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BarkyJ
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Posted: 20 May 2018 at 8:19pm | IP Logged Quote BarkyJ

Hi Dave

I tried to delete the first post, but cant.
I removed the image from my host, and its still there. I cant even edit the post now - which is really strange.

I dont get your comment of me editing a perfectly good image, I am trying to figure out how to wire in delta, so whether I draw one from scratch or I modify one, putting on it here will have the same result if its incorrect. Maybe you are referring to my first image only, you might have started posting when that appeared, rather than after seeing my 2nd post?

My 2nd image is correct, yes?
If someone can delete the first image post, that would be appreciated.

Thanks for the info on the blades etc. The materials I have allow me to make up to 1.5m, but if you think I should go smaller, then that is no problem.

With dual stator 4x3C Delta, if I can start applying load from 20V, then that is all good.
I assumed that if my load is enough to take all the power the windmill can generate, then it would have a similar effect as a battery in some ways, and I could essentially clamp the voltage to about 48VDC by simply raising and lowering the PWM, ie the load the stator sees.

Quote:
Your system is trying to emulate what I've already achieved utilising a form of MPPT using PWM to switch a high power resistive load to heat water.

So what I am doing is achievable then? Did you aim to try and keep your voltage at a set level, or were you focusing on another parameter such as Power? You were clamping the voltage with the load I assume?

Side question. The speed sensors on the F&P stator. I had assumed that with a 15VDC Powersupply, the output was going to be 15V pulses, however from what I can tell they are ragged looking TTL 5V pulse of sorts. So my current divider to reduce the voltage is wrong. The divider I have seems to load the sensor, and the output drops to about 500mV P-P, which is unusable. Even connecting it directly to my controller it is not happy and cant count the pulses.
Are these designed to have a pull up or pull down on the output phase line, or is some other circuitry required to use it?
Phase 2 output is better looking than Phase 1. Potentially this speed sensor is faulty, I have a few others I can try though.

Attached is a pic of the output I see, unloaded.
And then one of my test setup.





Thanks again


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BarkyJ
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Posted: 20 May 2018 at 8:25pm | IP Logged Quote BarkyJ

Regarding mechanical furling, yes that is the plan. I still have to read up more on this subject, but I have seen videos of other peoples solutions, and then Gizmos plans for his single stator build.
I have contemplated having a motor driven angle system, and using external wind direction sensors to point the windmill into the wind. If things get out of spec, have it turn out of the wind slightly or fully etc. But I am still thinking all this over.

Regarding blade design, I am still to finalise this also, I put the pipe I have into Solidworks and have cut out a basic shape in software, and played with angles of cut to give the blades curve etc, but still yet to figure out if it will have any advantage or not. The exact shape is still very much to be finalised, that will come in time. I have enough material to cut a dozen blades, so I can make all shapes and sizes and experiment potentially.

Thanks
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BarkyJ
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Posted: 20 May 2018 at 9:43pm | IP Logged Quote BarkyJ

Phase 1 of the RPM sensor were spikes up to 5V, and this I was able to read, but it doesn't look right.
Phase 2 is as above, squarish waves, but output seems very variable in terms of amplitude, sometimes going to 4V, often only getting to 2V, so this is not reliable for reading.
Phase 3 is a lovely square wave, 5.5V P-P or so.

So potentially Phase 1 and Phase 2 outputs are no good, but Phase 3 looks encouraging. I can read this one correctly.






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DaveP68
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Posted: 21 May 2018 at 6:58am | IP Logged Quote DaveP68

The drawing looks correct now. As per my photo of the 6x2C Delta I don't wire them the way you have drawn it. The reason for my wiring system is for electrical symmetry with all currents flowing equally, as all resistances are also equal (down to milliohms).

As for the RPS waveform the phase 3 signal is what you're after. Remember I did say you only need 1 phase output to measure RPM.

It's likely that RPS unit you picked to test is faulty as they have a high failure rate (1 in 4) in the field over time.

