First PMA With Lackluster Results

[electrondady1]

you can double the output with  a 2 phase wave wound stator by winding another layer of copper over the existing one but offset by one magnet. 
 where the copper skein is on the outside of a mag  on phase one, it will be on the inside on phase two.
 the conductors will overlap  between the loops .
you will need to double the width of the legs at that point so that two layers don't become any thicker .
you will need to rectify the two phases separately. 
 

[Adriaan Kragten]

I doubt if the offset in between both windings should be one armature pitch. I think it must be half the armature pitch to get a 2-phase winding. Only at half the armature pitch, there is place for a second row of coils. The phase angle in between the voltages of a 2-phase winding is 90° which is 1/4 of the total angle of 360° of one complete sine wave. So the angle in between the coils should also be 1/4 of the angle in between two north poles and that is half the angle in between a north and a south pole.

A 2-phase current can be rectified with two 1-phase bridge rectifiers but you can also use one 3-phase rectifier. A 2-phase winding can be seen as a 3-phase winding of which the third phase W contains no coils and generates a voltage which is always zero. The fluctuation of the rectified current is much stronger than for a rectified 3-phase current. Rectification of a 2-phase alternating current is explained in chapter 6 of my report KD 340. Figure 14 out of KD 340 gives the variation of the current and this curve has a rather strange shape.

[Bruce S]

BBT723;;
Looking at the picture you posted in reply #24, you can also start the 2nd WAVE winding just to the right of those start windings at the 9o'clock of the 1st Start/End set.
The 2nd winding starting at the 10o'clock and 3rd starting at the 11o'clock pole.

That will get you up to the 3-phase.
I whole hardly agree with MagnetJuice about the gauge of the wiring 18ga (1.02mm) maybe even go to 20ga(0.81mm) to get the voltage up higher. OF course this depends on what you already have !!

Most 3-phase rectifiers can handle couple hundred volts, just put in on a heat sink  .

Cheers;
Bruce S

[BBT723]

See picture below.  This was the only way to configure the wave coils in a manner that they would not have any legs stacked on top on another.  I'm sure there are issues with this, but it was the only way to orient them evenly after I tried the previous recommendations.  Thoughts?  I want to continue using a wave coil but it appears the most feasible way would be to just have 9 separate coils.  I appreciate each and every one of you for commenting and helping me out.  You guys are great and this forum is what it is because of people like you!

[ Specified attachment is not available ]

[Bruce S]

Before you go any further or WE lead you down another path  .
I have a few questions ;
Are you going to epoxy these in place like the dude on U-tube did?
 IF so have you already done this to the one you just built & tested?
IF you haven't done so just yet , how hard is it to mock up another rig like the one you did for the 6 loops?
Can you post a pic of the magnet layout too plz?

IN your newest reply, the offsets are about right. BUT , let's get a few other items out of the way before going any further.

Many Thanks
Bruce S

[Adriaan Kragten]

A picture says more than 1000 words. So I have made a picture of a 2-phase winding for a 12-pole armature with circular magnets and added this as an attachment. The winding has radial parts for the part for which it is overlapped by the magnets. This is done because you get the highest voltage in a wire when the wire is moving perpendicular to the direction of the magnetic field. The angle in between the heart of two adjacent magnets is 30°. The angle in between the legs of the phases V and U is 15°.

[BBT723]

Bruce: I have not casted the coil yet as I haven't made a confident decision on how best achieve the 3 phase coil set up.  I intend to make at least 2 more wave coils but haven't had the time.  I will most likely have to order additional wire as well.  I will take a pic of the magnets tonight and post it!

Adriaan: Ahhhhhhhhhh,  I didn't think about having straight legs because I was so concerned that the overall circumference of the coil would make the diameter too big for my jig! lol

[Adriaan Kragten]

Bruce: I have not casted the coil yet as I haven't made a confident decision on how best achieve the 3 phase coil set up.  I intend to make at least 2 more wave coils but haven't had the time.  I will most likely have to order additional wire as well.  I will take a pic of the magnets tonight and post it!

Adriaan: Ahhhhhhhhhh,  I didn't think about having straight legs because I was so concerned that the overall circumference of the coil would make the diameter too big for my jig! lol

Pure radial straight legs give the highest voltage but it is allowed to deviate slightly from the optimum geometry if you can get more copper in the available space. In figure 5 of KD 341, I give the optimum geometry for a 1-layer, 3-phase winding of an 8-pole PM-generator in the upper picture but a slightly modified winding with thicker coil bundles in the lower picture. This figure is added as an attachment.



