Driving a 2.5ohm resistance 40.000 RPM BLDC motor

[Valentine]

@Rimbaldo

FD6288T … EG2134

These two drivers are identical.

@Rimbaldo

N76E003AT20

This is an 8-bit / 16MHz processor, think Arduino Nano.

@Rimbaldo

MS51FB9AE

This is an 8-bit 24MHz processor, think Arduino Mega.

The drivers are identical but your “newer” board brain is somewhat faster/bigger (not too much) than the “old” board brain.

@Rimbaldo

board, V1, increased the current to compensate the “effort” and didn’t seem to loose speed

This is entirely due to the code running on the board. The second “new” board should be able to perform better, apparently however, the code is worse. Go figure.

@Rimbaldo

If I use 0-5V PWM signal to control it (it has a PWM port), instead of the internal trimpot that I used for testing, would it be possible to achieve a slower min speed, like the 2000 RPM I want?

Seems very doubtful. The min/max speeds are entirely dependent on the code executed and I do not believe that switching from a potentiometer to PWM would change internally the RPM min/max scaling. However, since yo do not know the algorithm, it may be worth trying, but no guarantee at all. This whole thing as you can tell is very random.

Cheers,
Valentine