I stand corrected here. Just did a quick search for a 7.5hp VFD with 220 single phase in and 3 phase out. NOT available at least at the Co I looked at. It is available in 3ph in 3ph out. They cost about the same as the rotary but you can't run them in a typical knife shop without the rotary. If you only have 110v then the highest I could find was 1.5hp. you still need to derate the motor but 1.5hp should do most things even with derated operation.