Mostly PM motor - Joe Flynn motor. My attempt to replicate

[zhorv324]

Hi Jetijs ,i put two picture of my prony brake it maybe helpful. As you see its two parts one is mesing pice(Cu+ZN alloy)who is mount on axle. another piece is teflon ring and rest is obvious. In that combination you don't worry about heating .Pleas put some result

[Jetijs]

Thanks zhorv324
I decided to make an iron disc much like in your picture and mount it on the motor shaft. I will make the braking pads from aluminum and the much increased friction surface should not give any heating problems anymore

I wont post any results until I get them from a stable operating motor under load as the results I have now might not be accurate and I don't want to get anyone overexcited, myself included
Thanks,
Jetijs

[zhorv324]

Thanks zhorv324
I decided to make an iron disc much like in your picture and mount it on the motor shaft. I will make the braking pads from aluminum and the much increased friction surface should not give any heating problems anymore

I wont post any results until I get them from a stable operating motor under load as the results I have now might not be accurate and I don't want to get anyone overexcited, myself included
Thanks,
Jetijs

Well I wait

[Jetijs]

Hi zhorv324,
I got my wheel and friction brake today and tried to test the efficiency again. This time the results were more stable, but the efficiency does not seem to be very good. I can reach 70% at best. In previous tests I did measure the RPM's on a different spot of the motor and that gave me incorrect RPM data, the RPM's were shown 2x higher than actual. That is why the previous results seemed so great. I am still confused, because You could achieve about 99% efficiency, but what is so different in my design that I got such bad results? What am I doing wrong?
Thanks,
Jetijs

[zhorv324]

Hi jetijs ,yes result is pretty bad. I say on my first post that my motor have efficiency about 95% and that is measured by prony brake ( on picture). Prony brake measurement is not really accurate and depends of many things. Only suggestion is that you tray measure your attraction motor and compare result. Yes another thing, do you calculate nominal power of your motor( see one of my post) and try to reach that power in your test by rising voltage(more rpm). Anyway post some result and god luck with experiment

[Jetijs]

Hi zhorv324
I am beginning to suspect that there are several reasons for this, one of them might be the core material itself. When I met my laser cutting guys a while back, they said that they have a new material available specially for motor core laminations, and compared to my transformer steel material this was way better attracted by magnets and you could lift several sheets of this material with one magnet, but with my material you could not lift that much. I guess that permeability of that material is way better. This could account for the poor performance. I will bring one of mu material sheets to a local solid state physics institute, maybe they can tell me more on this subject. My current material comes from used big old 3phase transformers in a sheets 20x80cm sheets. Also your motor had 4pole design, that should be more efficient and strong because the magnetic flux does not have to travel too long distances in the core which of course causes losses. I can't compare the results with my attraction motor because it has a different shaft size and I would need to get another friction wheel. To step up voltage I would need to get a separate 12v power source to feed the logic switching part separately, but that is not hard. I will inform you if I have any updates
Thank you!
Jetijs

[zhorv324]

Well guys from Italian forum use grain oriented steel laminate and maybe that give more efficient to motor . Anyway god luck and don't give up

[Jetijs]

Hi
Thanks for the info!
Today I was at my local physics institute and met a guy who will help me to measure the efficiency of my motor using a DC generator with a know efficiency index. Will see how this will go. Also they will help me determinate what silicon steel type I have been using so far and see if the problem is there, if it is so, then this means that I have been banging my head on the wall all the time for the wrong reasons and it will bring back my enthusiasm for attraction motors
Wish me luck!

[zhorv324]

Hi Jetijs," let force be with you" .Rely, god luck

[gotoluc]

Hi Jetijs,

maybe have a look at this: Sci-Spot.com - Dynamometer

I know it kind of looks like a toy but if the flywheel is large enough and and you make the shaft solid and use good bearings it should work.

Luc

[Jetijs]

Thanks Luc

Today I received the results from the efficiency testing at the local physics institute. They measured the power using a generator with a known efficiency index. The results are so bad it's hard to believe. I attached the report with the tables and diagrams.
The first set of tests were made using the voltage and amperage readings from my variable power supply. The second test was made using the voltage and amperage readings from an oscilloscope in series, those results were even worse. With the first method the best efficiency was 47%, but with the second method the best was only 20

Very weird.

Any suggestions?

[Ted Ewert]

Thanks Luc

Today I received the results from the efficiency testing at the local physics institute. They measured the power using a generator with a known efficiency index. The results are so bad it's hard to believe. I attached the report with the tables and diagrams.
The first set of tests were made using the voltage and amperage readings from my variable power supply. The second test was made using the voltage and amperage readings from an oscilloscope in series, those results were even worse. With the first method the best efficiency was 47%, but with the second method the best was only 20

Very weird.

Any suggestions?

