Thermoelectric simulation of electric machines with permanent magnets

The objective of this work is to describe some numerical tools developed to perform the thermoelectric simulation of electric machines. From the electromagnetic point of view, we will focus on the computation of nonlinear 2D transient magnetic fields where the data concerning the electric current sources involve potential drops excitations. From the thermal point of view, once the electromagnetic losses are known, we will show an application of a Galerkin lumped parameter method (GLPM) to simulate the thermal behavior of an electric motor. The proposed methods are applied to the simulation of a permanent magnet synchronous electric motor

Geometric Objects: A Quality Index to Electromagnetic Energy Transfer Performance in Sustainable Smart Buildings

Sustainable smart buildings play an essential role in terms of more efficient energy. However, these buildings as electric loads are affected by an important distortion in the current and voltage waveforms caused by the increasing proliferation of nonlinear electronic devices. Overall, buildings all around the world consume a significant amount of energy, which is about one-third of the total primary energy resources. Optimization of the power transfer process of such amount of energy is a crucial issue that needs specific tools to integrate energy-efficient behaviour throughout the grid. When nonlinear loads are present, new capable ways of thinking are needed to consider the effects of harmonics and related power components. In this manner, technology innovations are necessary to update the power factor concept to a generalized total or a true one, where different power components involved in it calculation, properly reflect each harmonic interaction. This work addresses an innovative theory that applies the Poynting Vector philosophy via Geometric Algebra to the electromagnetic energy transfer process providing a physical foundation. In this framework, it is possible to analyse and detect the nature of disturbing loads in the exponential growth of new globalized buildings and architectures in our era. This new insight is based on the concept of geometric objects with different dimension: vector, bivector, trivector, multivector. Within this paper, these objects are correlated with the electromagnetic quantities responsible for the energy flow supplied to the most common loads in sustainable smart buildings. Besides, it must be considered that these phenomena are characterized by a quality index multivector appropriate even for detecting harmonic sources. A numerical example is used to illustrate the clear capabilities of the suggested index when it applies to industrial loads for optimization of energy control systems and enhance comfort management in smart sustainable buildings

RF Sensors for Monitoring the Electrical Properties of Electrolyte Solutions

A radio frequency electrical sensor for the qualitative analysis and monitoring of the electrical properties of electrolyte solutions is designed, simulated and experimentally tested in this research. This work is based on the use of planar inductors for the detection of a change in the concentration of ionic species in a liquid sample. At first a literature review on the physical chemistry of electrolyte solutions is provided. This will include topics on the conductivity and relaxation properties of electrolytes. This will be followed by a look at dielectric spectroscopy sensors, electrochemical sensors and inductive sensing devices. The principles of electrodynamics and constitutive equations are discussed. Based on these, the principles of operation of the RF electrical sensors are analysed. Two methods of theoretical analysis of such structures are investigated. These methods are; analytical solution and finite element computation method. The former offers greater insight into the system’s parameters whilst the latter offers more information regarding the whole system. Given the qualitative nature of the sensors under investigation and finite element approach was selected and used in latter chapters to obtain grater insight into the behaviour of the system. Planar inductor coils are designed on an FR4 substrate and packaged using PDMS to be used as sensors in the monitoring of electrical properties of electrolytes. Experimental results on these sensors are provided and discussed. The effects of solvent, acidity of the solutions, and environmental factors on the behaviour of the sensors shall be discussed. This is followed by finite element simulations of the sensor and the effect of various parameters on the overall behaviour of the sensing device. A transformer apparatus is also constructed and experimental data are provided for it. An electrolyte is placed on one of the coils of the transformer and scattering parameters are looked upon for data analysis. The results obtained using the FE method, is then used to obtain further information about the principle of operation of the device

Systems of Differential Algebraic Equations in Computational Electromagnetics

Starting from space-discretisation of Maxwell's equations, various classical formulations are proposed for the simulation of electromagnetic fields. They differ in the phenomena considered as well as in the variables chosen for discretisation. This contribution presents a literature survey of the most common approximations and formulations with a focus on their structural properties. The differential-algebraic character is discussed and quantified by the differential index concept

Regularized maxwell equations and nodal finite elements for electromagnetic field computations in frequency domain

In this work we present an alternative approach to the usual finite element formulation based on edge elements and double-curl Maxwell equations. This alternative approach is based on nodal elements and regularized Maxwell equations. The advantages are that, without adding extra unknowns (such as Lagrange multipliers), it provides spurious-free solutions and well-conditioned matrices. Besides, its integral representation involves a less singular kernel (order 1 instead of 3), which makes this approach best suited to hybridization with integral numerical techniques. On the other hand, a new set of difficulties arises that were not present in the classical formulation. The main drawback is that a globally wrong solution is obtained when the electromagnetic field has a singularity in the problem domain. Also, boundary conditions and field discontinuities are more laborious to implement. This work explains how to overcome these difficulties and demonstrates that accurate solutions can be obtained with nodal elements and the regularized formulation. We also present ERMES, the C++ implementation of the finite element approach depicted above and the main deliverable of this work. We compute with ERMES the scattering parameters of microwave filters and the specific absorption rate induced in a body when exposed to electromagnetic fields. ERMES is also the computational tool used in two novel numerical models introduced in this work. The first one characterizes electromagnetic metal forming processes and the second one the transfer impedance of cable shields. The electromagnetic metal forming model calculates the driving Lorentz force and estimates the optimum frequency at which it is attained the maximum workpiece deformation. The main advantage of the approach is that it provides an explicit relation between the capacitance of the capacitor bank and the frequency of the discharge, which is a key parameter in the design of an electromagnetic forming system. The successful application of the regularized formulation in this model reveals its excellent behavior in the low-frequency (quasi-static) regime. The second numerical model introduced in this work computes the transfer impedance of cable shields. The model reproduces the high frequency behavior of the transfer impedance more accurately than the approaches found in the literature and, moreover, it is able to analyze a wider variety of geometries and materials