Any comments from our electronic experts?

Coan Gerber
Anyone know what brushed esc will handle a 36volt brushed motor? Wil run it on 4s but have no clue if there is an esc that will handle it brushed?
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James Garvin get a brushless esc you can put a brushed motor on it just use 2 of the wires
12 hours ago · Like

Coan Gerber thanks
12 hours ago via mobile · Like

Vikramaditya Chaudhury James - seriously - will that work? If that be the case, I am learning something new. Something that will save a LOT of woriies in future. PLEASE CONFIRM.
11 hours ago · Like

James Garvin yes i have done it and i know someone that has their scx10 like that right now you just have to figure out which wires to use
11 hours ago · Like

Sanjay Rai Wonder why Hobby stores sell brushed ESCs then
A few seconds ago · Like

Won't work - a brushed motor is a DC motor where as a brushless motor
is a ac motor - maybe Kalyan can chip in with a more technical explanation - I
would be happy to be proven wrong.

There are car ESCs that can run brushed and brushless but the highest rated one I know of can go upto 6s.(Not really useful when you have a motor rated for 36V)

A brushless only ESC cannot run a brushed motor.

I thought that the motors that we use are DC Brushless. Now I am confused, and after reading this: http://www.rcgroups.com/forums/showthread.php?t=609591 - I am completely nonplussed. Beware, it is written mostly in Greek and Latin..........

Brushless ESC will not power Brushed motors. BLDC motors (explains they're DC motors - detailed explanation below) need their coils to be activated in a sequence and voltage difference between two 'active' wires to work, brushed on the other hand only need a voltage difference in the two wires to run, both the wires are always 'active'

In the case of Coan, the gentleman will not get adequate rpm. The motor runs at a highest voltage of 36v which means, it will get best speed at 36v and enough torque. 4s will only amount to 14.8 v which is less than half of 36v.

Here's my explanation at demystifying the AC/DC confusion:

In simple words:

1. All motors are AC.
2. AC motors - the current alternates automatically so no conversion required
3. Brushed - batteries provide dc; To run from battery, the current must be converted to AC, conversion done mechanically
4. BLDC - batteries provide dc; To run from battery, the current must be converted to AC, conversion done electronically, since nothing is moving to change the contacts, there need to be more than one coil that can take care of in-between positions.

Further Explanation:

Magnets repel magnets or magnet attracts another magnet. magnetism of a coil depends on the direction of current. So if a coil is revolving, it is changing orientation and once it reaches 180 degreees, to maintain the magnetic polarity the current must be reversed. Due to the nature of Alternating Current (AC), this inversion happens automatically. This is an AC motor. current is automatically switching  (due to its alternating nature) so the motor goes on and on. Conceptually, a motor can only work on AC

But since batteries provide DC current, someone brilliant decided to attach the battery contacts to the commutator in such a fashion that  when the commutator revolves 180 degree, the brushes get inverted, mechanically alternating the current. The source current is still DC but what the motor sees is AC (and hence runs). DC to AC conversion is mechanical.

Brushless motors do not have a rotating commutator, only free magnets that start rotating due to attraction/repulsion, so mechanically contact switching is not possible. Again, someone brilliant thought of keeping the contacts fixed and have more than one coils inside, and wired up an electronic circuit (friendly name: ESC) that would electronically switch on and switch off current in the right direction to the coils so the magnets rotate. The source is still DC, the motor sees it as AC. The conversion is electronic.

Like all disciplines know to man, the story does not end here, other factors settle into the equation. but I feel this should satiate the introduction

Kalyan da, request your inputs.

Well, Brushless motors (standalone) are essentially AC motors as they work on PWM signals from ESCs.

There is a design differentiation aspect here, "brushed" DC motors have rotating winding and the commutator contacts keep changing the magnetic field as they rotate, hence creating the inertia and further movement. hence, ideally the current with the 2 inputs (+ve & -ve from DC source), which the commutator passes these to the "moving" rotor acts as changing the field forces enabling the motor to move.

In case of brushless motors, as the electrical contact is static (winding is static) i.e. no moving of winding or changing/switching of current through the windings take place, this is acheived electronically using ESCs which are essentially PWM current signal generators, the switching rate (hence the width of PWM wave) changes when we throttle up & down.

I have tried a bit to explain this using one slide. Sorry about my creativity here in limited time, I have drawn a line to explain the AC & DC part in the attached picture.

Actaully it depends what you consider an motor to quality as AC & DC, the line seperates the AC & DC part.

PS- ideally brushless motors are always associated with external circults (PWM) to run, hence if we consider a "Bushless motor unit" (comprising of Motor + PWM circuts) as one entity, certainly its "DC Brushless motor" then, if we consider this as standalone entity (without PWM circuit), its an AC then.

