Design Optimization of a Spoke-Type Variable Flux Motor Using AlNiCo for Electrified Transportation

This paper presents a design optimization method for a spoke-type variable flux motor for electrified transportation application. The proposed optimization method is comprised of analytical and finite-element-based methods to reduce the magnetization current, torque ripple, and maintain a constant torque value. The optimization objectives and the problem are stated based on the characteristics of an existing variable flux motor. A novel analytical criterion is proposed to select the magnet dimensions based on a desired torque and magnetization current of the variable flux motor. Besides the mentioned objectives, the no-load operating point of the AlNiCo magnets is monitored. Due to the complex relationship between the design objectives, the optimization procedure has two levels. The optimized case is finally compared with the existing variable flux machine.