The bistander thread

[bistander]

... So to think that attraction goes away "at speed" is hilarious. ...

I have never said or implied or think that attraction goes away at speed.
bi

[bistander]

Cogging

In PMSM (Permanent Magnet Synchronous Machine)

Cogging is the torque caused by the attraction of the Permanent Magnet to the core. The attraction is always present however the resulting cogging torque on the shaft varies with rotor position throughout the rotation cycle. The cogging torque contribution to the net shaft torque is constant with respect to speed. Net shaft torque is the sum of multiple sources of torque in the machine and load (if present). When rotating, the rotor develops momentum. This momentum increases as speed increases. It is zero at zero RPM.

Constant speed operation is hindered by cogging torque. The variable torque vs position due to cogging tends to accelerate or decelerate the rotor as it rotates. The momentum of the rotor will react to these changes in speed as they occur by imparting torque as to oppose any change in speed. The net torque is the sum of the cogging torque and torque from momentum. Momentum smoothes out speed ripple (variations) caused by cogging and this smoothing effect is greater at higher RPM.


1-s2.0-S0378475418301423-gr10.jpg

The image above is a graph showing the cogging torque versus rotor angular position. I lifted it from an article, which I will give the link later. It is typical in shape so I'll use it to assist explanation. For this use the heavier dashed trace. The horizontal axis is rotor position. Units are degrees electrical (degrees electrical = degrees mechanical for a 2-pole rotor (2 magnets). The graph shows one revolution. O° (zero degrees) is TDC (Top Dead Center) alignment of magnet to stator tooth (or coil core). 180° and 360° are also TDC alignment. TDC occurs at the zero crossing of the horizontal zero axis indicating zero torque caused by cogging (magnetic attraction). The magnitude of cogging torque is given on the vertical axis, units on the left side.

As the rotor moves away from TDC the cogging torque magnitude increases, positive in one direction and negatively in the opposite direction, as to resist the motion away from TDC.

Example:
Rotor is at 180°, a TDC aligned position, torque is zero, RPM is zero. A state of equilibrium. Now physically move the rotor to 200°. Let's assign that a CW displacement of 20° from TDC. The graph indicates torque is 500 units, CCW. (CCW has been assigned to positive torque). If you were to displace the rotor 20° from TDC the opposite direction, at 160°, torque is -500 units, or 500 units CW, again forcing the rotor towards TDC. Note: To continue rotation, you need to apply a torque greater than 500 units.

If you continue rotation to 270°, or to 90°, you encounter another zero torque point, this time midway between coil cores. Theoretically equilibrium here is possible but practically it would be pulled towards one core or the other.

Note that the graphical area enclosed by the characteristic trace and the zero torque axis represents energy or work. It is obvious that the area above the zero axis is equal to the area below it, meaning the net work, or net energy, or average power per revolution is zero. If it wasn't, it would self rotate.

Cogging is a net zero contributer to power in applications such as seen on this forum. Cogging can be a nuisance and if it bothers you, go ahead and mitigate it, but don't count on it to benefit power production. It will not.

I hope this can help some folks visualize what I've been talking about. There is much studied and written about cogging. I encourage "looking it up" and learning. bi

[Turion]

I have done the following HUNDREDS of time over the years. And this is EXA CTLY what I have shown to MANY interested individuals.
1. Gotten the motor up to speed. NOTED both the RPM and AMP DRAW
2. Added two coils and waited for the motor to settle out and attain the highest RPM and lowest NEW AMP DRAW. The amp draw is always HIGHER and the RPM is ALWAYS LOWER. The WEAKER the drive motor, like when I was using an MY1016, the more PRONOUNCED the change. But with only ONE coil you better be using some pretty delicate measuring instruments because the difference is very small.
3. Dial in magnetic neutralization. The RPM goes back UP and the AMP DRAW goes back DOWN.
4. At this point I have then BACKED THE magnets back off, and the RPM goes DOWN and the AMP DRAW goes back up.


But more significantly, I have run my machine using the MY1020 motor and gotten it up to speed. It runs, just turning the rotor on 7 amps. (This was the old clunker machine) I added a pair of coils at a time and waited until the machine settled out before adding the next pair. By the time the 12 coils were added, the amp draw was over 36 amps which is greater than the rated amp draw for that motor. I don't remember the RPM, but I know it went DOWN significantly. When magnetic neutralization was added, the amp draw was reduced down to 12 amps. MUCH OF THIS WAS SHOWN in the series of videos I posted. I don't remember if ALL of it was shown or not, but I really don't care. Those videos were made while we were working to document, not to show "how to." Eventually we got it down to 9 amps, but because the clunker was not a precision machine, it took constant adjustment to keep it that low and we decided to build the NEW machine. If you do not believe the difference between 9 amps and 36 amps to achieve operating RPM, or the DECREASE in operating RPM's is significant, you are an idiot. But I already knew THAT.

