# Thread: MPPT controller for wind turbine

1. srockriver Guest

## Re: MPPT controller for wind turbine

Cool, looks like its good to around 550 watts?

Not sure where ARE get their elements/heater coils but they must have a boatload. The have been rolling these diversion loads out with all their turbines including the high voltage grid tie ARE 2.5kw 110 and I believe their 10kw 442 turbines as well. Im looking to build a home brew axial flux turbine one day, and hope to maybe use this new Outback fm80 with it.

2. ## Re: MPPT controller for wind turbine

I think it's rated more like 400 watts. Small, but it's ~something~

boB

3. spacejunk Guest

## Re: MPPT controller for wind turbine

Hello all.
After burning out another turbine alternator, and doing a few calculations, without going into the maths here, my conclusions as follows:
Direct connect Off Grid battery charging Turbines
1. There is always a compromise between low wind performance and rated performance. Thus the theoretical Alternator efficiency at rated rpm may be around only 50%, but at cut-in speed it approaches 100%.
By "theroetical" I mean ignoring Flux losses, eddie losses etc, and considering ONLY Alternator open circuit voltage and effective Winding resistance (3ph) .
So a 1000W rated Turbine,in this example, thats outputting 1000W to the batteries, will be itself be dissipating 1000W. Thus the total power extracted from the wind is actually 2000W. 1000W dissipation on a 43°C day will have the turbine running pretty hot.
2. Now if we half the Alternator number of turns, thus halving the Voc & Rs, the efficiency increases at rated RPM, in theory, doubling the rated output power. But there will be no power output at all low or medium wind speed.

So to have the Alternator / Turbine delivering its power at peak eff, MPPT is the only way to go.
Wind Turbine MPPT are hard to design due to the ever changing RPM as the Wind gusts and drops in the real world.
A true Wind MPPT would need to collect data, and store a table of RPM vs power Output/PWM . The MPPT would need to learn the best power points over a long period.
It seems to me that the FX80 and other MPPT/Wind Turbine packages are not actually MPP Trackers but MPP Controllers. As they must be programmed with the RPM vs PWM data to suit a specific Turbine Charateristic, and do not Track the Max Pwr Point at all.
They should be called an MPPC not a MPPT !
The DIY Turbine maker needs a MPPT that will determine the MPP all on its own, as does a solar MPPT.

4. ## Re: MPPT controller for wind turbine

Since the main focus of most of the MPPT controllers, is for Solar, and they do an admirable job at it, they ARE MPPT controllers. Primary function is for solar, and in a pinch, they can control wind too.

There isn't really a "Controller" for a wind alternator, but more like a charge regulator, and load diversion. When the wind is blowing, and the batteries are full, the alternator needs to dump power into a load, to control the prop speed, otherwise, it will fly apart. If the prop is too large for the generator/alternator, it will burn up the unit, and then overspeed. Wind is SO tricky in that respect.

5. spacejunk Guest

## Re: MPPT controller for wind turbine

Mike,
My guess is that everyone here already has a grasp of what a conventional Wind turbine controller or regulator does, Thats pretty straight forward and a standard requirement as you say..
My discussion was regarding Maximum Power Point Trackers for wind Turbines. The goal is to match the Turbine impedance to the Battery/load impedance as best as possible, at any power point. It is indeed similar to the goal of the Solar MPPT ers. However, one would be brave to attempt to fit a Solar MPPT to a Wind turbine. The WTurbines output changes too rapidly and as you say the Turbine must be loaded. Thats why all existing Wind MPPT devices must be programmed with the RPM vs Voltage (or similar) curve of the WT that is connected to it. My point being that a Solar MPPT is continuously altering its PWM Step-down converter to find the optimum PV power point. Solar Panels being Current sources, not voltage sources. In contrast, the current Wind "MPPT's" dont track the power point but simply output the programmed PWM to the switch-mode converter section coresponing to the measured turbine RPM. This is cool if one knows the Turbine curve, but it is not active "tracking". A trivial point perhaps.

6. Solar Potentate
Join Date
Dec 2004
Posts
708

## Re: MPPT controller for wind turbine

well the axial flux turbine does work well with the mppt contrller by Midnite solar. I have a thread going on otherpower.com but in a nut shell early testing is showing 2-3 times the power out of the turbine just by following the wind speed with turbine.
We are in early stages of beta testing with the Classic but it really does rock. and the Classic will be able to learn the turbines curve as well as letting you set it. check out the thread at other power and feel free to ask questions http://www.fieldlines.com/story/2008/12/30/204712/79

7. ## Re: MPPT controller for wind turbine

I have to admit I stay away from forcefield ever since they went "commercial" with all the Google and other ads, so have not been following the wind threads there.

But that aside, I have never seen much in the way of good results from an mppt tracking a wind generator unless you have a pretty stable wind. that has always been the major downfall of using MPPT on small wind generators - the MPPT tracking cannot track the (often) widely varying voltage fast enough for good results.

I would be curious what the voltage input range is into the controller with your setup.

8. ## Re: MPPT controller for wind turbine

Originally Posted by Windsun

But that aside, I have never seen much in the way of good results from an mppt tracking a wind generator unless you have a pretty stable wind. that has always been the major downfall of using MPPT on small wind generators - the MPPT tracking cannot track the (often) widely varying voltage fast enough for good results.
Actually, it's not all "that" fast... Luckily there is inertia in the turbines and the wind is not 10 MPH to 30 MPH in 1/10 of a second or anything that fast. The electronics can be fast enough for wind speed changes. And it has to follow the wind because wind is never stable (or rarely AsFarAsIHaveSeen)

If you take a close, zoomed-in look at wind speed vs. time, you can see this with either a small turbine running open circuited or an anemometer.
However, either one may not spin down immediately (unloaded) when the wind suddenly drops. A smaller turbine with its smaller inertia should show up the fastest response.

Of course, the real proof would be in the increased kWh over plain old direct to battery connection method.

boB

EDIT:
Here is a 1 minute capture of a 200 Watt (rated) Chinook 12V (nominal) turbine free running at my house.
35 Volts is around 15 MPH and 10V is around 7 MPH (ball park values)... You can see that the wind, or at least
the turbine's response isn't all that fast and is easily trackable. A larger turbine, like 1KW, would be even slower
because of the greater inertia.
boB
Last edited by boB; January 2nd, 2009 at 1:29 PST. Reason: Adding Graph

9. Solar Potentate
Join Date
Dec 2004
Posts
708

## Re: MPPT controller for wind turbine

[QUOTE=boB;24357]
Of course, the real proof would be in the increased kWh over plain old direct to battery connection method.

boB

And proof there is we have seen 2 to 2.5 times the wattage out of our Hugh Piggot designed 10ft turbine with the Classic

10. srockriver Guest

## Re: MPPT controller for wind turbine

here are some youtube videos of my A.R.E. 2.5 kw wind turbine with the modified Outback FM80 as the controller. I recently registered 4160 watts from the turbine in the outback logs. I added some kyocera panels to the mix a while back and am able to keep the backup panel off grid most days.

So far it's been rock solid with no problems.

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