Analysis of hybrid vehicle transmissions with any number of modes and planetary gearing: kinematics, power flows, mechanical power losses

Abstract

This paper is focused on upgrading a unified parametric model, available in the literature, that can perform both the analysis and the design of Power-Split Continuously Variable Transmissions (PS-CVTs), which are particularly promising to deploy in the hybrid electric powertrain. In particular, this work is focused on the analysis of PS-CVTs and proposes a new matrix approach for identifying the basic functional parameters underlying the model from the constructive layout of the transmission. This new method does not rely on a case-specific formulation, thus befits any power-split transmission, regardless of the number of planetary and ordinary gear sets and their constructive arrangement. Moreover, it handles the clutches operations that perform the shift between different constructive layouts, therefore it is suitable even for multimode PS-CVTs. As a case study, we applied it to the complex multimode PS-CVT of the Cadillac CT6 and carried out a comprehensive analysis of its kinematics, mechanical power losses and power flows.