Feasibility of high frequency alternating current power distribution for the automobile auxiliary electrical system

This study investigates the feasibility and potential benefits of high frequency alternating current (HFAC) for vehicle auxiliary electrical systems. A 100Vrms, 50kHz sinusoidal AC bus is compared with 14V DC and 42V DC electrical systems in terms of mass and energy efficiency. The investigation is focused on the four main sub-systems of an on-board electrical network, namely: the power generation, power distribution, power conversion and the electrical loads. In addition, a systemlevel inquiry is conducted for the HFAC bus and a comparable 42V DC system. A combination of computer simulation, analytical analysis and experimental work has highlighted benefits for the HFAC power distribution sub-system and for low-torque motor actuators. Specifically, the HFAC conductor mass is potentially 70% and 30% lighter than comparable 14V DC and 42V DC cables, respectively. Also, the proposed cable is expected to be at least 80% more energy efficient than the current DC conductor technology. In addition, it was found that 400Hz AC machines can successfully replace DC motor actuators with a rated torque of up to 2Nm. The former are up to 100% more efficient and approximately 60% lighter and more compact than the existing DC motors in vehicles. However, it is argued that the HFAC supply is not feasible for high-torque motor actuators. This is because of the high energy losses and increased machine torque ripple associated with the use of HFAC power. The HFAC power conversion sub-system offers benefits in terms of simple power converter structure and efficient HFAC/DC converters. However, a significant limitation is the high power loss within HFAC/AC modules, which can be as high as 900W for a 2.4kW load with continuous operation. Similar restrictions are highlighted for the HFAC power generation sub-system, where up to 400W is lost in a 4kW DC/HFAC power module. The conclusion of the present work is that the HFAC system offers mass and energy efficiency benefits for the conventional vehicle by leveraging the use of compact lowtorque motor actuators and lightweight wiring technology

Feasibility of high frequency alternating current power distribution for the automobile auxiliary electrical system

This study investigates the feasibility and potential benefits of high frequency alternating current (HFAC) for vehicle auxiliary electrical systems. A 100Vrms, 50kHz sinusoidal AC bus is compared with 14V DC and 42V DC electrical systems in terms of mass and energy efficiency. The investigation is focused on the four main sub-systems of an on-board electrical network, namely: the power generation, power distribution, power conversion and the electrical loads. In addition, a systemlevel inquiry is conducted for the HFAC bus and a comparable 42V DC system. A combination of computer simulation, analytical analysis and experimental work has highlighted benefits for the HFAC power distribution sub-system and for low-torque motor actuators. Specifically, the HFAC conductor mass is potentially 70% and 30% lighter than comparable 14V DC and 42V DC cables, respectively. Also, the proposed cable is expected to be at least 80% more energy efficient than the current DC conductor technology. In addition, it was found that 400Hz AC machines can successfully replace DC motor actuators with a rated torque of up to 2Nm. The former are up to 100% more efficient and approximately 60% lighter and more compact than the existing DC motors in vehicles. However, it is argued that the HFAC supply is not feasible for high-torque motor actuators. This is because of the high energy losses and increased machine torque ripple associated with the use of HFAC power. The HFAC power conversion sub-system offers benefits in terms of simple power converter structure and efficient HFAC/DC converters. However, a significant limitation is the high power loss within HFAC/AC modules, which can be as high as 900W for a 2.4kW load with continuous operation. Similar restrictions are highlighted for the HFAC power generation sub-system, where up to 400W is lost in a 4kW DC/HFAC power module. The conclusion of the present work is that the HFAC system offers mass and energy efficiency benefits for the conventional vehicle by leveraging the use of compact lowtorque motor actuators and lightweight wiring technology.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

Feasibility study of a diesel-powered hybrid DMU

Nowadays the interest in hybrid vehicles is constantly increasing, not only in the automotive sector, but also in other transportation systems, to reduce pollution and emissions and to improve the overall efficiency of the vehicles. Although railway vehicles are typically the most eco-friendly transportation system, since commonly their primary energy source is electricity, they can still gain benefits from hybrid technologies, as many lines worldwide are not electrified. In fact, hybrid solutions allow ICE-powered railway vehicles, such as diesel multiple units (DMU), to operate in full-electric mode even when the track lacks electrification. The possibility to switch to full electric mode is of paramount importance when the vehicle runs on urban or underground track sections, where low or zero emission levels are required. The paper describes the feasibility study of hybridization of an existing DMU vehicle, designed by Blue Engineering S.r.l., running on the Aosta-Torino Italian railway line, which includes a non-electrified urban track section and an electrified underground section. The hybridization is obtained by replacing one of the diesel generators installed on the original vehicle with a battery pack, which ensures the vehicle to operate in full-electric mode to complete its mission profile. The hybridization is also exploited to implement a regenerative braking strategy, which allows an increase in the energetical efficiency of the vehicle up to 18%. The paper shows the sizing of the battery pack based on dynamic simulations performed on the Turin underground track section, and the results demonstrate the feasibility of the hybridization process

Characterization of Solar Roadways Via Computational and Experimental Investigations

