Windings: basic questions.

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Browser said:
Anomaly 1: 100VDC, 10A draw, and you cite a resistance of 0.5Ω. But R = V/I, so R should be 10Ω.

You are forgetting about the back-emf. V = IR + E. 100 V = 10 A x 0.5Ω + 95 V. That's a pretty elementary mistake to make, IMO.

For real motors, that motor velocity constant (and the back-EMF) is determined empirically.
For real motors, the back-emf waveform is calculated and then confirmed with testing.

You take the motor, with no load attached, and apply voltage to it whilst measuring the rpm. Slowly increasing the voltage until the rpm fails to rise further. At that point, the back-EMF must equal the EMF being supplied, and Kv is thus determined, Simply divide the final maximum, no-load speed by the input voltage required to achieve it and there's your motor velocity constant.

This is not the best way ... you will not get accurate results. The way motor manufacturers will measure back-emf constant is by back-driving the motor under test with another motor and measuring the open circuit voltage with an o-scope. I will usually measure peak and RMS voltage and the back-emf waveform. The back-emf constant can then be found if the speed is measured.

Now the physical layout of the motor, all its losses -- core, copper, hysteresis skin effect, proximity, et. al. and the back-EMF -- and thus its efficiency, are all ready set; and Kv simply records that; it does not determine it. .

The back-emf constant (1/Kv) has nothing to do with losses or efficiency. See my first reply to you 9 pages ago.
 
learningrc said:
Browser said:
Anomaly 1: 100VDC, 10A draw, and you cite a resistance of 0.5Ω. But R = V/I, so R should be 10Ω.

You are forgetting about the back-emf. V = IR + E. 100 V = 10 A x 0.5Ω + 95 V.

So, you are (he is) measuring the resistance, whilst the motor is running. Clever trick dat.

And giving the DC (static) voltage but the running resistance. Anomaly number 23896418723623874.

Its a puerile exercise try to argue against a (self-inconsistant) problem devised to show what it purports to demonstrate. A complete contradiction of the scientific process.

Ie. setting out to measure what you have decided you want to conclude.

learningrc said:
That's a pretty elementary mistake to make, IMO.

I agree he made an elementary mistake. And you compounded it.

learningrc said:
The back-emf constant (1/Kv) has nothing to do with losses or efficiency. See my first reply to you 9 pages ago.

See my 9 pages of replies to all in sundry showing that to be a self fulfilling prophecy.
 
Browser, I'm going to finally take your advise and stop replying to you. Good luck with your 1 turn, low voltage, high current motor.I hope it does what you want it to do.
 
learningrc said:
Browser, I'm going to finally take your advise and stop replying to you. Good luck with your 1 turn, low voltage, high current motor.I hope it does what you want it to do.

I've never once suggested that I'm building a "1 turn, low voltage, high current motor."

Indeed. I repeatedly said that the (as currently being analysed) design is using many (52) turns of 0.1 mm x 6.5 mm copper foil. I even posted a graphic showing that coil and how is was to be wound.

So, thank you for ceasing; if you haven't bothered to read what I've written and are responding on the basis of something you've plucked out of thin air; I'm firmly better off not having to give your input mind-space.

Proof: Notice the way the field lines are distorted -- reaching for the coils. That's torque. At 0 Hz. No back-EMF required.

91jy9u.jpg
 
One last question, because I'm' genuinely curious about your reasoning, then I'm done. I won't even reply to your answer. If you truly believe back-emf is bad and should be minimized, why would you use 52 turns? Why not 1 turn?
 
There are none so blind as those that will not see. The character flaws go beyond arrogance and general obnoxiousness to delusion and paranoia. I'm genuinely surprised you're not all over the conspiracy theory threads high-fiving nutspecial, etrike and megacycle.

We should all be grateful for the small mercies in life and today I'm very thankful that I've never had to sit in a technical meeting with Browser :)
 
Punx0r said:
There are none so blind as those that will not see.

See, you have learnt something: https://endless-sphere.com/forums/viewtopic.php?f=30&t=75622#p1142930https://endless-sphere.com/forums/viewtopic.php?f=30&t=75622#p1143041.

Keep on meeting like this and who knows, maybe you'll learn something else useful.

