Optimization of Accelerator Pedal Map for Improving the Low-End Performance Feel of an Electric Vehicle 2020-28-0505
In recent times, Battery electric vehicles (BEV) have gained a lot of popularity since they can contribute immensely to control the urban air pollution. However, to consider the BEVs as a sustainable mobility solution, a significant improvement is needed in several aspects including performance, range, cost, weight and recharging time. In the present work, the acceleration performance of an electric vehicle is improved to match with its diesel variant by optimizing the accelerator pedal map strategy.
Due to weight and cost constraints, the battery and electric machine capacity of the electric variant of the vehicle was considerably lower (41 % lesser power and 44% lesser torque). However, the expectation from the customers is to have no noticeable difference in the low-end performance feel between the variants. Hence, a unique method was necessary by which the subjective performance feel of the electric variant could be matched to the diesel variant despite the difference in powertrain and vehicle specifications. The experimental results revealed that the vehicle level acceleration with respect to velocity is the most critical factor defining the low-end performance feel of the vehicle. Hence, the higher low-end torque availability of the electric machine was leveraged to deliver a higher output torque even at the lower pedal position. This could be done by completely redefining the accelerator pedal map characteristic in which the motor output torque is defined as a function of accelerator pedal position and motor speed. As a result, the final acceleration performance feel of the electric variant could be closely matched with the diesel variant even with an 8% weight penalty. The results are quantified by doing a comparative vehicle level evaluation.
Thus, the proposed methodology could be used to improve the subjective performance feel of any BEV. Moreover, it can enable the BEVs to meet the customer expectations even with reduced size of the electric powertrain.