Pole Count on an RC Brushless Motor - RC Motor Basics
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- Опубліковано 13 січ 2019
- When one refers to how many poles an electric motor has, they are commonly referring to how many magnetic poles there are.
Here we look at the difference between pole counts specifically on inrunner motors.
Common in runner motors have 2 or 4 magnetic poles. There are some motors containing 6 poles as well. Outrunner motors may have in excess of 6 magnetic poles.
There are differences between a 2, 4 and 6 pole motor that does have an affect on the consumer. To most hobbyists, the performance differences will be quite subtle and may go unnoticed. However, there are a few key differences that will not go unnoticed and this is due to the inherit characteristics of a motors pole count.
In general 2 pole motors have a much larger range of options for kv selection vs a 6 pole motor for example. This is one key difference.
If you can't find the right kv motor, it makes no difference as to which pole count you can select. kv selection is prioritized over pole counts.
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An article on the topic:
www.radiocontrolinfo.com/brush...
#BrushlessMotor #MotorPoles #RCexplained - Наука та технологія
It's very hard for us to get the idea or understand, don't you think that you should show us some sketches or drawings? That will help a lot.
I would liked that on the Brushless Motor Windings video
great video, very helpful
Thank you for your comment!
Awesome video you're the man
Great video 👍.
Thank you!
I disassembled (2) Baldor 3 Phase motors last night, both were 5HP. One was 1800 and the other one was 3600 RPM; the 1800 had significantly less wire in the windings and the diameter of the rotor was bigger compared to the 3600 RPM which had a lot more wire used in the windings (taking more space inside the motor) and the diameter of the rotor was smaller. the resistance in the leads for both motors was the same.1&4,2&5 and 3&6 1.2 Ohms 7,8, and 9 1.9 Ohms. Both motors were physically the same size. I thought it was interesting.
Nice video buddy good stuff
Hey Mike, thanks for the comment!
Question for you? Some cars are built which "enough" power to move the car and a little extra play power. Then some cars light Ferrari and Lamborghini have excess power but can be driven slowly. In an instance like this, what is your suggestion to apply more power than needed and what would you suggestion for KV as you have stated, to over power an application on purpose?
Question on Motor Poles and current need help understanding please!
Given the same motor dimensions, kv, volts, and propeller/wheel how does the number of poles affect the amps/current under load.
one motor has 6 poles, the other motor has 10 poles.
how would the 10 pole perform? smoother rotation? more torque for sure, but would it draw fewer Amps with same load and RPM as it does not need to work as hard?
Hello,
With all else equal, there will be very little difference between the motors. I would not expect the average user to see any difference. Some potential differences off the top of my head include:
Smoother operation at low RPM's.
Easier for the ESC to turn the motor at extremely slow speeds
Lower theoretical Max. RPM limit
Potential for better efficiency (not enough information for a conclusion)
For the average user, I would say that the differences would be negligible.
In terms of torque, watch the latest video released:
ua-cam.com/video/xi7jxIkX2vY/v-deo.html
You teach me a lot
Hey Donovan Smith, thank you for your comment! Appreciate it!
អគុណបង
Awesome video Ryan!! I was wondering what was the difference with all the poles and turns. The rc hobby intrigues me and pushes me to use more equations to get answers. You arm me with a great base to start with and work from there. Anyway, as always, great video and keep them coming!!
Good video but it's alot of talking and not enough visuals. It would be much more digestible with some pictures of the internals of the motor you are talking about.
Thank you for the comment goztepe2003. I agree with you completely. As the channel grows I will be able to dedicate more time and get a lot more visuals in my video planning and editing.
Please share design parameters consider for design a bldc motor both internal and external rotor, from the basic, like material grade magnet, airgap, performance and etc it's very useful to me
If a gear in my transmission is breaking due to torque, should I gear up ( lower number) to decrease to tq multiplied by the pinion and spur or should I gear down and make the motor pull less amps and power ?
I have a 2 pole VXL system in my slash 4x4. If I upgrade to a 4 pole motor will I have to get a different ESC as well? Thanks!
