A DC charging circuit has a pair of switches and a battery pack with a maximum voltage capacity, and a power inverter module (PIM). The pair of switches connects/disconnects the battery pack to/from the PIM. An electric machine has phase windings sharing a motor neutral terminal. The phase windings are electrically connected to respective switching pair of the PIM. A switching module has one or two additional switches selectively connecting the PIM to the station, and a center switch selectively connecting the station to the motor neutral terminal. A controller executes a method that establishes a boost mode of the PIM when the maximum voltage capacity exceeds the maximum charging voltage. The boost mode is established by closing the pair of switches of the RESS, closing the center switch of the switching module and one of the additional switches, and opening the other additional switch if present.