Powertrain Simulation and Optimization of a Multimode Transmission

Plug-in hybrid electric vehicles are developed to reduce the fuel consumption and the emission of carbon dioxide. Besides the series, parallel and power split configurations as commonly used for conventional hybrid electric vehicles, multimode transmissions are in particular used for plug-in hybrid electric vehicles, which enable to switch between different modes like parallel or series operation of combustion engine and electric motor. Based on cost efficient configurations of multimode transmissions, improved concepts have already been discussed and presented. These concepts comprise novel structures and multi-speed operation for the combustion engine or the electric motor, respectively. For improving the fuel and energy consumption, a simulation based optimization of a multimode transmission is applied. Since the development of corresponding transmission models is a time-consuming and error-prone task, a method for an automated generation of transmission models is present in this contribution. The generated transmission models are integrated into an overall stationary powertrain model, which is used to optimize an operating strategy and the gear ratios of a multimode transmission with respect to fuel and energy consumption. The optimization is applied to a two and a three speed transmission for the internal combustion engine and to a two speed transmission for the electric motor. Afterwards, the optimization results as well as the fuel and energy saving results are presented.