Punx0r said:
{ad hominim} {ad hominim} {ad hominim}. I'm genuinely surprised you're not {straw man} {straw man} {straw man}

You really aren't very good at this are you.

Punx0r said:
I've never had to sit in a technical meeting with Browser :)

Let's face it. You wouldn't make it passed the telephone interview; let alone into a technical meeting.
 
Wait, that was what that seemingly-random string of letters meant earlier in this thread? I did Google it, but got no matches. Checking now, I see Google does have one result: that E.S. post by you. Your communication skills are as esoteric as your technical ones.

That you think my ways of thinking make me completely unsuitable to participate in a technical meeting run by yourself is great compliment. Thank you :)

We await the launch of the kickstarter campaign for your motor that will revolutionise academia and industry.
 
It's disappointing that a man of your age would behave so childishly, but there we go. Anyway, I'm done with this. You can direct your vitriol towards your next target.
 
Punx0r said:
It's disappointing that a man of your age would behave so childishly, but there we go. Anyway, I'm done with this.

My thoughts about you exactly.

Punx0r said:
You can direct your vitriol towards your next target.

My next target!? That's funny. (Well almost.)

The only place on this site you'll find anything by me, is right here in this thread. And barring my very first two posts -- the initial enquiry and a 'hm. No responses; did I ask in the wrong place' follow up, every single post I've made has been in direct response to someone replying to me.

This thread long since stopped serving any purpose, and I can only respond to your posts; the last N of which have been nothing but vitriol, from you directed at me. You've been like a jilted lover, stalking the only place you'll know I'll be trying to get that last decisive little dig in. 'cepting you ain't no good at it.

Like I said way back up there; look to thine own self. Or in less pseudo-religious terms; look back and read the crap you've been posting and judge yourself, before judging others.
 
I had hoped we could get some good points discussed on this thread regarding possibly expanding the usable RPM range of PMDC motors. That has since been somewhat dampened.

Rather than focus on specific personal statements, do we have anything we can collectively make of the thread. High KV and high voltage will allow you to run at the 25000 rpm design speed. Would love to have the best of both worlds (Low rpm torque and high RPM drive) but with the personal attacks it is a poor atmosphere to even get what we agree on into a summary for extending the discussion further. Maybe we can see what has worked so far in extending the RPM range (FOC) of a standard motor and discuss control hardware options /limitations to expanding those results further as hardware improves. Call me a dreamer! :|
 
Browser said:
Proof: Notice the way the field lines are distorted -- reaching for the coils. That's torque. At 0 Hz. No back-EMF required.

That's torque? Maybe; maybe not. It depends on the rotor position.

... synchronous motors are not self-starting motors.... Since a synchronous motor produces no inherent average torque at standstill....
https://en.wikipedia.org/wiki/Synchronous_motor#Starting_methods

Most inverter controlled PMSMs overcome this with design features which I don't see in what you are proposing. But I'm sure you'll figure that out.
 
learningrc said:
Browser said:
Anomaly 1: 100VDC, 10A draw, and you cite a resistance of 0.5Ω. But R = V/I, so R should be 10Ω.

You are forgetting about the back-emf. V = IR + E. 100 V = 10 A x 0.5Ω + 95 V. That's a pretty elementary mistake to make, IMO.

For real motors, that motor velocity constant (and the back-EMF) is determined empirically.
For real motors, the back-emf waveform is calculated and then confirmed with testing.

You take the motor, with no load attached, and apply voltage to it whilst measuring the rpm. Slowly increasing the voltage until the rpm fails to rise further. At that point, the back-EMF must equal the EMF being supplied, and Kv is thus determined, Simply divide the final maximum, no-load speed by the input voltage required to achieve it and there's your motor velocity constant.

This is not the best way ... you will not get accurate results. The way motor manufacturers will measure back-emf constant is by back-driving the motor under test with another motor and measuring the open circuit voltage with an o-scope. I will usually measure peak and RMS voltage and the back-emf waveform. The back-emf constant can then be found if the speed is measured.

Now the physical layout of the motor, all its losses -- core, copper, hysteresis skin effect, proximity, et. al. and the back-EMF -- and thus its efficiency, are all ready set; and Kv simply records that; it does not determine it. .

