Modeling and Simulation in Engineering

The general aim of this book is to present selected chapters of the following types: chapters with more focus on modeling with some necessary simulation details and chapters with less focus on modeling but with more simulation details. This book contains eleven chapters divided into two sections: Modeling in Continuum Mechanics and Modeling in Electronics and Engineering. We hope our book entitled "Modeling and Simulation in Engineering - Selected Problems" will serve as a useful reference to students, scientists, and engineers

Integrated on-board battery chargers for EVs based on multiphase machines and power electronics

The concept of integration of an electric vehicle (EV) drivetrain’s components into the charging process is not novel. It has been considered over the years in both industry and academia, which resulted in a number of published papers and patents in this area. Possibilities of charging from single-phase and three-phase mains were both considered. In the former group the charging power rating cannot exceed the limit set by the single-phase mains. Therefore, the topologies are characterised with low charging powers, leading to a long duration of the charging process. Although the topologies supplied form three-phase mains are capable of achieving fast charging, they were considered to a much lesser extent. The main reason is the undesirable torque production in machines integrated into the charging process during the battery charging, which is unavoidable when a three-phase machine of either synchronous or induction type is used. The thesis investigates integrated on-board battery chargers for electric vehicles (EVs) based on multiphase machines and multiphase power electronics. At present, EVs rely on three-phase systems for machine propulsion. However, recent advances in multiphase drive technology have firmly established their potential advantages over their three-phase counterparts for this application. One of the most notable features of multiphase drive systems is their excellent fault tolerance, which is highly desirable in EVs since it enables realisation of the requirement for “limp-home” operation in the propulsion mode, in case of a fault. The thesis demonstrates that multiphase drives have an additional major advantage over three-phase systems in vehicular applications, which is related to the aspect of battery charging. It shows a clear superiority of multiphase over three-phase systems in designing integrated charging topologies for EVs. In order to support the statement, the thesis provides a multitude of novel charging solutions that incorporate multiphase machines and multiphase power electronics into the charging process. The developed solutions could contribute to achieve significantly faster and cost-free (or at a minimum additional cost) on-board chargers in the near future. The thesis demonstrates how additional degrees of freedom that exist in multiphase systems can be conveniently utilised to achieve torque-free charging operation. Therefore, although three-phase currents flow through machines’ stator windings, they are not capable of producing a torque; thus the machines do not have to be mechanically locked. The principal advantage is that either very few or no new elements are required in order to realise the charging process. Thus savings are made with regard to cost and weight, and available spare space in the vehicle is increased. The novel integrated charging solutions, developed in the thesis, are based on primarily five-phase, asymmetrical and symmetrical six-phase, and asymmetrical and symmetrical nine-phase systems. Solutions with other phase numbers are also considered. Thus, in essence, all the possible phase numbers are encompassed by the research and the solutions are valid for both induction and synchronous machines. A common attribute of all discussed topologies is that they do not require a charger as a separate device since the charging function is performed by the drivetrain elements, predominantly a multiphase machine and an inverter. Further, each topology is capable of operating in both charging and vehicle-to-grid (V2G) mode. Three types of voltage sources are considered as a power supply for the charging process, namely single-phase, three-phase, and multiphase. For each supply type, and each phase number, viability of torque-free charging operation is theoretically assessed. Mathematical models of multiphase rectifiers are developed. For each topology equivalent scheme in the charging/V2G mode of operation is constructed. A control scheme, which aims at achieving unity power factor operation and complete suppression of the low order grid current harmonics, is designed for each solution. Finally, the validity of theoretical considerations and control algorithms for the developed solutions is experimentally assessed in charging, V2G, and propulsion mode of operation. Experimental performances of all discussed topologies are compared, and advantages and shortcomings of each solution are identified and discussed

Proceedings of the 8th International Conference EEMODS'2013 Energy Efficiency in Motor Driven Systems

