axial generator with lamination core

[mbouwer]

It seems important to me now to have a while to consider, build and try to improve my axial generator.
On the forum, and also in my region, I would like to meet more friends who also have that kind of ideas.
It would bring us more capabilities.

Inspiring design of Megawindforce   https://www.megawindforce.com/

[SparWeb]

How will you know what to improve, if you do not test what you have made?
Inspiration and ideas are great for getting you started, and we have seen plenty of them in your story.

Now is the time for proof.  We've all been there.  Having spent so much time building something, that we are afraid to risk its failure.  But if we don't overcome that fear, we will never truly know if it works or not.  The internet is full of talk about ideas that don't work.  You are in that special position of having something real, in your hands, and ready for proof that you CAN make it work.  That is far more satisfying than talking and sharing pictures, in my opinion.

[mbouwer]

The design and making of a generator is rather ambitious for me.
Nevertheless I want to go on because I think I will meet friends with electrical and electronics knowledge.

That is why I also show my progress on Dutch forums as Circuits Online and Ecologieforum.
So far I have no response from others who also want to build a mill.

Meanwhile I want to try to make an improved generator version. 
Later on scaling up is always possible.

[mbouwer]

Now is the time for proof. 

Every coil input and output is connectable
But how do I go further with this stuff?

[mbouwer]

Sparweb and Mmurray70 inspire me to also build a test stand.

[Mary B]

Now is the time for proof. 

Every coil input and output is connectable
But how do I go further with this stuff?

Individually rectify each coil then add them in whatever configuration you please as long as it is balanced(don't add only 1/4 of the coils in one spot, 1/4 of the coils balanced all the way around the stator, think of star and Y connections on steroids!)

[SparWeb]

Even if it's a repetitive exercise, creating a diagram of the coils and grouping them to visualize the connections is very valuable.
Then as you connect them as MaryB says, you will see the possibilities for Star and Delta patterns forming.
There are probably many interesting combinations with what you have built.

[hiker]

Jerry had a few gens with each coil rectified,,   https://www.fieldlines.com/index.php?topic=127282.5;wap2

[MagnetJuice]

mbouwer,
I believe that you have 50 magnets in each of your rotors and 45 coils in the stator. Can you verify if that is correct? If you tell us exactly how many magnets and coils you have, we can tell you how to wire it so you can start spinning that baby and start generating some power.

Like SparWeb said, many of us are itching to see those rotors spinning.

That test stand that you made can be used if it has good bearings, strong bolts and is anchored to a strong table.

If that motor is not DC, you will need a variable frequency drive to vary the speed.

Do you need Inspiration and Motivation?

This is a great quotation from Nikola Tesla:

“I do not think there is any thrill that can go through the human heart like that felt by the inventor as he sees some creation of the brain unfolding to success. Such emotions make a man forget food, sleep, friends, love, everything.”

Ed

[mbouwer]

50 magnets 20x10x5 mm and 45 coils. Like Reply# 61 and 62

I want to reinforce the test stand. But it must not become too heavy.
Then I am able to take it along in case I find someone in Holland who can help me with testing.

[SparWeb]

You are right to look for more reinforcements. 
Do you have welding equipment?  A frame made from steel angles would be ideal. 
That would also offer you ways to make a strong torque arm. 
1 meter is a good length but if it's flexible there will be issues.

[MagnetJuice]

Here is a diagram of the alternator to make it easier to visualize.


The minimum amount of phases that I can see is 9. That is a lot of phases.
Maybe somebody else can come up with a different configuration.

Ed

[SparWeb]

I see it connected with 9 phases, too. 
It should run pretty smoothly.  We'll see what Mbouwer gets when it's hooked up.

[joestue]

for three phases

aa|Ac|CC|cc|Cb|BB|bb|Ba|AA|aa|Ac|CC|cc|Cb|BB|bb|Ba|AA|aa|Ac|CC|cc|Cb|BB|bb|Ba|AA|aa|Ac|CC|cc|Cb|BB|bb|Ba|AA|aa|Ac|CC|cc|Cb|BB|bb|Ba|AA

each of the "|" is a coil. A is one polarity a is the other.

its a pretty simple repeating pattern. 5 sets per phase of 3 coils in series. if you get the polarity wrong on one coil you'll just have a reduced voltage in that set. since you have 5 sets of 3 coils in series, you only have one option for voltage: star or delta. (5 being both odd and prime)


there is a chance you could connect each set of 3 coils in series.. in parallel, you would have 1/5th the voltage.. and potentially a lot of recirculating current.

https://www.emetor.com/windings/

[mbouwer]

On schedule from Skylar/Felix Niessen    http://www.bavaria-direct.co.za/scheme/calculator/
The winding scheme is now:   AaABbBCcCAaABbBCcCAaABbBCcCAaABbBCcCAaABbBCcC

[MagnetJuice]

Well, it looks like you have the wiring all figured out.
If you need help with anything just ask.

When you got 50 Volts at 60 RPM last summer, how did you had it wired?

Ed

[mbouwer]

Starpoint:   A 1 in + B 4 in + C 7 in

[mbouwer]

A few reinforcements and a new drive shaft with safety coupling for the test-rig.

[MagnetJuice]

It is good to see that you are pursuing the testing of this alternator. The results of the testing will be educational to you and also to the rest of us.

With the wiring scheme that you showed, 15 coils will be connected in series. At 1.2 ohms per coil, that is 18 ohms of resistance per phase. That will produce a lot of heat in the stator.

