Electric machine cooling systems and methods

An electric machine including a shaft, a rotor back assembly surrounding a portion of the shaft, and two or more permanent magnets radially positioned around the perimeter of the rotor back assembly. The electric machine also includes a rotor fan with multiple fan blades formed in an exterior surface of the rotor back assembly and one or more ventilation channels extending through the rotor back assembly. Methods of exporting heat from an electric machine, wither from a machine housing or through the shaft is also disclosed. The heat exportation methods feature the circulation of a fluid with the rotor fan through the ventilation channels and into contact with the housing, or exporting heat from the rotor back assembly through the shaft.