1 0.95
~o | 0.85 CO
E
|
0.8 0.75 -180 0.7
-90
0
90
180
Angular Position, °E
Figure B-11. Air Gap MMF distribution for magnet shown in Fig. B-10.
portion of the magnet, the air gap MMF is fairly constant because of the assumed radial magnetization, but the MMF decreases quickly as one moves toward the magnet edges that coincide with the left and right ends of the plotted line. As a simple approximation of the air gap MMF, it is convenient to simply compute the MMF at the magnet center, 0=0.
B.8 Summary This appendix presents an analytic model for the magnetic field distribution in radial flux motors having surface-mounted magnets. This model results from the rigorous solution of the partial differential equations governing the field. This description is extremely valuable for accurately predicting brushless permanent magnet motor performance. Without it, one must resort to simplifications such as that considered in Chapter 4.