Mauricio Caldora Costa

Kriging: a useful tool for electromagnetic device optimization

This paper deals with the use of the Kriging models for objective function approximations and their use on electromagnetic device optimization. The models are compared with some radial basis function neural networks and with the diffuse element method. Comparative tests are done on an analytical function and on the TEAM workshop problem 25.

Comparison of radial basis function approximation techniques

This paper compares three different radial basis function neural networks, as well as the diffuse element method, according to their ability of approximation. This is very useful for the optimization of electromagnetic devices. Tests are done on several analytical functions and on the TEAM workshop problem 25.

Modified nodal analysis applied to electric circuits coupled with FEM in the simulation of a universal motor

In the last few years, several papers considering the finite element method coupled with electric circuits were published. Many of these works have been used the theory of mesh analysis to analyze the electric circuit. However, when we use a circuit with many current and voltage sources, it is not always easy to use this analysis. Aiming to avoid this problem, this paper presents the application of the modified nodal analysis in the analysis of coupled circuits, as a continuation of the previously presented work, where the use of nonlinear ferromagnetic devices was not considered. The analysis of a universal motor at stall is presented to validate this new approach.

Optimization of grounding grids by response surfaces and genetic algorithms

In this paper, we use an optimization technique based on the creation of response surfaces and the application of genetic algorithms to minimize the number of conductors of grounding grids, guaranteeing the safety levels defined by the maximum touch potential.

Diffuse-element method and quadtrees: two "ingredients" for an adaptive response surface

A new algorithm to obtain the response surface of objective functions is presented. The diffuse-element method and quadtrees are used in the implementation of this algorithm. The approximation of a two-parameter analytical function and the optimization of a switched reluctance motor are performed to show the robustness of this new approach.

Three-dimensional finite element analysis of MHD duct flow by the penalty function formulation

A numerical scheme based on the Finite Element Method (FEM) is presented to calculate the full solution of a three-dimensional steady magnetohydrodynamic (MHD) flow with moderately high Hartmann numbers and interaction parameters. An incompressible, viscous and electrically conducting liquid-metal is considered. Assuming a low magnetic Reynolds number, the solution method solves the coupled Navier-Stokes and Maxwells equations through the use of a penalty function method. Results are presented for Hartmann numbers in the range 10/sup 2/-10/sup 3/.

A multi‐objective analysis of a special switched reluctance motor

Purpose – The design of electrical machines includes the computation of several requirements and, in general, the improvement of one requirement implies in a degradation of another one: this is a typical multi‐objective scenario. The paper focuses on the multi‐optimization analysis of a special switched reluctance motor.Design/methodology/approach – Two design requirements were analyzed: the average torque and the ripple torque. The electromagnetic field computation was performed by the finite element method and the torque was computed by the Coulombs Virtual Work for several positions. This allows us to calculate the average torque and the ripple torque. Three different methods were used to obtain the Pareto set: a min‐max approach, the non‐dominated sorting genetic algorithm (NSGA) and the strength Pareto evolutionary algorithm (SPEA). In order to save the computation time, the objective functions (the average torque and the ripple torque) were replaced with surrogate functions. Kriging models were use...

Electromagnetic Analysis of Submarine Umbilical Cables With Complex Configurations

These studies present the electromagnetic analyses of different configurations of the so called “Integrated Production Umbilical,” or simply Umbilical Cables. Modern Umbilical Cables can have more than 4 independent 3-phase power circuits as well as steel tubes. There is no 2-D symmetry for these cable configurations and the 3-D simulations are very undesirable due to cable length. The adopted methodology to evaluate cable performance is a combination of 2-D-finite element analyses (coupled with electric circuit) and the transposition technique. The results have shown that the configuration B in which all power circuits rotates along its own center has better performance considering the load terminal voltages due to the compensation of the induction effect along the cable.

Evaluation of electromagnetic interference from railway electric power system harmonics

This work shows an evaluation methodology for the occurrence of electromagnetic interference in signaling and control equipment of a DC electrified railway under contingency conditions in which the traction rectifying unit works with 6 pulses instead of the 12 pulses of its normal operation. Thus, electromagnetic interference can result from the direct interaction of the magnetic fields close to the rails as well as the resultant induction in the cables that interconnect the signaling and control equipment