The development of technologies for the additive manufacturing, in particular of metallic materials, is offering the possibility of producing parts with complex geometries. This opens up to the possibility of using topological optimization methods for the design of electromagnetic devices. Hence, a wide variety of approaches, originally developed for solid mechanics, have recently become attractive also in the field of electromagnetics. The general distinction between gradient-based and gradient-free methods drives the structure of the paper, with the latter becoming particularly attractive in the last years due to the concepts of artificial neural networks. The aim of this paper is twofold. On one hand, the paper aims at summarizing and describing the state-of-art on topology optimization techniques while on the other it aims at showing how the latter methodologies developed in non-electromagnetic framework (e.g., solid mechanics field) can be applied for the optimization of electromagnetic devices. Discussions and comparisons are both supported by theoretical aspects and numerical results.

Model predictive control (MPC) represents an affirmed optimal control strategy, able to handle multivariable systems and their input-output constraints. However, MPC does not provide an integral control action for reference tracking control problems. Several methods have been proposed to overcome this limitation. Standard MPC methods include a disturbance observer to handle unmodeled uncertainties, such as external unknown disturbances and parameter mismatches. Among these formulations, the authors focus on the velocity form MPC, which considers the incremental formulation of the motor state-space model. This formulation gets rid of the bias errors in reference tracking problems. In this article, the MPC paradigm is applied to the current control of synchronous motor drives. The intent is to compare the velocity form and the MPC with disturbance observer. A theoretical analysis of the MPC coupled with disturbance observers and the equivalence between these formulations and the velocity form is presented. Input constraints are included in the MPC optimization process, thus requiring an online quadratic programming solver. Experimental tests consider a 1 kW anisotropic synchronous motor. Numerical aspects regarding the optimization problem are investigated for both methods.

In this paper, starting from the experimental experience of the road embedment of a transmitting coil for wireless power transfer, a numerical model of such device is constructed. The model is then used to perform several parametric analyses which aim at investigating the influence of the main electromagnetic parameters of the concrete and the geometrical parameters of the wireless power transfer on the overall behavior of the device. The results of such study allow for providing guidelines for the design of the coil and the choice of the materials for the embedment. Moreover, as a secondary result of the adopted methodology, the electromagnetic characterization of the concrete adopted for the road embedment is obtained.

A fast and general partial element equivalent circuit (PEEC) method based on the fast Fourier transform (FFT) is proposed for the first time. The numerical tool only requires common CAD data input files (e.g., $.\text{stl}$ format), then the discretization process is performed automatically by means of a fast voxelization technique based on ray intersection, thus, drastically reducing the human effort required to setup the model. The method allows for considering at the same time inductive and capacitive effects, and is focused on power electronics applications where propagation effects can be neglected, whereas all the other electromagnetic phenomena are considered. Specifically, the proposed method is particularly suited for problems where both electric and magnetic fields are equally important and, therefore, quasistatic approximations do not apply. An ad-hoc preconditioner which significantly speeds-up the solver is also proposed and, thanks to the FFT, both memory and computation time are significantly reduced, without the need of applying data compression. Both linear and nonlinear materials are considered by the proposed FFT-PEEC method. Sample implementation of the method is made publicly available.

Low-rank approximation techniques are useful approaches to reduce the computational effort required by integral equations methods. Here, two different libraries based on hierarchical-matrices and hierarchically semi-separable matrices are applied to the partial element equivalent circuit method for the study of high-frequency electromagnetic problems. The academic case of a dielectric sphere and the study of a complex device used in thermonuclear fusion science are considered in order to compare the performances of the two libraries.

A new and general Partial Element Equivalent Circuit (PEEC) formulation based on electric and magnetic vector potentials and the Cell Method is presented. The purpose of the paper is manifold. First, a comprehensive review of well established PEEC method is given and the state–of–the–art of the method with focus on the inclusion of magnetic media in the formulation is discussed. Then, a new and general formulation of the PEEC method based on integral equations is proposed. The formulation is valid for conductive, dielectric, and magnetic media and its advantages with respect to the state–of–the–art PEEC formulations are underlined. Unlike the existing PEEC methods, this novel formulation, thanks to the reinterpretation of PEEC in the context of integral equation methods, allows for maintaining a circuit interpretation for both electric and magnetic media. Thus, a standard Spice–like solver can in principle be adopted for the solution of electromagnetic problems also when magnetic media are involved. The imposition of the divergence condition for the current density vectors is guaranteed and also the case of inhomogeneous and anisotropic media is considered. A thorough discussion on the suitability of the method for the study of both low and high frequency electromagnetic problems is also presented. Finally, the case study of a Near Field Communication antenna is considered as an example of the applicability of the formulation to problems of industrial interest. Comparisons with commercial softwares, measurements, and the state–of–the–art PEEC method are given in order to demonstrate the accuracy and the advantages of the proposed PEEC formulation.