Instantaneous Velocity Optimization Strategy of Electric Vehicle Considering Varying Road Slopes

Economic cruising strategies of vehicles on terrain have been studied for years to reduce energy consumption by optimizing the profile of driving velocity. However, most controllers require prediction of future terrain information, with heavy computing load, which prevent them applying in real-time implementation. This paper presents an instantaneous energy optimization cruising strategy for pure electric vehicles (EVs), named normalized energy consumption minimization strategy (NCMS) to improve its cruising energy efficiency on roads with varying slopes. By converting the vehicle kinetic energy into equivalent energy consumption, the total energy consumption is minimized instantaneously to optimize the traction or braking torques. In addition, a velocity-related factor is designed to regulate the vehicle speed within a given cruising speed range. Since NCMS does not require the knowledge of future road conditions, it calculates the control rule within one millisecond, making it suitable for real-time control. Finally, energy saving potential of NCMS is explored by comparing to constant speed (CS) cruising strategy.