Compact electric range extender for an electric vehicle

An auxiliary power unit (APU) for an electric vehicle having a transmission, an electric traction motor having a motor output shaft that is mechanically coupled to an input member of the transmission, and a rechargeable energy storage system (RESS) that is electrically connected to the electric traction motor, the APU comprising:

• a set of induction windings;
• an outer ring and an inner ring, one of which is rotatable with respect to the other, wherein a rotation of the at least one ring generates an electrical current in the set of induction windings;
• a gear element in driving connection with the ring that one of the outer and inner rings that rotates;
• and
• an engine disposed radially within the inner ring;
• wherein the engine includes a power takeoff mechanism which is mechanically coupled to the gear element for powering the ring that rotates.

A method comprising:

• positioning an auxiliary power unit (APU) in a compartment defined by a body of an electric vehicle, including:
• affixing an outer ring of induction windings of the APU to a wall of the compartment;
• positioning a rotatable inner ring of the APU having permanent magnets radially within and coaxial with the outer ring;
• positioning an internal combustion engine radially within the rotatable inner ring;
• and
• connecting a power takeoff mechanism of the engine to the rotatable inner ring of the APU.