This book contains the papers presented at the eighth international conference on Energy Efficiency in Motor Driven Systems EEMODS 2013 EEMODS 2013 was organised in Rio de Janeiro, Brasil from 28 to 30 October 2013. This major international conference, which was previously been staged in Lisbon (1996), London (1999), Treviso (2002), Heidelberg (2005), Beijing (2007), Nantes (2009) and Washington DC (2011) has been very successful in attracting an international and distinguished audience, representing a wide variety of stakeholders in policy implementation and development, manufacturing and promotion of energy-efficient motor systems, including key policy makers, equipment manufacturers, academia and end-users. Potential readers who may benefit from this book include researchers, engineers, policymakers, energy agencies, electric utilities, and all those who can influence the design, selection, application, and operation of electrical motor driven systems.JRC.F.7-Renewables and Energy Efficienc

Third International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors

Método de estimación de las pérdidas de los conductores y del núcleo de componentes inductivos asimétricos mediante la técnica de análisis por método de elementos finitos en 3D

Tesis doctoral con la Mención de "Doctor Internacional"Dentro del campo de la ingeniería eléctrica, los convertidores electrónicos de potencia, que permiten generar una tensión y corriente de unas determinadas características a partir de una fuente de energía, juegan un papel crítico en las energías renovables, vehículos eléctricos o la ingeniería aeroespacial. Los componentes magnéticos constituyen uno de los elementos esenciales en los convertidores de potencia determinando el filtrado de corriente, la operación y la eficiencia del convertidor. Uno de los parámetros más críticos que influyen en la eficiencia de los convertidores son las pérdidas de los componentes magnéticos que dependen de determinados efectos electromagnéticos como el efecto pelicular, de proximidad, de entre-hierros y de borde. Estos efectos son aún más relevantes en rangos de alta frecuencia, a la que suelen operar habitualmente los convertidores electrónicos de potencia. La optimización del convertidor de potencia requiere un análisis detallado de los componentes magnéticos y de los efectos de frecuencia producidos en función de cada aplicación particular, y sus requisitos específicos, principalmente en los rangos de media y alta frecuencia. La trasmisión, almacenamiento y pérdidas de energía eléctrica y magnética son relevantes en este contexto y están determinadas por las ecuaciones de Maxwell, cuya resolución es compleja. Existen tres importantes enfoques para la resolución de estas ecuaciones: métodos analíticos, análisis utilizando herramienta de elementos finitos y por realización de ensayos. El primero de ellos consiste en la resolución analítica de las ecuaciones, con las necesarias simplificaciones, siendo la más habitual el asumir simetrías en las distribuciones de los campos magnéticos para poder resolver las ecuaciones de Maxwell en una o dos dimensiones. Como desventaja, dicha simplificación no permite determinar la distribución del campo magnético dentro de los conductores. El segundo enfoque utiliza un método de elementos finitos, resolviendo las ecuaciones de Maxwell en cada elemento finito, no siendo posible simular algunos componentes magnéticos complejos por precisar un tiempo de simulación sea muy elevado, haciendo que esta solución no resulte práctica para los ingenieros de desarrollo. El tercer enfoque, basado en la realización de ensayos de laboratorio, permite obtener los parámetros eléctrico de cualquier componente magnético. No obstante, el tiempo necesario es también alto y sólo es usado para los ajustes finales. La mayoría de los ingenieros electrónicos y científicos usan los análisis basados en elementos finitos de los componentes magnéticos realizando las posibles simplificaciones teniendo en cuenta la distribución de campo magnético y la simétrica del componente. Cuando el componente magnético no presenta ninguna simetría, deben utilizarse modelos 3D para la determinación de sus parámetros del circuito eléctrico equivalente y la optimización magnética del componente, así como un detallado estudio de los efectos pelicular y de proximidad, que son especialmente relevantes cuando el componente trabaja en alta frecuencia. En este trabajo, se proponer una metodología basada en elementos finitos en 3D con un bajo tiempo de simulación que permite obtener los parámetros que del modelo eléctrico equivalente para componentes magnéticos asimétricos a partir de la estimación de las pérdidas del bobinado y del núcleo.In electrical engineering, power converters, as devices that are able to transform a defined current and voltage from an energy source, have a critical role in different fields as renewable energy, electric vehicles or aerospace engineering. The magnetic components are relevant elements in power converters because determines the current filtering and conversion functions and converter efficiency and performance. One of the critical parameters that influence in the efficiency of converters are the losses in the magnetic components that depends on particular effects as they are the skin, proximity, airgap and edge effects. These effects are more relevant in the high frequency ranges where the power converters are usually operated. The optimization of the power converter requires of the detailed analysis of the magnetic component and the involved frequency effects according to the application when particular requirements are needed, mostly in the medium and high frequency. Transmission, storage and losses of magnetic and electric energy analysis is relevant in this context and are determined by the Maxwell´s equations whose resolution is a complex task. There are three main methods to solve this equation system: analytical method, finite element method analysis and experimental methodology. The first method consists on the analytical resolution of the equations with the necessary simplifications, being the most common approach the assumption of the magnetic field distribution in one or two dimensions to solve the equations system, however this simplification does not allow determining the magnetic field into the conductors. The second approach uses the Finite Element Method, solving the Maxwell equations in very finite element of the component, but is not possible to simulate some complex magnetic components because it requires a high computational time, being not useful for power electronics designers. The third method, based on experimental lab tests, allows to obtain the electrical parameters for any magnetic component. Nevertheless, the time cost is also huge and it is only used for adjustments in the final stage. Most of the power electronics designers and scientists use the analysis of the magnetic components based on Finite Element Method doing the available simplification taking into account the magnetic field distribution and the symmetry of the magnetic component. If the magnetic component has not any symmetric, a 3D model is necessary to determine the electromagnetic or thermal parameters for the electrical equivalent circuit and the magnetic component optimization, as well as a detailed study for skin effect and proximity effect, even more if the magnetic components work at high frequency. In this work, it is proposed a new method based in 3D Finite Element Analysis with a low computational time that allows obtaining the electrical equivalent model parameters for asymmetric magnetic components from the estimation of winding and core power losses

