Planar Magnetics Based Onboard Electric Vehicle Charger with Auxiliary Supply

Electric vehicles (EVs) are equipped with a main battery pack (MBP) for traction purposes and an auxiliary battery pack (ABP) to power the onboard auxiliary systems. Traditionally, the onboard charger (OBC) charges the MBP, and via the auxiliary power module (APM) connected to the MBP, ABP gets charged. To minimize the size of passive components on the OBC, higher switching frequencies are preferred. A planar transformer, which can operate at these higher switching frequencies and has a lower profile, is chosen for improved performance. This paper explores a charger design in which a tertiary coil is inserted between the planar coils to charge the ABP. The evaluation was conducted through simulations.