Design And Analysis Of Flux Switching Machines Adopting Hybrid Permanent Magnets

The flux switching permanent magnet(FSPM)machines has short history and are relatively new category to electric machines.The FSPM's are receiving significant attention from last two decades because of their advantages of high power density,mechanical robustness and torque capability.They employ expensive rare-earth permanent magnets as their source of excitation.This ultimately results in the increase in the cost of FSPM machine.To counter this problem,HPFS machine is designed.The core purpose to design the hybrid permanent magnet flux switching(HPFS)machine is to reduce the cost of the machine while maintaining the high torque performance.This feat is achieved by replacing half of the expensive rare-earth permanent magnets,NdFeB,with inexpensive ferrite permanent magnets.The model considered in this study is a 6-slots/5-poles hybrid permanent magnet flux switching(HPFS)machine which is based on the 6-slots/5-poles flux switching permanent magnet(FSPM)machine.JMAG Designer version 16.1 is used for design and 2-D finite element analysis of the 6-slots/5-poles HPFS machine.Due to the use of the ferrite permanent magnets having low magnetic energy density to replace the expensive NdFeB permanent magnets,the electromagnetic performance of the hybrid permanent magnet flux switching(HPFS)machine is reduced.In order to maintain the electromagnetic performance of the HPFS machine,the key parameters,i.e.stator tooth width,permanent magnet thickness and rotor tooth width,are optimized.After the optimization of the HPFS machine,the cogging torque is reduced,average torque is increased,torque ripples are reduced and the harmonic content in the back EMF is also reduced.The control system results shows that this machine reaches its reference speed and desired torque very quickly and is able to perform smoothly.Afterwards the performance of the HPFS machine is compared with the surface mounted permanent magnet synchronous(SPM)machine.The result shows that the HPFS machine has better torque performance at the same load.It is exhibits that the HPFS machines are better suited for high speed applications while SPM machines are suited for low speed servo applications.