The paper describes the sensitivity analysis of a wireless power transfer link involving an implanted antenna within the surrounding biological environment. The approach combines a 3D electromagnetic ...modeling and a surrogate model (based polynomial chaos expansion). The analysis takes into account geometrical parameters of the implanted antenna and physical properties of the biological tissue. It allows researchers to identify at low cost the main parameters affecting the efficiency of the transmission link.
Due to the high level of magnetic stray field around high power electromagnetic systems, the human exposure needs to be properly assessed in order to check the compliance with international standards ...and guidelines. Such analyses are usually made in two steps: first a proper map of the magnetic field in the vicinity area is computed, where, in a second time a human model is used to compute induced dosimetric quantities. Unfortunately, such high power systems have a high computational cost in addition to the complexity of 3D human models. Thus, this paper shows the useful combination of stochastic tools with numerical solvers in order to build accurate predictors at a low computation cost in the case of human exposure for various high power systems. These surrogate models can be used to accurately analyze the sensitivity of the exposure problem regarding various input parameters at a low computation cost. A dosimetric methodology for assessing the safety of a human body around an inductive power transfer system for automotive applications, using an adaptive metamodelling algorithm coupled with a voxelized 3D human model, has been developed. Such analysis has been successfully extended to a system where human exposure assessment are crucially needed: medium-frequency direct-current welding guns, treating the case of human exposure to a pulsed magnetic field. This methodology manages to reduce the computation time by more than 99.9% compared to a classical analysis for both exposure problems.
This paper proposes a methodology for the assessment of the human exposure to magnetic fields generated by dynamic inductive power transfer systems for automotive applications. Since the magnetic ...field is pulsed, current safety standards and guidelines require the use of time-domain approaches to evaluate the peak exposure, which has to be limited under the prescribed limits. This paper shows that, for these kind of systems, the peak exposure can be efficiently evaluated by means of a time-harmonic formulation. Furthermore, a methodology to identify the worst case scenario is proposed and applied to a real case.
The current charging technology for electric vehicles consists of plugging the cable from the AC utility to charge the batteries. This requires heavy gauge cables to connect to electric vehicles, ...which can be difficult to handle, presents tripping hazards, and is prone to vandalism. In addition to these inconveniences, electric vehicles must be immobilized for hours before being fully charged. Dynamic wireless power transfer has been studied worldwide as a promising technology. It is safe and convenient and allows electric vehicles to charge while moving. To improve the efficiency of a dynamic wireless power transfer system, the magnetic coupling coefficient must be maximized between the primary pad, which is integrated into the road, and the secondary pad installed in the electric vehicle. This article presents a parametric optimization of the ferrite structure used for a 3 kW dynamic wireless power transfer prototype. Different ferrite configurations are compared while studying the effect of the parameter values on their magnetic coupling coefficient. Finally, the proposed structure was validated during the experimental test, and its coupling coefficient was improved by 26% compared to the original structure.
We introduce a novel RF to DC wireless power transmission implantable rectenna system at Industrial, Scientific and Medical bands (ISM 902.8-928 MHz). An embedded circular antenna receives the ...externally emitted energy from a patch antenna and converts it to DC power by a rectifying circuit. The system is associated with a metallic reflector which is placed behind the human body enhancing the reception. The rectifying circuit efficiency and the total system's efficiency are determined for different external antenna to human body distances and various embedded depths with or without the reflector. Experimental results, obtained in a realistic environment, validate the predicted performance and provide an initial evaluation of the transmission link. Porcine tissue and bovine tissue are both used during the measurements and results are compared against simulations.
Glass fiber (GF) reinforced polymer composites have attracted increasing attention due to their excellent performance. In this study, GF was coated by a thin layer of nickel, and then grafted carbon ...nanotubes (CNTs) array by a chemical vapor deposition method (CVD). The CNT contents can be varied by changing the CVD conditions. Three types of fillers, nickel coated GF (GF@Ni), GF with CVD grown CNTs (GF-CNTs) and nickel-coated GF with CVD grown CNTs (GF@Ni-CNTs), were used to prepare the epoxy composites. The electromagnetic interference shielding performances were investigated as a function of CNT contents. The GF@Ni-CNTs reinforced epoxy composites, which had the CNTs mass ratio of 9.2 wt% to the hybrids, showed the best EMI shielding performance among the composites. Their total EMI shielding effectiveness (SE) was higher than 35 dB in the range of 1–18 GHz, and above 50 dB in the X band. By incorporating the nickel layer on the GF surface, the same EMI performance can be achieved with lower CNTs content. For achieving a SE value of 35 dB in the X band, it needed GF@Ni-CNTs/epoxy with CNTs mass ratio of 3.8 wt% to the hybrids, instead of GF-CNTs/epoxy composites with CNTs mass ratio of 5.2 wt% to the hybrids.
In this paper, we present an efficient modeling of sources of electromagnetic disturbance using the measurement, in near-field, of the magnetic field radiated from power electronic equipment. A model ...based on elemental magnetic dipoles is developed for the prediction of the radiated magnetic field. This model is obtained from measurements in the near field. For the determination of the parameters of the model, an optimization procedure is combined with a matrix inversion. Unlike standard approaches, this new technique allows us to find equivalent sources with a small number of dipoles in a reduced computing time. To check the efficiency of the proposed method, we perform a comparison between a classical optimization method and the new procedure. To validate this method experimentally, near field magnetic measurements are performed to find the equivalent model in case of a mono turn coil, a toroidal coil, and a dc/dc converter.
Due to mass constraints, composite materials are possible candidates to replace metal alloys for electromagnetic shielding applications. The design of standard metallic shielding enclosures often ...relies on finite-element calculations. But in the case of composite materials, the strong dependence on the shielding properties to the microstructure makes the finite-element approach almost impossible. Indeed meshing the microstructure would imply a huge number of elements, incompatible with usual computational resources. We propose in this paper to develop homogenization tools to define the effective electromagnetic properties of composite materials at microwave frequencies. The ratio between the characteristic size of the microstructure and the wavelength is shown to be a key parameter in the homogenization process. The effective properties can then be used as an input for electromagnetic compatibility standard tools, designed for homogeneous media.
The shielding design is one of the most difficult phases in developing an inductive power transfer system (IPT) for electric vehicles. In this aspect, the combination of metamodeling with a ...multiobjective optimization algorithm provides an efficient approach. Here, Polynomial Chaos Expansions (PCE) and Multigene Genetic Programming Algorithm (MGPA) methods are used and compared to describe the mutual inductance of the IPT system in the function of the design variables on the shielding. These metamodels are obtained based on a number of 3D Finite Element Method (FEM) computations. Then, a multiobjective optimization algorithm coupled with the PCE metamodeling technique is applied to determine the optimal design variables for a practical shielding design when considering the magnetic coupling as well as the cost of the shielding as objective functions. Such a multiobjective optimization algorithm based on a particle swarm algorithm coupled with a metamodel on PCE method is proposed, leading to improve around 104 % of the mutual inductance <inline-formula> <tex-math notation="LaTeX">M </tex-math></inline-formula> and save 14 % of the cost <inline-formula> <tex-math notation="LaTeX">C </tex-math></inline-formula> for the shielding compared to the initial design.
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