Most ESC's would be able to support a change in a motors pole count from 2 to 4. However, it does seem the VXL system has a commutation frequency limit preventing it to run 4 pole motors based on a quick search. I would ask on a forum if the VXL ESC has been updated to support 4 pole motors as I am not familiar with this system.
The setting and camera angle makes me feel like that time your parents had to tell you where people come from. I'm glad is him
thank you
You're welcome Sean!
If you were constrained to a 6" length and 3.5" diameter case dimensions and required at least 5000 rpm but other than that as much torque as you could cram in it, what would be your design?
Hi, 12pole/ 14magnets 215 and 300kv motors will cutout at 3/4 to full power when they unload at take off feel it could be ESC, Timing or Freq settings ESC is Hyperion Titan 90a HV from memory high timing 22-30 should I be also on high Frequency 16kHz turned OFF LCV and to eliminate voltage drop cutout any ideas
no heat issues doesnt happen with my YEP ESC
Hello bro, so if my motor have less slot, for ex: 4p12s motor vs 4p6s motor, which one have higher torque?
Thank you for the great info as always!
So if there is a 6 pole motor available in the kv/can size that works for my application, is it safe to say that it would be a better (more efficient) option than a similar 4 pole motor?
It can be, you can see this from the winding resistance and Io value of the motor.
I also own a blackjack24
Ok you got me, I’m subbed. Quick question, are you on any RC forums? I’m building my first brushless micro RC drift car & im feeling lost trying to figure out cogging, & the correct gear ratio + motor KV for peak efficiency.
I picked up a brushless car so it would be more efficient & run cooler then my brushed car. But now I have started researching the tuning aspect, & I feel overwhelmed. I’m afraid I will use the wrong KV & gearing combo & will end up making the motor inefficient.
I’m releasing a video tomorrow morning about the new car if you are interested. It seems like you are more into the larger cars, but I’m all about indoor micro fun.
I sink most of my time in to the channel and website. As a result I am not active on forums these days. If you have a question you can leave it right here and I will answer it.
I wouldn't worry about efficiency more then I'd worry about a reliable brushless setup.
If i have lets say 10 turn 4 pole motor. I bump up to 6 pole and keep everything else the same, i will get lower kv and more "magnetic torque"? (if we disregard saturation)
Correct
What would you recommend for a drag car? TY
No mention about smoother torque distribution over 1 cycle with higher pole count, strange…
hi RCexplained . very thank for your information. i want to ask you why an electrical motor efficiency going to decrease when we apply high load on it without gearbox ?
The resulting efficiency is based on how close the motor is operating at it's most efficient power output for a given voltage. If the load is too high or low, efficiency drops. The motor won't know if it's turning a gearbox or direct drive.
Very informative.. Im trying to find your inrunner vs outrunner video
Thank you! Here is a link:
ua-cam.com/video/m6TW1WZn9CA/v-deo.html
Thanks Ryan, good explanation. I always thought a 4 pole motor is less efficient then 2 pole motors…so that is not the case.
One question if you would like to answer. What are the cons on High kv brushless motors with vent holes in can? I know its better for cooling,but what about the efficience ?
Thanks
I would expect there to be little difference in efficiency.
@@RCexplained thank you!
let me ask if there are 2 motors DC of the same size, one with 2 poles and the other with 4 poles, which motor rotates faster and which one will bear the load better. thank you very much.
Basically any motor with lower pole count is designed for higher speeds and lower torque..and usually have a smaller effective diameter @ the air gap..( diameter difference between rotor & stator ).... That's where all the flux / magnetic ckt. TORQUE is produced.....for the rotor....
And torque is directly proportional to this effective diameter..
A higher pole count motor will , by design default be larger in size( dia) with lower max speed......if a small diameter higher torque motor with high pole count & high rpm is required..then the motor will be designed with a longer length...(like submersible pumps)..these are effective design tradeoffs to be considered & accepted...
Hi Ryan - i have a seawing 3660 3 wire brushless motor , can i connect it to a 2 wire esc, how ? - thanks very informative video
Hey Stephen, thank you for your comment. Brushless motors use 3 wires. Brushed motors use 2 wires. If your esc only has 2 wires it sounds like it's a brushed esc. A brushed esc will not work with a brushless motor.
