Is there currently a car that uses DC current Traction Motors, for the wheels, and a generator for power? Railroad engines use this method, on a much larger scale, of course, but has this been considered and used for automobiles?
Yes. Reliance Electric (purchased by Allen-Bradley and then GE) manufactured traction motors specifically for automobiles. These DC traction motors are currently manufactured by others. They are typically used in warehouse electric vehicles and golf carts. I'm not sure if the Hybrids in production use AC or DC. Electric automobile kits typically use high torque motors that are either D.C. or A.C. A.C. is more expensive but it has the potential to use regeneration to break and re-use some of the momentum energy to recharge the batteries. As fuel cost continues to increase because of peak oil, I'm sure that breaking regeneration will be found on trains, buses, trucks, and automobiles.
The full hybrids that can move under electrical power alone (Toyota, Ford, Lexus and Nissan hybrids) use 3-phase AC motors. One of the reasons is that AC motors don't have commutators so they tend not to wear out as often as DC motors. These hybrids have inverters that can convert the hybrid battery's DC current to AC for use with the motors or vice versa when the motors are being used as generators during regenerative braking or being cranked by the gasoline engine to charge the battery. Railroads have been moving to AC traction in the past 10 years as well.. These days on the Class-I railroads the majority of 6-axle diesel-electric locomotives are AC, like the SD70ACE locomotives from Electromotive and the ES44AC Gevo from General Electric.
