Electrical Propulsion Systems for Battery Driven Road Vehicles with Hydrodynamic Transmission of Power

In view of the low energy density of the electrochemical storage units available at the present time, only the development of such electric vehicles that are intended for transportation jobs within the cities appears to be worthwhile. The speeds mainly used with this type of application can be controlled by field weakening of the electric motor. The function of the power electronics which serves only to control the starting range can be taken over by a hydrodynamic transmission. In this case, the design of the drive must take into consideration the basic differences between the torque versus speed characteristics of a hydrodynamic converter and an electric motor. With a suitable design, this power train has, on the one hand, a good efficiency of transmission and can meet, on the other hand, further demands conditioned by the energy storage.