This paper looks at the effects of geometric irregularities such as magnet placement and magnet strength, on the resultant dipole moment of large permanent magnet machines. The object is to get relative dipole strengths and determine which designs are less susceptible to producing a dipole and what design tolerances should be imposed to limit the strength of the dipole. The machines are represented by a set of magnetic charges. Both radial magnet and axial field geometries are studied. The effects of magnet strength and magnet placement are considered, taking into account current permanent magnet machine design principles. From a set of charges, the multipole representation of the field is used and the dipole, as well as higher order terms, are found. The machine parameters, such as magnet strength and location are then varied in a stochastic fashion and a Monte-Carlo study was done to determining the probabilities of having a dipole greater than a specified amount.
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