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How does a brushless motor work?

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Old 01-17-2008, 08:50 PM
  #101
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Default RE: How does a brushless motor work?

Shinob1
The old WWI rotary engines did, in fact have the crank shaft stationary and the cylinders rotated, the prop was bolted to the crank case. Kinda like an outrunner with the prop mounted to the rotating bell.
I think you have a rotary mower, but the motor is not a rotary motor, if it's a single cylinder 4 stroke B&S, or any other motor I know of on a lawn mower, just a 4 stroke recip.
You are right about the outrunner not gaining torque due to rotational mass, the greater torque associated with outrunners is due to the magnets beig at a greater distance from the shaft center, just like when you have rusted bolt and your and you can't break it loose with your socket wrench, just add a big piece of pipe on the end of the wrench, somethings gotta give There's a high falutin tecnical term for that, but it escapes me.
Cheers,
Pete
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Old 01-17-2008, 11:54 PM
  #102
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Default RE: How does a brushless motor work?

That is very interesting... Yes it is a Briggs and Stratton engine. So I must have confused where the rotary aspect was applied. Sorry. And as for a rotating engine... That sounds like a bad idea for a lot of reasons. Sorry I had never heard of it before. Do you happen to know the name and or the manufacturer of it? Anyway, for future reference on the inrunner vs ourunner topic, there is an entire thread devoted to that elsewhere on this site. So back to "How does a brushless motor work."
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Old 01-18-2008, 12:14 PM
  #103
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Default RE: How does a brushless motor work?

Hi Shinob1,
I don't believe they were made in any quantity after WWI, here's a link, it has a clear explanation of the difference between radial and rotary engine. While they may look a lot alike when not running, when you see a rotary being started, there'll be no mistaking one
http://en.wikipedia.org/wiki/Rotary_engine

Now back to brushless dc motors[8D]
I can remember seeing the first Aveox sensored BLDC motors roughly 15 years ago, dang'd were they pricey and the controllers were a bit bulky, bet heck, this was roughly only 20 years after the development of brushless technology by the computer industry, don't make the mistake of confusing them with Mr. Tesla's invention, the induction motor, different fish altogether.
It would be fantastic if a cost effective way to implement this technology could be developed to replace the brushed universal (series wound) motors that power our AC powered devices around the house, such as vacuums, mixers, blenders, all your corded power tools, the list is almost endless. We have a problem with the Ozone layer now, if we eliminated brushed motors we would produce a lot less Ozone, would that make the Ozone problem better or worse, since Ozone at ground level is a pollutant. When I get a whiff of Ozone from my DeWalt drill/driver, it immediatly brings back memories of my Lionel trains, guess that makes me a geezer
Cheers,
Pete
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Old 01-18-2008, 03:01 PM
  #104
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Default RE: How does a brushless motor work?


Quote:
... The weight of them spinning creates a lot more torque...
Bill, inertia/mass is not responsible for generating torque/force. You need more torque to acceleratie/decelerate a spinning mass but that's a different story. However, more inertia means less torque ripple and less noise.

More distance between shaft and stator/magnet airgap is responsible for generating more torque.

Prettig weekend Ron van Sommeren
• int. electric fly-in, Nijmegen, the Netherlands
• brushless motor building tips & tricks
• diy brushless motor discussion group
• Drive Calculator download & discussion group


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Old 01-18-2008, 03:04 PM
  #105
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Default RE: How does a brushless motor work?

Quote:
ORIGINAL: pilotpete2
It would be fantastic if a cost effective way to implement this technology could be developed to replace the brushed universal (series wound) motors that power our AC powered devices ...
Christian Lucas earns his hobby money here:
http://www.magnetmotor.de/ (English available)
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Old 01-18-2008, 03:56 PM
  #106
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Default RE: How does a brushless motor work?

Greetings Ron,
Good stuff in that link.
I was recently looking at some information regarding the GM/Chevrolet Volt concept car. The idea of a plug in hybrid with a purely electrical drive (gas engine/generator for maintaining charge on cross country trips) looks very promising, with a range of around 65Km without running gas, I could make 3 to 4 trips to town per day on an overnite charge, that would save a lot of gas and since most of the electricity in my area is Hydro and Nuke, a lot less carbon emissions.
Best Regards,
Pete
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Old 01-21-2008, 02:39 PM
  #107
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Default RE: How does a brushless motor work?

When GM was doing battery research in the 1980's they had a sign hanging on the lab's wall:
Far.
Fast.
Cheap.

Pick any two.....
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Old 01-21-2008, 02:52 PM
  #108
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Default RE: How does a brushless motor work?

Yeah, but we want it all
Dare to dream
Pete
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Old 01-21-2008, 03:13 PM
  #109
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Default RE: How does a brushless motor work?

As I've told my children (until they moved out) - Everything/all things is not an option....
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Old 02-09-2008, 02:56 PM
  #110
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Default RE: How does a brushless motor work?

