450 How Do Brushless Motors Really Work?

Rob Lancaster

Rob Lancaster

Active Member
Hi guys, me again..
I've been having fun flying my 450 around. The ESC's gov and gyro gain settings are good now and the weather has been perfect sooooo……
Anyway now that she's flying great, I want to learn more about how these high tech motors work. For example, my Scorpion HK-2520-3500kV motor has specs like this,, 5 degree timing, drive freq-8khz, 3 turn delta, 12 stator arms, 10 poles and say what!?? What da heck does all that mean?

I'll just bet Tony and friends, has much data on this topic; right bro or bros.....
Tanks ah,
Rster...
 
Tony

Tony

Staff member
Lets start with the basics. A brushless motor is nothing more than a 3 phase motor. The ESC is just a very fast on/off switch for each pole of the motor. When the Armature charges a pole, it pulls the stator towards it. When it gets close, it will turn that one off and charge the next one. Rinse and repeat for the third phase. But in the example below, that is only 1/2 revolution. Your motor has 12, so my example here would only be 1/4 turn. I can get more in depth, but lets start here lol.

SoeJ.gif
 
Rob Lancaster

Rob Lancaster

Active Member
Ok, now I know why their called digital motors...
Yeah that's a great graphic. I liked the way the poles flip polarity as to push the armature along.

I don't understand the 1/2 or 1/4 revolution part though...
Rster...
 
Tony

Tony

Staff member
Every brushless motor will be divisible by 3. So the animation above is a 6 pole motor. You state you have 12 poles in yours. So 1/2 revolution on the animation is only 1/4 turn on your motor. It just changes phases faster to keep the motor spinning.
 
Rob Lancaster

Rob Lancaster

Active Member
Gotcha! And I have 10 pole motor, 12 stator arms, motor wind- 3 turn delta, timing 5 degrees, drive frequency 8 kHz and on and on… Keep it coming boss.....

Oh hey, does anyone know where I can get two quality 1.5mm hex wrenches?
Rster...
 
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Tony

Tony

Staff member
Timing is just like it is on a car engine. If you fire the armature early, that is advancing the timing. It will produce more power, but it will also produce more heat. If you retard the timing, it will fire much later and it will also run cooler.

It's hard to explain, maybe I will do a video on timing.

Frequency is how many times per second the FET energizes. 12GHz is 12,000 times per second.
 
Rob Lancaster

Rob Lancaster

Active Member
Ok I understand the car ignition part because of all my back ground on this.
When my motor says it's timing is 5 degrees, am I to assume that that is 5 degrees advanced? And what is the reference point? You know top dead center?.....
Thanks,
Rster...
 
Tony

Tony

Staff member
Yes, it always (most times lol) means advanced. And reference is when the stator and pole are lined up exactly together, straight on.
 
Rob Lancaster

Rob Lancaster

Active Member
Oh, ok I get it now..
Is it ok to deviate from the recommended 5 degree for my motor? Or should you always set it to what the manufacture recommends?
 
Tony

Tony

Staff member
You can play with the timing, but only fly it for 2 minutes max and land to check motor and ESC temps. More timing, more heat. Mainly in the motor though. Too high of timing and it can and will cook a motor.
 
Rob Lancaster

Rob Lancaster

Active Member
Excellent, got it...
Yeah the reason I ask is, I think my motor runs a bit hot and the flight time is short, 6 minutes max before she hits 3.7 volts on the ESC.
The ESC seems to run on the cool side...
Battery's are Glacier 2200 30C 3s packs... No puffing, warm though..
 
Tony

Tony

Staff member
What motor are you running? Motors like Scorpion are known to run a little warmer than most. But if you can hold your finger on the motor for 2 seconds or more without burning yourself, it 'should' be safe. Still hot, but safe.
 
Rob Lancaster

Rob Lancaster

Active Member
Ok...…
Hey she really does fly great.
The weather has been good and I have some relatives in town. Their all blown away at this babee! Oh the sound of those blades as they cut through the air is great!! It's music to my ears!!!!!!!!!
Rster...
 
murankar

murankar

Staff member
I have been super busy lately. Had an army weekend that ran into my 2 week summer and working second shift at the civilian job. So with that said in have read everything. I want to point out that the V4 hobbywings have the freq set to 36 as default. At one point it was adjustable but I think they turned that off. Hobbywing escs are designed to operate at the higher freq.

Timing is going to play a role in top power output along with heat. Just remember that timing is a function for the motor and freq is a function for the esc .
 
Rob Lancaster

Rob Lancaster

Active Member
Oh hey; thanks for your service!! I say that to all the military personal I run across so why not you too... These are very dangerous times we live in so stay safe!...

About the frequency, your right about the Hobbywing V4 esc. I can't reset that parameter with this esc...
So that brings me to the question of the day. If the V4 ESCs are preset to 36, and my motor has a drive frequency of 8kHz. Isn't that a mismatch?
 
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