 

[MattM]

I'd argue that you could save a lot of coil by keeping focus on the radial wires, those running from the center out and from outside to center.  Fat coils are going to add capacitance, cost more, and perform very similar.  Each side of your coil can literally be considered a spoke of a wheel.  Skinny coils and fat coils, as long as the radial line lengths are the same, should perform nearly identical.  If your magnets are on dual rotors - both sides of the coils - then you could even lay the coils on their sides so half faces forward, and half to the back; and they will still work because the key is the radial alignment of the wire and proximity to their magnetic field as they move past the coil.

I've seen people on the internet do single magnetic rotors and dual stators.  I'm not sure which is better, dual rotors or dual stators.  But its your project in this thread we are here to see and we enjoy your sharing!

Edit: removed example to avoid debate with Adrian.  Literally he's disputing how an armature works but this isn't the place for it.

[joestue]

capacitance doesn't matter.

given the ratio of copper to magnet cost, more copper=better. almost always, provided its in the right place to generate more volts than resistance.

[Adriaan Kragten]

I'd argue that you could save a lot of coil by keeping focus on the radial wires, those running from the center out and from outside to center.  Fat coils are going to add capacitance, cost more, and perform very similar.  Each side of your coil can literally be considered a spoke of a wheel.  Skinny coils and fat coils, as long as the radial line lengths are the same, should perform nearly identical.  If your magnets are on dual rotors - both sides of the coils - then you could even lay the coils on their sides so half faces forward, and half to the back; and they will still work because the key is the radial alignment of the wire and proximity to their magnetic field as they move past the coil.

I've seen people on the internet do single magnetic rotors and dual stators.  I'm not sure which is better, dual rotors or dual stators.  But its your project in this thread we are here to see and we enjoy your sharing!

Here's an unorthodox design that minimizes copper:
(Attachment Link)

To my opinion, this winding is completely wrong. The winding has a left leg and a right leg seen in the cross section. The voltage generated in the left leg has the same direction as the voltage generated in the right leg because both legs are in the same magnetic field. So the currents will also have the same direction and so the final current is zero. For a circulating current, the current in the right leg should be flowing outwards if the current in the left part is flowing inwards or opposite if the magnetic field has an opposite direction.

For a normal winding as given in figure 5 of KD 341, the left leg of coil U1 is opposite to a north pole and the right leg of coil U1 is opposite to a south pole. So if the current is flowing outwards in the left leg, it is flowing inwards in the right leg and this results in a circulating current.

Another point is that you don't get a 3-phase winding by using three different colors for the coils. You only get a 3-phase winding if there is a shift in between the coil pattern of each of the three phases which is 1/3 or 2/3 of the angle in between two north poles.

[BBT723]

Here is a pic of the magnet setup on my rotor.  They are just screwed to a .25 wooden disc I got from a store.  I will eventually put them on a steel disc but I haven't gotten that far yet!

[Bruce S]

Thanks for posting the pic!!
I may have missed it in one of the posts, but what is the gauge of the wire you are using? 18ga?

Thanks
Bruce S

[BBT723]

A picture says more than 1000 words. So I have made a picture of a 2-phase winding for a 12-pole armature with circular magnets and added this as an attachment. The winding has radial parts for the part for which it is overlapped by the magnets. This is done because you get the highest voltage in a wire when the wire is moving perpendicular to the direction of the magnetic field. The angle in between the heart of two adjacent magnets is 30°. The angle in between the legs of the phases V and U is 15°.

(Attachment Link)

Will the revised layout shown below satisfy the straight leg requirement?

[BBT723]

Thanks for posting the pic!!
I may have missed it in one of the posts, but what is the gauge of the wire you are using? 18ga?

Thanks
Bruce S

22 gauge!

[SparWeb]

That looks good, BBT

I'd like to show you something else that I think is important and I hope it helps you with this project.  My photo shows the idea BUT I make generators in a very different way, so I don't want this to muddy things up by accident.  I'll attach a photo at the bottom.  Just know that magnetically this motor works EXACTLY the same way your generator will, except it has some differences in the construction, namely it's a radial-flux motor not an axial-flux alternator and it has iron stator teeth.  But for the purposes that I want to show it to you, those differences do not matter.