How about the Tesla car. Any of you ever heard about that? I am thinking about going to the Junkyard and finding a nice old car (geo metro for the win), and converting it much like the tesla is.
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Old 03-24-2008, 03:51 AM
  #111
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Default RE: How does a brushless motor work?

hiya all. I've been building RC boats and working with BL motors for a while now. I bought a catamaran a couple of days ago, intended to be run on twin brushless outrunners. Now as far as i knew all i needed was two outrunners, two BESCs, two drive shafts and counter-rotating props, a y-cable to connect the two BESCS in parallel and feed into 1 receiver channel. Problem is i bought the boat from ebay, as an unfinished build, and amongst the bits and bobs (all new), the guy i bought it from supplied a v-tail servo mixer. Why? have no idea what this does (although i'm guessing its used mostly for aircraft applications), and since i'm only running 1 servo for steering, the only remaining possibility is to hook up the two bescs to it....any reason for doing this?

thanks in advance.....
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Old 03-24-2008, 09:59 AM
  #112
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Default RE: How does a brushless motor work?

My guess is, the guy's wondering, "Where did I put that v-tail mixer, hmmmm?"
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Old 03-24-2008, 12:43 PM
  #113
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Default RE: How does a brushless motor work?

Better start a new thread Stokes, this is a FAQ.
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Old 03-24-2008, 03:47 PM
  #114
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Default RE: How does a brushless motor work?

yes that was my question, and i'm sorry i presented you guys with an ooq (one off question) rather than a faq...will start my thread when i get the motors and bescs - thanks anyway
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Old 05-13-2008, 02:08 PM
  #115
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Default RE: How does a brushless motor work?


Quote:
ORIGINAL: Matt Kirsch

A popular myth that I fell victim to myself. Turns out that even though the ESC does switch the polarity back and forth on the various phases of the motor to make it turn, it's still putting out DC voltage. It's similar to AC, but the wave is a "square" type. Unlike AC, where the voltage gradually changes from maximum + to minimum -, producing a "sine" wave, this switched DC changes from full + to full - instantly.

The picture below kind of shows what I mean. This is what you'd see on the screen of an oscilliscope if you compared true AC to what the brushless ESC is doing, sort of, kinda, maybe


ac current runs above and below 0v (thats why we call it alternating current). dc current runs 0v or higher. sorry if i'm wrong all my text books show a very different graph
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Old 08-23-2009, 10:49 PM
  #116
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Default RE: How does a brushless motor work?

Hello!!

I am experimenting with a 24 leg stator and 26 Poles (PM) outrunner Brushless motor,  I am kind of confused on which way to wire it would be more efficient as torque and RPM's, ABC,ABC...or in a site to calculate the wiring way it gave me   AaAabBbBCcCcaAaABbBbcCcC..I guess with Distributed Wiring, but the sense according to CCW and CW don't look good...
Is this right?
I see Ron has a 24 teeth stator....how did you wind it, Ron, and what are the spec's as RPM's and Torque you obtained on this model?
Thanks in advance

Raul
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Old 08-24-2009, 07:29 AM
  #117
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Default RE: How does a brushless motor work?

Quote:
ORIGINAL: RAULOR
... I am experimenting with a 24 leg stator and 26 Poles (PM) outrunner Brushless motor, I am kind of confused on which way to wire it would be more efficient as torque and RPM's ...
More magnetpoles will give lower Kv (rpm/Volt) and higher Kt (torque per Ampère, NOT torque just by itself!)

Quote:
ORIGINAL: RAULOR
... it gave me AaAabBbBCcCcaAaABbBbcCcC ...
Yes, that is correct.
The number of statorpoles is almost equal to number of magnet poles. Two adjacent rotorpoles have opposite magnetic fields (one is north, the other south). Both have to generate a force in the same direction (toghether we stand, divided we fall ). Therefore the two adjacent coils opposite of the magnetpoles most be wound differently: Aa. 26magnetpoles is not a must, you could also use 28magnets (different winding diagram). 30 will not work. 32magnetpoles will give more cogging and noise and must be wound ABCABCABC...
Have a look at the 24statorpoles -designs and -diagrams here:
http://www.powercroco.de/ (English & German)

Quote:
ORIGINAL: RAULOR
... AaAabBbBCcCcaAaABbBbcCcC..I guess with Distributed Wiring ...
Is this right? ...
All poles wound. The term 'distributed' is only used when talking about 12slot/14magnetpoles LRK versus dLRK.

