DC-DC boost system and methods for recharging higher voltage battery packs with lesser rated charging stations

A direct current to direct current (DC-DC) boosting and fast charging method for an electrified vehicle, the method comprising:

• providing an inverter electrically connected to a direct current (DC) power source and to an electric motor, configured to convert the DC power source into three phase alternating current (AC) power, and comprising three inductor phase legs configured to generate and output three AC phase currents, respectively;
• providing a plurality of relay switches electrically connected between the DC power source, the inverter, and a high voltage (HV) battery system rated at a first voltage, wherein at least one of the plurality of relay switches is connected to a midpoint of one of the three inductor phase legs of the inverter;
• and
• controlling, by a controller of the electrified vehicle, a boosted fast charging mode wherein the DC power source is a DC charging station rated at a second voltage that is less than the first voltage and the plurality of relay switches are opened/closed such that the second voltage is provided to the inverter and to the HV battery system for recharging,
• wherein providing the second voltage to the inverter via the plurality of relay switches causes the inverter to generate and output one AC phase current that causes the electric motor to inductively generate and provide two AC phase currents back to the inverter, which are converted to a third DC voltage for further boosted recharging of the HV battery system.