You believe what you want bi. I really don't give a crap about you. YOU don't matter. And this is going forward despite you continual BS. I have a bunch of people on board now, and we are working together. ALL of them have seen that this works, so you babbling that it doesn't isn't going to stand in the way. Stand on the tracks and keep shouting that the train isn't coming. Be my guest.

https://youtu.be/0iHy2w0rK6M
https://youtu.be/aCKz-ARdy_k
https://youtu.be/NUvZjPa08fw
https://youtu.be/cQ-RFKm_LjA
https://youtu.be/uT4znAicN8I

There is a drag caused by the MASS of the magnets passing the MASS of the cores. It has an effect on the RPM and amp draw of the prime mover. PERIOD. You tried to dissmiss this by arguing that cogging goes away at speed. It does. I don't disagree with that. But that DRAG, or attraction of the magnets to the core material, does NOT go away without magnetic neutralization. If it DID, the cores would absorb NO magnetic flux and the coils would produce NO power. But it cn be neutralized.

[BroMikey]

But more significantly, I have run my machine using the MY1020 motor and gotten it up to speed. It runs, just turning the rotor on 7 amps. (
I have a bunch of people on board now, and we are working together. ALL of them have seen that this works,

Hope your hand feels better so you are not so crankyTake your time, you can always switch the cores if they don't put out

[bistander]

...
Here's what's going on TODAY. I started up the machine with two coils in place on the generator to see what the output of one coil pair would be, and just like yesterday, the 300 watt light did not come on when I flipped the switch. So I tested the bulb and it is OK. Then I connected the coil output directly to the bulb, bypassing the in-line panel amp meter and volt meter, but got it up to speed before I screwed the bulb all the way in. It wouldn't light up. So I replaced the 300 watt bulb with a 100 watt bulb connected directly to the coil. But only ONE coil because I didn't want to risk blowing the bulb. The bulb lit up and it measured 34 volts across the bulb, and 75 volts across the unloaded coil. I expected it to measure 150 across the unloaded coil since that is what I got across the TWO coils in parallel yesterday, unloaded. So I connected the second coil to the load, screwed the bulb in, and it lit up. I measured 64 volts across the load. This is FAR less than we got using the SAME coil on the old clunker with only 12 magnets instead of the 24 the new rotor has, so I am at a loss. I called my guys who did the testing on all the coils and they confirmed that they were getting over 300 volts open voltage from these coils on the old machine at 2800 RPM and over 120 volts across the load. He was at work, so is going to check his notes when he gets home at 5:00 and call me back. Output IS what it IS unless something is wrong with BOTH the coils. But I wound them, and I can's see the wire as a problem, unless the connections aren't any good. But bad connections on BOTH of the coils I chose out of a possible 12? Not likely. I have never heard of TOO MANY magnets on the rotor being a problem, so I don't know WHAT to think. I'm going to double check that the magnets on the rotor are N/S is all I can think of that I can do right now.

Hi Turion,

Be interesting to know coil span overlays pole pitch. Let's see, you have 4 poles per coil. Hmmm. Core and magnet diameters are what, 3/4 inch? Don't have the core circle diameter or the outer coil diameter. What would be really helpful is a waveform of generated voltage. Got a scope? But you're not big on sharing data or doing a simple requested test.

Post up what you will. I'll be watching. Good luck.
bi

[bistander]

I have done the following HUNDREDS of time over the years. And this is EXA CTLY what I have shown to MANY interested individuals.
1. Gotten the motor up to speed. NOTED both the RPM and AMP DRAW
2. Added two coils and waited for the motor to settle out and attain the highest RPM and lowest NEW AMP DRAW. The amp draw is always HIGHER and the RPM is ALWAYS LOWER. The WEAKER the drive motor, like when I was using an MY1016, the more PRONOUNCED the change. But with only ONE coil you better be using some pretty delicate measuring instruments because the difference is very small.
3. Dial in magnetic neutralization. The RPM goes back UP and the AMP DRAW goes back DOWN.
4. At this point I have then BACKED THE magnets back off, and the RPM goes DOWN and the AMP DRAW goes back up.


But more significantly, I have run my machine using the MY1020 motor and gotten it up to speed. It runs, just turning the rotor on 7 amps. (This was the old clunker machine) I added a pair of coils at a time and waited until the machine settled out before adding the next pair. By the time the 12 coils were added, the amp draw was over 36 amps which is greater than the rated amp draw for that motor. I don't remember the RPM, but I know it went DOWN significantly. When magnetic neutralization was added, the amp draw was reduced down to 12 amps. MUCH OF THIS WAS SHOWN in the series of videos I posted. I don't remember if ALL of it was shown or not, but I really don't care. Those videos were made while we were working to document, not to show "how to." Eventually we got it down to 9 amps, but because the clunker was not a precision machine, it took constant adjustment to keep it that low and we decided to build the NEW machine. If you do not believe the difference between 9 amps and 36 amps to achieve operating RPM, or the DECREASE in operating RPM's is significant, you are an idiot. But I already knew THAT.

