Industrial frequency inverters (or "variable speed drives") can be thought in three parts: A mains rectifier, that converts two- or three phase input current to DC, a DC energy storage (large capacitor) and a three phase driver, that converts DC current to three phase AC currents of the wanted frequency.
The mains rectifier is often just a passive rectifier circuit.
The output driver usually is made of microcontroller driven FET bridges.
Question is, if the rectifier stage of one inverter can be removed, and replaced by the same circuit as the output driver stage taken from another inverter. Like we would treat mains power just as another motor.
With right control, the inverter then would become fully symmetric and would be able to feed current either way, from the mains to the motor but also from the motor to mains (recupation).
As the motor is also meant for running of the mains directly, voltage and current of both (motor and mains) somehow fit well, and I guess the driver circuit could serve both of them. Would this be feasable?