385 research outputs found
Automated Design Optimization of Synchronous Machines: Development and Application of a Generic Fitness Evaluation Framework
A rotating synchronous electric machine design can be described to its entirety by a combination of 17 to 24 discrete and continuous parameters pertaining the geometry, material selection, and electrical loading. Determining the performance attributes of a design often involves numerical solutions to thermal and magnetic equations. Stochastic optimization methods have proven effective for solving specific design problems in literature. A major challenge to design automation, however, is whether the design tool is versatile enough to solve design problems with different types of objectives and requirements.
This work proposes a black-box approach in an attempt to encompass a wide variety of synchronous machine design problems. This approach attempts to enlist all possible attributes of interest (AoIs) to the end-user so that the design optimization problem can be framed by combination of such attributes only. The number of ways the end-user can input requirements is now defined and limited. Design problems are classified based on which of the AoI’s are constraints, objectives or design parameters. It is observed that regardless of the optimization problem definition, the evaluation of any design is based on a common set of physical and analytical models and empirical data. Problem definitions are derived based on black-box approach and efficient fitness evaluation algorithms are tailored to meet requirements of each problem definition.
The proposed framework is implemented in Matlab/C++ environment encompassing different aspects of motor design. The framework is employed for designing synchronous machines for three applications where designs based on conventional motor construction did not meet all design requirements. The first design problem is to develop a novel bar-conductor tooth-wound stator technology for 1.2 kW in-wheel direct drive motor for an electric/hybrid-electric two wheeler (including practical implementation). The second design problem deals with a novel outer-rotor buried ferrite magnet geometry for a 1.2 kW in-wheel geared motor drive used in an electric/hybrid-electric two wheeler (including practical implementation). The third application involves design of an ultra-cost-effective and ultra-light-weight 1 kW aluminum conductor motor.
Thus, the efficacy of automated design is demonstrated by harnessing the framework and algorithms for exploring new technologies applicable for three distinct design problems originated from practical applications
Index to 1983 NASA Tech Briefs, volume 8, 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 1983 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
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
Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine
Optimal performance of the electric machine/drive system is mandatory to improve the energy consumption and reliability. To achieve this goal, mathematical models of the electric machine/drive system are necessary. Hence, this motivated the editors to instigate the Special Issue “Mathematical Approaches to Modeling, Optimally Designing, and Controlling Electric Machine”, aiming to collect novel publications that push the state-of-the art towards optimal performance for the electric machine/drive system. Seventeen papers have been published in this Special Issue. The published papers focus on several aspects of the electric machine/drive system with respect to the mathematical modelling. Novel optimization methods, control approaches, and comparative analysis for electric drive system based on various electric machines were discussed in the published papers
Index to 1985 NASA Tech Briefs, volume 10, 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 1985 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
NASA patent abstracts bibliography: A continuing bibliography. Section 1: Abstracts (supplement 14)
Abstracts are cited for 213 patents and applications for patent introduced into the NASA scientific and technical information system during the period of July 1978 through December 1978. Each entry consists of a citation, an abstract, and in most cases, a key illustration selected from the patent or application for patent
High Frequency Permanent Magnet Generator for Pulse Density Modulating Converters
This thesis describes an investigation of high frequency permanent magnet generators for use in a novel power generation system for aerospace applications. The system consists of a high frequency generator (in the 10s of kHz range) which feeds a full-wave rectifier to produce to a high frequency pulse train as input to a pulse-density modulated soft-switched converter.
Various topologies of flux-switching, flux-reversal and Vernier machines are investigated using electric-circuit coupled finite element analysis. Having demonstrated the limitations of these topologies, a comprehensive design study into a single-phase, surface mounted permanent magnet machine based on a single turn serpentine winding is described. This study covers both internal and external rotor machines with pole numbers of 192 and 96 which correspond to generator fundamental frequencies of 32kHz and 16kHz at the rated speed of 20,000rpm. Several aspects of the machine design are optimised through extensive use of finite element modelling, including mechanical analysis of the rotor containment. This study includes a detailed consideration of iron loss, including consideration of iron powder based cores. This study has resulted in a down-selected design based on a low permeability but high resistivity powdered iron core.