A little disappointing, but it's just a reference point. There are ways to make the motor more efficient.
The mechanical efficiency is about as good as it will get, so not much to gain there without a total rebuild.
It's interesting that as a pulse motor you're current rises under load. that means your coils are doing all the work. I think you need higher inductance coils so that doesn't happen. The best efficiency with a motor like yours is in the low RPMs where the PM will add current. The PM doesn't kick in much until the load gets heavy. When the frequency of the pulses goes down, so does the impedance of the coil. With higher inductance that won't be as much of an issue; where higher inductance (impedance) will prevent the current from rising under those conditions. With a constant current draw your efficiency numbers will get much more encouraging.
I would also add a high impedance recovery circuit. This allows you to have a single, high inductance wind, and a way to raise the impedance for the recovery pulse. Raising the impedance, or blocking voltage, will significantly lower your input current. Recovering and reusing the energy is only a small part of the power savings. Keeping the blocking, or standing, voltage high dramatically increases the efficiency of the coil. I've tested this concept and would be happy to provide the data if there is any interest.
You have a great motor and you're a hell of a builder. I predict you'll do a whole lot better on the next test.

Ted

[zhorv324]

Hi Jetijs , yes result is disappointing .And this time i agree with Ted. You may tray to wind new coils with more turns and with thicker wire(if space allow that) and tray connect coils to series (give more inductance) anyway this result is pretty weird ( my opinion only). Soon I will tray another motor geometry (like axial flux motor) and I think that change some things

[Jetijs]

Thanks guys
I have yet to find out if the material I am using for the cores is good enough for my purposes. I can rewind the coils, but the space is limited so I can't wind more windings with the same wire gauge, to get more windings I will need to use thinner wire, but I will give it a try. The coils that are on the motor now are already connected in series. I doubt that the coils will change much since even if the efficiency will triple, it will still be way below 100%, there is something else wrong, but I will try the different coils nevertheless. It is really frustrating to put so much work in it just to see that it sucks big time. I am slowly starting to get tired from all the disappointments I had all these years Thanks for your encouragement.
Ted, I did not get the part about blocking and standing voltages and the recovery part. Could you elaborate more?
Thanks,
Jetijs

[Ted Ewert]

Thanks guys
I have yet to find out if the material I am using for the cores is good enough for my purposes. I can rewind the coils, but the space is limited so I can't wind more windings with the same wire gauge, to get more windings I will need to use thinner wire, but I will give it a try. The coils that are on the motor now are already connected in series. I doubt that the coils will change much since even if the efficiency will triple, it will still be way below 100%, there is something else wrong, but I will try the different coils nevertheless. It is really frustrating to put so much work in it just to see that it sucks big time. I am slowly starting to get tired from all the disappointments I had all these years Thanks for your encouragement.
Ted, I did not get the part about blocking and standing voltages and the recovery part. Could you elaborate more?
Thanks,
Jetijs

It's hard not to get discouraged, but hang in there buddy.
The blocking voltage is something that Bedini always referred to as impedance matching. The "collapse" pulse is a very high impedance critter. It doesn't like to see a low impedance like a big cap or a low impedance battery.
When it goes out through the diode and "sees" a high voltage, this is the same as a high impedance. No current flows until the pulse overcomes the "blocking" voltage. This voltage can be on a cap, or it can be on some batteries. The higher this voltage is, the better the pulse likes it. Here's a test I did to illustrate this concept:



When I used only one battery between the pulse and the source voltage, the total current draw of the motor (not the recovery circuit, the picture is a little misleading) was 1 amp. When I put two batteries in series, the total current draw went down to .65 amps. Three batteries in series-.360 amps, etc. The batteries represent the "blocking" voltage. I reduced the total current draw of the motor by over 60% just by stacking some batteries in the recovery portion of the circuit. This doesn't even count what I gained charging the batteries, and I didn't return any of the energy to the front end.
The motor remained at a constant RPM and no power was lost as a result of this current savings.
I used small batteries for the first three, and a larger battery for the last step to 48 volts. You can see that the larger battery, with a lower input impedance, didn't save as much current as the first three.
The trick is to get as much "blocking" voltage as you can, without frying your transistor, and draw the least amount of current out of the pulse. This combination will dramatically raise the efficiency of your motor without sacrificing any power. A Newman motor, with a giant coil and a mechanical switch, illustrates this concept beautifully. That's why it's so efficient.
You won't see this savings as much with a low impedance coil. That's why I keep harping on small wire, lots of turns and a higher drive voltage. You only want your coil to act as a switch, not as a drive element. That's why your current should remain constant throughout your total operating range. The magnets are there to provide all the current the motor can use. As soon as you see your current rise at the low RPMs, that's a red flag.
I recently took my motor down to 100 RPM without any increase in drive current. Nevertheless, my torque went up dramatically. That's where the permanent magnets kicked in and provided power.
I know you can get your motor to run far more efficiently. Try a few of the things I mentioned and I think you'll be pleasantly surprised.

Ted