Minimisation of torque ripple in slotless axial flux BLDC motors in terms of design considerations

This study presents an analytical method to calculate instantaneous electromagnetic torque in slotless axial flux brushless DC (BLDC) motors. This method is based on Lorentz force theorem and using phase induced back electro-magnetic force (EMF) and phase current. A new analytical method was introduced to compute induced back EMF. 3D finite element computations validate the proposed method. This method requires much less computation time than conventional 3D finite elements, and is therefore suitable for optimisation purposes. Due to practical limitation, phase current approximated by the trapezoidal function. Torque ripple dependency on design parameters was studied and optimum parameters were extracted for slotless axial flux BLDC motor.