ATO VFD converts the power frequency AC 220V power supply into a DC power supply through a rectifier (double voltage rectification) on the basis of the ordinary frequency converter, and then converts the DC power supply into a three-phase 380V AC power source whose frequency and voltage can be controlled. Supply the motor. This method does not boost through the transformer, but only boosts through the rectifier boost circuit, which greatly reduces the size and weight of the inverter. Compared to the voltage booster, the cost is lower. Single Phase To 3 Phase Vfds are best if you have a small number of 1/2 hp motors or specifically need the speed control, soft start, or other motor control features of the VFD.