Need help with a sensorless vector VFD and 2.2kw motor.

[kajuk]

Did you read section 5.2.4 of the manual ?

Yes, this is what I follow when doing autotuning.

It's strange how the trimpot works in v/f but does not seem to work in vector mode.

The inverter kinda responds to the trimpot and increases/decreases frequency but the spindle doesn't follow it. Even if I set minimal allowed frequency to 400, the spindle doesn't want to know and still jerks around a few rpms.

Also the motor speed is an issue. It appears that spindle motors are rated at the theoretical speed of 24000 rpm but this is not the actual speed, a thing called 'slip' has to be taken into account.
The manufacturers of my spindle say the slip is about 4% of full speed which works out at 23040 rpm (they said they used a figure of 23100) so this is the speed you should enter for parameter PB.04

Do you think such a small difference may have an effect? Even when I tried your suggested settings (1.1kw/200Hz/12000rpm/110V/9.5A) it didn't make a much difference. I'll try anyway.