I have a factory 3ph, 5 hp motor on my 18" Delta wedgebed planer and I bought the cheapest VFD I could find that would support 5hp, accepted 1ph input power and had a return option.  So far it's worked great but I've yet to try and plow of 1/8" of thickness from a 16"+ wide maple slab so when I'm ready to (and several are close to being done air drying), that will be the real test!