windmill heat controller

[hallmgr]

I have constructed a 1kw, 110v, 3ph windmill and have it running a storage heater in my home.  At present I have a series of electronic switches which turn on and off elements in the heater, but this means I am limited to what size of load I can connect to as too big a load being switched on at one time would do damage to the generator.

I would need some kind of PWM controller which would work like a dimmer switch and only connect a percentage or the waveform to one load, depending on the windspeed.

Any help would be much appreciated.

[Putte]

Hi Hallmgr.

Now this is a system that i have tried and seams to work good from 20hz to some 100hz.

in a 3 phase system it looks like this and to work ok the higher volt the better i have seen some 450 volt down to heating element in my system and then 100 volt over resistor.

You have to "tune" in the system wiht the right amount of uf to match your turbine and there must be a good furling system when there is storm and so.

Maby some help..

Putte.

[JW]

"I would need some kind of PWM controller"

Possibly...

 another route you could give some thought too, is staging several (smaller)heaters thru independant relay's that could turn on/off in sequence. The sequence could be voltage driven/controlled. This would be easy to do with ziener diodes. the trade off is, you'd have to make some dc power to drive the ziener sequencing.

JW

[kitno455]

what about using a freq counter to voltage chip like the otherpower guys use for their anemometer? dont know how much current it can source/sink, but it might be enough to run a multi-stage voltage divider to open/close the gates on a bank of fets, one per element. should be possible to chose one of the phases from the gen to count.

but i am no EE, so i dont know if i would try it

allan

[drdongle]

Voltage multipliers typically only offer very limited current capacity. I think that in this application this is the wrong approach.

[JW]

I agree DR.D,

 fer-sure, a 3kw system output would require some decent capacitors and diode's with heat-sinks. But hallmgr, specifiy's a 1kw system, to me this means 300watts per phase, not too much to ask.

 My parents have some property in Gatlingburg, perhaps I will have to cruise out to cosby sometime and say hi. I visit tenn once in awhile, hey, know of any gold placer deposits in your area. Im also very interested in tormaline of anykind.

JW

[Putte]

Sorry for my bad drawing its 3 phase ac and you are right JW i guess the most have to low volt for a system like this or it going to be expensive with capacitors the higher volt the smaller amount of "uf" needed.

My current experiment looks like this.

But its so simple no relay or switches.

Putte

[hallmgr]

JW,

The system I have consists of a series of ac switches which switch on and off small elements.  What I am looking for is some kind of smooth proportional control instead of the on-off system, and would also allow me to connect to an existing storage heater or immersion heater without having to alter it.

Hallmgr.

[hallmgr]

Putte,

Could you please tell me a bit more about how this system with capacitors works?  I am not the worlds best when it comes to electronics but i would try to build the controller.

Hallmgr.

[JW]

I follow you now hallmgr,

 perhaps a heavy duty light dimmer could do what your looking for. Im just unsure about how you are going to combine the phases(without a diode rectifier). also if your stator is wound to output high enough voltages for the load you want to power. if you do go the water heating route, take special care to include a ground fault interupter of some sort.

JW

[joelhacker]

I would suggest not going with PWM control, especially if it is

three phase...that is a lot of pulsing and a lot of control circuitry.

From your picture it looks as though your heating elements are

sub-divided and that's what your switches control...

Why not just keep them divided and then use a circuit that uses

a voltage divider and comparators to turn on and off relays (don't

forget the bypass diodes across the relay coils) to do the same type

switching based on the voltage comparison that you would normally

do manually.

I think the best way is to keep it simple and make it switch those

individual coils on and off in a individual fashion.

[Putte]

I will try Hallmgr i am a hobby electronic man :-)

The thing i like with this is that there is no relay and the genny starts with almost no load and the more wind speed the more volt so for a pmg it works in good contact with wind speed the thing i have experiens is when there is a storm things can go bad if the load can not get the turbine to stall but with a good furling system it works ok. For measure power i have to measure the volt over the resistor * amp *3 in a 3 phase system(i think this is the right way). Volt from genny (my genny) can be up to 450 volt so there most be low loses down from genny. It starts from some 20 hz up to around 100 hz. And its easy to tune in the system more "uf" for lower RPM/Volt or less for more RPM/Volt. For me i try to tune it so that it starts easy in light winds.

I dont know if this is a efficient system but it very simple and if one replace capacitors by there lifespan there would be very little trouble.

I use "motor" 450 volt 50/60 hz ac capacitors.

I hope this is to some help.

Putte.

[joelhacker]

Is your generator a 3 phase alternator?

Your wiring setup is okay as far as the lines to the

heater elements, but I see absolutely no reason for the

capacitors in your heater project.

If you are trying to create a DC voltage to supply other

areas of your household power, then you need to put some

diodes in there before your capacitors.

IF you are going to do that, then you might as well move

your heater elements to the other side of the diode bridge

and wire them up in parallel with a switch before each

element...else you will experience cogging on your alternator

as only 1 or 2 phases of the three phase system will be excited.

If your system is not running something else, but is only

for your heater array, you will still have cogging with your

current design and your capacitors are doing your no good.

[Putte]

Hi Joelhacker.

My pmg is a ac generator and with the ac capacitors there is no cogging thats the best part it starts with almost no load it starts easy in slow wind. When the wind starts to blow it raises voltage and it starts to load heating element.

