Port-Hamiltonian model and load balancing for DC-microgrid lift systems

This paper considers the problem of modeling a multi-source lift system where power balancing-realized through a power DC bus-should be optimally controlled. The system includes the mechanical part, a Salient Permanent Magnet Synchronous Machine (SPMSM), a battery energy storage unit, a super-capacitor, a solar panel (PV) generation unit as well as the corresponding converters to DC-links. This microgrid is connected to a three-phase utility (external) grid. A port-Hamiltonian model is proposed for the system. It includes the descriptions of nonlinear characteristics and the limitations for each components as well as some typical operation demands. Then, different optimization objectives are formulated in view of an efficient energy management within the microgrid system

Surveyor batteries Final engineering report

Design and performance of Surveyor spacecraft silver-zinc main batter

Definición de la gestión energética de un vehículo híbrido basada en la simulación del funcionamiento de los componentes del sistema propulsor en las condiciones de operación de diseño

La tendencia actual hacia el incremento de la movilidad en las sociedades más avanzadas va en contradicción con criterios de control de la contaminación local y la explotación de los recursos de combustible. Entre las soluciones planteadas, se encuentran los vehículos híbridos. En este artículo se presenta la definición y simulación de la gestión energética de uno de estos vehículos, a partir de las condiciones de operación. El vehículo híbrido diseñado en su totalidad combina propulsión con un motor eléctrico alimentado por baterías y un motor térmico, incluyéndose, además, paneles solares, así como carga externa por red eléctrica. Se han desarrollado modelos de simulación de los componentes y su integración. Analizando el campo de aplicación del vehículo, se ha planteado un ciclo de conducción a partir de ciclos estándar. Con el modelo, se ha analizado la idoneidad de diferentes estrategias de control de la energía, considerando diversas condiciones operativas

SystemC-AMS Simulation of Energy Management of Electric Vehicles

Electric vehicles (EV) are rapidly invading the market, since they are clean, quiet and energy efficient. However, there are many factors that discourage EVs for current and potential customers. Among them, driving range is one of the most critical issues: running out of battery charge while driving results in serious inconvenience even comparable to vehicle breakdown, as an effect of long fuel recharging times and lack of charging facilities. As a result, the dimensioning of the energy subsystem of an EV is a crucial activity. The choice of the power components and of the adopted policies should thus be validated at design time through simulations, that estimate the vehicle driving range under reference driving profiles. It is thus necessary to build a simulation framework that takes into account an EV power consumption model, dependent on the characteristics of the vehicle and of the driving route, plus accurate models for all power components, including batteries and green power sources. The goal of this paper is to achieve early EV simulation, so that the designer can estimate at design time the driving range of the vehicle, validate the adopted components and policies and evaluate alternative configurations

Research and technology highlights of the Lewis Research Center

Highlights of research accomplishments of the Lewis Research Center for fiscal year 1984 are presented. The report is divided into four major sections covering aeronautics, space communications, space technology, and materials and structures. Six articles on energy are included in the space technology section

Capacity Fade Modeling of Li-Ion Battery using Evolutionary Algorithm

Renewable sources are seasonal and cannot be considered as available energy source as their generation varies with time. The insufficient forecasting techniques lead to thought of storage of energy. Even though many techniques of energy storage are available, batteries play a vital role as the time taken to start delivering the stored energy is very less. The life period of the battery depends upon the charging and discharging characteristics which in turn depend on the internal parameters such as life period, charge rate, discharge rate of the battery. The energy stored in the battery can be calculated by finding these parameters. In this paper these parameters are estimated for a Sony lithium ion battery by evolutionary algorithm CMA-ES under different Charging and discharging rates. As the batteries are charged and discharged there is capacity loss in the battery. This loss is modelled by modified Arrhenius equation on practical conditions. Capacity loss of the sample battery is modelled for five different cycles starting from 50th cycle to 100th cycle in an interval of 10 cycles. The results are validated with those of manufacturer catalogue. The optimized battery capacity loss are found to coincide with the measured values

The effectiveness of energy storage in hybrid vehicles

Public awareness of finite oil resources and concerns over climate change have spurred efforts to improve vehicle efficiency and reduce emissions by road transport. Hybrids have become an increasingly popular alternative to conventional powertrain vehicles. Large fuel savings are claimed (typically 70 + mpg) (Toyota, 2014), however, collective anecdotal evidence from owners of these vehicles suggests a more modest performance. A literature review yielded an abundance of literature relating to specific hybrid vehicle technologies, and control strategies, however the variation in energy savings over different journey types for different classes of vehicle has received less attention. A simulation tool was developed to compare the energy saving effectiveness of parallel hybrid powertrains with regenerative braking and energy storage across a broad range of vehicle and journey types. The realism of the simulation (in non-hybrid mode) was evaluated by comparison with practical trials. A range of validation methods showed that average fuel consumption could be calculated to within +/- 5-10% of measured consumption and, in cases where detailed data for a vehicle was available, this improved to within 3%. Simulated fuel consumption was around 15% greater that manufacturers’ claims – reasons for this were explored. Using the backward and forward looking simulation it was possible to calculate likely fuel savings in various scenarios. Results indicate a trend of improved potential savings with increased vehicle mass. Over urban journeys results ranged from around 16 to 23% energy savings for a small car and large coach respectively. On extra-urban journeys much more modest savings were calculated ranging from a maximum of 0 - 4 % across the same range of vehicles. The likely effects of vehicle mass and drag coefficient has also been explored along with the energy saving potential of start-stop engine technology, often used in hybrids and non-hybrids alike. The broad part of the study confirmed quantitatively that greatest fuel savings might be achieved on urban routes with public transport buses. The study then narrowed to consider this application, particularly with respect to exhaust emissions which are cause for growing concern. Possible reductions in exhaust NOx and PM emissions of up to 10 to 12% respectively were predicted through the application of parallel hybrid powertrains to existing bus designs and simulated on the MLTB cycle

Computational modelling of the effect of side chain chemistry on the micro-structure and electrolyte interactions of mixed transport polymers

As we scale up our use of energy storage facilities to meet the demands of the future, the prob- lems associated with current energy storage technologies will grow to unacceptable levels. In this work I explore how we can develop high performing polymers for use as cathode materials in energy storage devices operating with aqueous electrolytes. Energy storage devices using these materials have the potential for low cost production and safe operation. Through a combination of atomistic simulation methods, this thesis relates aspects of the polymer chemistry to their microstructural properties, and subsequently to their ability to operate successfully as electrodes.Open Acces