What I do want to show you in the photo are the windings in bundles, and that they overlap.  Yours will, too.  The bundles do go through slots and while you don't have slots, I think you can guess that lining up the legs of the windings in parallel will make it easier to lay them flat on your axial-flux stator.  Also look at how bundles overlap on each other in the picture, but they are pushed away so that they don't combine into a very thick set of overlapping bundles.  This is important so that the bundles don't scrape your magnets.  You will want to make it possible for your 3 bundles to lay on top of each other without their thicknesses stacking up.

It's hard to tell by just this photo, but that motor is also wave-wound, just like yours.

Watching with interest, good luck!

[SparWeb]

Maybe this is a better way to show it:

[Adriaan Kragten]

A picture says more than 1000 words. So I have made a picture of a 2-phase winding for a 12-pole armature with circular magnets and added this as an attachment. The winding has radial parts for the part for which it is overlapped by the magnets. This is done because you get the highest voltage in a wire when the wire is moving perpendicular to the direction of the magnetic field. The angle in between the heart of two adjacent magnets is 30°. The angle in between the legs of the phases V and U is 15°.

(Attachment Link)

Will the revised layout shown below satisfy the straight leg requirement?
(Attachment Link)

This winding might work but it is still not optimal. For an optimal winding for a 12-pole armature, there must be an angle of 30° in between the radial legs of the winding. Then the voltages generated in both radial legs are in phase to each other and you get the maximum voltage. In an outwards bulge of your winding, the distance in between two radial legs is much smaller than the pitch in between two magnets and so the generated voltages are out of phase.  If you have realized the correct pitch in between the legs at the pitch circle of the magnets, it is no problem if you turn the legs somewhat around a point lying on the pitch circle such that the legs are not exactly radial. This is what I have done in the lower picture of figure 5 of KD 341. It might be that by a little twisting of the legs you can prevent triple overlapping coil heads. The coil heads must lay outside the path of the magnets.

I have made a provisional drawing of a 12-pole winding with perfect radial legs at an angle of 30° with respect to each other for phase U. The coil heads of this winding are bent backwards. If you rotate this winding right hand by 40°, you get the winding of phase V. The coil heads of this winding are not bent. If you rotate the winding of phase V right hand by 40° you get the winding of phase W. The coils heads of this winding are bent forwards. So now there is a radial wire every 10° and the winding is spread evenly over the available space. Nowhere you get triple crossings of the coil heads so the legs can be perfectly radial. My drawing is hand drawn in pencil and so not very accurate but I give a copy of it as attachment. You can make a much nicer computer drawing yourself with three different colors for the phases.

[electrondady1]

this thread has taken on a life of its own  BBT723 .
i hijacked your image to demonstrate MY concept of 2 phase,
it over comes the problem of over lapping conductor,
between  mags in order to keep the stater thickness
 constant.

[Adriaan Kragten]

this thread has taken on a life of its own  BBT723 .
i hijacked your image to demonstrate MY concept of 2 phase,
it over comes the problem of over lapping conductor,
between  mags in order to keep the stater thickness
 constant. (Attachment Link)

This isn't a normal 2-phase winding with a phase angle alpha of 90° in between the phases but a strange 2-phase winding with a phase angle of 180° in between the phases. If you rectify both phases, you get a rectified DC current with the same fluctuation as for a 1-phase winding (see figure 4 report KD 340). Another problem is that now you get crossing coils at the pitch circle of the magnets. There is simply a certain place for the radial part of the coils at this pitch circle and so you can't get more copper at this place than for a 1-phase winding with the double thickness of a coil bundle. The generated voltage is also much lower than for a coil with exactly radial legs for the part of the coil in between the magnets. So I don't see any advantage of this winding above a 1-phase winding. It's only more work and you need two different bridge rectifiers.

For a normal 2-phase winding and for a 3-phase winding, you use the space in between the radial parts of one phase for the other phase or phases and therefore much more copper can be used for a normal 2-phase winding or for a 3-phase winding than for a 1-phase winding or for this strange 2-phase winding with a 180° phase angle. For a normal 2-phase winding, the angle in between the left radial legs of coils of different phases must be 1/4 of the angle in between two north poles (see figure given in one of my earlier posts). For a 3-phase winding, the angle in between the left legs of coils of different phases must be 1/3 or 2/3 of the angle in between two north poles.