You believe what you want bi. I really don't give a crap about you. YOU don't matter. And this is going forward despite you continual BS. I have a bunch of people on board now, and we are working together. ALL of them have seen that this works, so you babbling that it doesn't isn't going to stand in the way. Stand on the tracks and keep shouting that the train isn't coming. Be my guest.

https://youtu.be/0iHy2w0rK6M
https://youtu.be/aCKz-ARdy_k
https://youtu.be/NUvZjPa08fw
https://youtu.be/cQ-RFKm_LjA
https://youtu.be/uT4znAicN8I

There is a drag caused by the MASS of the magnets passing the MASS of the cores. It has an effect on the RPM and amp draw of the prime mover. PERIOD. You tried to dissmiss this by arguing that cogging goes away at speed. It does. I don't disagree with that. But that DRAG, or attraction of the magnets to the core material, does NOT go away without magnetic neutralization. If it DID, the cores would absorb NO magnetic flux and the coils would produce NO power. But it cn be neutralized.

I have done the following HUNDREDS of time over the years. And this is EXA CTLY what I have shown to MANY interested individuals.
1. Gotten the motor up to speed. NOTED both the RPM and AMP DRAW
2. Added two coils and waited for the motor to settle out and attain the highest RPM and lowest NEW AMP DRAW. The amp draw is always HIGHER and the RPM is ALWAYS LOWER. The WEAKER the drive motor, like when I was using an MY1016, the more PRONOUNCED the change. But with only ONE coil you better be using some pretty delicate measuring instruments because the difference is very small.
3. Dial in magnetic neutralization. The RPM goes back UP and the AMP DRAW goes back DOWN.
4. At this point I have then BACKED THE magnets back off, and the RPM goes DOWN and the AMP DRAW goes back up.
...

Cool. Let's see the video of the ammeter as you back out the magnet.

You also say "I have a bunch of people on board now, and we are working together. ALL of them have seen that this works."

Did any of them bother to record the evidence?
bi

[BroMikey]

You also say "I have a bunch of people on board now, and we are working together. ALL of them have seen that this works."

Did any of them bother to record the evidence?
bi

Nope, not for you. And yes these are great men who stick together. Maybe you have a lapdog you could go feed?

[bistander]

...
There is a drag caused by the MASS of the magnets passing the MASS of the cores. It has an effect on the RPM and amp draw of the prime mover. PERIOD. You tried to dissmiss this by arguing that cogging goes away at speed. It does. I don't disagree with that. But that DRAG, or attraction of the magnets to the core material, does NOT go away without magnetic neutralization. If it DID, the cores would absorb NO magnetic flux and the coils would produce NO power. But it cn be neutralized.

Hi Turion,

You have consistently misconstrued what I've told you about cogging and core loss. So I'll tell you again.

... There is a drag caused by the MASS of the magnets passing the MASS of the cores.

Gravity is the only attractive force caused by the "mass" of the parts.

It has an effect on the RPM and amp draw of the prime mover.

Gravitational attraction between those parts is too little to affect the prime mover.

You tried to dissmiss this by arguing that cogging goes away at speed.

Cogging does not "go away at speed". The effects of cogging, like torque and speed ripple, diminish as RPM increases.

It does. I don't disagree with that.

But that DRAG, or attraction of the magnets to the core material, does NOT go away

I never said it did. What I say is that "DRAG" is caused by friction, aerodynamics and core loss. "attraction of the magnets to the core material" is cogging.

without magnetic neutralization.

What you refer to as "magnetic neutralization" is an anti-cogging scheme and does nothing about friction, windage or core loss, except to possibly increase it.

If it DID, the cores would absorb NO magnetic flux

Cores do not "absorb" magnetic flux, they provide a low reluctance path for magnetic flux.

and the coils would produce NO power. But it cn be neutralized.

Core loss can not be neutralized by addition of anti-cogging magnets unless those magnets reduce the primary field in the core(s), and that would be counterproductive to the generator.

So when you refer to my opinion on the subject, please get it right.

Thank you,
bi

[Turion]

You are an idiot. That part I have always had right. You argue semantics instead of concepts, and have nothing to share.

[bistander]

You are an idiot. That part I have always had right. You argue semantics instead of concepts, and have nothing to share.

I know how generators work and you don't. Have you got your light bulb lit up to full power yet or are you going to build a new rotor, again?
bi

[Turion]

I built a new rotor because I was building a new machine anyway. I built a new machine because the magnetic neutralization adjustment mechanism on the old one was sloppy and caused a “clacking” sound that was extremely loud and they wouldn’t stay adjusted. As usual, you don’t know anything. And yes, I think I have solved the problem with my lights not lighting up. I will know for sure tomorrow.

