In order to reduce higher harmonic of magnetic field in magnetically levitated permanent-magnet planar motors with moving-coils,a novel principle of magnet parameter design was proposed,which was based on the average relative mean-square deviation between the real magnetic density and expected air-gap magnetic density.According to harmonic model of magnetic field,the three-dimensional magnetic density of this magnet arrangement was analyzed and then the average fundamental amplitude in different height levels was calculated.The expected fundamental model of this magnet arrangement was then presented,which together with the obtained harmonic model giving the average relative mean-square deviation between the real magnetic density and expected air-gap magnetic density.The principle of magnet parameter design was presented,which could be described as “to achieve the maximum average fundamental amplitude and minimum average relative mean-square deviation as far as possible”.Finally, the finite element simulation and measured results of the experimental prototype illustrated that the presented design method has a good inhibitory effect on the higher harmonics,especially on the second harmonic.
