Influence of design parameters on output torque of flux-switching permanent magnet machines

The influence of design parameters of a flux-switching PM (FSPM) machine for maximum output torque has been investigated by finite element analyses and validated by measurements made on a prototype FSPM motor. These parameters include the split ratio of the inner diameter to outer diameter of the stator, the stator tooth width, the stator magnet thickness, the stator back-iron thickness, the stator lamination bridge, the rotor tooth width and height, and the rotor back-iron thickness. In addition, the influence of the shape of the magnets and the rotor teeth has been investigated. It shows that the FSPM machine having equal stator tooth width, stator magnet thickness and slot opening produces the maximum output torque. The torque can be increased if the stator back-iron thickness is reduced to ~70% of the stator tooth width to increase the slot area. The output torque can be increased by ~8% if the rotor tooth width is increased by 40%~60%. The optimal split ratio for maximum output torque is ~0.55-0.6 when the copper loss is fixed to 50 W and increases with an increase in the copper loss. The influence of other design parameters is found to be less significant for an appropriately designed motor.