The manufacture of a demonstrator is described including the need to re-design the machine to employ ultra-thin Nickel Iron laminations because of the difficulties encountered in the machining of a powdered iron core. The performance of this Nickel Iron variant is investigated and a final design established. The numerous challenges involved in manufacturing this novel machine are described
Welding of X100 linepipe
The benefits of high strength steels in terms of reduced material volume due to
enhanced mechanical performance have been known for some time. Large diameter
transmission linepipe steels of minimum 690MPa ('XIOO') yield strength have been
developed throughout the previous decade, and have recently become commercially
available. Before these steels are used in linepipe construction projects, fimdamental
work regarding their ability to be field welded required undertaking. This thesis presents
data arising from girth welding experiments involving a variety of X 100 linepipe steels,
welding consurnables and welding processes.
Target girth weld mechanical properties thought suitable for a strain-based MOO
pipeline design were proposed at the outset of the research. Optimisation of pulsed gas
metal arc welding waveforms for the single and tandem wire processes, alongside the
establishment of the base material properties formed an early part of the research. An
extensive programme of solid wire welding consumable evaluation was then undertaken
for single, tandem and dual torch narrow gap welding processes. The majority of
equipment and procedures used throughout the work were as close to current field
practice as possible, to minimise the time required to transfer the technology to the field
situation. Work then focussed on the optimised alloy levels and welding procedure
requirements for the production of full girth welds, using a variety of industry pipeline
welding standards and supplemental techniques to assess the joint integrity.
It has been demonstrated that, subject to careful selection of welding consumable and
fairly precise control of welding process variables and parameters, there are no major
problems in obtaining weld metal strength levels of at least 120 MPa above the 690
MPa specified minimum yield strength (SMYS) of the parent pipe. This objective has
been achieved in welds made usirig all three mechanised process variants examined.
The desired target properties of strength and toughness were achieved with a variety of
consumables and pipe materials of different composition.
Tie-in and repair procedures were also developed during the course of the research, with
particular attention focussed on the application of high strength rutile flux cored ýVires.
These wires attained strength levels overmatching the pipe specified minimum yield
strength (690MPa), but would not reach the guaranteed overmatch level of 81 OMPa.
An examination of the thermocycles associated with four mechanised narrow gap
welding techniques (single, tandem, dual and dual tandem) was undertaken. The
experimental technique developed allowed the solidifying weld bead to be monitored, as
well as the cumulative temperature cycles experienced by the underlying layers.
Succesful determination of the cooling rates, times and transformation temperatures
allowed a comparative evaluation of the four processes, using an optimum weld metal
composition suitable for single wire welding of X100. This led to an understanding of
the metallurgical history, and its consequent effect on the associated mechanical and
microstructural properties. A similar series of experiments was undertaken to examine
these effects using variations in preheat with a single wire process. In most cases
considerable property variations were attained for'the same weld metal chemistry, joint
geometry and arc energy, highlighting the sensitivity of the process and procedure in
achieving the required properties. The high cooling rates determined from the thermocycle experiments explained the
microstructural and mechanical properties attainable from lean alloying levels. A series
of metal cored wires, based around the same alloy as for the thermocycle experiments,
was consequently manufactured to examine small changes in weld metal chemistry. The
individual wires involved changes in carbon, nickel, molybdenum and chromium to
examine potential property variations arising from a highly controlled narrow gap
welding procedure. The results again highlighted the sensitivity of the narrow gap
welding technique in generating considerable property variation within the weld metal.
Tolerance ranges for specific alloying additions to attain the proposed strength levels
with a single and tandem wire process were derived from the data
- …