Technology 2000, volume 1

The purpose of the conference was to increase awareness of existing NASA developed technologies that are available for immediate use in the development of new products and processes, and to lay the groundwork for the effective utilization of emerging technologies. There were sessions on the following: Computer technology and software engineering; Human factors engineering and life sciences; Information and data management; Material sciences; Manufacturing and fabrication technology; Power, energy, and control systems; Robotics; Sensors and measurement technology; Artificial intelligence; Environmental technology; Optics and communications; and Superconductivity

Learning Motion Skills for a Humanoid Robot

This thesis investigates the learning of motion skills for humanoid robots. As groundwork, a humanoid robot with integrated fall management was developed as an experimental platform. Then, two different approaches for creating motion skills were investigated. First, one that is based on Cartesian quintic splines with optimized parameters. Second, a reinforcement learning-based approach that utilizes the first approach as a reference motion to guide the learning. Both approaches were tested on the developed robot and on further simulated robots to show their generalization. A special focus was set on the locomotion skill, but a standing-up and kick skill are also discussed. Diese Dissertation beschäftigt sich mit dem Lernen von Bewegungsfähigkeiten für humanoide Roboter. Als Grundlage wurde zunächst ein humanoider Roboter mit integriertem Fall Management entwickelt, welcher als Experimentalplatform dient. Dann wurden zwei verschiedene Ansätze für die Erstellung von Bewegungsfähigkeiten untersucht. Zu erst einer der kartesische quintische Splines mit optimierten Parametern nutzt. Danach wurde ein Ansatz basierend auf bestärkendem Lernen untersucht, welcher den ersten Ansatz als Referenzbewegung benutzt. Beide Ansätze wurden sowohl auf der entwickelten Roboterplatform, als auch auf weiteren simulierten Robotern getestet um die Generalisierbarkeit zu zeigen. Ein besonderer Fokus wurde auf die Fähigkeit des Gehens gelegt, aber auch Aufsteh- und Schussfähigkeiten werden diskutiert

