Hybrid vehicles may include a first set of drive wheels powered directly by an internal combustion engine and a secondary set of drive wheels powered by a direct current motor. The direct current motor may be powered by a battery or directly by a generator running off the internal combustion engine. When the generator is used to directly power the direct current motor, the torque of the direct current motor, and thus the secondary drive wheels, may be controlled by controlling the voltage output from the generator.
USPTO Backgrounds
USPTO Backgrounds