@@RCexplained hey thank you for your speedy reply - i thought as much , just been out of it a bit long and getting back into things - thanks
I have a 2310kv 2 pole motor and it has noticeably less speed than a 4 pole motor with the same kv and specs. Will gearing help me with more speed or are 2 pole motors just slower?
Hey Mo Hawk, do you know how many watts each motor is pulling? Do you know the temperature of each motor when running?
If i Have to design a bldc motor of particular Kv rating and low very low cogging torque than how should i start designing the motor do you any specific documentation for designing motor of particular size and parameter.Please help
To completely eliminate cogging torque a slotless design can be considered. Otherwise you will have to focus design efforts on the stator.
I was hoping the title was going to address out & In running motors.
Primarily addressing the question is if an “Outrunner” motor has 14-magnets is that considered a 14-pole motor or not? Love to know that answer very badly.
Depending on how the magnets are arranged, yes it can be a 14 pole motor.
14 magnets is 14 poles..but for a motor designer..it's considered as a 7 pole pair motor...because pole pairs (always N & S ) will make a working motor..A motor with odd pole count or all of either one type do not and probably cannot exist as a functional one...
I don't think you hit on two major variables affected by the number of poles. What about torque and cogging?
Hi Dartheomus, thank you for your comment. You raise a good point. Cogging and the torque produced from a brushless motor are related to pole count. If I have not talked about it in this video, you can follow the link to the article written on the website.
A 4 pole can be smoother than 2 pole, but I wonder how it delivers more power or torque, If there are 4 poles the size of one pole is smaller , exactly half of a 2 pole one, strength of 1 pole is half.
I think the maximum output of a motor is limited by it size , if 2 motors fully packed with maximum space utilized (A 4 pole motor and the 2 pole ) the same amount of copper is inside , motor should have the same output watts. even if the rotor is bigger in 4 pole motor then its stator would be smaller and have less copper which makes less electromagnetic field. What is your idea about it? please correct me if I am wrong
Hey Gehan, I agree, the maximum output of a motor is defined by size. Pole count is not as critical when considering the output power. However, kv/torque will be different. On a higher pole count motor the ESC is going to fire more times per revolution than a lower count motor.
Is it possible to make a dual runner? A motor that has magnets inside and outside stator.
Yes such motors do exist and are built as such......but since outer & inner magnets rotate @ different " rates " their alignment w.r.t. each other ( outer/inner )is very critical...accurate tooling is also required.....
Also the design & assembly is very difficult
(ours { p.m.brushless dc. } was a prototype for feasibility study)..
ultimately abandoned because calculated mass production/manufacturing cost & time outweighed everything else. ...
everything else... it's large physical size too was another negative... ..this was in 2004..
Just to add here.... "different. rates" is also the rate of flux linkage between inner rotor magnet and stator wdg. whilst the outer rotor magnets and same stator wdg. will have another rate of flux linkage ....
would have helped if you made an animation I think you are exceptiopnal at teaching that would help some of us to visualise.... would it be possible if you can get an animation app
would a 6 pole motor give you a shorter run time than a 4 pole motor?
@@RCexplained so it does not make a difference
What will happen if I keep the number of poles the same and increase number of slots ?
A lot can happen if you increase just the stator slots. The motor design is highly dependent on this. Anything from torque output, Cogging torque, efficiency and a lot more can be affected.
A very general example is going from 4p12s to 4p15s. Torque output could be reduced however Cogging torque can be significantly improved. To wind a 15 slot stator would take some expensive equipment and may not be all that practical for our application. For this reason, we just let the motor manufactures determine which combination is best for their specific design.
Sangat membantu bagi kami yang hobi dengan rc, dan saya harap, anda membuat translate dalam bahasa indonesia, karena kebanyakan orang Indonesia tidak mengerti bahasa Inggris. 😊👍☕
Derita mu..
What ant 3 pole?
