An integrated onboard charger and accessory power converter using WBG devices

Integrating the function of onboard battery charging into the traction drive system and accessory dc-dc converter in plug-in electric vehicles (PEVs) is shown to significantly reduce the cost and increase the power density of onboard chargers due to a substantially reduced component count. Replacing silicon (Si) based power devices with wide-band-gap (WBG) devices can further increase the power density and efficiency and lower the cost as WBG device technology matures and production volume increases. This paper presents a bidirectional integrated onboard charger (OBC) and accessory power converter using silicon carbide (SiC) MOSFETs and Schottky Barrier Diodes (SBDs). The galvanically isolated integrated OBC is formed by using the segmented traction drive system of a PEV as the frond converter and a phase shifted dual-active full-bridge converter (PHDAFBC) that is comprised of the transformer and high voltage converter of the 14 V accessory dc-dc converter and an additional full-bridge converter. Experimental results for a 6.8 kW OBC prototype that is implemented on a 90 kW segmented SiC traction inverter and a 6.8 kW SiC PHDAFBC is included.