Operation and Control of Smart Transformer-based Electric Vehicles Charging System

Integration of charging stations for electric vehicles (EVs) will result in severe stress on electric grid. The EVs connected to the grid can also act as a source of energy and this demands greater control as well as coordination for better utilization. Conventional power transformers (CPTs) utilized in the EV charging stations are not well equipped for meeting these challenges. Recently, smart transformer (ST) has been proposed as an alternative to CPT. The ST connects medium voltage (MV) grid to low voltage (LV) grid with two intermediate MV and LV dc links. This paper utilizes the availability of the dc links of the ST to integrate the EVs charging station to electric grid rather than connecting these through the CPTs to the grid. A comprehensive analysis of sizing of the power converters utilized in the considered system has been presented. A comparison of efficiency for the different configurations is carried out and the possible more efficient scenario is suggested. Infact, the ST based EV charging system is found to be more efficient in comparison to CPT based EV charging station. The performance of ST based EV charging station is verified through simulation studies.