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ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 03:14am 14 Aug 2024
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Many here know, with the help of forum members I built an inverter specific for my homemade, neo magnet generator. Works Great ...., having a blast with it ! Hopefully some can help me with another problem. In doing solar, many must be familiar with adding multiple power sources together and the associated headaches involved. I realize right off, this is comparing apples to oranges, but here is my problem in the nutshell. My neo mag "alternator" has 12 coil outputs. I have many coils/core selections to produce many different voltages. I`ll use these simple ones for discussion. A single coil will output 48vac @ approx. 1 amp. Normally I test 2 opposing coils together, as this greatly increases the output. So, ... (2) coils, in series and adding a 5uf run cap will output up to 135vac @ approx. 2 amps under a load of (2) 90 watt flood lights fully lite. Coils can be added in "series" to achieve the required voltage. In most cases they will add up accordingly with some loses. Depending on speed and cap size this can be anywhere from 300 to 500 Hz. So many variables can affect accurate measurements, especially amp readings and precise readings are difficult. So..., adding coils in series works pretty well with some loses,... but adding in parallel is a real issue. In theory, 12 coils should add up to 10 - 12 amps but in reality, I never gets much over 4 or 5 amps. So, while a single coil, (or pair) makes a beautiful sine wave on a scope, add in more and it becomes quite chaotic and always a problem with AC, as with the power grid being a fine example. Now you would think converting to DC and adding a Full Wave Bridge Rectifier to each coil might be an answer. For whatever reason, you can`t use a AC run caps any more before the bridges, so that's a really choppy output right off, but with a 1000uf DC cap at the inverter input you can make it work, which is how I run my inverter. But there is still great loses (amps) and the DC waveform, at the cap, on a scope can appear sawtooth and far from smooth. Hoping some here can help me figure out how to combine my coil outputs without losing so many amps. I will provide answers to all questions any one has as this is getting pretty long. Not looking for anyone to solve my problems, just some ideas and things to try. Thanks
phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2129
Posted: 03:54am 14 Aug 2024
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Many decades ago had a similar issue with a small experimental wind turbine. The problem with the bridge rectifier outputs in parallel is that at any instant only the coil with the highest voltage will deliver any current. The ones with a lower voltage can't drive any current into a higher voltage.
On mine I reconnected the rectifier outputs in series, each with it's own capacitor across its output. Now the current was a little less but the voltage was the sum of the individual voltages. Now too high for the battery so used a buck converter to reduce it and increase the current.
The end result was significantly more power. Edited 2024-08-14 13:59 by phil99
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 03:24pm 14 Aug 2024
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I`ve always assumed something like that was happening. I have read that lower producing coils actually "sink" power, like the lowest battery in a group. I know there are companies that specialize in this, usually for large commercial applications. Haven`t been able to figure out how they do it.
Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 453
Posted: 08:30am 15 Aug 2024
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Is your alternator connected as single or three phase? If it is three phase connected then try changing the start point of each phase. In a normal electric motor or generator the phases start at the first coil, then the next phase starts after missing one coil group, then the next phase start is after another missed coil group. If you don't miss a coil or group of coils then your phases are not 120 degrees apart and the motor or alternator will not function. I am thinking that your phase relationships are out and you are not getting sine waveforms on each phase. good luck Pete
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 04:20pm 15 Aug 2024
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OK, lets talk about this. I`m happy to explain the inner working of my project. The rotor has 24 neo mags alternating North, South. All coils are precise lined up with the opposing coil on the other side and all coils hit at the same time, North then South, then North est. so in that respect it would be single phase, I guess ?? or 6 phase depending on how you look at it. (or maybe 12). All coils can be independent or as I usually test, 2 opposing each other as long as they are properly connected. Best output for 2 coils is always opposing each other. Otherwise, they can be connected together any way you like (I think I have tried them all) keeping in mind that while 6 coils on one side are being simultaneously hit with North the other side is being hit with South. If you just connect all coil outputs together it will show a perfect sine wave on a scope. It is just messy, fuzzy and hard to keep steady as you would expect it to be. Like I said earlier, there are so many variables to consider. Even a few RPMs will change it all, not to mention that all coils are not perfect, cores may vary a little. Rotor to core distance may vary slightly. This is a big one as this can greatly change the voltage output. Even if a core vibrates a little inside a coil it can cause a wild spike. Now consider that with neo magnets this machine creates a lot more "reactive" power than most gens. I said on my inverter thread that it is prone to wild mood swings. Thats because just about anything you add to the circuit causes unexpected effects. Especially caps. You have to watch caps. I have blown untold multimeters and light bulbs. Sorry to rant, but yes, I expect there is phase shift problems and lets not forget is all running at about 300 - 500 Hz. Help me sort it all out because it can be an incredibly efficient generator. Opps, alternator. Sorry
Godoh Guru Joined: 26/09/2020 Location: AustraliaPosts: 453
Posted: 09:05am 16 Aug 2024
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The alternator you have built seems very complicated. It seems to me that using a normal three phase electric motor and turning it into an induction generator would been much easier. I don't understand how your alternator is producing sine wave outputs. Usually the pole pieces have to be shaped with a curve on the edges to produce a sinewave. It is hard to see but it looks like the white cups with the bolts are where each coil sits. So maybe you could try connecting the coils so that they alternate, so One coil north on one side connected to the next south coil in the direction of rotation Then continue on like that. Unfortunately I am used to working with electric motors and alternators that are designed totally differently. Sorry I don't have the answers you are looking for Pete
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 03:56pm 16 Aug 2024
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Maybe a few pics will help. Here 2 coils are connected as you describe and the resulting output and scope shot. Load is 195 watts. Also a few types of coils I use. Doubt you can see the settings on the scope but were approx. 550Hz.
