Design of electric machines for electric vehicles based on driving schedules

This paper presents a specialized design evaluation tool for electric machines intended for use in electric vehicles that seeks to maximize the machine´s efficiency in the operating regions that most closely correspond to the vehicle´s driving schedules. The influences of different designs on a production battery-electric vehicle are studied. A combination of closed form and finite element analysis is applied in the design process to incorporate both vehicle driving patterns and machine electromagnetic characteristics in order to optimize the machine efficiency optimization in the most frequent operating regions. The total required energy and relative losses of each of the candidate machines is calculated for the driving cycles using the predicted machine and vehicle performance characteristics. Finally, the Nissan Leaf´s energy consumption is calculated using simplified combined city/highway driving schedules and compared to the EPA´s published range, demonstrating that the developed analytical model can deliver promising accuracy.