Analytical Formulation of Radial Magnetic Forces in PM Linear Tubular Machines with Translator Eccentricity

Due to mechanical couplings, permanent magnet tubular linear machines are subject to eccentricity of the mover and hence to a non uniform circumferential distribution of the no load magnetic field in the air-gap. The intensity of radial forces arising thereof is such that it must be taken into account both for flexion analysis and for choice of bearings. This paper illustrates an analytical formulation of the no load magnetic field distribution in tubular IPM machines with translator eccentricity in order to facilitate the computation of the radial forces. Measurements on two prototypes in a test rig illustrate the validity of the approach.