Edited 2024-08-17 02:50 by ramblin
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 04:50pm 16 Aug 2024
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Sorry for the delay... We been having some internet problems . Try these..
Edited 2024-08-17 12:38 by ramblin
Bryan1 Guru Joined: 22/02/2006 Location: AustraliaPosts: 1343
Posted: 05:43am 17 Aug 2024
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The first question to ask what size motor are you driving with ? as reality really does bite as the output power will always be less than the input power.
phil99 Guru Joined: 11/02/2018 Location: AustraliaPosts: 2129
Posted: 07:19am 17 Aug 2024
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What material are the coil cores made of? If solid iron the efficiency will be low, if powdered iron the cross-section seems too small compared to the diameter of the coil. There doesn't appear to be a laminated iron yoke to complete the magnetic circuit between the free ends of the cores.
Conventional generator designs are the result of almost 150 years scientific research and engineering development by many thousands of people. This has resulted in reliable, predictable and energy efficient machines (98.7% for the biggest ones).
I think it will be difficult to achieve stability and efficiency with this design.
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 02:47pm 17 Aug 2024
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Nothing fancy going on with the drive motor. It capable of variable speeds up to 3200 RPMs which is way more than ever necessary. Just a means of critical speed control and indoor testing. Not looking to break any law of physics here.
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 03:22pm 17 Aug 2024
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You are correct, iron is not efficient and causes a lot of drag. Core material is what we have researched the most and is a key factor. I have experimented with the iron yoke with little results on this machine. It played a larger roll in my early designs when rotor mags were all N on one side and S on the other. Now you are correct, stability has always been a big issue to overcome. Efficiency, however, I would argue can be very high. Conventional it is not and one of the reasons I picked up the project. Neo mags are remarkable things and are becoming stronger and more affordable. Many experimenters are playing with smaller, slower versions of this and having great results. I`m told this is has been employed in experimental windmills (might be why I see so many burn to the ground). I thought this project might be of some interest to the windmill guys here. My biggest issue lately has been combining the inputs and getting all the available amp out of it. Really need some guidance there.
And besides, wheres all the fun in conventional ! Edited 2024-08-18 03:02 by ramblin
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 10:27pm 17 Aug 2024
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OK, here is a test I just did based on phil99s reply: I have 6 low power coils that are all the same. Each one produce about 53-54VAC @ about an 1 amp. Connected a FWBR to each and then connected all in Series and installed in the machine. Now I can add/remove each "core" while running and effectively stop output. Now all 6 coils are connected in series so there is some resistance. But a single core placed in ANY coil will output approx. 33-34vdc. When a core is added to each coil it will add up accordingly to approx. 210-215vdc, slightly more than you might expect. NOW, add a 500watt heat lamp as a load. With 1 output and a DC amp meter will show 1.2 amps. Add in all 6 outputs will show only 1.6-1.7 amps. The bulb will only glow slightly more orange with all 6 outputs. This test was done without any DC caps added but from experience, this would greatly increase the voltage. I would expect the 500watt halogen would light brightly (even DC) or maybe even blow. This is what I am seeing.
jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 84
Posted: 06:53am 29 Sep 2024
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Lets get down to basics
you should have 3 pair of poles set at 120 deg for the stator
the rotor should have 3 pairs of poles set at 120deg
the stator poles should be in series and polarised correctly
use a magnet and an analogue meter across the 2 coils to check
if you sweep a N Pole across one coil note the deflection then sweep a S pole across the other one IN THE SAME DIRECTION the deflection should be the same ;
you will now have a 3 phase generator
connect one the end of the coils to make a star point.