The back-emf constant (1/Kv) has nothing to do with losses or efficiency. See my first reply to you 9 pages ago.

Thanks learningrc,

You are correct.

I'd add that his method for testing back-emf constant "Slowly increasing the voltage until the rpm fails to rise further." is particularly stupid. The rpm will fail to rise further when the rotor self destructs and you will not only not have the value of the constant, but no longer have an operational motor.

Clearly Browser understands little about motor calculations due to his problem with generated voltage (back-EMF as he calls it). Despite a lesson from crossbreak on page one.
crossbreak said:
Browser said:
If that generated voltage opposes the applied voltage, we call the machine a motor.

Hm. If its a generator, there is no applied voltage to oppose?

in a simple model, armature voltage is simply back-EMF + voltage drop over motor resistance (let inductance out of the equation, it does not matter that much here)

fig2.jpg

"Va" is the voltage source (motor controller) or armature voltage (they are equal, since they are connected), "Ra" is armature resistance, "e" is the back EMF voltage source.

Motor: Va = EMF + resistive voltage drop = e + Ra * I
Gernerator: Va = EMF - resistive voltage drop = e - Ra * I

Here is one from the Naval Academy:
http://www.usna.edu/EE/ee301/supplements/Rotating%20DC%20Motors%20Supplement%20II.pdf

And this one from National Instruments which uses an example with values similar to my example:
http://www.ni.com/white-paper/14921/en/

Regards,

major
 
Browser said:
Okay. You wanna play some more. So, answer a question: How did you measure the back-EMF in this example?

My guess: You didn't measure anything. You decided upon a motor velocity constant and derived the numbers in your example from that.

I didn't measure anything. It is an example. I specified it. The values are perfectly reasonable and serve to demonstrate the performance calculation process.
 
Browser said:
If all the energy in that energised but stationary motor was being converted to heat, there'd be no energy left to create a magnetic field.

All the energy put into the stalled motor is being converted to heat. The magnetic field takes some energy initially and stores it but requires no further energy to maintain itself and exhibit the interacting force with the magnets. All the continuing power into the stationary motor is converted to heat in the resistance of the windings even though the motor continues to produce torque. No electric to mechanical energy conversion is taking place. No mechanical force is acting on a mass causing displacement therefore no work is done.

You knew this is what we were talking about as I said so on page one and you gave the example of the dam doing work.
major said:
Browser said:
If you are on a hill and the motor is supplying just enough torque to stop you rolling back, but not enough to allow you to move forward, IT IS STILL DOING WORK!

It is not doing mechanical work.
major said:
A motor with zero generated voltage (BEMF) has all armature current producing heat in the resistance and therefore zero power output. You can get a lot of torque, but without power, you're not doing any mechanical work.
 
major said:
The magnetic field takes some energy initially and stores it but requires no further energy to maintain itself and exhibit the interacting force with the magnets.


Hey, hey, hey, waddayaknow. PROGRESS. Small. Tiny. And you'll deny it. Repeatedly, at length. Starting about 2 days from now (it always seems to take about two days for you to catch up with everyone else) and continuing, ... for the rest of your life probably. You're not the sort to let sleeping dogs lie.

And the progress? Well, previously, you vehemently insisted that ALL THE ENERGY WAS CONVERTED TO HEAT. Now, ten pages on you admit to:
The magnetic field takes some energy initially
.

It's a breakthrough; your eureka "moment" (well, eureka two weeks really, but never mind), and then ... dun, dun, dun. You immediately throw it all away.

If, all we need to do to create the
interacting force with the magnets
(in a rotational motor, it called 'torque'), is inject a little energy to get the coils producing a field and then
stores it but requires no further energy to maintain itself
, then we could just turn of the power and the torque would continue to exist. (Now, even you can surely see that it total crap.)

In order for the magnetic field to be produced, the current has to flow through the wire. And in order for the current to flow (outside of cryogenicly cooled superconductors), it has to overcome the resistance of that wire, and that produces heat. stationary or moving. And right there, is the entire process of converting electrical energy to mechanical energy. Nothing else is required. Just the flow of electrons through a wire in the presence of a magnetic field. It is described in its entirety by Lorenz.

