People that have been around the RE scene for a while have seen these supposed "breakthroughs" in solar cell technology for years now. To date, very little of these pipe dreams have ever come down the line and come into production. Solar cells are basically the same thing today as were put on satellites in the 1960's.

I'm not saying that there won't be major improvements in wind generator charging controllers in the near future, but look at the history of RE, we have been promised time and again of these exponential increases, yet time and time again, over a thirty year period, we get incremental increases.

The thing that makes me think that building a MPPT wind controller might not be as easy as pie, is that the guys at Outback seem to have been working on it for over a year now and have come up with exactly zero products to sell to the general public.

These are the observations of a realist, with no engineering or electronics training, and hoping he is wrong because innovation helps me immensely in my daily life. But like Fran Drescher said in the movie Spinal Tap... Money talks and bullshit walks.

Volvo Farmer

". . . and I find it a bit frustrating how frequently folks are promoting what I would call 'vapor ware' (MPPT for wind turbines with PMA's) to a crowd that for the most part cannot understand - or afford it . . ."

I take exception to this view. The concept and implementation of MPPT has been around for a long time and is being used in some of the utility-class machines. Just because it hasn't yet filtered down to popular use by DIY people doesn't mean that it should be classed as "vapor ware". There is no basic reason or limitation why it can't be used with our PMA's to good benefit. I also think your characterization of most of the people on this forum is unfair. I think most folks here could understand it if they made the effort.

"To date - as far as I know, there is not a single product available on the market, nor a single schematic posted on the internet that works."

I believe the reason we haven't yet seen a commercial product is simply because there's no money in it. The number of small wind installations compared to solar panels is miniscule. Also, the variations in DIY wind machines are considerable, making the design of a universal product more difficult. Solar panels are pretty uniform by comparison. Here's an article with schematic for a MPPT controller. Although primarily for solar, the author acknowledges suitability for wind and hydro. It's a low power version but modifications for higher power is straight-forward. I suspect one could be made for $50 in parts. Is this too high?

http://www.elecdesign.com/Articles/Print.cfm?ArticleID=6262

There are many technical papers about MPPT on the web.

". . . as far as I can tell its very complicated and not suitable for most homebrew systems."

Some people would find what you do in making an axial flux dual rotor PMA very complicated. Different strokes for different folks.

". . . and when it comes out I expect it will be very expensive.

Probably, as most things are for a small, specialized market. The alternative is to roll your own, just as you do for your PMA's.

This situation reminds me of 1959 when the transistor first made it out of the laboratory into the public market. Many of my friends and co-worker die-hards pooh-poohed the idea, being well entrenched in their `hollow-state' (vacuum tube) technology. The real reason was that they didn't want to expend the effort to learn something new. We all know how that turned out.

For the electronic tinkerers there is no basic reason why that can't make a big improvement. True tracking mppt as done with solar is difficult and all the thought seems to be wasted in the tracker bit.

There is no need for this with wind power, if the alternator and control scheme combined has the right characteristic to track the wind that is all you need, if its characteristic is right today it will work tomorrow. It may not be perfectly on peak but as long as it is an order of magnitude better than we have now the improvement will be there.  I am not convinced that you can effectively track such a fickle thing as the wind with any degree of certainty. The best this method could do would be to store data of the machine curve and learn it into software like an engine management system. This way it would eventually learn its own characteristic without the user having to program the load curve.

Regarding the power side which everyone seems to dismiss as trivial, that is where the trouble starts for the average constructor. There are literally hundreds of dc converter circuits on the internet but are all the basic configurations, none cover the aspects that decide whether they work or go up in smoke.

High power dc converter design is partly fundamental knowledge which designers don't disclose and partly a black art based on previous experience. The layout and control of stray parameters is so critical that unless the thing is repeated exactly results would not be certain. Someone would have to develop a complete design including exact layout as a kit or something if others were to have any chance of copying it.

