1. PMSM Design
Liping Zheng
06/06/2003

2. PMSM Configuration Litz-wire: 1.78 mm x 2.27 mm 50 strands @ AWG 30
Gap : 0.5 mm
Stator Di: mm
Do: 38 mm
Length: 25.4 mm
Shaft diameter: 16 mm
No major shaft stress problem if we select high stress shaft material.
We’ve sent out the purchase requisition form to the university.

3. PMSM Loss Motor Efficiency: Control Efficiency: Total Efficiency:
Copper loss
16.9 W
Iron loss
10.4 W
Bearing loss
10 W
Windage loss
12.8 W
Total loss
50.1W
Motor Efficiency:
Control Efficiency:
Total Efficiency:

4. Other Possible Loss (I)
Copper loss associated with eddy current.
Skin depth :
Litz-wire : AWG 30 (D=0.01 in or 0.25 mm)
 Eddy current can be ignored.
Copper loss associated with the airgap flux leakage.
Twisted Litz-wire can greatly reduce the loss. Twisting pitch is the same as the motor active length.

5. Other Possible Loss (II)
Loss in the shaft.
Slotless stator can reduce this loss greatly.
Loss in the permanent magnet.
Loss due to nonideal control
Loss associated with non ideal control.
Loss associated with current harmonics.
Loss of the low pass filter.

6. Verify Stator Core Loss Using FEM Simulation
Two methods to get the stator core loss:
Based on the frequency and flux density vs. Loss curve.
Based on finite element method (FEM) simulation.

7. Stator Material (Arnon 5) - Loss
45W/lb
Core loss= 10.4 W

8. Core Loss Using FEM
At a given frequency, the iron loss for electrical steel can be calculated from:
Where Kh is the hysteresis coefficient.
Kc is the classical eddy coefficient.
Ke is the excess eddy current coefficient.
F is the frequency.
Above coefficients can be calculated by the curve fitting of the manufacturer’s loss data sheet.

9. Setup Executive Parameters
Curve Fitting Results:
Unit

10. Stator Core Loss of the PMSM
Core loss is 9.5W

11. Stator Core Loss of Current or PM Only
Winding mmf contributes only smaller portion of the core loss

12. Further Work Estimate the loss in the shaft.
Estimate the loss in the permanent magnet.
Simulation the loss of the low pass inductors.
Optimize the shaft structure.