OPTIMAL DESIGN AND CONTROL OF AXIAL-FLUX BRUSHLESS DC WHEEL MOTOR FOR ELECTRICAL VEHICLES

A multi-objective optimal design of a brushless dc wheel motor is presented. This axial-flux permanent magnet motor is designed to achieve a high torque-to-weight ratio and motor efficiency, and is suitable for the direct-driven wheel applications. The dedicated motor is modelled in magnetic circuits, and designed to meet the specifications of an optimisation scheme, subject to constraints, such as limited space, current density, flux saturation and driving voltage. Finite element analyses are then carried out to obtain the electromagnetic, thermal and modal characteristics of the motor for modification and verification of the preliminary design. The prototypes are fabricated and controlled by the pulse-widthmodulation drive with optimal current waveforms. Experimental results show that the direct-driven power system installed on an electric motorcycle has good overall efficiency and long driving range.