I'm sure you have another RPS unit of the same type you can also try out.
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BarkyJ
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Posted: 21 May 2018 at 7:43am | IP Logged Quote BarkyJ

Hi Dave

Yep I was only using 1 output, however the 1st two I tried were not looking great, however the 3rd one looks good, so am using that one.
I have 2 more RPM sensors so might change one out, as if this one has 2 failed channels then likely the 3rd wont be far away.

I will try and study your picture some more for the balanced wiring, however really struggling to see the detail at that resolution. I think I get the idea of what you are talking about though.

Would love to hear more about your 'solution' to the torque problem, and the external modifications.

Thanks

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BarkyJ
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Posted: 21 May 2018 at 6:01pm | IP Logged Quote BarkyJ

Just wanted to share a test I did.

This is still the same Star 2x6C stator, 36 pole with black cap.

So I have a test load of 26ohm on my FET, PWM controlled to attempt to maintain a voltage around 32VDC at this stage.
You can see in the video as I increase the speed the voltage comes up to set point and then load then starts to increase. RPM continues to increase, as does load, as done current and power, until near 100% load.

So this test works, however I dont believe it to be the best way to get the most amount of power, based on previous posts.

Here is the video: https://youtu.be/GVbN3XEnHKU

So Dave, based on what you were saying.
If I do 4X3C Delta, then in theory I can start adding load from about 20V at about the 110-140RPM mark. Peak power will then be around 45V at around the 500RPM mark. Have I understood that correctly?

If I then do dual stator, both 4x3C Delta, at 110-140RPM around 20V, I should expect to see 1 to 1.5A, and then 500RPM around 45V, I should expect to see around 22A. Correct?

With my current Star 2X6C configuration, I would expect peak current to be around the 2.9A mark before the stator starts saturating, and if I am limited to 45VDC then my peak power is only going to be in the 100-200W range, so really its not an ideal configuration for what I want to achieve. Correct?

So I should rewire to Delta 4x3C and then continue my testing with the controller to instead of controlling to a set voltage (32VDC in the video), I should try and control power based on RPM and voltage, in order to make the most out of the power produced.

I hope I have grabbed the correct pieces of information there, as this sounds really good.

Edited by BarkyJ on 21 May 2018 at 6:03pm
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DaveP68
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Posted: 21 May 2018 at 8:56pm | IP Logged Quote DaveP68

Good progress so far and did also watch the YouTube video.

You keep stating the term fixed voltage. That's not the end game as such and I do understand the power MOSFET is limited to 60 V max.

Here is what I pointed out on page 3 of this topic which you may have missed.

DaveP68 wrote:
One extra point of note, the working output voltage of an F&P stator must rise in proportion to RPM and the current needs to increase at a rate of 2x RPM. This is also known as Maximum Power Point Tracking. This is the most efficient way to extract electrical energy out of any wind turbine.


You should be safe to let the working voltage rise to a maximum of 55 VDC if required to keep everything under control.

The cut in voltage is expected to be around 20 VDC and you should be able to take 1 to 1.5 Amps at that point without stall the blades.

The 45 VDC at 22 Amps is an expected high end set of numbers but doesn't mean it will be it's maximum output, that is dependent the upper wind speed.

This is a graph of Torque vs RPM on a set of GOE 222 blades 3 m diameter TSR 5.7



Note the Torque range is from around 2.5 Nm all the way up to 39 Nm. I suspect your blades will have a higher TSR of 7 to 7.5 so upper RPM will be around 500 with Torque being about 25 Nm.

Here is another graph of Wind Power vs RPM, note the RPM is linear and the power follow the cube law of the wind speed.



This is exactly what MPPT is trying to achieve.

On a separate note you asked about how to boost the power output of F&P stators. This can be done using resonance capacitors and is best done on at high voltage to keep the capacitor size to a minimum.

Capacitors I've used in Delta mode, 3 sets of 6 uF (12x 0.47 uF) AC rated at 305 V.



A graph of the difference in power output with them added 852W at 375 RPM and without 390 W at 375 RPM.



The resonance capacitors over double the output power by increasing the working voltage. They also over double the amount of torque the stator can take.

There is a small drop in output efficiency but that is of no concern at they only operate at high power levels where there is power to burn

At low to medium power levels the stator efficiency remains > 80 %.