Ironless Inductive Position Sensor for Harsh Magnetic Environments

Linear Variable Differential Transformers (LVDTs) are widely used for high-precision and high-accuracy linear position sensing in harsh environments, such as the LHC collimators at CERN. These sensors guarantee theoretically infinite resolution and long lifetimes thanks to contactless sensing. Furthermore, they offer very good robustness and ruggedness, as well as micrometer uncertainty over a range of centimeters when proper conditioning techniques are used (such as the three-parameter Sine-Fit algorithm). They can also be suitable for radioactive environments. Nevertheless, an external DC/slowly-varying magnetic field can seriously affect the LVDT reading, leading to position drifts of hundreds of micrometers, often unacceptable in high-accuracy applications. The effect is due to the presence of non-linear ferromagnetic materials in the sensor’s structure. A detailed Finite Element model of an LVDT is first proposed in order to study and characterize the phenomenon. The model itself becomes a powerful design tool for possible countermeasures to the interference effect. In particular, a combination of magnetic shielding and DC polarization is proposed to reduce the drift due to the external field. Nevertheless, such solutions cannot lead to complete immunity, given the unavoidable presence of magnetic materials in the sensor. Taking the CERN application as a starting point, this thesis aims at conceiving, modelling and characterizing a valid alternative to LVDTs for harsh magnetic environments, which would guarantee magnetic-field-immune position sensing while keeping all the advantageous properties of LVDTs. The Ironless Inductive Position Sensor (I2PS) is an air-cored structure made of 5 coaxial coils. The position sensing is achieved by spatially-variable magnetic fluxes, which give rise to position-dependent coil voltages, just as for LVDTs. The complete electromagnetic model of the sensor is proposed, showing the working principle and demonstrating the magnetic-field immunity from a theoretical viewpoint. In addition, a high-frequency electromagnetic analysis is performed, in order to model the skin and proximity effects in the conductors and foresee their impact on the sensor’s functioning. The models are validated with FEM simulations and experimental measurements. The thermal behaviour of the sensor is also investigated and an effective compensation algorithm is proposed to cancel the temperature-dependence of the position reading. In addition, a smart real-time reading algorithm is proposed in order to significantly reduce the estimation error of standard three-parameter Sine-Fit algorithms when an additional sinusoidal signal is present on the main waveform. Finally, a generic optimization procedure is proposed in order to maximize the performances of the sensor in terms of sensitivity. Taking this procedure as a guideline, an actual I2PS optimized prototype is designed and manufactured, having the specifications of the LHC collimators application as a reference. The optimized prototype shows immunity to external ramped and sinusoidal fields, as expected. In addition, it is used for the experimental validation of the models and the reading techniques, which demonstrate their effectiveness

Non-US electrodynamic launchers research and development

Electrodynamic launcher research and development work of scientists outside the United States is analyzed and assessed by six internationally recognized US experts in the field of electromagnetic and electrothermal launchers. The assessment covers five broad technology areas: (1) Experimental railguns; (2) Railgun theory and design; (3) Induction launchers; (4) Electrothermal guns; (5) Energy storage and power supplies. The overall conclusion is that non-US work on electrodynamic launchers is maturing rapidly after a relatively late start in many countries. No foreign program challenges the US efforts in scope, but it is evident that the United States may be surpassed in some technologies within the next few years. Until recently, published Russian work focused on hypervelocity for research purposes. Within the last two years, large facilities have been described where military-oriented development has been underway since the mid-1980s. Financial support for these large facilities appears to have collapsed, leaving no effective effort to develop practical launchers for military or civilian applications. Electrodynamic launcher research in Europe is making rapid progress by focusing on a single application, tactical launchers for the military. Four major laboratories, in Britain, France, Germany, and the Netherlands, are working on this problem. Though narrower in scope than the US effort, the European work enjoys a continuity of support that has accelerated its progress. The next decade will see the deployment of electrodynamic launcher technology, probably in the form of an electrothermal-chemical upgrade for an existing gun system. The time scale for deployment of electromagnetic launchers is entirely dependent on the level of research-and-development effort. If resources remain limited, the advantage will lie with cooperative efforts that have reasonably stable funding such as the present French-German program

The 1982 NASA/ASEE Summer Faculty Fellowship Program

A NASA/ASEE Summer Faculty Fellowship Research Program was conducted to further the professional knowledge of qualified engineering and science faculty members, to stimulate an exchange of ideas between participants and NASA, to enrich and refresh the research and teaching activities of participants' institutions, and to contribute to the research objectives of the NASA Centers