Hello

I am currently building a cnc router table. Everything is working fine so far... steppers, mechanics, ball-screws etc.
the only thing that makes me lots of trouble is my spindle.
It is not one of the cheap ones you can buy from china. It is from a little bit higher price segment (500 USD). It has 1.5kW total power with water cooling and 3x cermaic bearings. From the manufactorer it is rated to be able to mill metal (the ceaper ones are clearly stated for wood craving only)

The spidle turns really great, makes smooth nice operation sound. I have it running with an mitsubishi VFD that I grabbed from eBay some time ago (FR-E520S-2.2K-EC) The VFD has lots of nice features.
The spinlde can spin easiliy from 0-400Hz, but the problem is, that it requires more current than the spindle is rated. I have set 5.5A current rating in the VFD parameters. The motor protection kicks in when its is load 150% for a longer time (a minute or so). Anyways the spinlde requires 7.2A (at 220V) when its full speed (400hz). I havent set the total motor power anywere. It is 1.5kW - and that is to total spindle power at 220V (220V * 7,2A)
I am too afraid to damage the motor, if I set the current limit any higher. Than the rated 5.5A. Unfortunately I dont have any information or data about the motor. I read that 5.5A just from the chinese engraving on the motor itself

In my mind the motor should require less current when it is with no load. So in idle full speed, I would have expected 1-2A at 220V.
So for now the spinlde gets up to 45°C when running for longer time (the temperature saturates then - I pump it into a 20l bucket with about 15l/h flow)
Hopefully you guys can give me a hint. I am searching for the proper parameter for over three entire days now - with still no success.

What currents I get at different speeds:

100Hz 3,97A 66V
150Hz 4,00A 92V
160Hz 3,80A 98V
184Hz 4,10A 111V
--> 185Hz 7,00A 111V (jup thats a problem... but why??)
200Hz 7,20A 120V
250HZ 7,10A 145V
300Hz 7,01A 170V
350Hz 7,10A 196V
400Hz 7,20A 225V


Here I post you the important configurations I made so far:

Base frequency: 400Hz
current for motor protection circuitry: 5.5A
Maximum output frequency: 120Hz
Minimum output frequency: 0Hz
current limit: 150%
current limit at higher speeds: 150% (I guess it is meant above 120Hz)
energising current: (set to "self cooled motor" - but can be also set from 0-500A)

I honestly still dont know the diefference between the base frequency and the output frequncy... (does anyone know?)

Thanks for you help anyways, even if it doesnt work then.

regards Max

Attachment 198676
Here is a picture of the motor engraving: