Powering three separate shaded pole axial fan motors with one 3-phase VFD
Most VFDs have a mode of control that is not senseless vector. That mode is often called the "V/Hz" mode. If you select that mode, it should be possible to power three shaded pole motors driving fan loads. Some VFDs may have a "load loss" or "load imbalance" protection feature, but I don't think that either of those features is common. VFDs usually have sufficient configuration adjustment ranges to allow setting up for 115V output at 60 Hz.