Torque ripple reduction of a variable flux motor

This paper examines torque ripple in a new topology of variable flux machine with AlNiCo magnet. To reduce the torque ripple, the design and finite element modeling of this machine are reviewed and the finite element model results are verified with the prototyped motor. The effects of various electrical, magnetic and geometrical parameters such as load, magnetization level of the magnet, tooth and yoke width and magnet dimensions, on both torque mean value and torque ripple are discussed using the verified finite element model. Finally, modified rotor structure is presented that reduces the torque ripple by 35% with the same torque mean value and magnetization current for the motor. The torque ripple of the modified design is analyzed for a wide range of load and speed.