High Efficiency Bidirectional LLC Converter for Solar-Charged Electric Vehicles

Abstract

Recent interest in electric vehicles with on-board solar generation presents a new opportunity for using solar electric vehicles (SEVs) for distributed generation when the traction battery is fully charged. This presents a new power electronic challenge: the on-board charger should have high efficiency in the grid-to-vehicle direction for normal charging power levels (i.e., 6.6 kW) and also high efficiency in the vehicle-to-grid direction for much lower solar power levels (i.e., <800 W). However, typical on-board charger topologies have low efficiency at light loads. This paper proposes a novel bidirectional LLC converter to address this challenge. PLECS simulation results show that the proposed converter is 1–7% more efficient than the traditional dual bridge converter at low loads for vehicle-to-grid power flow.