Quote:
ORIGINAL: RAULOR
... how did you wind it, Ron ...
Last time I flew a model was in '91, IC helicopters. Never flew a plane, or anything electric. Never built a motor. I'm an EE though

Quote:
ORIGINAL: RAULOR
... what are the spec's as RPM's and Torque you obtained on this model? ...
Hard to say, depends on stator-diameter and -length, number of winds, magnetstrength.
About quick'n dirty determination of number of winds for desired Kv:
http://www.rcgroups.com/forums/showt...0#post12784300

I guess this one will be a biggie, an real Ampère hog. Have you wound motors before? If not, I suggest you get some experience with a smaller motor first. Unless you like the smell of electrons in the morning
Dry testing BEFORE connecting newly wound motor to ESC:
http://www.wattflyer.com/forums/showthread.php?t=35216
http://www.rcgroups.com/forums/showthread.php?t=240993

Motor_rewinding_101, must read, if you haven't done so already
http://www.gobrushless.com
-> knowledge base
-> basic overview (1-5)

Tips and tricks, checks and tests, may keep you from frying yer ESC and/or controller:
http://www.rcgroups.com/forums/showthread.php?t=240993

BTW. Motor building is not the subject of this thread. Better start a new one and post a link to the new thread for those who are interested. I suggest you do that on RCGroups, it has a dedicated motor design and build subforum, more experience overthere:
http://www.rcgroups.com/electric-mot...struction-361/ (RCU moderators won't mind this I hope)

Vriendelijke groeten Ron
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Old 08-24-2009, 02:45 PM
  #118
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Default RE: How does a brushless motor work?

Hello Ron, and thanks much for a fast reply!!

Yes it is a "biggie"...Stator Inner Diameter is 85.0 mm and OD (Outer Dia) is 112.0 mm, and yes, I have experience in winding motors, however I have never wound a Brushless..
It is a project I have been working for a while that are two motors assemble in one center casing for the two stators, the outer bell housing (rotor) is made of carbon fiber and polyester resin (very light).
I am designing the stators in CAD before they Waterjet cut it for me in steel, so I could change the design anytime.
Iam using2-3c Lipo batteries, 2100 Miliamps, 11.1 Volts, I already run a prototype at 2800 RPM based on a brushed motor, but had not the right torque (only 12 fields).

I want to reach around 3000 RPM in each motor, but with enough torque to control the air flow to create the needed lift force. the two motors will rotate opposite (CW and CCW)
I particuiary like the WYE=Star configuration better,because of simplicity and speed,but in 24-26 it would not work...

Do you think of a better configuration for this model?

Thanks a lot for your time, and eventually I will open a forum with this subject very soon
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Old 08-24-2009, 06:17 PM
  #119
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Default RE: How does a brushless motor work?

Hello again,

I have worked on the wiring schematics and according to the Y method it sould look like this...
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Old 10-03-2009, 10:32 PM
  #120
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Default RE: How does a brushless motor work?

Here are some pictures ofan outrunner electric brushless motor. I included my own with mounting kit to show what moves and what doesn't.
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Old 10-11-2009, 10:21 AM
  #121
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Default RE: How does a brushless motor work?

I need some help: I am new to brushless motors & lipo batteries. How do I wire a lipo, esc & brushless motor? Thanks, Walter
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Old 10-11-2009, 02:53 PM
  #122
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Default RE: How does a brushless motor work?

Hello,

The ESC have two12 gauge or heavy wires for input to the batteries, normally they are black and red,black (-) , red (+),the ESC output of three heavy wires goes to the motor, some ESC have them colored different or they mentione the phase #...it does not matter how they are conected to the motor as long as they give you the right rotation sense, in order to change the rotation sense, all you do is change any two of the three output to motor wires.
The ESC have also the connector to the receiver, like a brushed motor, and some have BEC included.
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Old 10-15-2009, 02:38 AM
  #123
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Default RE: How does a brushless motor work?

And NEVER EVER reverse battery wires, will cost you your controller.

System wiring diagrams:
http://www.scriptasylum.com/rc_speed/_wiring.html

Battery pack wiring:
http://www.scriptasylum.com/rc_speed/_lipo.html

Vriendelijke groeten Ron
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Old 02-17-2010, 07:43 PM
  #124
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Default RE: How does a brushless motor work?

Hi everybody, i'm a new here.
i want some help about ESCs and how it work, specially about THROTTLE signle,
- how dose ESC deal with it ?
- what signles outlet to the Brushless motor?
- how dose Brushless respond to the Throttle (PWM Signle)?
- what are the modes of brushless motor ?brake,...).
- is there a certain width to the throttle pulses (is it just low throttle (1ms), mid ...(1.5ms) and Hight throttle (2ms)).

i want ask if there is anybody try to operate brushless motor via ESC without using Transmitter / receiver? that what i'm trying to do....

what i want to do is to operate the brushless motor(align RCM-BL650L) via the ESC(RCE-BL100g) without using Transmitter / receiver:
I know that the receiver support the throttle signle to the ECS, and its vary from 1ms(low throttle) to 2m(high throttle). the ECS is programmable and has tow modes: user mode (low throttle sent for seconds for this mode) , and Setup mode (high throttle), and you can choose what mode you want. lets suppose that we choose the user mode by sending a train of 1ms pulses, then after we enter the user mode: there are about 5 options (brake, electronic timing, Aircraft status, throttle response speed) and every option has also 3 option we can choose by varying throttle (low mid high) .
my problem is how to choose from the 5 option.

thanks all,


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Old 07-08-2010, 09:53 PM
  #125
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Default RE: How does a brushless motor work?

I were an lectrician a long time ago. This thing was very interesting. However it told me more than I needed to know....

Really glad for the discussion jerry dearmond
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