Evaluation of transmission losses of various Dedicated Hybrid Transmission (DHT) with a lossmap-based simulation model

This paper presents a simulation methodology developed at the Institute of Automotive Engineering (IAE). With this simulation method, transmission lossmaps can be calculated for Dedicated Hybrid Transmission (DHT). These transmission lossmaps are considered within the control strategy section of a modular simulation model, which can lead to more realistic simulation results. Four DHT concepts are investigated using this simulation methodology: three multi-mode DHT (MM-DHT) transmission concepts and a Power Split DHT (PS-DHT) concept. All concepts have two electric machines (EM). The first concept is a MM-DHT, which was developed with the transmission synthesis of the IAE. This DHT concept has two planetary gear sets (PGS), four shifting elements, and two EM. The other MM-DHT concepts are based on the Voltec 2 and the CT6. They also have two EM. The Voltec 2 has two PGS and three shifting elements. The CT6 has three PGS and five shifting elements. The power split DHT has one PGS and no shifting elements. For the evaluation of the transmission concepts, consistent and representative performance requirements are first defined, which must be fulfilled by all concepts. Afterwards, the transmission losses of the individual concepts can be subdivided via the lossmap-based simulation model for the different loss components. Finally, the DHT concepts are examined and evaluated with regard to mechanical efficiency and fuel consumption in the WLTC.