A Single-Phase Interleaved Buck-Boost PFC Based On-Board EV Charger

This article proposes a two-stage battery charger using an interleaved bridgeless buck-boost-based power factor correction (PFC) AC-DC converter at the first stage. The converter at the front end improves the input current shaping and power factor while providing adequate DC link voltage. At the back end, a half-bridge LLC converter is used to charge the battery. This onboard charger (OBC) executes nearly unity power factor throughout a broad input voltage range. Furthermore, input current and voltage sensors are not required for AC-DC conversion due to the discontinuous inductor current conduction mode (DICM), further increasing the converter's reliability and reducing the overall cost. This OBC solution practically suits the majority of low-voltage (LV) battery chargers. The design equations and a thorough steady-state analysis of the proposed charger are also presented. Finally, the validity is demonstrated by showing both simulation and hardware results. A laboratory prototype of 1 kW for this OBC results in an input current THD as low as 2.08%, and a peak efficiency of up to 93%.