A simple model for compound split transmissions

Abstract

Hybrid vehicles are the most promising technologies that can lead to significant improvements in the efficiency and the performance of a vehicle through several drivetrain architectures. The automotive research is direct towards architectures with multiple modes. In this context, design and optimal control models of these transmissions are of great importance. In order to obtain a simple model, we propose a novel and original approach for evaluating the performance of a compound electric continuously variable transmission. A ‘four-port mechanical power-split device’ is examined and, using this, a novel method is described by considering an ‘equivalent electric continuously variable transmission’ within a power split. Finally, kinematic conditions are obtained to evaluate which power flow occurs and to determine simple models for the efficiency of the transmission.