Second order air-gap element for the dynamic finite-element analysis of the electromagnetic field in electric machines

To obtain a dynamic analysis for the electromagnetic field in electric rotating machines working under unbalanced conditions or supplied by non sinusoidal current we previously conceived a first order Air-Gap-Element (AGE-1). Such an element allows to keep a constant topology while the rotor is moved ; in fact the relative position of the rotor is automatically taken into account by the method [1], [2]. In the present paper a second order Air-Gap-Element (AGE-2) is developed to be consistent with second order isoparametric finite elements, using the FLUX field computing program [3] which gives more accurate calculations. Moreover the use of AGE-2 permits us to consider a solution domain corresponding to either two pole-pitches or one pole-pitch To optimize the computing time spent on solving the equation system, we used the SICCG method [4]. The paper contains the development details of the AGE-2 and examples showing the merits of the proposed model.