For your strange 2-phase winding, both windings compete for the same optimum positions so every winding can have only half the coil thickness as for a 1-phase winding if there is a certain amount of copper at an optimum position. This thinner coil bundles result in smaller coil heads but this isn't an advantage. So you winding may look nicer than my 2-phase winding but that isn't relevant as a winding isn't a piece of art.

[MattM]

Adrian, it is not clear what you are describing.  If I understand you're saying the 2nd and third phases should be 15⁰ out of phase with the previous?

[electrondady1]

"This isn't a normal 2-phase winding" that much is true, its my own design
" but a strange 2-phase winding with a phase angle of 180° in between the phases." strange to you .
"If you rectify both phases, you get a rectified DC current " that is true as well
"can't get more copper at this place than for a 1-phase winding with the double thickness of a coil bundle." this is not true
as instructed , you simply spread the conductor bundles  to twice their width resulting  in and over lap that is the same thickness as the rest.
 1/2+1/2=1
"The generated voltage is also much lower than for a coil with exactly radial legs for the part of the coil" it's just quick sketch to demonstrate the concept.
" I don't see any advantage of this winding above a 1-phase winding.' i think it would double the power output.

[Aamir]

Respected Adrian and Electrodandy1, I am not an expert in 1,2 and 3 phase generators but if the winding shown by electrodandy1 is a 2 phase winding with a phase angle of 180° then it's exactly like a center tapped transformer. We can use a 12v center tapped transformer for 12v, 24v or 12v + 12v dual output. This is same for 2 phase winding of electrodandy1.

 " I don't see any advantage of this winding above a 1-phase winding.' I think it would double the power output.
Yes, it will double the power output.

[Adriaan Kragten]

Adrian, it is not clear what you are describing.  If I understand you're saying the 2nd and third phases should be 15⁰ out of phase with the previous?

There is a difference in between the phase shift of the generated voltages and the phase shift in between the coil patterns. How much difference depends on the number of armature poles and on the number of phases. Assume that the armature has 12 poles. Assume that the angle in between the shift of the voltages is called alpha and that the angle in between the shift of the coil patterns is called beta. If the armature of a 12-pole armature has rotated 60° from a certain starting position, a north pole is at the same position as at the starting position. A full sine wave is generated for this angle of rotation of the armature. So a rotation angle beta = 60° of the armature corresponds to a phase angle alpha = 360°. So a phase angle alpha = 1° corresponds to an angle beta = 1/6°. This means that if you want a phase angle alpha = 90° in between the phases, you need an angle beta = 90 / 6 = 15° for the phase shift in between the coil pattern of the two phases for a 12-pole armature.

For a 2-pole armature, the angle beta is the same as the angle alpha
For a 4-pole armature, the angle beta is half the angle alpha
For a 6-pole armature, the angle beta is 1/3 of the angle alpha
For an 8-pole armature, the angle beta is 1/4 of the angle alpha
For a 12-pole armature, the angle beta is 1/6 of the angle alpha
For a 16-pole armature, the angle beta is 1/8 of the angle alpha

If you want a 3-phase winding in stead of a normal 2-phase winding with a phase angle of 90°, the phase angle alpha must be 120° in between all three phases. So in this case the angle beta in between the phases must be 120 / 6 = 20° for a 12-pole generator but 120 / 4 = 30° for an 8-pole generator. One gets the same coil pattern if the angle beta is doubled, so if beta = 40° for a 12-pole armature and if beta = 60° for an 8-pole armature. The double angle is always used for a 1-layer, 3-phase winding with separate coils. Figure 5 of report KD 341 shows the 1-layer winding of an 8-pole PM-generator which has six separate coils. In the upper picture, it can be seen that the angle in between the left leg of adjacent coils is 60°.

It may look strange that the phase angle is 90° for a normal 2-phase winding and not 180° but that is because only for a phase angle of 90° you can make a rotating magnetic field for an asynchronous motor. There has been a big struggle in the past in between a DC-grid and an AC-grid and in between a 2-phase AC-grid and a 3-phase AC-grid. Finally the 3-phase AC grid has won but there are still towns in America which have a 2-phase AC-grid and for those towns you need 2-phase asynchronous motors. The voltage fluctuation of a normal 2-phase grid is given in figure 13 of my report KD 340.

