An On-Board Charging System for Light EVs with G2V and V2G Power Transfer Capability

An onboard charger (OBC) topology having bidirectional power exchange functionality and transformerless structure, is realized in this paper for the LEVs (Light Electric Vehicles) applications. On one side, the bidirectional power flow capability effectively enables active/reactive power exchange between grid and vehicle through Grid to Vehicle (G2V) and Vehicle to Grid (V2G) mode functionality. Whereas, the transformerless structure reduces the cost and size of the charger and optimizes its losses. Unlike transformer based approaches, the presented two stage charger topology incorporates a switched capacitor high gain buck/boost bidirectional (SCHGBB) transformerless converter at the DC-DC power conversion stage. The SCHGBB converter effectively achieves the desired gain characteristic between the grid voltage and LEVs battery packs. It is noteworthy that, the continuous input and output currents, and reduced voltage stress characteristics of the SCHGBB converter, considerably enhance the performance of the OBC. Considering this, the functioning, component selection criteria, control implementation, and performance of the OBC for both G2V and V2G modes are comprehensively evaluated under certain and uncertain operating conditions. Finally, the relevant results are presented to verify the satisfactory performance of the presented charger topology.