Variable frequency drives sometimes can also be used as single to three phase converters so as to allow users to run a three phase motor on a single power supply. And VFD is a more affordable solution to the lack of three phase power compared to rotary phase converters and static phase converters. A single phase VFD can convert 1-phase 220v-240v to 3-phase to power the three phase motor. It also can reduce the inrush current of the motor during starting up.