Spaceba! I have a book on how to do this - I think I need to read it again. I think I remember that the size (uF) of C1 is proportional to the load on the motor - I imagine that the thing gets unhappy if you load the motor too heavily, if it runs well with no load? People here used to use a very large 3-phase motor on 'idle', run with capacitors like your scheme, and then take the 3 phases from that motor's terminals, to drive the smaller lathe, milling machine etc. Some people use a flywheel on the big motor, but I imagine the rotor itself adds plenty of inertia. The Japanese VFD is very nice, but it is a complete box of mystery - if it breaks, I have no chance. I can't even see most of the components, or count the legs on the computer chips inside it 
