Digital simulation of variable frequency transformer

This paper presents digital simulation of variable frequency transformer (VFT). The variable frequency transformer (VFT) is a device which produces desired voltage and frequency supply for constant and variable V/f control of ac drive. The main parts of VFT is a rotary transformer with three-phase windings on both stator and rotor. A controlled drive system is mechanically coupled with the VFT, to control the speed of the rotor. Therefore controlling the magnitude of rotor voltage and frequency. The number of simulation and experimental results have been obtained to verify the viability of VFT based V/f control of a three-phase induction motor drive. The proposed VFT may control below rated and above rated frequency control at constant and variable V/f control of ac drive.