Post on 31-Dec-2015
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Radial Flux PMSM Design and Optimization
Liping Zheng
02/21/2003
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
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).
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.
)2/sin(
)2/sin(es
es
ci
poled q
q
Eq
Ek
957.0)30/sin(5
)30/5sin(
dk
Short-pitching Use short-pitching to further reduce harmonics. The pitch factor for the fundamental:
For nth harmonic pitch factor.
3rd and 9th are not harmful.
5th and 7th have negative effect to the torque.
2sin
2sin
WnnK pn
2sin
2sin1
WK p
W=23 τ=30
Kp
0.891
0.156
0.707
0.988
0.454
0.934
0.454
0.259
0.839
0.988
0.966
0.707
0.259
0.259
0.707
BEMF of Fractional & Concentrated Winding
Fractional winding and short-pitching reduce the harmonics greatly.
Simulated BEMF
Simulated Airgap Flux
Arnon 5- BH Curve
Arnon 5- Loss
45W/lb
Efficiency
Copper Loss 16.8W
Iron Loss 11W
Estimated Stray Loss 11W
Windage Loss 21W
Motor Efficiency* 97%
Control Efficiency 95%
Total Efficiency 92%
* Bearing loss is not included.
Shaft with the Bearings for Test
Motor length = 43mm
End length = 20mm
Total length = 83mm
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.