Searching for phase change device
Industrial crossovers are expensive. YOu want to choose ZCS SSR's and use 3 with Exclusive OR Logic to prevent catastrophic enabling of more than one. Current monitoring of each phase is needed which might require a custom setup with suitable time delay to prevent hunting for the next available phase in case the motor creates an overload on all phases. In a power outage situation there must be a default phase chosen followed by the "low man wins" in current sensing in case of time averaged current overload. You don't want transients to trip it.  What's your budget. $200 or $2K 1st needs design and time. 2nd needs capital  Both need installation and testing and calibration of trip points. It may be practical to decide when to to switch in 1 second and actual transfer phases in 1 cycle.  Are these line to line or single phase? Assuming latter.

Where do you live that has 3 phase going to a home?

Here is one Industrial example (not cheap ) http://www.indiamart.com/srielectronics/power-transformers.html#automatic-phase-selector