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The spectral stochastic finite-element method makes it possible to convey some random aspects of input data to the output data. However, the system size dramatically increases with the number of input random variables. Using matrix Kronecker tensor products for system solving noticeably reduces the computation time and the storage requirements. Index Terms--Electrokinetics, finite-element method, hermite polynomial chaos, linear system resolution, random media.

This communication deals with a comparison between two methods of discretization: the well known finite element method and the natural element method that is a meshless method. An error estimator, based on the nonverification of the constitutive law, is used. This estimation has been applied to two examples: a device with permanent magnets and a variable reluctance machine. Index Terms--Error estimation, finite element method, magnetostatics, natural element method.

Numerical modeling of nondestructive testing (NDT) by eddy currents has been applied for qualification of two monitoring devices. Experimental data have enabled us to validate reliable and relevant finite-element method models. The encountered difficulties due to geometry (size and topology), the nature of the control signal (weak flux differences), and the movement accounting have been successfully overcome by evaluating the A - [phi] and T - [OMEGA] dual formulations with appropriate source fields and applying classical method to suppress the mesh numerical error and choosing the well-known lock-step technique. Index Terms--Eddy currents, finite-element method, magnetic fields, nondestructive testing (NDT).

Spectral stochastic finite element method (SSFEM), used in mechanics to take into account random aspects of input data, has been implemented, as an extended version, in the 3-D finite element method (FEM) software CARMEL dedicated to electromagnetic field computation. As a test case, this approach has been applied to a 3-D electrostatic problem and successfully validated by comparing with the Monte Carlo simulation method involving usual 'deterministic' CARMEL resolutions. Index Terms--Random problem, spectral stochastic finite element method (SSFEM).

The natural-element method, which belongs to the family of meshless methods, is applied in the context of two-dimensional magnetostatics with moving parts. The method is reviewed and its interest for handling discontinuities in electromagnet devices with moving parts is illustrated through a numerical example. Index Terms--Magnetostatics, movement, natural-element method (NEM).

This paper presents an error estimator which enables to control the quality of finite element solution in nonlinear magnetostatic. This method, based on the works of P.Ladeveze in mechanics, consists in constructing a complementary admissible field from the one calculated by the finite element method. This method has been transposed in the cases of non-linear vector and scalar potential 2D formulations. The results given by the proposed estimator are compared to the one based on two finite element solutions on two examples. Index terms - error analysis, finite element methods, nonlinear systems, magnetostatics.

This paper contributes to the modeling of vibration of magnetic origin of electrical machines. It is generally difficult to calculate the damping matrix of actual mechanical structure of electrical machines. Mechanical model that we present here is known as the modal superposition method. It allows us to take into account the damping coefficients of the mechanical structure which can be inferred from experience. Associated with a numerical code for the computation of magnetic force it can be of a great help in the predetermination of the vibration of an electrical machine.

A computation procedure of vibrations of magnetic origin is used to study the effects of the feeding currents on the vibratory behavior of a permanent magnet synchronous machine. Similar studies are effected on an experimental bench dedicated to test electrical machines and their electronic supply devices. Characteristics of the vibrations produced by feeding currents are deduced from the comparison of the simulations results and measurements.

A method to determine the supply current waveshapes for torque ripple compensation in permanent magnet motors without saliency and damping bars, by means of a finite element code, is presented. First, a theoretical analysis shows that current waveshapes producing constant torque can be determined. This analysis leads us to an expression for the current as a function of the motor emf and cogging torque. Several methods, based on finite element computation of the magnetic field, for computing the cogging torque and emf are proposed and compared. A special experimental bench for motor torque measurement is used to validate the theoretical results.

A parameter identification of the Jiles-Atherton hysteresis model for a soft magnetic composite (SMC) is realized directly by a nonlinear optimization technique coupled with a 2D field calculation. The identification method fits experimental instantaneous voltage and current measurements realized on a transformer with a cylindrical symmetry, made of a soft magnetic composite material. The method is integrated in a global CAD environment for the optimal design of SMC transformers and used to take account of technical constraints related to the production and assembly of SMC transformers. Index Terms--Hysteresis, parameter identification, optimization methods, soft magnetic composites.