Onboard DC charging circuit using traction drive components

A direct current (DC) charging circuit for use with an off-board DC charging station providing a maximum charging voltage, the DC charging circuit comprising:

• a positive bus rail and a negative bus rail;
• a rechargeable energy storage system (RESS) connected across the positive and negative bus rails, and including a pair of switches and a high-voltage battery pack having a maximum voltage capacity;
• a power inverter module (PIM) that is electrically connected to the RESS through the positive and negative bus rails and the pair of switches, the PIM including a plurality of PIM switching pairs, wherein the pair of switches of the RESS selectively connects or disconnects the battery pack to or from the PIM, respectively;
• an electric machine having first, second, and third phase windings sharing a motor neutral terminal, wherein the first, second, and third phase windings are electrically connected to a first pair, a second pair, and a third pair of the plurality of PIM switching pairs, respectively;
• a switching module having positive and negative input terminals configured to receive a DC charging voltage from the DC fast-charging station during a requested DC fast-charging operation of the battery pack, the switching module having a first additional switch selectively connecting the PIM to the DC fast-charging station through one of the positive or negative input terminals, and a center switch selectively connecting the DC fast-charging station to the motor neutral terminal;
• and
• a controller in communication with the PIM and the switching module that is configured, as a charging control action, to selectively establish a DC-DC boost mode of the PIM responsive to a detected condition in which the maximum voltage capacity of the battery pack exceeds the maximum charging voltage of the DC fast-charging station, wherein the controller establishes the DC-DC boost mode by closing the pair of switches of the RESS, and closing the center switch and the first additional switch of the switching module.