Evaluation Tool for Current and Future Powertrains

摘要

Research and/or Engineering Questions/Objective The paper describes a simulation tool for determination of vehicle energy consumption under dynamic conditions, suitable for early stages of design. It describes vehicle dynamics in longitudinal direction and the appropriate efficiencies of engine, transmission and accumulation components (if used). The simulation tool is targeted to the optimization of vehicle powertrains with respect to reducing the vehicle fuel consumption, CO_2 production and increasing the overall efficiency of the vehicle. It is also used to evaluate the possible benefits of new powertrain concepts. The objective of this paper is to demonstrate the possibilities of the developed tool on a comparison study of several powertrain layouts. Methodology The simulation tool is based on ordinary differential equations and a dynamic expandable library of vehicle component features. Various powertrain components are represented by a dynamically expandable library of component modules. Each module represents a particular component of a powertrain such as gearbox, engine, wheels, vehicle body etc. Modules may be modified to more complex models at any time or even replaced by different modules to represent different powertrain layouts. Mechanical part of the powertrain is modelled with multi body simulation approach. Particular powertrain elements are represented either by mass elements or stiffness/damping elements. Electric part of vehicle powertrain such as electric engines and battery models are based on simple circuit models and/or look-up table based models. All required input data may be obtained by targeted simulations using multi-dimensional methods or by experiments. Results The result of this study is a comparison of various less or more common powertrain layouts. Its aim is not to present accurate results that correspond to each powertrain type, but more to point out the advantages and disadvantages of particular powertrain types. The simulation tool itself should also be considered as a result, because it provides a powerful tool for powertrain evaluation, topology layout optimization and may be adapted for various simulation tasks. Limitations of this study This simulation tool is designed to provide quick initial estimates with minimal input data or to serve as a part of X in the loop (XiL) tests, where X stands usually for hardware, software, man, etc. Therefore a lot of simplifications must have been applied. However, the dynamically expandable library allows the replacement of any part of the model with a more sophisticated model if needed and thus adapt the simulation tool to various computational tasks. What does the paper offer that is new in the field in comparison to other works of the author This paper is more focused on less common powertrains, such as pure electric vehicles or fuel cell vehicles. Presented simulation approach is far more complex than ever before. The simulation environment is completely new as well. Conclusion The simulation tool that calculates quick initial estimates of vehicle qualities in a transient driving cycle was created in a specialized graphical programming language. The demand on its transparency and modularity was satisfied by a dynamic expandable library of vehicle component features. The great advantage of presented simulation tool is its low computational time and easy realization of XiL approach. Comparison of various less or more common powertrain layouts was performed with this simulation tool and its results are presented within the paper.