I am no expert but it do work this system.

Putte.

[RP]

Actually its rather clever.  The capacitiors will act like an open circuit at DC or very low frequency AC.  As the rpms come up they'll conduct more and more.

The power drawn will be proportional to rpm giving the genny a light load at start up.  In essence this will act as a controller that automatically lowers the resistance of the load as the genny turns faster.  With a little tuning to find the appropriate values for the capacitors this is kind of neat!

[Putte]

Thanks for the comment RP :-)

Putte.

[hallmgr]

JW,

Would it be possible to run the output through a three phase rectifier, and then use the PWM to control the rough DC?  I would be grateful if you could provide a diagram of the layout for me to build.

Hallmgr.

[hallmgr]

Putte,

I would be grateful if you could provide a more detailed drawing of this controller, so I may attempt to build it.

Hallmgr.

[Putte]

Hello Hallmgr.

I will try with a maby better drawing?

Weiring from the genny is always connected so not much can go wrong there and then after the heating element connect the capacitors "one" between two phases. The minimum is then 3 capacitors. Or if you connect more in series or parallel for the right load on your genny. its a try and error for the most power/rpm/volt/amp. I dont know your pole numbers (hz) but mine work from some 15-20 hz to some 100 hz.

This is one of the capacitors i am using you can connect parallel or in series for the right amount of "uf"

Or the can look like this a bigger 3 phase 3*89 uf (have not used this big yet)

I think meby one would need to match the load for the generator 1kw to similar heating element 1-2kw for the best efficiency. I have even tried with 100watt 230 volt light bulbs 6 (600 watt)in total and in 2 parallel pear phase (trouble to find so small 3 phase load) worked perfect even tho i overpower them to some +300 volt.

I hope i can help you.

Putte.

[hallmgr]

Putte,

I think I understand you now, it looks like a very simple system, just three capacitors and three elements if I understand you correctly.

With my 1kw windmill I find I can produce between 2 & 3 kw in a gale, so would that mean I could have say, three 800w elements, one per phase for this system? or would I still need to devide the loads up?

By the way my windmill does have a furling system which turns it side on to the wind when it is very strong, still I find i can produce over 2kw.

I would estimate my windmill would need to start being loaded around 20hz so the capacitor values you have shown me may do.

When you connect capacitors in series does that mean its 'uf' value increases?

I sould be able to get hold of capacitors like these so I will try this control method.

Cheers.

[TomW]

hallmgr;



When you connect capacitors in series does that mean its 'uf' value increases?



When you connect capacitors in series the "uf" value decreases and the voltage rating increases.

When you connect them in parallel the "uf" value increases and voltage rating remains the same or the value of the lowest rated capacitor's voltage rating.

So, as an example you connect 2) 20 microfarad 450 volt capacitors in series you end up with the equivalent to a 10 microfarad capacitor at 900 volts rating. The same 2 capacitors in parallel will give you the equivalent of a 40 microfarad capacitor at 450 volts. Hope that helps.

Cheers.

TomW

[hallmgr]

Cheers,

Hallmgr.

[Putte]

It sound like your in to a good start then Hallmgr. I think one reason if you may have problem is if the voltage is a bit low then it may get expensive with capacitors it seams your hz is very good.

Good luck and i would like to hear how its goes.

Putte.

[hallmgr]

Putte,

One question, these capacitors are basically working like resistors, the higher the frequency the lower the resistance so more current flows, correct?

This would mean then that the capacitors will be dissapating power just like the heating elements, so will the capacitors not get really hot?

Hallmgr.

[Putte]

Not really like resistors it get loaded and unload at 90 degrees from the main phase. I think at full load the might be a little warm. It may not be the best solution having reactive effect bouncing back but i think some will end up as heat in the resistor (element).http://en.wikipedia.org/wiki/Real_power

Putte.

[hallmgr]

Putte,

As my alternator starts to generate power at over 100v phase to phase, does that mean I will need 100v capacitors?

Hallmgr.

[Putte]

You have to go for the maximum volt it may be that you are going to have higher volt down from the genny with this system. More 'uf' gives lower volt and rpm. I try to experiment when there is not to high wind to make room for errors. At what rpm/hz do you have 100 volt(load?)?

Putte.

[hallmgr]

Putte,

I would start to load my generator at around 100v 20hz.  The voltage goes up to a maximum of around 200v in a gale.

Hallmgr.

[Putte]

That sound good i think you will have more than 200vac with this system capacitors may raise voltage a bit. About the rating go for 300-450 volt if you can.

Putte.

[hallmgr]

Cheers.

Hallmgr

[hallmgr]

Putte,

Where is the best place to get hold of large capacitors like these?

Hallmgr.

[Putte]

You got me there Hallmgr..The are called "motor" capacitors. Try to find a dealer on internet near you. I guess you need some 20-40 'uf' pear phase the more voltage you have the less 'uf' you need. its a good idea to use smaller 5-8 'uf' capacitors an connect them in parallel for the right amount. It may be a little try and error before you got the best setup. Or if you can find used capacitors for experimenting and then you now what you need you can find them in "older" florescent tube armatures the only problem then would be the volt rating.

Putte.

[ghurd]

Anywhere with scrap motors should have a lot of large caps.

Also commercial heating and a/c repair places (I have better luck walking in right after lunch than calling).

G-