Hello..Can esc that ussually work with 4poles motor can work on 2poles motor? Thx u
Yes, most ESC's have a wide range of operation in terms of pole count.
@@RCexplained are there any differences in speed? Could it harm the motor or esc? Thx
There's not a significant different from 4 pole to 2 poles. As you increase pole count, maximum output ESC RPM does decrease, however nothing that should impact you.
@@RCexplained so if 4pole esc used on 6pole, the esc rpm will drop. Than how can we tell that an esc has 2pole or 4pole programmed?
The maximum capable ESC RPM decreases not motor RPM. More than likely your ESC is capable of over 100,000RPM on 4 poles. You will not have to worry about this. It is rare that the maximum ESC RPM ever limits the maximum motor RPM for a standard application. I use 4 pole motors and 12 pole motors on the same CC ESC, not a problem, excellent performance.
still no clue why to have more poles then two. I kept asking why, why, no reason, efficiency?
First reason that comes to mind is a higher pole motor offers lower kv for the same amount of winds. Meaning you can go to the next available wind to get back to the same kv increasing the current potential of the motor.
All the reasons why are based on what more poles has to offer.
@@RCexplained I do understand that, but why would I want that? It does not explain much. Especially that the magnets are smaller and maybe the motor gets more or less powerfull? It should be smoother per rotation, but that does not mean more powerfull. But I have looked into it alot, couldn't find alot of definitive reasons to switch to 4 pole, then I looked at my new motors and both already were 4-pole :D. So....Did not know that. What I am looking for is more torque at the bottom, less at the top for a crawler so i do not break stuff but still can go really slow. I am at the max of my gearing already.
@@mrDarksand : From my experience and understanding: Higher poles gives a motor higher torque and less rpm (kv).. Just like changing your gearing (and includes all the same side effects to heat, effieciency etc)
@@justinmallaiz4549 What I usually see on KV ratings of motors (and the rest stays the same) low kv motors have the same torque as high KV ones. And this is because the output power stays the same. both KV have a max powerlevel, lets say 1000Watts. This Means, at top speed, both will deliver that at the same RPM, the only difference is that a low KV will get that from more Volts where the High KV one gets it from amps. P=UxI. So in theory they should both have the same strength. I am now gearing down and getting myself a low KV sensored motor. And the only reason I go lower is because I can not gear it lower and it is still too fast. and my hope is the sensores will make the motor smoother on startup.
@@mrDarksand I just came across this video with quality info and probably applies well to you and crawling.
ua-cam.com/video/BcuhdkCucGA/v-deo.html
Why are there so many Canadians named Ryan and Justin? That’s the real mystery.
I thought the popular name was Mike?
You should add animation for better
Watch my new videos. This is 5 years old
@@RCexplained link please
So 2 pole is best?? Haha
So you could put a lot more volts into it
Seeing is believing 😞
Great video! Would you mind if I share it on my Facebook group? I think I can help give you a bump in subs. 😎
Absolutely. That would be great!
What's KV?
Check this out:
ua-cam.com/video/24dhlGVTlP8/v-deo.html
No mention of rpm.
Correct. RPM is not a function of pole count
@@RCexplained ah no. Look at the plate.
Hi Ryan so the higher the pole the motor tourq??
As you increase in pole count, kv decreases giving you the opportunity to produce more torque.
Diameter!
less talk alone without any prop and animation
I have seem many of your videos, but you just give a bunch of information about poles, kv, winding, turns, battery size but it is too disorganized because you talk about one theme in one video and the other video is a completely different topic that just create really more confusion and not telling really a nice way to choose a motor application and also focusing as you said in other video about your battery size and voltage or the maximum rpms to choose a motor that I am not agree, so in conclusion you give a bunch of information that varies the power, kv, current and efficiency from many aspects that leave no clue to choose a motor
Hi rotoR Col. Nearly every single video in the last 1.5 years is a topic suggestion from the viewers. The video topic suggestion queue is almost 3 months long.
I'm working on picking power systems for specific applications, however it's not an easy topic to place in to simple terms within 25 video minutes or so.
Dude! your hands do NOT look like an engine!
Lip service