Efficiency of traditional solar panels is known to be very low and hence necessitates the use of extensive open spaces for producing solar-based electric power. In solar roadways concept, open spaces such as roads, parking lots, bicycle lanes, footpaths are proposed to be utilized. An in-depth quantitative feasibility study for implementing solar roadways in Canada is carried out considering the total available surfaces, solar panel efficiency and effects of fast moving shades. The load carrying capability of commercially available materials for the solar panel top cover is studied in an effort to examine the current as well as near-future implementation of this proposed concept. In addition, a piezo-based auxiliary energy harvesting system is proposed for harnessing the vehicle-induced strain on the solar panel top cover. The positions of the piezoelectric elements are optimized by studying the vibration characteristics of the top cover via numerical as well as experimental methods

Simulation model for driving dynamics, energy use and power supply

Dissertação para obtenção do grau de Mestre em Engenharia Electrotécnica Ramo de EnergiaO objetivo deste trabalho é simular a interação entre o sistema de alimentação de tração elétrica e o planeamento dos veículos de tração. Por forma a simular o sistema de tração elétrica são usados modelos e métodos de cálculo para a dinâmica de condução, para o uso de energia e aindapara o sistema de alimentação elétrica. Nestes modelos estão incluídas funcionalidades tais como: níveis de eficiência, aspetos térmicos e sistemas auxiliares dos veículos de tração. A escolha adequada do sistema de alimentação e as suas características técnicas implicam um estudo prévio do cálculo do trânsito de energia, por forma a se poder efetuar a escolha correta para ademanda do transporte ferroviário. Os modelos apresentados para a caracterização do sistema de alimentação em corrente alternada, assume diversas metodologias e interage com vários procedimentos distintos. A caracterização dos veículos de tração no seu percurso específico é efetuado através do software Pulzufa, embora o consumo dos mesmos veículos de tração seja calculado através de um método não interativo, o método de Aubepine. O cálculo do trânsito de energia é realizado através da análise nodal, usando um método não interativo. Além disso, algumas suposições adicionais são implementadas por forma a obter resultados viáveis e por forma a validar o modelo de simulação no sistema de alimentação convencional monofásico. O principal objetivo desta dissertação passa pela utilização de um modelo aproximado que simula a interação entre o sistema de alimentação de tração elétrica e o planeamento dos veículos de tração através da utilização de métodos de calculo não interativos, a fim de reduzir a complexidade do próprio sistema assim como o tempo de cálculo computacional.Abstract: The aim of this thesis is to simulate the interaction between the traction power supply system and the traction vehicles planning. Models and calculation methods for driving dynamics, energy use and traction power supply systems are developed in order to simulate the traction power system. In these models are included functionalities as the efficiency degrees, thermal aspects and auxiliary systems of the traction vehicles. The choice of an adequate power supply system and their technical characteristics implies a previous study on the power flow calculation in order to do the accurate option for the railway transportation demand. The presented models for the power supply characterization in alternating current, assumes several methodologies and interacts with several distinct procedures. The characterization of the traction vehicles behavior in the specific route uses the Pulzufasoftware, although the traction vehicles consumption over the route is calculated through a noninteractive method called Aubepinemethod. The power flow calculation is carried out through the nodal analysis, using a non-interactive method. In addition some further assumptions are implemented to obtain more workable outcomes in order to validate the simulation model for the conventional single-phase feeding system. The main contribution of this thesis is the approximate model which simulates the interaction between the traction power supply system and the traction vehicles schedule thought a non-interactive method in order to reduce the system complexity andthe computational calculation times

Preliminary power train design for a state-of-the-art electric vehicle

The state-of-the-art (SOTA) of electric vehicles built since 1965 was reviewed to establish a base for the preliminary design of a power train for a SOTA electric vehicle. The performance of existing electric vehicles were evaluated to establish preliminary specifications for a power train design using state-of-the-art technology and commercially available components. Power train components were evaluated and selected using a computer simulation of the SAE J227a Schedule D driving cycle. Predicted range was determined for a number of motor and controller combinations in conjunction with the mechanical elements of power trains and a battery pack of sixteen lead-acid batteries - 471.7 kg at 0.093 MJ/Kg (1040 lbs. at 11.7 Whr/lb). On the basis of maximum range and overall system efficiency using the Schedule D cycle, an induction motor and 3 phase inverter/controller was selected as the optimum combination when used with a two-speed transaxle and steel belted radial tires. The predicted Schedule D range is 90.4 km (56.2 mi). Four near term improvements to the SOTA were identified, evaluated, and predicted to increase range approximately 7%

A review of power electronics equipment for all-electric ship MVDC power systems

Medium Voltage DC (MVDC) distribution Power Systems for all-electric ships (AES) can be regarded as functionally composed of three subsystems, namely the power sources, the load centers and the distribution network. Extensive use of power electronics is required for connecting power sources and load centers to the MVDC bus and for protecting the MVDC power system through properly placed DC circuit breakers. In this paper, an overview is given of the power electronics equipment found in the literature and on the market that could be suitable for use in future AES MVDC power systems. Some industrial experiences regarding DC generator systems, energy storage apparatus and solid-state DC circuit breaker prototypes are reported in the paper as examples of state-of-the-art realizations. Different DC/DC converters, which can be employed as solid-state transformers, are also discussed and a structure obtained by combining them is proposed