Two-Stage On-Board Charger Using Bridgeless PFC and Half-Bridge LLC Resonant Converter with Synchronous Rectification for 48V e-Mobility

Abstract

This paper proposes a new bridgeless buck-boost and half-bridge LLC resonant onboard battery charger for low voltage electric vehicles. A new bridgeless buck-boost derived front end topology is operating in discontinuous conduction mode (DCM) befitting reduced conduction losses, attains natural power factor correction (PFC) at variable AC input, and robust to high-frequency (HF) noise. The second stage comprises a half-bridge series LLC resonant converter to provide galvanic isolation. The LLC converter is operated in the inductive region in order to achieve ZVS turn-on of primary switches and minimize switching losses resulting in maximum efficiency. Detailed design and analysis procedure is described for a 1 kW converter with a wide input range of 80 to 130 V, from a single-phase AC grid. To verify the feasibility of the proposed scheme, the proposed battery charger topology is simulated in PSIM11 software. The first stage illustrates the input current THD of 3.10% and a power factor of 0.9994. Whereas the second stage consisting of series LLC converter demonstrates ZVS turn-on of secondary switches, low switching losses, conduction losses to achieve good overall efficiency. Also, synchronous rectification is employed to enhance the efficiency further.