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Anonymous Poster #1

Difference of Poles In AC Three Phase Induction Motor

06/15/2017 7:13 AM

Hello Everybody, i wanted to know that can we have a 2 pole three phase Ac induction motor? And if we apply that to Electric car engine would Not that increase the speed of rotation of tiers as the poles are decreasing and revolution increasing given by the formula Rpm=F*120/P where p = Number of poles. and also what are the cons and pros of having a 2 pole three phase ac Induction motor. thanks .

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#1

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 7:17 AM

<...a 2 pole three phase Ac induction motor...> is widely available.

<...can...have...> CR4 is not a permission-giving entity.

<...we...> is undefined, and its abilities cannot be assessed from here.

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#2

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 7:44 AM

Incoherent question.

Of course you can have a two-pole motor. At 60 Hz its synchronous speed would be 3600 rpm, but slip speed would be somewhat less; at 50 Hz its synchronous speed would be 3000 rpm, with slip speed somewhat less.

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#3

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 8:13 AM

The reason for having <...a 2 pole three phase Ac induction motor...> applied conceptually <...to Electric car engine...> is somewhat abstruse.

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#4

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 8:20 AM

I wanted to know that is it a possibility that a 2 pole three phase ac induction motor can be used as a normal ac induction motor is used to rotate the wheels of the tire which are control by a controller. Basically the controller regulate the voltage that is supplied to the motor. So i wanted to know. have a look at this links to understand better.

https://www.afdc.energy.gov/vehicles/how-do-all-electric-cars-work

http://www.conserve-energy-future.com/howelectriccarswork.php

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#5

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 8:30 AM

There is little point in doing so, when DC motors and controllers are also readily available. One can save the weight of the required inverter and the additional wiring.

Perception of the abilities of the <...we...> is in decline.

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#6

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 9:50 AM

Yeah but I want to use ac induction motor. I mean DC motor are fine , but if the use of ac induction is applied then and compare it with the DC motor then what will be the cons and pro of such a system as compare to the DC motor system .

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#7

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 10:07 AM

The DC arrangement will give higher power-to-weight ratio, meaning the performance of the vehicle in terms of available range will be better.

The AC arrangement is a solution looking for the right problem: why lug all that transformer mass around just so a 3-phase AC motor can be deployed when rare-earth magnet DC motors are already in such widespread use (rhetorical question - NNTR)? After all, it cannot be needed in terms of adhesive weight, such as in a rail vehicle, can it (rhetorical question - NNTR)?

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#10

Re: Difference of poles In Ac three phase Induction motor

06/15/2017 10:40 AM

You are hereby granted permission to experiment with 2-pole 3-phase induction motors on the wheels (tires, not tiers) of an electric automobile. You are not granted permission to install on a mobile nuclear reactor.

As to pros and cons: It depends upon whom is seated within the interior regions of the automobile, if they carry any professional licenses, and whether any convicted felons might be riding along as well.

I think in the long run, you will find the weight penalty from going with 3-phase will outstrip any perceived advantage of performance.

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#8

Re: Difference of Poles In Ac Three Phase Induction Motor

06/15/2017 10:11 AM

Increasing the speed of rotation by reducing the number of poles does not mean that the motor would be more efficient or deliver more power. I suggest you study the fundamental principles of AC induction motors. (Google is your friend).

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#9

Re: Difference of Poles In Ac Three Phase Induction Motor

06/15/2017 10:24 AM

It's no wonder this thread is largely anonymous. No sensible person would want to be so embarrassed.

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#11

Re: Difference of Poles In Ac Three Phase Induction Motor

06/15/2017 6:37 PM

It can be done, in fact it's done all the time. Ever hear of Tesla cars? They use 3 phase induction motors in their cars, run from inverters that take the DC stored energy and invert it using PWM to provide controlled AC of variable frequency and variable voltage for the motors.

I know of several people who have successfully replaced internal combustion engines in small cars with standard off-the-shelf 3 phase induction motors and used standard off-the-shelf industrial VFDs to run the motors. Here's a link to one. http://www.evalbum.com/1149 I myself have been looking for a suitable candidate pickup truck shell to do this on so that I can have a small truck for running to the lumber yard or the dumps.

