The rectifier transformer is acting as link between the grid and the AC to DC converters. Application of rectifier transformer is to provide required number of phases, voltage shifts needed to realize the conversion and to adjust the rectifier input to vary the DC output voltage.

A rectifier is an electrical device used to convert alternating current (AC) into direct current (DC) by allowing a current to flow through the device in one direction only. Diodes work like one-way valves within the rectifier to maintain this flow of current.