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Topic: L298N + ESC + Brushless Motor. (Read 11672 times) previous topic - next topic

whitebank

#30
Jan 13, 2018, 02:31 pm Last Edit: Jan 13, 2018, 02:37 pm by whitebank
No, it's not possible to drive brushless motors with an L298
Really? I made it run with L298. You won't believe? See result here

https://www.youtube.com/watch?v=f9KxO_V0Abc

raschemmel

#31
Jan 13, 2018, 09:05 pm Last Edit: Jan 13, 2018, 09:14 pm by raschemmel
Really ? You reply to tell me I'm wrong but
you won't post any schematic or code to help the OP !
REALLY ?
Who does that ?
Why are you even on this forum if it's not to help others (like the OP, remember him ? HE's the one asking HOW to do it and you
jump in to show you've done it without so much as a word to the OP.)
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

slipstick

Why are you even on this forum if it's not to help others (like the OP, remember him ? HE's the one asking HOW to do it
Well the OP was asking to how to do it 3 years ago. Probably either worked it out by now or lost interest.

And to be fair to whitebank the link he posted contained plenty of information about how it was done.

Essentially it's possible for a certain class of brushless motors but given the limited capabilities of an L298 it's fairly pointless except as an entertaining little exercise.

Steve

raschemmel

Ok, I missed the DIY link in his first reply. I only saw the Youtube link.
@Whitebank,
My apologies. You did provide the
"how to" info.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

TomGeorge

#34
Jan 14, 2018, 05:22 pm Last Edit: Jan 14, 2018, 05:24 pm by TomGeorge
Hi,
The L298 driving the BLDC motor is pulsing the three phases with square-waves like a stepper motor.

An ESC uses a high frequency PWM signal, modulated to give an approximation of a 3 phase AC,sinusoidal, signal.

Here is an example of an ESC output to a BLDC motor, the inductance of the motor windings helps to smooth out the PWM to give a sinusoid and smooth efficient running.

https://www.youtube.com/watch?v=Jdhgi5_kmvk

You can hear the difference, the L298 circuit sounds rattly compared to the ESC unit.

An ESC is a small version of a VSD that uses high frequency PWM to produce a variable sinusoidal AC current on 3 phases.

http://www.acdrivesguide.com/vsd-controltheory.html

PWM frequencies can be as high as 16Khz, to produce a sinusoid AC of 50Hz or higher if overspeeding a 415Vac 3phase 50Hz motor.

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

raschemmel

I agree there is no logical justification for using L298s instead of an ESC driven using the SERVO
LIBRARY. The "rattly" sound is due to fact that the two L298s are only driving TWO of the three phases ( in Whitebanks example), and also due to the squarewave instead of sinewave drive.
Arduino UNOs, Pro-Minis, ATMega328, ATtiny85, LCDs, MCP4162, keypads,<br />DS18B20s,74c922,nRF24L01, RS232, SD card, RC fixed wing, quadcopter

whitebank

"rattly" sound because output frequency for motor is still low. Now i have no time to make it run with high frequency, but i believe it can with L298
Sure this project run motor by 3 phase. I try to take out 1 of phase, motor not run!
I will return with better result which using sine PWM to control motor speed.

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