Electric Power Train Configurations with Appropriate Transmission Systems 2011-01-0942
Referring to the transmission development, three different classifications of the power train are useful. These are the conventional power train with combustion-engined drive of the wheels, the electric power train with electromotive drive of the wheels and the hybrid power train with both types of drive. Due to this division, the micro hybrid belongs to the conventional power train while the serial hybrid is classified with the electric power train. Subdivisions of the electric power train are the decentralized drives near the axle shafts or the wheel hub drive and the central drive with differential.
The choice of the electric motor is dependent on different influences such as the package, the costs or the application area. Furthermore the execution of the transmission system does influence the electric motor. Wheel hub drives are usually executed on wheel speed level or with single ratio transmission. Drives near the axle shafts and central drives are also executed with single ratios whereas especially for the electric central drive a multispeed transmission can be reasonable.
Simulations and field tests show that one additional gear can bring benefits in terms of energy consumption. If the electric motor is performed smaller and on high speed level, the additional gearing can serve to obtain a high starting torque and also enable high speed driving. In addition the choice of the gearing and the power of the machine are strongly depending on the operating points.