Later you might want to consider an alternative way of wiring the stator to lower the resistance. Maybe connecting some coils in parallel after they have been individually rectified to avoid parasitic currents.

A parallel wiring of the coils will produce a lower voltage, so it has to turn at a higher RPM. But since there are so many coils producing voltage, you might get a usable voltage at a reasonable RPM.

Ed

[SparWeb]

Looking at the test setup, I would like to ask why do you want the drive shaft to be so long?  Long thin shafts develop move vibrations than short ones.

I also hope to see the final mounting of the drive motor and generator will put their axes in alignment with each other.

[mbouwer]

@MagnetJuice,
Now for these 45 coils the average measure is 0.8  Ω  per coil
and 13 Ω  per phase.

@SparWeb,
With this length of shaft I wanted to show a clear separation between the drive and the generator.

[mbouwer]

At 100 rpm I measure 72.5 volts between the phases and 41 volts between the phase and the 0
How to exploit this?

[Adriaan Kragten]

Assume we have a 3-phase winding connected in star. Assume you measure a certain open AC voltage U in between the star point and one of the open phase wires. If the coil bundles of all three phases are identical, you should measure the same voltage for every phase. However, if you measure the voltage in between the phases it will be a factor square root of three higher than the phase voltage. So now you measure the voltage over two coil bundles connected in series. The voltage is not a factor 2 higher because there is a phase angle of 120° in between the sinusoidal voltages generated in each phase.

In The Netherlands we have a 3-phase grid connected in star. The voltage in between the star point and a phase is 230 V and the voltage in between the phases is about 400 V (398.37 V). The difference is just the same factor square root of 3. What you have measured is about in accordance to this rule.

[Bruce S]

It's good to you're getting readings from the mill.

Do you have the setup to also start getting Amps?

My best guess is it's going to be a high voltage low current mill.
This can be a good thing with regards to wire sizes for power distribution.

Keep going!

Cheers!
Bruce S
 

[MagnetJuice]

That is a good setup to estimate the power output. Find a resistor of between 30 and 50 ohms and use it for the load and measure the Amps. The resistor should be able to dissipate at least 100 Watts.

If a resistor like that is hard to find, you can use nichrome wire from the heating element of a heater or a hair dryer. The resistance of nichrome wire doesn't change a lot with the increase in temperature.

An incandescent light bulb is not good to use for this purpose because the temperature coefficient of the tungsten element is high. That means that the resistance is going to increase too much with temperature to get accurate readings. You want a known resistance value so that you can more accurately predict the alternator output.

And because the wire of those coils is so thin, make sure to MONITOR THE TEMPERATURE OF THE STATOR. You don't want to exceed their current limit and burn it up.

Keep up the good work!

Ed

[Bruce S]

MagnetJiuce

Is correct, I cut the wire out of trashed toasters and use those.
Depending on what you're doing, they and the stator can get toasty quickly.

Keep Going

Bruce S

[mbouwer]

To be able to work on the blade adjustment I want to go on with a more realistic test setup on the upper part of the mast.

[SparWeb]

Setting the blade pitch requires knowledge of the generator's load characteristics.  I still believe you should test your generator first.

[mbouwer]

You are right. But electrical is not my field and I do'nt want to ruin my generator.
So I am searching for expertise around here.
Meanwhile I can work on the hardware for blade suspension.

[midwoud1]

With a bridge rectifier and a load you can see more.

[MagnetJuice]

You said:

“But electrical is not my field and I don't want to ruin my generator.
So I am searching for expertise around here”

I'm glad you said that, because now we have a better idea about what to do to help.

That's OK, nobody can be good at everything. You are very talented. I have never seen anybody that can build all kind of parts as fast as you do.

To try to help you with the testing of your Alternator, I put together an image with the setup that you can use and some numbers to guide you along.

I decided to get this image instead of trying to describe the procedure with words. That could have been confusing. Somebody said: “A picture is worth a thousand words” I don't have time for that many words right now. (My coffee would get cold)

To make sure that you don't damage your alternator, keep your current below 2 amps.
Those coils can safely handle that load. Because they have an iron core, some of the heat will be absorbed by the core so you'll be OK.

You can use a setup with bulbs as shown by midwoud, but like I said in my previous post, you can get a more accurate power estimate by using a power resistor for the load. Try to find a resistor with a resistance of between 40 and 80 ohms and with a rating of 100 watts for the initial tests.

As for the rectifiers, those 3-phase ones are not easy to find and cost more than a regular bridge.
If you can get a 3-phase as shown by midwoud fine; if not, use 3 singles as shown on the picture. 10 amp rectifiers will be adequate. 25 amp will be overkill but they are found cheap in many places.



If your tests are successful and the stator doesn't get too warm, then later you can try to increase the load to something in the range of 20 ohms. And make sure that you increase the RPM slowly.

Judging by the size and number of magnets, I estimate that alternator can produce around 200 watts or a bit more. That is if the construction is strong and the air gap is not too wide.

If you cannot get the right size and value of a resistor, you can combine resistors in series, parallel or both to get the value and power that you need.

[MagnetJuice]

I forgot to tell you about the 59 Volts shown on the table. I chose that voltage because I know that the alternator can produce that much and 59 Volts would be ideal to charge a bank of 48 Volts battery.

But don't worry about trying to get 59 Volts, get whatever you can get.

Ed

[mbouwer]

Very usefull information, but regarding the generator
allow me to stop for a moment, and focus on a matching blade suspension.

New arm with slide bearing  ø 72 mm and SS bolt M 12