Thanks.

They are called DC Brushless because it is run using LOW voltage DC batteries, unlike AC motors which are designed to run on AC.

However they can run only with a ESC without which it cannot run on DC supply. ESC in effect is supplying AC to the Brushless motors. Most of the RC Motors are with 3 phase windings which runs on non sinusoidal three phase AC supply produced by ESC.

You can run the Three contact Commutator DC motor using Brushless ESC. if you are able to remove the rotor which has the windings and three contacts and fix it as stator. Solder the three wires of ESC to the three contact of the commutator. Put the outer Can with magnet on the same axes on a bearing fix load shaft to it. Then with the brushless ESC you can run the same DC motor.

In case of a Brushless DC motor commutation is done by ESC. Even in DC Motors the current inside the coils of the rotor is AC which is achieved by commutation with help of brushes.

Typical three contact commutator cross section where the rotor is in the center with load shaft. Make the rotor as stator. fix three wire of ESC to the three contacts of the commutator. when you supply through ESC the Outer Can with Magnet will rotate as rotor.

DC cannot run motors which changes rotation by 180 degrees with every 1/2 rotation. which is a phase change in itself.

DC can only produce a electromagnet with fixed poles in one direction. To change the direction of Poles of electromagnet, the direction of DC has to be changed for every 180 degrees of rotation, then it becomes a AC. Its no longer a DC.

Hi ..

I am sure people know the fundamental principle that AC current can be very easily converted to a DC using a couple of DIODE or a diode bridge while this can not be done so easily the other way round, to convert DC to AC we need more complex circuits..

so...

the thing is mainly if you are able to run a DC (brushed) motor on a regular ESC ..

and that is the concern of flyers if they are able to do so or not.. 

DC Brushed motors on Brushless ESC?

Not without modifications.

Food for thought for all.

If the ESC is producing AC. If it is given through  6 diode Rectifier Bridge. Can it run a DC motor?

 

Hmmmm. A lot of theory and jargon flowing here. Unfortunately, the conversation is not meant for idiots - so I can't participate constructively. However, before we shoot James Garvin, Esq., no matter how implausible it may sound - has anyone tried it practically?

Probably, I being the least educated, will try it. Keep you all posted.

VC Bhai    yes you can 

It looks like I've stirred up a hornet's nest here! 

VC sir! Just do it!

After all you have nothing to lose but your motor......and you have plenty DC BMs 

"If ya ain't got the ejucation - make Google yer best pal........." VC 2013

Check the first and last replies on this page:

http://www.rctech.net/forum/radio-electronics/458618-brushless-esc-brushed-motor.html

So the ejucation finally says it may, or may not 

We don't need no ejucation
We don't need no thought control

VC sir no offence but when i hear ejucation something awkward comes in my mind.
So if you know what i mean i think plain education would be a lot better .

Dirty mind.........

Nothing awkward about it laddie - its all about growing up. Perfectly normal at your age - the wonder of it is, that these awkward moments will 'arise' well past middle age and perhaps, well into old age..................hopefully..........

Amazing things these raging hormones in teenagers. Even a dry subject like ESCs.....

It might be coz im a teen but education is better its like if you put mandatory as mandatery
its a bit awkward. 
Well anyway its after all you saying. Pink Floyd just rocks!!!
Sanjay sir the subject was esc but my point was on vc sirs saying
No offence anyone

 

Before the effects of raging hormone distracts our no so young teenagers   away from the subject let me get all of you back to the topic at hand.

There is a thread dedicated in rcgroups on how to convert a coreless brushed DC motors to a brushless motors. I am still searching for it.



I deliberately planted this here to get you guys thinking, will it actually work knowing that all Brushless ESC of RC which are not dependant on sensors for timing, whose timing is controlled by the feedback from the back EMF of the motor.

I think one has to try it out to find out.

Woah so much happened here while I sipped on about 10 cups of coffee...mood for the coming weekend is already settling in.

Sandy sir, looks doable with a 6 diode bridge. Only my gut feeling is one would need high speed switching (fast recovery) diodes like FR301. simpler ones like IN4001 might not cut it.

Original point still remains, not without modifications.

What happens when we remove one wire of ESC out of the three. No reaction on motor since no feed back from motor. So will a Diode rectifier actually work?  >

Like you correctly said, one has to wire it up to see the effects. At the outset I feel latkas and jhatkas for the motor or motor stalls will occur. Btw, why would you want remove the wire if everything worked... pange, huh?  

I'm already smelling poofed up p-n junctions, or perhaps its the coffee