Modeling of Energy Losses During Cornering for Electric City Buses

Accurate energy consumption prediction is essential for optimal operation of battery electric buses. Conventional prediction algorithms do not consider energy losses during turning of the vehicle, which is especially relevant for city buses driving curvy routes. This paper presents a model describing steady-state cornering of such buses and analyses the additional energy consumption. The model includes multiple nonlinear effects, such as large steer angles, double rear wheels, and lateral load transfer. The resulting four nonlinear equilibrium equations are solved iteratively to obtain steady-state solutions. These reveal that both cornering resistance at the front wheels and tire scrub of the double rear wheels cause energy losses, varying as function of vehicle velocity and corner radius. Combination of the results with a recorded city trip of a battery electric bus reveals that these effects combined may account for 2.3% of the driveline energy consumption.