Resolution:
To have a power factor closed to 1 (not the cos) it is necessary to suppress all the current harmonics.
For that, use an active filter from Merlin Gerin (Sinus filter product range)
This device measures the current harmonics and generates the opposite harmonics in the line supply.

I would like to catch your attention on one important point:
the customers make often the confusion between the power factor needed for all an installation and the power factor of our ATV.
For instance, that means they want the speed drive to have a PF of 0,98 if the total installation needs to have a PF of 0,98.
If an other equipment has a lower PF, all the installation will have a lower PF.
So, even the speed drives have a PF=0,98 it doesn't`t mean the installation will have a PF=0,98.
It is the main supply of all the installation which has to be treated regarding the power factor.

On the other hand, you can improve the PF of the ATV by adding a line choke or passive filter from the catalogue as it is often requested.
With the harmonics levels of ATV you can estimate its Power Factor:
PF = cos phi(1)/SQR(1+THDﾲ) where cosphi(1) is from the fundamental current.
So, you can take into account this formula => PF = 1/SQR(1+THDﾲ) because cosphi is closed to 1.