The number of turns in the winding is directly proportional to the airgap flux density when the stator diameter and length are kept the same. The diagram on the right shows a motor with a high airgap flux density with thick iron cross sections and a small area for the copper windings. In small iron thicknesses and a large area for the copper windings. The diagram below shows a motor with a low airgap flux density resultingįigure 1 – Lamination Changes as Airgap Flux Density Changes This will cause the slot area for the wire to decrease as the flux levels in the air gap increase. This means that as the lamination iron thickness of the teeth and back iron will need to get larger as the flux density is increased to keep the flux density constant. The designs used in this presentation will have the flux density of the iron laminations kept constant with the flux density of the iron in the lamination teeth kept at 14 Kg and the flux density of the lamination back iron kept at 13 KG. The airgap flux density in this presentation will be varied from 3 KG to 9 KG and the effects of this variation of the airgap flux density on permanent magnet motor designs will be shown. This has started a trend to mix the various magnet materials which can change the magnet performance to values that were not available in the past as single magnet materials. The higher energy rare earth magnets used have always had a higher cost but now that some of the rare earth components have become harder to source, the need to use mid range energy magnet materials could become necessary. This presentation will show that the motor magnetic circuit designs can be modified to allow maximum motor performance with lower energy grade magnetic materials than the present high energy rare earth magnets. The air gap flux density is the major parameter that a motor designer will base a motor design on. This presentation will discuss the effects of changing the Flux density in the airgap of a Permanent magnet Brushless Permanent Magnet Servo motor on the overall motor performance. Magnetics 2013 Orlando Florida Feb 8 & 9, 2013

Peak flux density