There is a catch, if the RPM is able to go to high and go past the peak resonance point the Torque will start to drop off again.

The idea is to always stay on the low side of peak resonance which can provide up to a 2.75 times gain in power. Plenty of head room to stay safe anyway.
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BarkyJ
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Posted: 21 May 2018 at 9:00pm | IP Logged Quote BarkyJ

Dave, sorry more questions.

I have mapped out your photo now, and I get what you have done - finally.
However for 4x3C I am unsure how the pattern goes.

Around yours, following your wiring colours, you go:
RED, BLUE, YELLOW, YELLOW, RED, BLUE - all the way around, where RED goes to RED, YELLOW goes to YELLOW, and BLUE goes to BLUE (in the coloured wires). I can see the copper is swapping phase colours as you explained - that is all good.

For 4x3C, what is the colour pattern equivalent as you go around?

Thanks
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BarkyJ
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Posted: 21 May 2018 at 9:27pm | IP Logged Quote BarkyJ

Wow Dave, thanks for that last post. I will read that a few times and absorb it all.

Your cap system, is that something similar to what is on here, or quite different?
https://www.thebackshed.com/windmill/articles/GordonsCapMod.asp

These caps you connect to the 3 phases of the stator, before the rectifier I am guessing, and are connected all the time yes?
I wont do this immediately, but it sounds truly awesome how you are making the most of this.
Are they something like this?
https://www.aliexpress.com/item/Free-Shipping-10PCS-NR3010-180M-18UH-3010-SWPA3010-SMD-Glue-inductance/32785406144.html
You have them wired in Delta you said? Can you take a photo of the back of the board? Very interested :)

Going back to your comment above about the voltage. If my 60V FET's are going to be an issue here, I can look for something with a higher rating. I guess my concern is just handling what comes out and putting it to work. What would be the peak voltage ideally that you think this would output, and have you used this directly into a resistive load, or would it be best to put this into an inverter or something which can take a range of input voltages? As mentioned I just want to dump into hot water to start with, but going into something like an inverter would be very neat down the track.

Then if you add your Capacitor setup into the mix, the output voltage would go up even higher, so Im guessing the answer will be that I should hunt for a better FET or IGBT etc...

Now to read your post a few more times and figure out what my next move is.

Thank you so much for sharing all this
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DaveP68
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Posted: 22 May 2018 at 6:22am | IP Logged Quote DaveP68

Camera failed the other day that I usually take photo's with.

The wiring isn't in a ring as per your drawing, that's only done on Star configurations not Delta.

the Delta wiring per set "each of 2x poles" loop from R-B, B-Y, Y-R. Then each group of 6x sets of 2 coils is then "all wired in parallel" to the termination point.

Carefully look at the picture and it will become clear to you.

Go high voltage AC with a Delta 1x12C stator wiring problem solved...
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BarkyJ
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Posted: 22 May 2018 at 6:34am | IP Logged Quote BarkyJ

Hi Dave

Yes I was referring to your photo in my statement. I know its not in a ring like the drawing I did is. I am referring to your photo and the wiring colours as you go around the outside, not of the poles themselves.
So when you go around the outside of your photo, the WIRE colours you have used go R, B, Y, Y, R, B and then repeat.
When looking at the original pole colours, I can see its R-B, B-Y, Y-R like you said.

My question is, what is the configuration when its in 4X3C Delta instead?
Does each set of 3x poles loop from R-B-Y, B-Y-R, Y-R-B this time? or something like that?

I can see how your photo is wired, I just am not sure how it translates into 4X3C delta now.

Quote:
Go high voltage AC with a Delta 1x12C stator wiring problem solved...

Sorry I dont understand what this is referring to.

Thanks
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BarkyJ
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Posted: 22 May 2018 at 8:43am | IP Logged Quote BarkyJ

Ok I think I have clicked as to how to do it... I think.

Drew it by hand using a blanked template. The colours didnt scan that well sorry of the hand drawn wires, but I hope its visible enough.

Click on the image to make it bigger:


Can you please confirm if this is correct.
Thanks
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