So can you run an unloaded motor off a VFD that is only rated at half
the motors hp? Well the answer is that you can not at least with the
VFD that I was trying. After a second or so, the vfd would stop and
show an error code. But wait, the motor can be connected for either
....

I had the same result trying a 5 hp. VFD on a 7.5 hp motor.

Karl