B-G431B-ESC1 does not respond to PPM input

sspry · ‎2021-03-07

Hello, I generate a 4.4V 1400us on (2000-1400)us off signal and verify its existence with scope. This signal does not induce movement in the motor I have attached to the ESC evaluation board.

The board beeps using the motor when powered on. When I connect a cable to my driving board (NUCLEO_L432KC) the beeping stops. I've verified they share a ground.

I'm not sure what else to check.

Orso · ‎2021-04-15

Well,

it's seem we have almost the same problems. When we try to reach full rpm we get an overcurrent fault, the motor brutally stop and consequently we get a speed feedback fault. I verified I have both fault at same time with the function MC_GetOccurredFaultsMotor1().

Yesterday night I tryed to increase the current threshold from 45 Apk to 120 Apk and higher and that solved my problems. Now I can reach almost full speed without any fault. Phase currents stay always under 18 A so I think to be safe. It's not so elegant but for now seem to work.

sspry · ‎2021-04-16

@Orso & @SBurc.1

It is a typical problem that sensorless BLDC drives have issue starting under load, as in a pump or mechanical servo. The drive algorithm supplied with the evaluation board may not be sufficient. There is usually a second algorithm to start the motor under mechanical load.

The second algorithm cogs the motor with jumpy, high torque, low RPM movements for some time before you are up to speed. This usually must be done blind, without feedback. If you can get the supplied code to do this then it will work, but usually you must be spinning very slow for some amount of time in a way that is incompatible with most sensorless BLDC loops.

(Also if you're driving a pump you are unlikely to get motor's highest rated RPM, the rated RPM is usually unloaded. There is or should be a torque/RPM curve in the motor datasheet.)