Small-signal modeling and stability analysis of a bidirectional electric vehicle charger

This paper addresses the stability challenges that exist in a bidirectional grid connected electric vehicle (EV) charger. The EV charger under consideration comprises of an ac-dc single phase active rectifier stage followed by a dc-dc dual active bridge (DAB) stage. small-signal models suited for stability analysis of this charger are derived. Controller design considerations are discussed in order to ensure closed loop stability of individual stages and to prevent any instability due to interaction between the stages. Experimental results on an EV charger hardware prototype are presented to validate the proposed models and control design considerations.