Energy Modeling of Deceleration Strategies for Electric Vehicles

Abstract

<div class="section abstract"><div class="htmlview paragraph">Rapid adoption of battery electric vehicles means improving the energy consumption and energy efficiency of these new vehicles is a top priority. One method of accomplishing this is regenerative braking, which converts kinetic energy to electrical energy stored in the battery pack while the vehicle is decelerating. Coasting is an alternative strategy that minimizes energy consumption by decelerating the vehicle using only road load. A battery electric vehicle model is refined to assess regenerative braking, coasting, and other deceleration strategies. A road load model based on public test data calculates tractive effort requirements based on speed and acceleration. Bidirectional Willans lines are the basis of a powertrain model simulating battery energy consumption. Vehicle tractive and powertrain power are modeled backward from prescribed linear velocity curves, and the coasting trajectory is forward modeled given zero tractive power. Decel modes based on zero battery and motor power are also forward modeled. Multi-mode decel (using a low power decel mode with regenerative braking) is presented as a set of intermediate strategies. An example vehicle using these strategies is modeled in fixed-route simulations, and scoring is based on travel time, energy consumption, and bias towards minimizing one of those metrics. Regenerative braking has the lowest travel time, and coasting the lowest energy consumption, but such bias increases overall cost. Multi-mode strategies lower overall cost by balancing reductions in travel time and energy consumption. Model sensitivity to grade and accessory load fluctuation makes it adaptable to different vehicles and environments. Simulation results demonstrate how regen braking alternatives could be modeled to enhance connected and automated vehicle systems in battery electric vehicles.</div></div>