A multifunctional onboard charger (MOC) is a two-stage converter, which charges the traction-battery in grid-connected mode (GCM), and supplies power to low voltage bus in drive mode (DM). Magnetic integrated high frequency transformer (MI-HFT) based bidirectional dual active bridge (DAB) as second stage of (MOC) is proposed in this paper. The MI-HFT has three limbs and three windings. Two windings are wound on the center limb, while the third winding is split equally and wound on other limbs. Depending on the mode of operation, the third winding is configured such that it acts as either interface inductor (in GCM) or transformer (DM). For the considered application, the DAB is required to transfer 7.2 kW power at 360 V (nominal) to the traction-battery in GCM, and 2.4 kW at 72 V to the intermediate DC link in DM. These different voltage and power levels require different turns-ratio and interface inductances for efficient operation. The proposed MI-HFT satisfies these conditions and improve the ZVS range of DAB, therefore, the power density and efficiency are improved at reduced cost. The proposed MI-HFT is verified using simulation and experimentation.
