Study of braking energy recovery impact on cost-efficiency and environmental safety of vehicle

The article addresses the evaluation of the impact of regenerative braking on fuel consumption and, consequently, on pollutant emissions from vehicles operated under conditions leading to frequent acceleration and deceleration. We assume that the vehicle is equipped with a system of conversion and accumulation of electric energy obtained only from braking. Basic analyzed characteristics are determined by a comparison of gasoline engine operation modes with braking energy recovery and without it. As initial physicomathematical tools, we use relationships of propulsion power and energy analysis and propulsion drive operation, which were previously suggested by one of the authors. As an example of using the mentioned relationships, the article presents the analysis results for a vehicle moving in the low-speed segment of the WLTC driving cycle. Energy passing through the battery and energy reserve in it are calculated. It is assumed that the accumulated braking energy makes it possible to start moving at the next segment not using the gasoline engine; the engine starts its operation only after the energy in the battery is exhausted. Superposition of the curves of gasoline engine operation modes with and without recovery allows us to estimate changes in the energy generated. In order to account for different values of specific fuel consumption, the authors use an adjustment factor, which takes into account pollutant emissions from the vehicle depending on the average speed. Functions of changes in fuel consumption and pollutant emissions when using regenerative braking are obtained by the integration of values. The authors compare the obtained results with the results of road tests of vehicles with the energy recovery system. The materials suggested expand our knowledge of the operational properties of vehicles with electromechanical and electrical power units. © 2020 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the scientific committee of the XIV International Conference 2020 SPbGASU “Organization and safety of traffic in large cities