Of course, you'll deny it. You'll revert to your reading, and regurgitate again (as you've done throughout this thread, ad nauseum) some guff derived from the misunderstanding of something you read somewhere that .... No need for me to repeat it cos you've done so a zillion times and no doubt will again.

But here's the thing. History is replete with books full of such misunderstandings. It used to be thought that Barnacle Geese spent the winter attached to rocks in the form of Goosehead Barnacles. Luigi Galvani (of galvanometer fame) thought that 'animal electricity' was different to ordinary electricity; it took Alessandro Volta (of voltage fame) to set him straight. Both great men, but even they can have misunderstandings.

And you're not a great man. Indeed, you are what Feynman called 'the worst type of technician'; a rote learnt scientist. One who's only method of debate is '"proof" by reference'. A 'scientist' who has no understanding of what you regurgitate; no intuition or feel for the subject they bang on about; just a potted collection of facts and formulae you regurgitate ad nauseum. And if one of those 'facts' is dubious, weak and baseless -- like the bland aphorism that "back-EMF (induced or generated voltage as you call it) is fundamental to energy conversion" -- you are simply ill-equipped to discern it. Even when it is pointed out to you.

And when presented with, even simple scenarios that weren't worked examples in your texts, you 're lost. And when you get lost, out of your depth, you revert to type and start repeating yourself over and over. You try to bludgeon your opponents to death with 'proof by reference'. And in your case, the references are usually yourself. I've never encountered anyone who quoted himself so much.

And I've never encountered anyone else who so obviously vehemently believed he could prove his argument by quoting himself saying the thing he wanted to prove.

All in all, arguing with you is a complete waste of time; you simply don't have the mental capacity and acuity -- sod it -- you don't have the intelligence to construct an argument that stands up to scrutiny; to the scientific process. Your idea of proof is to make up a set of numbers -- that bear no relationship to any reality -- that show what you want them to show; and claim they prove what you claim they show. A tortuous illogicality.

Basically, you're a waste of an expensive education. A rote learnt quoting machine with no intuition, no feel for the subject, and no ability to question what you read in a book.

So, dear boy. Have at it. See if quoting yourself some more, re-regurgitating the same meaningless aphorisms a few more dozen times will change anything.
 
Browser said:
And right there, is the entire process of converting electrical energy to mechanical energy. Nothing else is required. Just the flow of electrons through a wire in the presence of a magnetic field. It is described in its entirety by Lorenz.

You are wrong again (still). Lorenz says nothing about energy. It is about force. Force is not energy. This is a concept which you apparently cannot understand.
 
major said:
Lorenz says nothing about energy. It is about force. Force is not energy.

That! That right there^. That explains a very great deal.

The force F acting on a particle of electric charge q with instantaneous velocity v, due to an external electric field E and magnetic field B, is given by ...

Do you see that "particle of electric charge q with instantaneous velocity v, due to an external electric field"? Even the symbol chosen "E".

"NOTHING ABOUT ENERGY".

[OT personal attack deleted by moderator]
 
Browser said:
major said:
Lorenz says nothing about energy. It is about force. Force is not energy.

The force F acting on a particle of electric charge q with instantaneous velocity v, due to an external electric field E and magnetic field B, is given by ...

Do you see that "particle of electric charge q with instantaneous velocity v, due to an external electric field"? Even the symbol chosen "E".

How much energy does that charge q at velocity v represent? And "E" represents the electric field, not energy.
 
major said:
How much energy does that charge q at velocity v represent?

That kinda depends on the values of q and v doesn't it!

major said:
And "E" represents the electric field, not energy.

And what does it take for an electrical field to exist?

Like I said. No understanding whatsoever, just regurgitation. (This isn't even Physics 101; it effin' kintergarten stuff.)
 
major said:
Browser said:
major said:
Lorenz says nothing about energy. It is about force. Force is not energy.

The force F acting on a particle of electric charge q with instantaneous velocity v, due to an external electric field E and magnetic field B, is given by ...
Note that the above is an incomplete quote from wikipedia placed here by Browser. It is also found in other references.

How much energy does that charge q at velocity v represent?

Browser said:
That kinda depends on the values of q and v doesn't it!

Charge is 2 Ampere hours and velocity is 299,792,458 meters per second.
 
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