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A complete analytical design and analysis procedure of permanent magnet motors for ‘in-wheel’ traction application system is developed. Method to obtain minimum power requirement and optimal torque-speed profile to meet acceleration performance is explained. Analytical design procedure to optimize electric motor parameters, such as, back emf and torque constants, inductance and magnet thickness is developed that are based on the torque-speed requirement of the system. The optimization technique focuses on minimizing the power and volt-ampere rating of the entire electrical system. The design process is validated through experiment and field-testing. Although the paper is focused on electric bicycle system, the approach is also applicable to electric and hybrid electric vehicles.

Vehicle dynamics requires extended-speed, constant-power operation from the propulsion system in order to meet the vehicle's operating constraints (e.g., initial acceleration and gradeability) with minimum power. Decrease in power rating will decrease the volume of the energy storage system. However, extending the constant power operating range of the electric drives increases its rated torque, thereby, increasing motor volume and weight. This paper investigates the effect of extended constant power operation on battery driven electric vehicle (BEV) propulsion system taking the change in motor weight and battery volume into account. Five BEV systems with five traction drive having different base speeds are simulated for this study. The performances of the BEVs are obtained using FUDS and HWYFET drive cycles. Two EV-HEV software packages ‘V-ELPH’ developed by Texas A&M University and ‘ADVISOR’ from NREL are used for simulation testing.