Start-up failure every time

[MLang.7]

I am using the sensorless + PLL control scheme which requieres to pass a ramp a start-up. Allthough the motor runs smooth a start-up failure always occures at the final speed of the ramp. I tryed lowering the final speed to avoid this failure, but it keeps occurring even with speeds as low as 600 rpm. This is quite annyoing and I would like to omit this ramp-up procedure at the start.

[GMA]

Dear MLang.7,

Firstly, we would like to sincerely apologize for the delay in replying to your post.
If your point is still pertinent, you can find more details about "start-up failure" in our FAQ "ch.2.11 Why do I have a “Startup failure” error message during the rev-up phase and why does the motor stop?"

[Tinnagit]

I'm not sure what is your speed control model that you use to drive motor so it is very hard to figure out what happen on your drive.

But there are usually case that it's mostly happen with drive.
Motor drive has a relation between voltage - frequency - motor speed and current - motor torque.
For sensorless, if you won't use any feedback from motor, No speed - No position.
you use only feedforward to drive as RC-BLDC, if your motor has some load a heavy load, you have to focus on bemf from your undriven pole to find motor speed and you can sync voltage and frequency to drive it.

but the most mistake is about dead time to release bemf before drive new pole which it can be take long time more you prepare and you may cannot sync voltage and frequency to motor speed so you motor won't run in this situation.

and another one is the acceleration of motor, for sensorless is hard to find angular of pole because it's measured by bemf which it's maybe make a wrong step while the driver increase speed with high acceleration.

but I'm unsure what is your really problem.