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In this work author proposed complex alghorithm where field and circuit parts are strictly linked so that circuit and mechanical parameters are calculated strictly. In this case field analysis was based on two dimmensional integrated boxes finite difference, distributions of the flux density for some excitations values and rotor positions allow to calculate some very important integral parameters, flux inkeage and the coenergy — static torque. In presented paper author show full description of the motor dynamic with the speed feed back.

The purpose of this paper is to apply a 3D methodology to assess the heating hazard on transformer covers and present a practical tool to design amagnetic inserts arrangement.

A practical 3D methodology linking an electromagnetic analytical formulation with thermal finite element method is used for computation. Such methodology allows the evaluation of the temperature on metallic device elements heated by electromagnetic induction. This is a 3D problem which in the case of power transformers becomes especially difficult to apply due to the discretization requirement into the thin skin depth penetration compared to big machine dimensions.

From the numerical solution of the temperature field, decisions on dimensions and different amagnetic inserts arrangements can be taken to avoid hot spots on transformer covers.

Some parameters presented in the model as heat exchange coefficients and material properties are difficult to determine from formulae or from the literature. The accuracy of the results strongly depends on the proper identification of those parameters, which the authors adjust based on measurements.

Differing from previous works found in the literature, which focus their results in power loss computation methods, this paper evaluates losses in terms of temperature distribution, which is easier to measure and validate over transformer covers. Moreover, an experimental work is presented where the temperature distribution is measured over a steel cover plate and a cover plate with amagnetic insert.

The purpose of this paper is to describe a parameter identification method based on multiobjective (MO) deterministic and non-deterministic optimization algorithms to compute the temperature distribution on transformer tank covers.

The strategy for implementing the parameter identification process consists of three main steps. The first step is to define the most appropriate objective function and the identification problem is solved for the chosen parameters using single-objective (SO) optimization algorithms. Then sensitivity to measurement error of the computational model is assessed and finally it is included as an additional objective function, making the identification problem a MO one.

Computations with identified/optimal parameters yield accurate results for a wide range of current values and different conductor arrangements. From the numerical solution of the temperature field, decisions on dimensions and materials can be taken to avoid overheating on transformer covers.

The accuracy of the model depends on its parameters, such as heat exchange coefficients and material properties, which are difficult to determine from formulae or from the literature. Thus the goal of the presented technique is to achieve the best possible agreement between measured and numerically calculated temperature values.

Differing from previous works found in the literature, sensitivity to measurement error is considered in the parameter identification technique as an additional objective function. Thus, solutions less sensitive to measurement errors at the expenses of a degradation in accuracy are identified by means of MO optimization algorithms.