Análisis computacional de circuitos eléctricos y geometrías de bobinas para sistemas de estimulación magnética transcraneal

Transcranial magnetic stimulation systems have had a heyday in the last two decades, both in the development and commercialization of equipment, as well as in areas of application in medicine and research, which has made them tools for the diagnosis and treatment of important diseases of the nervous system. Most of the analyzes of the general operation are still limited to the separate study of the elements of the system. In this present work, the analysis is carried out through simulations of the electrical excitation circuit using the Matlab®/Simulink®and Micro-Cap tools, likewise, three coil geometries of transcranial magnetic stimulation systems are analyzed by using the finite element method in COMSOL Multiphysics®software. The computational analysis lies in studying the basic architecture of the electrical excitation circuit, which is made up of an RLC circuit with switching elements and power electronics, in charge of generating high-magnitude current pulses (between 1 and 3 kA) and short duration. (between 0.5 and 1250 ms). The magnitude of the current and the shape of the signal in the elements of the RLC stage are analyzed, performing a calculation of the power dissipated. This first stage is complemented with the analysis by means of the finite element method of the magnetic flux density and maximum operating temperature of three coil geometries commonly used for therapies. The computational analysis gives rise to a proposal for a system that reduces the maximum operating temperature of coil geometry by up to 20 %, maintaining the maximum magnitude of the magnetic flux density, which consists of the design of a single solenoid coil geometry with windings. concentric, which from the electrical point of view, are inductors in parallel.

Comparison of the Efficiency and Load Power in Periodic Wireless Power Transfer Systems with Circular and Square Planar Coils

In the article, a wireless charging system with the use of periodically arranged planar coils is presented. The efficiency of two wireless power transfer (WPT) systems with different types of inductors, i.e., circular and square planar coils is compared, and two models are proposed: analytical and numerical. With the appropriate selection of a load resistance, it is possible to obtain either the maximum efficiency or the maximum power of a receiver. Therefore, the system is analyzed at two optimum modes of operation: with the maximum possible efficiency and with the highest power transmitted to the load. The analysis of many variants of the proposed wireless power transfer solution was performed. The aim was to check the influence of the geometry of the coils and their type (circular or square) on the efficiency of the system. Changes in the number of turns, the distance between the coils (transmit and receive) as well as frequency are also taken into account. The results obtained from analytical and numerical analysis were consistent; thus, the correctness of the adopted circuit and numerical model (with periodic boundary conditions) was confirmed. The proposed circuit model and the presented numerical approach allow for a quick estimate of the electrical parameters of the wireless power transmission system. The proposed system can be used to charge many receivers, e.g., electrical cars on a parking or several electronic devices. Based on the results, it was found that the square coils provide lower load power and efficiency than compared to circular coils in the entire frequency range and regardless of the analyzed geometry variants. The results and discussion of the multivariate analysis allow for a better understanding of the influence of the coil geometry on the charging effectiveness. They can also be valuable knowledge when designing this type of system.

DESIGN OF INDUCTION COIL FOR OXYGEN FREE COPPER PRODUCTION

This paper deals with the design of an induction coil (IC) intended to be used for an oxygen free copper production. This coil differs in design because it should be placed in a vacuum or in a chamber filled with noble gas, such as Argon. The designed coil must be suitable for melting the copper in this environment. The coil design means, using the simulation of the melting process to determine the best, coil geometry, type of crucible, the required current, frequency, the consumed power, and time required for this process. These results will be used to determine the parameters of the induction furnace AC power source suitable for feeding such a melting process efficiently. The Finite Element Analysis (FEA) intended to simulate the heating process to determine the best coil dimensions, and choosing the crucible. It is found that the best crucible used for the melting of copper is the carbon crucible.

Influence of Compression Coil Geometry in Electromagnetic Forming Using Experimental and Finite Element Method

Electromagnetic forming process is a high velocity forming technique which is widely used in automotive and aerospace sectors for forming and joining metallic sheet/tubes. The geometrical structure of compression coil have significant effect on the performance of the system in terms of current output and deformation of workpiece. The present work aims to analyse the effect of structural parameters of compression coil like cross-section of turns (X), pitch circular diameter (PCD) and effective turn (n) using both experimental and numerical simulation. A bitter compression coil of variable geometrical structure have been considered to see the effect of its parameters by deforming an AA6061 tube experimentally. Parameters like magnetic field, velocity, Lorentz force, displacement and stress are difficult to measure experimentally but have significant indication on performance of the coil in EMF. The trends of numerically predicated parameters find good agreement with experimental deformation value of tube. The Finite element analysis is carried out to correlate deformation results.The results indicate that n have higher significant in performance of compression coil as compared to X and PCD of coil.

A brief review: basic coil designs for inductive power transfer

The inductive power transfer (IPT) has contributed to the fast growth of the electric vehicle (EV) market. The technology to recharge the EV battery has attracted the attention of many researchers and car manufacturers in developing green transportation. In IPT charging system, the coil design is indispensable in enhancing the EV battery charging process performance. This paper starts by describing the two charging techniques; static charging and dynamic charging before further presents the IPT system descriptions. Afterwards, this paper describes a brief review of coil designs which discusses the critical factors that affect the power transmission efficiency (PTE) including their basic designs, design concepts and features merits. The discussions on the basic coil designs for IPT are of the circular spiral coil (CSC), square coil (SC), rectangular coil (RC), and double-D coil (DDC). Furthermore, the significant advantages and limitations of each research on different geometries are analyzed and discussed in this paper. Finally, this paper evaluates some essential aspects that influence the coil geometry designs in practical.

Thermal and Mechanical Analyses of Compliant Thermoelectric Coils for Flexible and Bio-integrated Devices

Three-dimensional coil structures assembled by mechanically guided compressive buckling have shown potency on enabling efficient thermal impedance matching of thermoelectric devices at a small characteristic scale, which increases the efficiency of power conversion, and has the potential to supply electric power to flexible bio-integrated devices. The unconventional heat dissipation behavior at the side surfaces of the thin-film coil, which serves as a 'heat pump', is strongly dependent on the geometry and the material of the encapsulating dissipation layer (e.g., polyimide). The low heat transfer coefficient of the encapsulation layer, which may damp the heat transfer for a conventional thermoelectric device, usually limits the heat transfer efficiency. However, the unconventional geometry of the coil can take advantage of the low heat transfer coefficient to increase its hot-to-cold temperature difference, and this requires further thermal analysis of the coil in order to improve its power conversion efficiency. Another challenge for the coil is that the active thin-film thermoelectric materials employed (e.g., heavily doped Silicon) are usually very brittle, with the fracture strain less than 0.1% in general while the overall device may undergo large deformation (e.g., stretched 100%). Mechanic analysis is therefore necessary to avoid failure/fracture of the thermoelectric material. In this work, we study the effect of coil geometry on both thermal and mechanical behaviors by using numerical and analytical approaches, and optimize the coil geometry to improve the device performance, and to guide its design for future applications.