I was once asked for a circuit to double a voltage here and I posted a step up inverter circuit that I have used. Within minutes several people had re designed it as a boost converter that would then have needed feedback control to do what the original poster wanted, so I have not felt inclined to post any other circuit designs. In this case the circuit as I posted may not have worked if copied exactly with a different layout.

I have used boost converters for years to improve the low wind curve of faster alternators, but I have had trouble with some and not others, when I have cured the bugs they work for years with no trouble, but if I published the circuits I suspect few would get anything to work.

Attacking it from the other end is even more difficult, a 200W boost converter is far less problematic than a 6kW buck converter. I have run an experimental 1kW version with very good results but under carefully watched conditions. If it lost battery connection I know it would not survive and I see no hope of protecting from lightning so I have to continue to regard it as experimental.

For small machines it just isn't worthwhile, a slightly larger prop does the thing more effectively.

For the larger machines I think the issue is different and the issue may change.

To hold a 20ft machine so hard into stall to protect it at 20 mph will play havoc with its performance in winds above 10 mph so improvements are available even if the big kWs in the high winds are not required.

Take one SMA Windy Boy, (Wind MPPT tracking inverter), one of the turbines that the WB supports and connect its AC output to that output of a a bi-directional Inverter/Charger such as the OutBack FX or possibly Trace SW that is inverting off its battery.

What happens with a Sunny Boy and PV (which I've done), at least with the FX/VFX Inverter is that the Sunny Boy thinks the inverter is grid and tries to raise the AC voltage.
This will send current into the battery, backwards through the inverter.

However, if the battery is already fully charged, or no other DC loads are present, the battery voltage will start to rise, along with the AC voltage.   This works as long as the AC voltage (as far as the Sunny Boy (or Windy Boy) is concerned does not go out of the "window" of around 132 VAC (UL 1741 requred operation).  A diversion load can be hooked to the battery or AC side to keep the voltage from rising if necessary.

As far as I know, the Windy Boy should work the same as the Sunny Boy in this
configuration.

I think the Windy Boy as it is now comes ready programmed for a couple different
turbines.  AWP and maybe a Whisper ?  I can't remember.

As for vapor-ware, I have to sort of agree on that (as far as 1 unit for battery
charging goes anyway)  I've been talking about it for a couple years now myself.

I think there's a misunderstanding here. I wasn't promoting adding line resistance but simply referencing that it is often recommended by others. I wouldn't use it myself. It's basically a bandaid for the wrong blades.

I agree with most of what you have to say.

The turbine will produce the maximum potential power at a certain RPM at each wind speed.  The RPM can be estimated using a simple formula: 60*(Wind speed in m/s)*TSR/(pi*diameter/blade count).  Optimum TSR can be checked against a table or determined experimentally.

The next question is how to present the generator with a load that produces that RPM.  That is where the electronics come in.

You need to create a control/interface box that can vary the input impedance to hold the RPMs at the optimal rate.  Simultaneously the output characteristics have to be appropriate to the users needs such as battery charging, synchronous AC, etc...

For battery charging that's going to be a constant voltage and variable current.  For heating the goal might be as a current source.  For synchronous AC it will be whatever the load mix is at that time.

WELL TWO VOLUNTEERS FOR A HIGH voltage controller
Let's see if more appear.

To easy up the process, let's do the following:

Send a message to me ( email address in heading of message).

Please every body, even those that have contacted me in the past.

COPY THIS MESSAGE TO YOUR EMAIL processor and add the data to each question

supply INFO :

1) Name of contact
*
2) Description of what you have :
*
3) Location of the wind mill and Wind regime.
*
4) Battery Bank voltage
*
5) Wind mill diameter
*
6) CUT IN RPM
*
7) Volts/RPM unloaded
*
8) PEAK Voltage
*
9) Peak Power at peak RPM
*
10) Generator phase winding resistance
*
11) Type of wind mill :