 300W@24V.

I guess Ill have to make that clearer as its not really an issue of watts, it is an issue of how much current that diode can handle. Fixed that now. So, as you see, the total power into the batteries after boost is delivered by both, the output diode and the main rectifier.

Because of the nature of a boost converter there will always be current through that diode no matter if its boosting or not.

There are ways to completely disconnect it from the circuit after cutin but that would kind of defeat the purpose and will also bring additional losses into the system.

[Sly]

Hi,

I know we are all busy but I was just curious to find out if you have made progress with the 48V version or is it even in your plans?

If you have this option available please let me know as I am interested.

Tks

sly

[oztules]

I think that what you are driving it with makes a huge difference in attitude.

 My mill will push out 45 amps @55+ volts or more in a gust if the furling is caught the wrong way at the wrong time into batteries trying to stall it.

It may last for only a few seconds until it sorts itself out, but it means that the buck would have to easily absorb that kind of power..... that is a big ask and a big buck.

From a reliability point of view, smaller mills may be ok to keep under control, but mine has seen 5kw before when I let it loose at higher voltages (145V @ A40+ amps), so where do you design for with a buck? what kind of peaks would I expect with this mill? I don't know, but I gave up on it (raw fear) rather than it giving up, It would do more than 5kw if you continued to match the load to it via buck in a big blow.

And don't think that furl will save you, I have 8" offset now, and an overlight tail, starts to furl at only 500w, but if confused will still pull over 30A for a short time before cutting back to 500-1000w in full furl. If I tried to mppt it, you can bet that things would go out of control for short periods... enough to blow things up I suspect.

At least boost has a design max limit.... simple stuff.

...........oztules

[s4w2099]

Sorry I have not done anything about 48V just yet. I do plan to do it but there are more stuff I need to improve in all of my designs. 48V increases the complexity and cost unfortunately :-(

Ill make sure to post progress with it when ready.

Thanks