MODELING AND ANALYSIS OF ELECTRIC AND MAGNETIC COUPLED PROBLEMS UNDERNONLINEAR CONDITIONS

In this paper the authors define a numerical method to solve nonlinear combined magnetic and electric problems using reliable general purpos e calculation codes. This method has been applied to analyze the behav ior of a busbar system built with a saturable steel enclosure and conn ected with an arbitrary external circuit. The enclosure magnetic chara cteristics have been determined by means of experimental tests execute d by the authors. To analyze this electrical system, the skin and prox imity effects in the massive conductors, as well as the load condition s of the external circuit, must be taken into account. The present for mulation permits us to solve the previously described coupled problems by means of an iterative procedure. Using this technique, it is possi ble to solve separately the field and the circuit equations by means o f specific codes. In particular, an iterative procedure it is pointed out so defined: for each estimated load condition, a finite element co de has been used to evaluate the relating busbar cross parameters, tak ing into account the nonlinear behavior of the steel enclosure, while, for each assigned set of the busbar cross parameters, a circuit simul ator has been used to determine the relating load conditions of the bu sbar. In addition, a specialized post-processor has been developed to manage the data flow between the calculation codes. The originality of this work is linked to the use of general purpose commercial software to solve the nonlinear magnetic and electric coupled problems.