Objective

  • Achieve significant efficiency improvement for the dc-dc stage of OBC by using high voltage variable dc link and matrix planar transformer design (40% loss reduction at 250 V & 450 V battery voltage).
  • Achieve significant power density improvement on dc-dc stage of OBC by pushing the switching frequency up to 500 kHz (achieve > 200 W/inch3 for dc-dc stage and > 50 W/inch for overall OBC).

Features

  • Use bridgeless interleaved Totem-pole PFC for ac-dc stage to improve the efficiency & power density.
  • Employ CLLC resonant converter for dc-dc stage to achieve bidirectional power flow (G2V & V2G).
  • Use variable dc link to make CLLC converter operate at very narrow frequency range.
  • Employ both SiC MOSFET and GaN HEMT as the power switches.
  • Use planar transformer & planar inductor to improve system efficiency & power density.