Designing and Optimization of 9/12 Stator Permanent Magnet SRM to Improve Torque Ripple

In this paper, design and optimization of a 9/12 switched reluctance motor with Nd-Fe-B permanent magnets in stator wide pole is presented. Proposed structure produces lower torque ripple and higher minimum torque. Using permanent magnets in stator is feasible due to flux-reversal-free structure and also existence of wide pole without winding in E shape core. In order to find effects of permanent magnets in proposed motor, first, 9/12 SRM with three separated E-core in stator is presented and optimized by 2-D FEM, then permanent magnets are inserted to stator common poles with same direction with flux windings. In order to find optimum design of magnets in proposed structure, length (l), width (w) and distance (d) between two magnets are optimized. Finally, torque characteristic of proposed motor and conventional structure are compared to each other and results show that in comparison with conventional 9/12, proposed motor has 24% lower ripple and 0.4 N.m higher minimum torque.