Bidirectional Transformerless EV Charging System with Low Device Cost and Leakage Current

In electric vehicles (EV), the charging circuit is an important component which needs to be carefully designed. This research proposes a novel concept to reconfigure the traction circuit to achieve a low-cost bidirectional charging circuit that is capable of providing V2G services. High charging efficiency is achieved omitting an isolating transformer and parasitic common mode currents are attenuated by controlling the common mode voltage with suitable common mode paths. Compared to typical EV charger topologies, the proposed concept increases efficiency, adds bidirectional operation, and reduces costs by repurposing existing drivetrain components. Then the proposed reconfiguration concept is analyzed and the specific working principles are described. The analysis is verified by simulation and on an experimental test bench.