An Analysis of Braking Behavior in Formula-E® Racing

As Pure Electric Vehicles have become a recent entrant to the higher end Passenger Vehicle Market, general interest in the overall technology has expanded beyond the environmental interest into the pure performance opportunities associated with electrically driven vehicles. Recently a new Racing Series has formed that is dedicated to Electric Vehicle Racing. Specifically the Formula-E® series has emerged as a venue for competition for Pure Electric open wheel race cars competing on Road Courses throughout the world. Success in the race series is influenced by the available energy that can be stored in the battery along with the applicable electrical efficiencies associated with the drive and control of the Propulsion Motors. The Race series also allows Regenerative Braking. Therefore the performance and ultimate success in the race is additionally influenced by the magnitude and the efficiency of the Regenerative Braking as it is employed by the associated Control System and the Drivers ability to utilize it through the operation of the vehicle controls over the course of the Race.

This paper will provide an analysis of the Driver usage profile of energy utilization throughout an exemplar Race Event. The Formula-E® Long Beach Race conducted during the 2015 Race Series was chosen for this analysis. The paper will evaluate the overall energy usage during the race and characterize the Energy dissipation associated with Regenerative Braking as well as friction braking. This will offer some insight into the proportion of energy management that can be attributed to each and also identify changes in these relationships throughout the course of the race and in different sections of the course. This knowledge may provide insight to the Brake System Designers, Regenerative Controls Systems Designers and Race Car Drivers on how to more effectively utilize their skills and technologies to produce better performance in this racing series and perhaps more broadly other High Performance Driving situations. It should be understood this analysis is intended to provide an exemplar analysis looking for typicality and potential opportunities to 1^st characterize and 2^nd identify potential optimization of the use of Regenerative Braking in racing environments. This analysis is intended to be a motivator for additional and more complex analysis that can be verified in specific track circuits and adapted to driver skill and preference.