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May 17, 2018, 11:20 AM
Registered User
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BLDC Motor Explosion - For your entertainment. :D


FPV BLDC Motor at 24s. Explosion @ 200,000 RPM. (3 min 56 sec)


My Analysis..

At:
0:45 10% throttle is applied
0:48 100% throttle applied
0:49 Rotor Explodes. Sending shrapnel everywhere
0:50 No-BEMF means 1000+ Amps into the stator. Stator vaporizes.
1:00 Rotor can stops spinning

**
1:31 Check out the 3x phase leads (far left coming down from ESC) repel eachother..
Huge fault currents means strong magnetic field.

1:58 Motor Can (Rotor) starts coning out.

Im currently building a bigger/stronger blast chamber and will be blowing many motors and props up. (for failure mode analysis purposes)
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May 18, 2018, 06:46 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Barbarian OZ practices Clearly the winding wire was not thick enough

Typo in the title? 200,000rpm or 20.000rpm?

200krpm on a 14 or 12 magnetpole motor would mean that controller can handle 1400 respectively 1200krpm on a 2-pole motor.

The higher the number of motor magnetpoles, the lower the max. rpm a controller can handle, computations-/microprocessorwise.
Max. rpm table
www.bavaria-direct.co.za
→ more info
→ ESC max. RPM Limits

Prettig weekend Ron
Last edited by Ron van Sommeren; May 18, 2018 at 08:30 AM.
May 18, 2018, 08:27 AM
Jack
jackerbes's Avatar
If I understand his setup, he could have had up to 94V on that motor at full throttle. So the result is not surprising...

I don't think the RPM killed that motor, the voltage did it.

Jack
May 18, 2018, 08:32 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by jackerbes
... he could have had up to 94V on that motor at full throttle. ...
Even minor changes in setup can have surprisingly considerable/huge effects. This is hardly a minor change, this is hardcore
E.g. each voltage doubling will four(2²)fold current, doubling Kv will eight(2³)fold current, and doubling prop diameter will sixteen(2⁴)fold current.

Motorcurrent is proportional to pitch¹, voltage², Kv³ and diameter⁴.
Power-drawn is proportional to pitch¹, voltage³, Kv³ and diameter⁴.

Prettig weekend Ron
Last edited by Ron van Sommeren; May 18, 2018 at 11:19 AM.
May 18, 2018, 09:22 AM
Registered User
Quote:
Originally Posted by Ron van Sommeren
Barbarian OZ practices Clearly the winding wire was not thick enough

Typo in the title? 200,000rpm or 20.000rpm?

200krpm on a 14 or 12 magnetpole motor would mean that controller can handle 1400 respectively 1200krpm on a 2-pole motor.

The higher the number of motor magnetpoles, the lower the max. rpm a controller can handle, computations-/microprocessorwise.
Max. rpm table
www.bavaria-direct.co.za
→ more info
→ ESC max. RPM Limits

Prettig weekend Ron
Hi Ron,
Not a typo. The motor is a 2700Kv (FPV motor with 2207 stator) , normally rated for 4S use itll do 43,000 RPM.
Its a 14 Pole motor therefore normal use the ESC will need to do 14/2 x 2700 = 300,000 eRPM.

But this controller can do up to 2,000,000 eRPM and up to 24S - 100 volts and 200Amps continuous.
May 18, 2018, 09:47 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by Ub3r
.. this controller ... ... up to 24S - 100 volts and 200Amps continuous.
You can always take up welding if you don't like your current job
Quote:
Originally Posted by Ub3r
... for failure mode analysis purposes ...
Can you tell us a bit more about the bigger plan? Background for this testing?

Prettig weekend Ron
May 18, 2018, 09:59 AM
Registered User
Quote:
Originally Posted by Ron van Sommeren
You can always take up welding if you don't like your current job
Can you tell us a bit more about the bigger plan? Background for this testing?

Prettig weekend Ron
Yep sure. My plans are to find the physical limits of various propellers and motors. The FPV racing market these days is demanding more power everyday, and pushing over 500W through those tiny motors and props at very high RPM's. Need to find out how much headroom we have available to ease my curiosity.
May 18, 2018, 10:16 AM
Registered User
Quote:
Originally Posted by Ron van Sommeren
Barbarian OZ practices Clearly the winding wire was not thick enough

www.bavaria-direct.co.za
→ more info
→ ESC max. RPM Limits

Prettig weekend Ron
Im happy to send you an ESC for testing. You may add it to the table.
Im sure you would be pleasantly surprised.
May 18, 2018, 11:17 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by Ub3r
Im happy to send you an ESC for testing. You may add it to the table.
Im sure you would be pleasantly surprised.
www.bavaria-direct.co.za is not my site, it is owned/mainted by Christo van der Merwe (South Africa), a.k.a. RCG user Skylar.

Prettig weekend Ron
Last edited by Ron van Sommeren; May 18, 2018 at 04:10 PM.
May 18, 2018, 11:58 AM
Registered User
Quote:
Originally Posted by Ub3r
Im happy to send you an ESC for testing. You may add it to the table.
Im sure you would be pleasantly surprised.
What kind of ESC do you have? .. I am very curious !
May 18, 2018, 03:48 PM
Registered User
Skylar's Avatar
Quote:
Originally Posted by Ub3r
Im happy to send you an ESC for testing. You may add it to the table.
Im sure you would be pleasantly surprised.

I'll add your ESC test results to the table if you send it by PM.
May 18, 2018, 04:18 PM
Ignorance is hard to Bare!
1boho's Avatar
Do u have datalog capability? How do you know it reached 200K before self destructing?
May 18, 2018, 05:32 PM
Registered User
Quote:
Originally Posted by Skylar
I'll add your ESC test results to the table if you send it by PM.
Yep Noworries.

Quote:
Originally Posted by 1boho
Do u have datalog capability? How do you know it reached 200K before self destructing?
Has full datalogging with 1mS (1KHz) interval. Stores data to local 16Mbit Nand Flash.
May 18, 2018, 06:02 PM
Ignorance is hard to Bare!
1boho's Avatar
Can you post the log of that run?
May 18, 2018, 06:20 PM
Registered User
Quote:
Originally Posted by 1boho
Can you post the log of that run?
Didnt save it for that run. But im happy to run another motor and extract the log.
Ill do it tonight.

The results are quite repetitive.


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