Investigation of the Applicability of a Two-Engine Concept for Electric Utility Vehicles

A common approach to enhance the overall efficiency of an electric driven vehicle is to use a double motor concept. In the hereby presented research project TIOM (Two in one motor) two different electric motors are used for traction and the pump of the hydraulic system. The main research questions in the following paper are first which motor concept fits best for this system and second if the developed operation strategy leads to higher efficiencies. For this purpose a simulation model of the vehicle including the hydraulic system was built in Dymola. As a use case a reference vehicle and a typical driving cycle were defined. The model contains a strategy that can select between five different operation modes for the two motors based on the efficiencies of the motors, the torque requirements and the rotation speed of the wheels. As a result the energy consumption in the different variations is evaluated and compared to a vehicle with a conventional motor concept with one large motor for the traction and hydraulic system.