To determine the hysteresis loss in a sample, usually the enclosed area of the B - H loop is evaluated. In the drag force method, based on a proper energy balance, the hysteresis loss is obtained by analyzing the drag force profile when slowly moving the sample forward and backward through the strong field of permanent magnets. A numerical time-stepping model is presented that calculates the drag force profile. At every time step, the sample is slightly moved. The model is based on 2D-FE computations including magnetic hysteretic material behaviour using the Preisach model. In order to improve the numerical stability, we reformulated the Maxwell equations in such a way that the material behaviour is described through differential permeabilities. Consequently, the basic unknown for the FEM becomes the time derivative of the vector potential. The drag force is obtained by using the Maxwell stress tensor. Simulations were carried out in which a sample was moved back and forth through the field of one or two permanent magnets. The numerical model is validated by measurements and by comparing the "drag force" hysteresis losses with the hysteresis losses computed conventionally by the integral of H.dB.
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