In English

Vehicle Dynamics and Energy Consumption Evaluation Tool

Silviu Virgil Margoi ; Mahesh Shetkar
Göteborg : Chalmers tekniska högskola, 2017. Diploma work - Department of Applied Mechanics, Chalmers University of Technology, Göteborg, Sweden, ISSN 1652-8557; 2017:11, 2017.
[Examensarbete på avancerad nivå]

Regenerative braking systems are a key feature of electric and hybrid vehicles as they allow for significant energy efficiency improvements. However, in certain situations, detailed in the thesis, a mismatch between maximizing the recovered energy and vehicle stability can occur. The aim of this thesis is to create a high level analysis tool that facilitates the optimization of potential regenerative braking control algorithms, with respect to energy recuperation and vehicle stability. The starting point is a forward dynamics energy model provided by ÅF. Required additions were made in two stages of increasing complexity. The first part of the project relies on pure longitudinal dynamics simulations. Braking strategies and visualization method are added along with a suitable tire model and idealized traction control and ABS. A modified NEDC cycle is developed with more realistic (aggressive) braking. Evaluation criteria for the vehicle stability are defined. An evaluation method is devised entailing various surface friction simulations for which vehicle stability and energy consumption criteria are computed and visualized. The second part of the project adds lateral dynamics to the model in the form of a one-track vehicle model. An evaluation method similar with the one in the first part is used, this time with an open loop steering input. The aim is to expand the evaluation of vehicle dynamics and also verify the results from the more simple pure longitudinal simulations. In both the parts of the thesis a test case comparing two brake distribution strategies is used. The vehicle configuration involves a pure electric, 100 kW, rear wheel drive motor. The main finding is that both the pure longitudinal dynamics model and the more complex model which includes lateral dynamics are successful in capturing the compromises between energy recuperation and vehicle stability for different regenerative braking strategies. Also, the two methods are found to have a good correlation of results. The second model provides additional data such as curvature influence on energy consumption. Future work recommendations involve testing additional braking strategies and refining the vehicle model to a two track one, with path tracking capabilities.

Nyckelord: Regenerative braking, vehicle stability, brake force distribution, energy recuperation

Publikationen registrerades 2017-03-23. Den ändrades senast 2017-03-23

CPL ID: 248666

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