IC for converting single phase to three phase
You can take a look at the various methods of building a phase converter and pick the one that fits your needs. This technology is very old and well documented even in the oldest handbooks you will find. You may find something smart and simple from e.g. 1960 that will work perfectly well.

The second approach is more straightforward: first convert AC to DC and then, using three synchronised and phase-shifted inverters, create three phase AC of any desired frequency and magnitude: