Assessing the impact of cornering losses on the energy consumption of electric city buses

https://doi.org/10.1016/j.trd.2020.102360Get rights and content
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Highlights

  • A nonlinear steady-state cornering model for an electric city bus is developed.

  • In corners, cornering resistance and rear wheel tire scrub cause energy losses.

  • Results of full-scale steady-state cornering experiments validate the model.

  • On average, the considered effects account for 3.1% of the energy consumption.

  • The effects are most significant for city routes, where the contribution is 5.8%.

Abstract

In view of the increasing electrification of public city transport, an accurate energy consumption prediction for Battery Electric Buses (BEBs) is essential. Conventional prediction algorithms do not consider energy losses that occur during turning of the vehicle. This is especially relevant for electric city buses, which have a limited battery capacity and often drive curvy routes.

In this paper, the additional energy consumption during steering of a BEB is modeled, measured, and assessed. A nonlinear steady-state cornering model is developed to establish the additional energy losses during cornering. The model includes large steer angles, load transfer, and a Magic Formula tire model. Model results show that both cornering resistance and tire scrub of the rear tires cause additional energy losses during cornering, depending on the corner radius and vehicle velocity.

The energy consumption model is validated with full scale vehicle tests and shows an average deviation of 0.8 kW compared to the measurements. Analysis of recorded real-world bus routes reveals that on average these effects constitute 3.1% of the total powertrain energy. The effect is even more significant for routes crossing city centers, reaching values up to 5.8%. In these cases, cornering losses can be significant and should not be neglected in an accurate energy consumption prediction.

Keywords

Electric vehicle
Energy demand
Modeling
Vehicle dynamics
City bus
Tire slip

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