Now, can YOU do it? Given the difficulty I see in your ability to even describe it correctly, I would hazard a guess that the answer is "NO".

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#12

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 4:36 AM

Comparing this with post #5 is interesting. I found this account to be informative.

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#13

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 5:02 AM

Good spot. Thanks.

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#17

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 8:55 AM

...but look at all the fun he will miss if he discourage him from trying.

I say let the dude run with it. Maybe he will come up with a power amplifinder.

It turns out as pointed out by the link phph001 put up, it is about brushed DC motors at the their voltage limit before brush arcing takes place (bad, bad, bad), and AC induction motors that are brushless. Then the choice is made clear why.

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#14

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 6:05 AM

Q: i wanted to know that can we (you mean You?) have a 2 pole three phase Ac induction motor?
A: Yes.. you can. go to any electric motor store and they will sell you one. BUT do you know the required horse power, and can you carry it home?

I think this is a question..
Q: And if we apply that to Electric car engine.....
A: An electric car does not have an engine, it has an electric motor! Or you can call it the prime mover!

Now you've confused yourself
A:would Not that increase the speed of rotation of tiers as the poles are decreasing and revolution increasing given by the formula Rpm=F*120/P where p = Number of poles
A: you have just given the formula for calculating the speed of an AC induction motor running on a set input frequency. However.. increase the speed compared to what? Faster than a DC motor? You will have to explain this one!

Q: and also what are the cons and pros of having a 2 pole three phase ac Induction motor.
A: You will never get a 2 pole three phase ac Induction motor running off DC batteries so you will need an inverter! Now average inverter losses are about 20%, so you will have to do the maths! Add to that the slip of the motor, and your system losses start to add up. Plus with an inverter, more to go wrong!
Have you thought about regenerative braking to recharge the batteries?

To be honest, you've not thought this through have you? I'm not sure what you're trying to achieve here, maybe you can enlighten me!

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#15

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 7:03 AM

<...To be honest...>

Always be honest.

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#16

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 7:12 AM

Inverter losses are nowhere near as high as 20%. (Maybe not quite as low as 2%, though, but close.)

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#18

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 9:15 AM

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#19

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 9:27 AM

In engineering terms being off by a magnitude of order, IE 20% verses 2%, doesn't really count as "about".

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#20

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 9:55 AM

Are we playing eng horseshoes today? Or hand grenades.

If physics were only as good as 20% when doing theoretical derivations, we would all be drinking free Bubble-UP, and eating Rainbow stew (from a silver spoon).

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#21

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 12:05 PM

We just need to get involved in bigger and better-subsidized projects, with 50% error bars each way. Gravy train!

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#22

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 1:28 PM

You are onto something there. The Big-buck hotter than skeeter's _____ Fusion Reactor crowd has been saying "we are a mere ten years away from break even" for the last 40 years, well documented fact.

You and I both are working stiffs, not into the high level gravy train that those guys are.

We used to say, "We are in the wrong profession," and it wasn't even the oldest profession.

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#25

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 4:44 PM

Growing up I was told that if you want to make money get into 'the oldest profession' early.

I did, but Hunter-Gather just ain't paying the bills like they implied it would.

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#27

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 5:56 PM

Really is that the best reply you got when the OP is as dense as a bag full of spare spring washers!??

What would be the point of me being exact to the Numbnuts that started this thread when he probably can't even find his A£@\$hole without help!

Please don't call me out on something as petty as a percentage quoted to a moron who couldn't even switch on a solar powered calculator!

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#28

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 7:27 PM

Well, now we know why, Bumf#ck Egypt , got its reputation for being someplace nobody wants to end up in by accident or otherwise.

It's because of the people who live there, as you have just proven!

(check his location if you don't follow the context here.)

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#34

Re: Difference of Poles In Ac Three Phase Induction Motor

06/19/2017 9:04 AM

You did not spell that correctly, it is Buoumfooque, Egypt. It is a well-traveled hamlet far off any known cartography collections.

Yes, indeed, here we are arguing vociferously about 2% vs. 20% error bars, when the whole conversation is not only not in the wheel house, it is not even in the same ball park, race track, or any other known venue of the wide-world of sports.

I say let him try his plan, and report back to how that is working for him.

