I'm cleaning up my shop and I have a homemade rotary phase converter built around a 15 HP motor. I used it for 10 years on a Bridgeport BOSS IV CNC mill without a problem. I now have three phase from the power company so I no longer need this.
It has electronics that start the motor through capacitors then disconnect the capacitors, wait a few seconds, and energize the load through a relay. There are no "ballancing" capacitors but it doesn't need them. The three legs stay withing a couple volts of each other. It has digital voltmeters on each output phase.
I ran it from 240 VAC single phase through a 50 Amp breaker. It probably needs new motor-run capacitors (about 200 microfarads at 330 VAC). The last few times I used it the capacitors sort of "gurgled" at startup. Also the motor is missing the shroud that directs airflow from the motor's impeller so the motor eventually overheats. I ran a box fan blowing on the motor but a more elegant solution would be a new shroud. It has a smoke detector to shut down the whole thing in case of smoke or fire.
I'm just north of downtown Seattle off Dexter Street. If you live in the area and want to come by and pick up this thing email me.