A. Savini

Field Models in Electricity and Magnetism

Covering the development of field computation in the past forty years,Field Models in Electricity and Magnetism intends to be a concise, comprehensive and up-to-date introduction to methods for the analysis and synthesis of electric and magnetic fields.A broad view of the subject of field models in electricity and magnetism, ranging from basic theory to numerical applications, is offered.The approach coherently assumed throughout the whole book is to solve field problems directly from partial differential equations in terms of vector quantities.Theoretical issues are illustrated by practical examples. In particular, a single example is solved by different methods so that, by comparison of results, limitations and advantages of the various methods are made clear.The subject of the synthesis of fields and of the optimal design of devices, which are growing in research and so far have not been adequately covered in textbooks, are developed in addition to the more classical subject of analysis.Topics covered include:vector fields: electrostatics, magnetostatics, steady conduction;analytical methods for solving boundary-value problems;numerical methods for solving boundary-value problems;time-varying electromagnetic field;inverse problems;optimization.Field Models in Electricity and Magnetism nresults from the cooperation of three authors, after collecting a separate experience in teaching electromagnetic theory at various levels and in different countries.

An improved technique for enhancing diversity in Pareto evolutionary optimization of electromagnetic devices

When a multiobjective optimization problem is tackled using Pareto optima theory, particular care has to be taken to obtain a full sampling of the Pareto Optimal Front. This leads to variability of individuals in both design space and objective space. We compare two different fitness assignment strategies based on two individual sharing procedures in the space domain and in the objective domain on some test cases.

Non-Linear Multi-Physics Analysis and Multi-Objective Optimization in Electroheating Applications

The design optimization of an induction heating device is considered. The non-linear multi-physics analysis is carried out by means of finite-element method, while the optimal design problem is solved by NSGA-II genetic algorithm. A comparison with the results obtained by a simplified linear analysis is shown. The original contribution of this paper is the Pareto front identification for a design problem in which the field analysis is multi-physics, dynamic, and non-linear.

Optimal shape design of devices and systems for induction‐heating: methodologies and applications

The paper reports recent experiences of the authors in the automated optimal design of devices and systems for induction heating. The results presented have been obtained in the frame of a long‐lasting cooperation between Laboratory of Electroheat, University of Padova and Electromagnetic Devices CAD Laboratory, University of Pavia. In particular, two case studies are discussed; in both cases, the shape design of the inductor is carried out in a systematic way, by minimizing user‐defined objective functions depending on design variables and subject to bounds and constraints. When the design problem is characterized by many objectives which are in mutual conflict, the non‐dominated set of solutions is identified.

Biogeography-Inspired Multiobjective Optimization and MEMS Design

A new version of the biogeography-based optimization algorithm is proposed in order to consider multiple objectives. In fact, by exploiting non-dominated sorting of habitats, it is possible to approximate Pareto-optimal solutions in the objective space. The optimal shape design of an electrostatic micromotor, which is a benchmark in the Micro Electro-Mechanical Systems design, is considered as the case study.

3-D computer aided analysis of the "Berkeley" electrostatic micromotor

The basic ideas of IC-processed electrostatics are reviewed. The three-dimensional field model of a variable-capacitance electrostatic micromotor is then presented and the underlying analysis problem is solved by means of the finite element method. The micromotor, acting as a position actuator, is investigated at steady state and particular attention is paid in the calculation of the torque-angle curve featuring the device. The influence of stator geometry on the electromechanical performance is also investigated and design considerations are accordingly drawn. Finally, the step-transient response of the actuator is simulated. >

Multiphysics field analysis and multiobjective design optimization: a benchmark problem

A magneto-thermal inverse problem, dealing with the optimal design of an induction heating device, is proposed as a benchmark. The coupled-field problem is analysed by means of a higher order finite element method. Then the optimal design problem is solved in terms of the Pareto front trading off two conflicting objective functions.

Influence of flux collectors on stray losses in transformers

The paper proposes a reluctance network method for the three-dimensional analysis of a three-phase transformer. The analysis is aimed at assessing as to whether a laminated flux collector is effective in controlling the power losses of the transformer. The results are thoroughly superimposable to those which can be obtained by the traditional theory of the transformer. The main advantage is that the required number of nodes and elements for the analysis is definitely lower than with other techniques.

Loney's solenoid multi-objective optimization problem

A multi-objective optimization problem for Loneys solenoid consists of the determination of the current system which produces a uniform magnetic field within a domain of finite extent inside the solenoid and a low stray field outside it. In order to solve the multi-objective problem, four different approaches have been utilized and compared. In all cases evolution strategy (ES) techniques are utilized for the minimization procedure.

Application of global optimization strategies to the shape design of a transformer winding

Abstract In the paper the leakage field in a transformer, produced by windings of variable shape, is investigated. The two-dimensional axisymmetrical analysis of the magnetic field enables short-circuit forces on the two windings to be accurately evaluated. The design problem consists of improving the shape of the primary winding in order to minimize the total force exerted on it under short-circuit conditions. Numerical results achieved using evolution strategy are reported and discussed.