Abstract: This paper presents a unidirectional three-stage power electronic transformer (PET) for interfacing the low voltage (LV) and medium voltage (MV) distribution networks. The input stage of the PET system converts the incoming medium voltage to DC voltage. The second stage is the isolation stage which consist of a converter and rectifier that are connected to the primary and secondary side of the transformer respectively while the output stage is made up of a 2-level 3-phase inverter which connects the LV distribution network.