I still insist that you get only doubling of the power for a 2-phase winding for which you have 90° phase shift of the voltages in between the phases. For such a winding you use positions of the wires every 15° for a 12-pole armature. Therefore you can use the double amount of copper than for a 1-phase winding. For a 2-phase winding with 180° phase shift of the voltages in between the phases, both phases compete for the same optimal positions at every 30° and therefore every coil can have only half the amount of copper as for a 1-phase winding. But if people don't agree with my conclusion, I can't help them.

[MattM]

The 20º shifts for the 3 phase are much better.  This is an illustration. 

Likewise, the 15º shifts for the 2 phase are much better.

Not the prettiest illustrations but they demonstrate what Adrian is saying.

[Mary B]

Respected Adrian and Electrodandy1, I am not an expert in 1,2 and 3 phase generators but if the winding shown by electrodandy1 is a 2 phase winding with a phase angle of 180° then it's exactly like a center tapped transformer. We can use a 12v center tapped transformer for 12v, 24v or 12v + 12v dual output. This is same for 2 phase winding of electrodandy1.

 " I don't see any advantage of this winding above a 1-phase winding.' I think it would double the power output.
Yes, it will double the power output.

(Attachment Link)

(Attachment Link)

(Attachment Link)

I have a sneaking suspicion this will create a twice per revolution vibration that could tar things apart...

[Adriaan Kragten]

Respected Adrian and Electrodandy1, I am not an expert in 1,2 and 3 phase generators but if the winding shown by electrodandy1 is a 2 phase winding with a phase angle of 180° then it's exactly like a center tapped transformer. We can use a 12v center tapped transformer for 12v, 24v or 12v + 12v dual output. This is same for 2 phase winding of electrodandy1.

 " I don't see any advantage of this winding above a 1-phase winding.' I think it would double the power output.
Yes, it will double the power output.

(Attachment Link)

(Attachment Link)

(Attachment Link)

I have a sneaking suspicion this will create a twice per revolution vibration that could tar things apart...

You are right. This is also a disadvantage of a 1-phase winding or of a 2-phase winding with a phase angle of 180°. Both voltage and current vary about like a sin function and the power therefore varies like a sin^2 function (see figure 2 KD 340). This gives strong torque fluctuations which can give resonance and can make the generator rather noisy at high rotational speeds. So to limit vibrations, it is better to use a 3-phase winding.

[MattM]

The only way to break resonance is to have unique distances for every sequence of repetitions.  Think how expensive tires with quiet treads are different than cheap tires that hum.  Asymmetrical patterns, non-repeating patterns, odd number of segments, and variable-lengths in each segment.  Much more complicated than it sounds.

[electrondady1]

  so its going to hum? cool.
i guess I've made a musical instrument  that produces electricity

i'll let you know when my new album drops

[Mary B]

The only way to break resonance is to have unique distances for every sequence of repetitions.  Think how expensive tires with quiet treads are different than cheap tires that hum.  Asymmetrical patterns, non-repeating patterns, odd number of segments, and variable-lengths in each segment.  Much more complicated than it sounds.

My thought was this would create 2 LARGE pulses per revolution versus the many smaller ones from a machine with multiple windings in 3 phase. I may be wrong...

[MattM]

Wouldn't it be 9 pulses every 2 turns?  Still not an ideal resonance.

[Adriaan Kragten]

If you rectify a 3-phase current, you get a DC current with a small peak every phase angle alpha = 60° (see figure 8 report KD 340). So you get six small peaks for one complete sine wave. The number of complete sine waves per revolution depends on the number of armature poles. For an 8-pole armature, you have four complete sine waves per phase per revolution and so you have 6 * 4 = 24 peaks per revolution in the current. A peak in the current also gives a peak in the torque and so you have 24 small torque peaks per revolution. The frequency of these peaks are so high at a reasonable rotational speed, that you will feel nothing of it. I have measured several 4-pole PM-generators made from asynchronous motors which were rectified in star and in delta and for rotational speeds in between 0 and 1500 rpm and never found some resonance.

[MattM]

I thought she was referencing the 2 phase proposal.