[bistander]

I built a new rotor because I was building a new machine anyway. I built a new machine because the magnetic neutralization adjustment mechanism on the old one was sloppy and caused a “clacking” sound that was extremely loud and they wouldn’t stay adjusted. As usual, you don’t know anything. And yes, I think I have solved the problem with my lights not lighting up. I will know for sure tomorrow.

That was besides having 22 poles of the same polarity facing the stators? OK. You still might want to check that coil span against the pole pitch. Strange that you didn't notice your coil/core assembly seating problem when you installed it. Maybe tomorrow, hey?
bi

[BroMikey]

nothing strange about it. Dave is a one hand man and his helpers missed one detail, so what. cool it

[Turion]

bi,
You're right. I forgot about the machine in between that didn't work at all.

Before I even assembled this machine I made sure the coils slid in and the cores would fit into the 3/4" diameter hole in the plastic the must fit into. But then when I fired the machine up, the cores were projecting out and rubbing on the rotor. Not MUCH, but still rubbing. So they had to be cut off. When they were cut off, it left roughness at the edges which is preventing the cores from sliding into the holes they previously fit in. That needs to be fixed. Maybe tomorrow.

[bistander]

So my partner in Sacramento tested the output of the two coils both loaded and unloaded. Unloaded they put out around 300 volts, but loaded, one coil put out 85 volts (2820 RPM) and the other one put out about 90 volts (2835 RPM) at about .6 amps each. There was about a 15 RPM difference between what he ran the two coils at, so that could account for the difference in volts out.

So even with twice the magnets on the rotor at around the same RPM (he ran at 2820-2835 and I was running at 2800) I am only getting 6 volts MORE. Around 96 volts...IF my coils are all the way in now, and I am beginning to believe they ARE.

WHY he told me these coils would put out around 120 volts, I will never know, but obviously they do NOT. Maybe it was just the test equipment he was using at the time. Right now we are using the same meters and same RPM gauge so there is no disparity. What there IS appears to be DISAPPOINTING results.

But there are some positives, so I will share the information should anyone ever attempt to replicate this stuff. Be aware that the following are my ASSUMPTIONS, and they could be well off the mark. Since voltage is a product of magnetic flux in the core and turns of wire on the coil, and 24 magnets on the rotor is producing very little additional output over the 12 magnet rotor, (much of which could be due to differences in spacing and other variables) I am assuming that the core is absorbing as MUCH flux with the smaller number of magnets as it can HOLD for the RPM that the rotor is traveling.

The depth of the plastic that holds the coil bobbin is approximately 1" deeper that the length of the bobbin, so they are currently inset into the plastic that far. That "extra" space is approximately 30% of the length of the 3 1/4 x 3" diameter" bobbin.

So working with that 30% number...
If I extended the core by 1"...
The current bobbin holds 3 strands of 1,000' each.
If I were to increase the length of the coil bobbin somehow by that additional 1 inch, I could get an additional 900 feet of wire on the coil or 300 feet more on each of the 3 strands. That should improve output as long as the flux remains the same with the greater core mass.

Hi Turion,
Interesting data. Is the 300 volt measured on one coil? At what RPM? Unloaded means open circuit or nothing connected to the coil terminals except the voltmeter, right?

And loaded (with a resistance?) to draw 0.6 amps, the reading on each of two coils separately is 85V at 2820 RPM and 90V 2835 RPM, right? 90V / 85V = 1.06 and 2835. RPM / 2820 RPM = 1.005. These two ratios should be the same if the coils were identical.

0.6A at 85 or 90V is 51 or 54VA (W if load was purely resistive). For example purpose let's use 300V open circuit and 90V at 0.6A with purely resistive load, both at same RPM. To find the coil resistance, (300V-90V) / 0.6A = 350 ohms. Also, means load resistance = 90V / 0.6A = 150 ohms.

I have mentioned Jacobi's law before. Look it up. What it says is maximum power transfer occurs when load resistance equals source resistance. Which for this coil and speed, is 350 ohms yielding 64W at 0.428A. And this (using a 350ohm load) will give you 150V across the load or coil output voltage.

Adding turns of the same wire size will not alter the maximum power at that RPM with those magnets. I'd suggest that you take time to do the math before taking time (& cost) to add an inch of core and copper to the existing coil as you mentioned.

Well, just checked wire table. Something is screwy. Room temp resistance of AWG #23 copper is 20.8 ohms/1000ft. That means your coil should be about 7 ohms, right? Ever measure it? Perhaps there is large reactive component at that frequency. Some analytical tests would help. Generated voltage vs frequency sweeps with various loads would tell. Scopes shots also.
bi