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The influence of rotor eccentricity on airgap flux density components in direct-drive permanent magnet (PM) machines has been studied using 1-dimensional (1D) analytical model and 2-dimensional (2D) finite element (FE) method. The flux density components have been classified with respect to their MMF and permeance origins, while the rotor eccentricity impact has been decomposed into time and space domains using 2D FFT. Based on the study it is shown that the influence of rotor eccentricity on slotting permeance components is much more significant than that on the PM MMF components, which explain the underestimated increase of the cogging and ripple torque based on 1D analytical model. Furthermore, it is shown that larger rotor eccentricities give rise to more airgap flux density side bands which are expected to contribute to the cogging and ripple torque. (5 pages)