ELECTROMAGNETISM

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Carlo De Falco, Politecnico di Milano | Paolo Ferrandi, Moxoff Spa

Abstract

A system based on electromagnetic induction to heat water for domestic purposes has been studied. The device consists of an inner ferromagnetic pipe surrounded by insulator layers with an outer coil where alternating current flows. As different physics and time scales are involved, sophisticated multiphysics numerical and modeling are required. Thanks to the hypothesis of long solenoid and tightly packed windings, the electromagnetic problem is 1D in the radial coordinate and is described by Ampere’s law. In the thermal model the temperature depends on the axial coordinate and the mean power of the eddy currents is a constant generation term in the conduction equation since the voltage variation is much faster than heat transfer. The overall system is discretized using the finite element method and implemented in Octave, showing good agreement with experimental measures. Simulations have been performed varying the main design parameters, in both stationary and transient conditions.

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Antonio Manna, ELT - Elettronica SpA

Abstract

A radome is a cover placed above an antenna to protect it from the external environment. An ideal radome would protect the antenna from any physical damage and be electromagnetically transparent in its operational frequency band. During the last decades, composite materials became the preferred choice for antenna radome due to their low thickness and high mechanical strength. A radome is often designed in a multi-layer configuration, where each sheet of prepreg can be modeled, in a first approximation, as an inductance on an equivalent transmission line. In Elettronica SpA we design and produce system for electronic warfare (EW), typically working with ultra-wide band (UWB) antennas. In this scenario, we designed a radome covering an entire signal intelligence system, with height and width of 1 m and 0.8 m, respectively. The radome has to be transparent from DC to 40 GHz. Such a design represents a great challenge both from an electromagnetic (EM) and a mechanical point of view. The measurement of the first prototype showed unexpected results, not observed on the approximate simulation performed during the design. In particular, the radiation pattern of some UWB antennas suffered from an extreme ripple, due to the contribution of the reflected waves on the antenna itself. A smart simulation environment had to be tailored to reproduce this effect and redesign the radome stratification. The solution has been found in cooperation with EnginSoft, making use of ANSYS Savant. The software, based on a ray-tracing method, was able to reproduce the measurement behavior, giving us more confidence redesign. A second radome has been, then, manufactured, exhibiting performance in line with the expectation.

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Asad Mazhar Khan, Meta System

Abstract

The on board Power Units (OBC, DC/DC) are a very important part of the electric vehicle (EV), because the requested high power density, the high efficiency and the reduced volume require a very robust design; therefore simulations are the right instruments in order to reduce the time to market and the failures. Simulations start from the design of the product and must follow also the further steps of validation and testing. The aim of the work is to describe the workflow for the EMC and thermal model, of a 7kW battery charger for EV, and how models have been used to improve the design. The EMC model generates information about functional power path (electrical connection between HV and LV parts, functional voltages and currents for HV and LV, noise level inside the charger) and parasitic elements (common or differential mode coupling path, parasitic inductance capacitance due to connections, heat sink, PCB or passive elements). The thermal model considers the power dissipated by components and PCBs. The calculation of losses has been done with Simplorer or Designer for the components and with Siwave for the PCBs; all these data are passed as input to Ice Pack that takes into account also the geometry of the cooling circuit. The proposed workflow provides the right projection of: • functional problems related to the frequency behavior of the components, • conducted and radiated emission level, a comparison with measurements will be explained • thermal behavior of the unit with a particular focus on the temperature of components and the right design of the cooling circuit.

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Abstract

In this work we present the unique challenges faced in the development of a new generation of flexible hybrid electronic devices and the critical role of 3D EM simulations as a tool to take key architectural decisions. Hybrid system are electronic devices where traditional silicon integrated circuits are embedded within functional smart substrate comprising flexible batteries, sensors, interconnects, antennas and displays and represent the only viable solution to integrate sophisticated functionalities in miniaturized systems in a cost effective way. Such systems are the natural endpoint of the rush to ubiquitous computing and while still in their early days, are ultimately aimed to be deployed in a number of industries from logistics to medical devices, from consumer electronics to industrial sensing in mass volumes (hundreds of millions to billions per year) and usually have ultra-low target prices (few tens of c$). The design and development of these tiny while complex devices thus poses tight constraints from system design to process development, from materials selection to assembly equipment design. In this presentation we show how an articulated set of simulation runs were executed in a collaboration between Flex and Enginsoft. The scope was to drive the selection of a base conductive substrate that minimizes costs while maximizing electrical performance. This enabled us to select the most appropriate antenna topology and finally optimize its characteristics considering the power requirement for the given application.

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Claudio Mazzon, Electrolux | Giovanni Falcitelli, EnginSoft SpA

Abstract

In this paper, a multi-physics approach for simulation of microwave oven efficiency is presented. The aim of the described research was to investigate the effects of stirring on the EM field distribution, through the evaluation of temperature rising of a set of water samples placed inside the oven cavity. The microwave oven was modeled entirely including the magnetron antenna, the transition waveguide, the full cavity and the shielded door. Moreover the presence of functional elements like shelves and correspondent supports, heating elements and stirrers were taken into account. EM simulations were performed through harmonic analysis with ANSYS HFSS to calculate power dissipation inside water samples and ANSYS Mechanical was used to execute thermal transient analysis. The multi-physics project was developed within the ANSYS Workbench environment, that allowed fast and easy integration, as well as sharing of geometries, meshes and physics between different solvers. Additional functional elements and the oven geometry were parametrized to investigate their effect on performances. Results are presented in terms of power distribution and temperature versus time evolution along the prototyped experimental test. The proposed setup was used by engineers to foresee crucial physical effects, and helped significantly in the development phase of a new product by saving time and reducing costs for prototyping.

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