Electric Vehicle Acceleration Performance and Motor Drive Cycle Energy Efficiency Trade-Off

During passenger car design, both high acceleration performance and low energy consumption are targeted. For battery electric vehicles (BEVs) to reach these objectives, it is vital to evaluate the consequences that different motor design choices have on them. This paper presents a quantitative analysis of the effect on acceleration performance and motor losses during BEV driving, when the motors power rating is varied. Two reference traction machines are sized and evaluated using finite element analysis, for a small and large BEV. Via axial scaling, the motors' power is then varied linearly by factors between 0.5-2, and the changes in motor losses are accounted for. Both the 0-100km/h acceleration time and motor losses during several low, middle and high speed drive cycles are calculated. Depending on drive cycle, scale factors between 0.5-1.0 give the lowest motor losses with both BEVs. The lowest are down to 67% and 61 % of the losses with scale factor 1.0, for the small and large BEV respectively. Yet, then the acceleration time varies non-linearly between 28s-13s for the small BEV and 20s-10s for the large, respectively. Hence, the results demonstrate a clear trade-off between targeting high acceleration performance and low energy consumption during driving.