1. Radial Flux PMSM Design and Optimization Liping Zheng 02/21/2003

2. Radial Flux PMSM Structure Stator Outer Diameter = 30mm Stator Inner Diameter = 21.7mm Rotor Diameter = 14mm PM Width = 7mm PM Height = 13mm PM Material=NdFeB39H Motor Active Length = 43mm Laminated low loss core PM Shaft Winding

3. Winding Method  2-pole, 3-phase.  5 coils/phase/pole.  Two layer lap winding.  Pitch: 23/30.  First coil: btm1->top12.  Round copper wire –AWG14.  Bare diameter: 0.0641in (1.63mm).  Diameter after insulation: 0.0673in (1.71mm).

4. Fractional (Distributed) Winding  The coils of a fractional winding within each pole region are distributed over many pairs of slots.  Distribution factor: Reduce the harmonics of the spatial mmf distribution.

5. Short-pitching  Use short-pitching to further reduce harmonics.  The pitch factor for the fundamental:  For nth harmonic pitch factor. 3 rd and 9 th are not harmful. 5 th and 7 th have negative effect to the torque. W=23 τ =30

6. BEMF of Fractional & Concentrated Winding Fractional winding and short-pitching reduce the harmonics greatly.

7. Simulated BEMF

8. Simulated Airgap Flux

9. Arnon 5- BH Curve

10. Arnon 5- Loss 45W/lb

11. Efficiency Copper Loss16.8W Iron Loss11W Estimated Stray Loss11W Windage Loss21W Motor Efficiency*97% Control Efficiency95% Total Efficiency92% * Bearing loss is not included.

12. Shaft with the Bearings for Test Motor length = 43mm End length = 20mm Total length = 83mm

13. Conclusion  Have modified the winding structure and re- adjusted the pitch factor.  Have selected the high energy NdFeB39H.  The motor active length is reduced from 50mm to 43mm.  Have considered the ball bearing connection structure for the test purpose.  Will do mechanical drawing using pro/E in the next step.