mahmood : Is this all one thread? If so where did the ac motors come from?
No It is not good engineering to parallel Two motors on a variableffrequency d rive controler. It works (sort of ) if they drive separate loads and slightly better if they are driving the same load. Motors only do "work" when a load is applied and the are running below the free running speed thus they will share the work load, the real problem is that the current setting on the controller is likely to be unable to protect the remaining motor if one of them faults or a fuse blows. Also you could get some interesting harmonic noise on the lines. Starting inrush should not be a problem as the VFD will control it. btw how big are these motors? hope this helps Terry