The frequency will be NP/60 N no of pairs of poles N RPM
As the magnetic N pole passes the coil the end will go positive then when the S pole passes will go negative, What the wave form will be I don't know
to get dc you will need a pair of suitably rated diodes back to back from pos and negative busses you can add capacitors here if required
Not sure how the magnetic field is set up Just relying on the magnets sweeping past the poles would not be the best, the field should be closed as much as possible
There are some good videos on Mr Google "How does an alternator work"
best of luck I hope this helps
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 04:39pm 29 Sep 2024
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Appreciate this info but I`m afraid not much of this applies as this is an experimental design. Let assume for argument sake we have 6 separate outputs (coils) and they are all in perfect phase with each other and all polarities are correct. Now we have a single coil that will output 120vac @ 2 amps. If we add another identical coil just sitting on the bench to the output it becomes a load (resistance) and voltage drops. Now place this coil in the machine and it outputs 120vac @ 2 amps. Now assuming everything is in perfect phase we should have 120vac with available 4 amps. Am I correct in my thinking? Because we do not get 4 amps. The additional coil is still a load and we only get around 1/4 amp additional. I have been able to overcome this problem by adding isolation transformers to the outputs and I get my 4 amps. But this is a long way to go and it seems there must be a better way. Forgive me. I realize this is a crude analogy on my own words but its the only way I know how to explain it. The problem is combining the outputs and getting all available power out.
jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 84
Posted: 02:02am 30 Sep 2024
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maybe I dont understand what you are trying to do
Looking at the photos I can see a shaft I assume inside the box is a disc with magnets attached If this is correct and you connect all the coils in series the induced currents will all be out of phase' re 2nd para If you have two coils in the machine and they are correctly polarised you will get 120 v on each ie 240 v but still 4 amps When you put the other 4 coils in the machine you will get the same voltages but out of phase by 120 deg each This does not matter when you rectify the 3 outputs
I am surprised that you get 4 amps as the magnetic field is not closed. If you look inside any induction motor or alternator you will see that the stator has a magnetic core and so has the rotor and a small air gap between the two . To get this to work you need to close the magnetic path to approx 1 mm If you try mild steel you will have a lot of losses due to eddy currents generated by the ac and put a lot of load on the driver . In motors and generators the magnetic field comprise of laminations of electrical steel. these are 12 thou thick and insulated on each surface to block eddy currents
nickskethisniks Guru Joined: 17/10/2017 Location: BelgiumPosts: 458
Posted: 04:52pm 02 Oct 2024
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Ok, things that might help:
If it's a single phase alternator:
* Check magnets alternating N/S
* A little shifted angle is to be expected, so this can lead to voltage loss.
* Match your load, it might be to heavy causing the voltage to collapse, little bit like a solar panel or current source. Put some resistors in series with the lamp to search for a maximum powerpoint. Idealy you could do this with one coil and a variable resistor for example. Then you should look at the voltage and current meter not at the brightness of the lamp.
* Wire your phases in series, but keep in mind the polarity, you can put them in series and in theory they give 0V. Winding direction need to be the same, otherwise turn around or swap cables! But you might know this already
* The biggest point, others already pointed out, is the magnetic field is not closed, and while this works for relatively flat coils and low power, your coils are really big/high, only a limited part of the coil will induce the strong magnetic field and create power, so you loose a lot of potential their, the rest of the coil more acts as resistor. (edit: ok, forgot you put some kind of material in the coils as well, but still...) You can experiment with a less high coil to verify/test find the optimum point. You can add an extra plate/rotor with magnets wich would greatly improve your design and close up the magnetic field. I would search google for some kind of theory behind it or perhaps look at: endless-sphere.com Those guys are building motors with permanent magnets and stuff, I'm sure you can find some good reading material over there. Edited 2024-10-03 03:38 by nickskethisniks
ramblin Newbie Joined: 26/03/2024 Location: United StatesPosts: 39
Posted: 03:15am 03 Oct 2024
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jeffj Regular Member Joined: 04/02/2012 Location: AustraliaPosts: 84
Posted: 04:58am 05 Oct 2024
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A couple of things that you may find of value
You must alternate the magnets, as the magnetic material stays in its magnetised state and has to be reversed at each 1/2 cycle see Mr Google re B/H curves for magnetic steels
You are getting 4 amps and 35 volts simultaneously? I suspect 35v is on open circuit and 4 amps on short circuit .Power is volts X amps
one other thing you seem to be getting confused re resistance. When dealing with ac the reactance maybe 10 times more than the resistance What matters is the impedance which is a combination of inductance and resistance .
Notice. New forum software under development. It's going to miss a few functions and look a bit ugly for a while, but I'm working on it full time now as the old forum was too unstable. Couple days, all good. If you notice any issues, please contact me.
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