the VFD's are a VERY efficient way to power small motors, no sense anymore to use a phase converter with all that power wasting caps and rotor motor online just to run another..over 5hp then you might have to use a rotary but for under 5hp the VFD is the way to go. I recommend the Hitachi VFD's..I've used a lot on customer equipment that run them daily and never had a failure..the China made VFD's are coming along with the quality, pretty impressive for the price..with good applications assistance in our English language via email if you need it. Impressive. FWIW