the Art of the VAWmT: using ceiling fan alternators

[aerotron]

I am planning a vertical axis wind micro-turbine farm using as many  120v ceiling fan alternators as it takes to trickle charge 3 deep cycle 12v batteries (connected in parallel under the floorboards of my shack). My prototype, spinning smoothly at 120 rpm and endowed with 14 or so ceramic round magnets( 1"x 3/8")  yields over 14.7 vdc and yet when I apply one 63v22uf capacitor over the rectified current, yields just over 20 vdc. HOW CAN A CAPACITOR APPEAR TO INCREASE THE VOLTAGE and will this translate into the need for fewer rpms for battery charging as I don't require each turbine to produce much more than 14.7 vdc. All my micro turbines will be connected into a power combiner which while maintaining the 14.7vdc allows for the convenience of the increase of amperage to be conveyed to the charge controller via one connection.   Each alternator will be styled with a three-blade savonius propellor cut from plastic semi-circular eavestrough of 4 inch width , thus with a circumference near 1 metre, I should then be able within reason to adjust the length of each blade set so as to get the desired RPM of 120 at the lowest possible wind speed. (1 mph = 0.45 m/s).   I have eight  15watt solar panels which up until the vernal sun are quite satisfactory. After september,  I rely on a delco alternator belted to a 3.5 hp lawn mower idling for 3+ hours on 1.5 litres of gas to get through nearly 2 days of electrical needs but it would be reassuring to know that through novembers' darkness, a micro wind farm was carrying on the charge.                                     

[tecker]

Pictures are worth a thousand words here . There are several Ceiling fan models . All but a few have speed windings and most use 30 awg or smaller . You have a doable Charging circuit here , higher voltage small current . Upload some more pics . Build the turbine and match torque of both .
  The capacitor is in the charging circuit I assume , shows some impedance weirdness . Large batteries will load the  high resistance stators and stall a VAWT  so a cap won't help much if any .
I love these motors as small charges though  . I'm  in to building houses and outbuildings docks with wind . Keep hammering on those circuits and see what you come up with  .

[electrondady1]

you have a working unit now?
the speed of rotation is mostly dictated by the diameter.
 increasing the length of the vanes  will increase the speed to a certain extent but mostly it will increase the torque.
most ceiling fan motors will have multiple speeds. multiple sets of coils.
 you need to rectify those separately for two phase.
if your set up is in a remote location you will need a charge controller with a dump load.

[Bruce S]

I noticed you have the batteries in parallel.
What voltage are you looking to use? and what are the Ahr ratings of the batteries?
Pic would be nice too .

[GoVertical]

Hi, I have been testing two different MPPT controllers and my test circuit has the same beneficial results. It takes a high voltage with low current and converters it to a lower voltage with higher current.
It is a buck converter with a manually set duty cycle. I found that a duty cycle below 50 % works best.
VAWTs are slow and this circuit will defiantly help.



http://usvawt.com/cgi/windpower.cgi?h=12;hunit=0.3048;d=4;dunit=0.3048;Calculate=Calculate

The bigger you make the blades the better it will work.

I hope this helps







 

 

[XeonPony]

The capacitor Does NOT increase voltage, rather it smooths it out, it is the rectifier that makes the unloaded voltage apear to be higher.

An A/C wave form has peaks, the RMS of an A/C source in a resistive load will be the average DC equivalent power delivered with is usually just above one cycles zero point cross over.

In over wo0rds the rectifier catches the peaks, the capacitor stores them and poof you get a higher Appearing Voltage  put a load on it and measure through the RPM range again, I'd be willing to bet you'll see little if any voltage!

As stated be for you need to isolate the phases and the various speed windings, isolate them, and rectify them separately then feed them into the capacitor then finally to the load.

If you have not re-wound the stator you must use a 200V capacitor or you will blow the electrolytic up if a good enough gust cuases it to spin at a sufficient rate, or you need some other regulation method to ensure it never goes over the 63Uf (Which will happen if the dump load fails and they are not connected to the battery!)

[GoVertical]

The capacitor Does NOT increase voltage, rather it smooths it out, it is the rectifier that makes the unloaded voltage apear to be higher.

An A/C wave form has peaks, the RMS of an A/C source in a resistive load will be the average DC equivalent power delivered with is usually just above one cycles zero point cross over.

In over wo0rds the rectifier catches the peaks, the capacitor stores them and poof you get a higher Appearing Voltage  put a load on it and measure through the RPM range again, I'd be willing to bet you'll see little if any voltage!

As stated be for you need to isolate the phases and the various speed windings, isolate them, and rectify them separately then feed them into the capacitor then finally to the load.

If you have not re-wound the stator you must use a 200V capacitor or you will blow the electrolytic up if a good enough gust cuases it to spin at a sufficient rate, or you need some other regulation method to ensure it never goes over the 63Uf (Which will happen if the dump load fails and they are not connected to the battery!)

Hi, are talking about a buck converter? I am not sure what you trying say. Are you familiar with MPPT technology?

[XeonPony]

yes I am familiar with it I am using a morning star for my solar system.

And no I am not at all talking about ANY high level stuff there, I was simply explaining why it appeared he had a higher voltage when he added a cap, it is more of an illusion then any thing ells

The only meaning full test is under load, unloaded tests are meaningles with AC most the time. to test my hydroturbine I use increments of a 100w till I find the sweet spot, then from there decide all ells.

[GoVertical]

Hi, thanks, the confusion was on my end.