Investigation of the Applicability of a Two-Motor Concept for Public Transportation Systems

Abstract

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, the compressor of the air conditioning (AC) system and the air compressor for the pneumatic systems in a public bus used in urban and suburban traffic. The main research questions in the following paper are first how the TIOM concept can be adapted to urban busses and second if the developed operation strategy leads to higher efficiencies. For this purpose a use case was defined and modelled with Dymola. A typical driving cycle was defined as use scenario. The model contains an operation strategy that can select between 16 different operation modes for the two motors based on the efficiencies of the motors, the torque requirements, the rotation speed of the wheel and the rotation speed range of the compressors. As a result, the energy consumption for the use case is evaluated and compared to a bus with a conventional motor concept with one large motor.