If someone wants to install an induction (squirrel cage) motor, should he not first genetically engineer the squirrels, so they look like small muscle bound Arabian horses?

Is it not written that in the end of days, the science will be absent from all human interactions?

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#23

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 1:51 PM

How about if I Do not use Batteries at all but a different power source which gives Ac current in place of Dc current. Then what would be beneficial ? DC or AC motor? Because to Generate Ac you need to have slip rings (like that used in generators) And to produce dc you need commutator. And what about Synchronous motor being used with the help of permanent magnet and not dc. but i am concerned that the rare earth magnet would bring the cost up. Thanks for your reply. And i have think this through .

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#24

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 2:37 PM

A squirrel cage motor does not use slip rings. They don't call them brushless for nothing. Seriously? Think this through some more, as you obviously have not learned much.

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Anonymous Poster #1
#29

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 10:11 PM

When did I said anything about using slip rings on ac induction motor ? What are you talking about ? And just because I am silent does not mean I don't know anything .

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#30

Re: Difference of Poles In Ac Three Phase Induction Motor

06/17/2017 2:57 AM

You said....
And just because I am silent does not mean I don't know anything

I would disagree here!

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#33

Re: Difference of Poles In Ac Three Phase Induction Motor

06/19/2017 8:57 AM

You are not silent, but you are anonymous, so hushie poo.

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#26

Re: Difference of Poles In Ac Three Phase Induction Motor

06/16/2017 4:48 PM

Here's a checklist of the essential items a vehicle needs for your intended goal then start asking questions once you have defined how to accommodate each.

Steering.

Brakes.

Variable speed.

Variable power/torque.

Power/effort required to move at top speed.

Energy/fuel source.

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#32

Re: Difference of Poles In Ac Three Phase Induction Motor

06/19/2017 8:07 AM

Then the <...power source...> could be connected directly to the wheels and no intervening transformer, inverter or motor would be needed.

This thread is beginning to sound like a solution looking for a suitable problem.

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#35

Re: Difference of Poles In Ac Three Phase Induction Motor

06/19/2017 9:10 AM

I could not agree more, especially when there are any number of other valid solutions to automotive power, including hydraulic, pneumatic, electrical, and ICE/drive trains configurations.

I want to see more about the IFbattery power cars, and light trucks (or even heavy ones). Out of the six reported chemistries (we are still waiting for a detailed paper on the subject) out of Purdue University, which one is the most favorable for longer duration with most net energy delivered to wheels?

Then there is this MIT work up on the Aluminum/sea water battery with alkaline electrolyte, where they make aluminum oxide out of a gallium/aluminum alloy anode (trace gallium I suppose), and they discard the cathode hydrogen. Why discard that hydrogen? Why not run it through a PEM fuel cell that uses the oxygen out of the sea water? I think they are not squeezing all the good available free energy out of that new battery.

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#36

Re: Difference of Poles In Ac Three Phase Induction Motor

06/19/2017 5:34 PM
• How about if I Do not use Batteries at all but a different power source which gives Ac current in place of Dc current.

Pray, tell us of this mystical energy storage solution of which you speak?

• Then what would be beneficial ? DC or AC motor?

If said magical machine can "give" mobile AC without storage in batteries exists, then AC induction motors would be the least expensive option.

• Because to Generate Ac you need to have slip rings (like that used in generators) And to produce dc you need commutator.

Not if you use a Brushless Synchronous Exciter on an AC alternator or Permanent Magnets on the DC generator.

• And what about Synchronous motor being used with the help of permanent magnet and not dc.

Yes, that exists as well, called Permanent Magnet AC (PMAC) motors.

• but i am concerned that the rare earth magnet would bring the cost up.

And well you should be, they are about 2x the cost of a standard AC Squirrel cage Induction Motor and currently limited in HP sizes. That may change some day, but not as long as the sources of the rare-earth materials for the magnets is still a political football at play in the giant world economic game.

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#31

Re: Difference of Poles In AC Three Phase Induction Motor

06/17/2017 3:36 PM

Its hardly surprising you are anonymous, you know nothing at all.....go and learn electricity instead of bothering us......but to do it properly will take 3 years plus!!

Byeeeeeee

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