Thanks for your reply!
I don't know the manufacturer the drivers are chinese copy Special AC servo motor 110ST-M06030 6N. M 1.8KW+ drive Kit line - iBuyLa_Tmall_Taobao Angent - Online Shopping at iBuyLa.com in Singapore .
I have oscilloscope so i can see the curve of voltage after rectification so i can find if smoothing is ok or not .
The enclosure of driver does not have space for extra caps so if i add more i will put them outside the drive.
The pcb has 2 rectifiers (4 legs each one) much be change them with bigger rectifiers ?