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1 – 10 of over 3000Auxiliary power system is an indispensable part of the train; the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways, which are…
Abstract
Purpose
Auxiliary power system is an indispensable part of the train; the auxiliary systems of both electric locomotives and EMUs mainly are powered by one of the two ways, which are either from auxiliary windings of traction transformers or from DC-link voltage of traction converters. Powered by DC-link voltage of traction converters, the auxiliary systems were maintained of uninterruptable power supply with energy from electric braking. Meanwhile, powered by traction transformers, the auxiliary systems were always out of power while passing the neutral section of power supply grid and control system is powered by battery at this time.
Design/methodology/approach
Uninterrupted power supply of auxiliary power system powered by auxiliary winding of traction transformer was studied. Failure reasons why previous solutions cannot be realized are analyzed. An uninterruptable power supply scheme for the auxiliary systems powered by auxiliary windings of traction transformers is proposed in this paper. The validity of the proposed scheme is verified by simulation and experimental results and on-site operation of an upgraded HXD3C type locomotive. This scheme is attractive for upgrading practical locomotives with the auxiliary systems powered by auxiliary windings of traction transformers.
Findings
This scheme regenerates braking power supplied to auxiliary windings of traction transformers while a locomotive runs in the neutral section of the power supply grid. Control objectives of uninterrupted power supply technology are proposed, which are no overvoltage, no overcurrent and uninterrupted power supply.
Originality/value
The control strategies of the scheme ensure both overvoltage free and inrush current free when a locomotive enters or leaves the neutral section. Furthermore, this scheme is cost low by employing updated control strategy of software and add both the two current sensors and two connection wires of hardware.
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FOR a number of years now it has been evident that a successor to the well‐tried Vickers Viscount and Convoir 240/340/440 series was required. However, the big problem was to…
Abstract
FOR a number of years now it has been evident that a successor to the well‐tried Vickers Viscount and Convoir 240/340/440 series was required. However, the big problem was to design an aircraft such that its economics and passengerappealweresub‐stantially better than the machines it would ultimately replace. Other important factors which had to be con‐sidered were improved reliability, easier and cheaper maintenance, higher standards of safety and means of reducing ramp times. Furthermore, the difficult choice of passenger capacity and cruising speed had to be made. Probably the easiest decision was to employ the twin‐engine configuration with the power plants placed in the now familiar rear position, one on cither side of the fuselage.
Xingquan Wang, Xiuyuan Lu, Wei Chen, Fengpeng Wang, Jun Huang, Lingli Liu, Mengchao Li and Kui Lin
This paper aims to improve the general circuit of driving and protection based on insulated gate bipolar transistor (IGBT) in dielectric barrier discharge power supply by…
Abstract
Purpose
This paper aims to improve the general circuit of driving and protection based on insulated gate bipolar transistor (IGBT) in dielectric barrier discharge power supply by designing a novel half-bridge inverter circuit with discrete components.
Design/methodology/approach
With one SG3524 chip, the structure based on discrete components is used to design the IGBT drive circuit. The driving waveform is isolated and sent out by photo-coupler 6N137. The protection circuit is realized by Hall sensor directly detecting the main circuit current, supplemented by a few components, including diodes, resistors, capacitors and triodes. It improves the reliability of the protection circuit.
Findings
In the driving circuit, the phase difference of signals from two channels are 180°. Moreover, when the duty cycle is set at 40%, it can ensure sufficient pulse width modulation response time. In the protection circuit, when over-current occurs, an intermittent output signal is automatically sent out. Furthermore, the over-current response time can be controlled independently. The peak voltage can be adjusted continuously from 0 to 30 kV with its frequency from 8 to 25 kHz and the power output up to 150 W.
Originality/value
The novel circuit of driving and protection makes not only its structure simpler and easier to be realized but also key parameters, such as frequency, the duty cycle and the driving voltage, continuously adjustable. Moreover, the power supply is suitable for other discharges such as corona discharge and jet discharge.
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THE development of air transportation since World War II has been dramatic, consistently exceeding the predicted rate of expansion resulting from market surveys throughout the…
Abstract
THE development of air transportation since World War II has been dramatic, consistently exceeding the predicted rate of expansion resulting from market surveys throughout the period. This has been at least partly due to the boost given to originality and inventiveness by a continually expanding market, and the present speed, comfort, reliability and economy of modern aircraft far surpass the wildest dreams of pioneers. At the time of writing there is no indication of a slackening off in the rate of progress, indeed, rather the reverse, and the scope for imaginative exploration in all areas of aircraft design and operation has never been so wide as at the present time.
Christophe Versèle, Olivier Deblecker and Jacques Lobry
This paper presents a computer‐aided design (CAD) tool for the design of isolated dc‐dc converters.
Abstract
Purpose
This paper presents a computer‐aided design (CAD) tool for the design of isolated dc‐dc converters.
Design/methodology/approach
This tool, developed in Matlab environment, is based on multiobjective optimization (MO) using genetic algorithms. The Elitist Nondominated Sorting Genetic Algorithm is used to perform search and optimization whereas analytical models are used to model the power converters. The design problem requires minimizing the weight, losses and cost of the converter while ensuring the satisfaction of a number of constraints. The optimization variables are, as for them, the operating frequency, the current density, the maximum flux density, the transformer dimensions, the wire diameter, the core material, the conductor material, the converter topology (among Flyback, Forward, Push‐Pull, half‐bridge and full‐bridge topologies), the number of semiconductor devices associated in parallel, the number of cells associated in series or parallel as well as the kinds of input and output connections (serial or parallel) of these cells. Finally, the design of an auxiliary railway power supply is presented and discussed.
Findings
The results show that such tool to design dc‐dc power converters presents several advantages. In particular, it proposes to the designer a set of solutions – instead of a single one – so that he can choose a posteriori which solution best fits the application under consideration. Moreover, interesting solutions not considered a priori can be found with this tool.
Originality/value
To the best of the authors’ knowledge, such a CAD tool including a MO procedure taking several topologies into account has not been suggested so far.
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Zhiyong Fan, Zhen Zhao and Zhexu Liu
This paper aims to automatically generate load shedding sequences due to insufficient power supply, to ensure flight safety and complete flight task.
Abstract
Purpose
This paper aims to automatically generate load shedding sequences due to insufficient power supply, to ensure flight safety and complete flight task.
Design/methodology/approach
In this paper, a power allocation and load management model, including logical and physical submodels of the distribution system, is first established according to different requirements of the loads in different flight phase and the current total power supply. Then, an optimal load management scheme based on an improved ant colony algorithm is proposed to automatically generate load shedding sequences for both safety-critical and nonsafety critical loads, to achieve a reliable and safe power supply.
Findings
To verify the efficiency and feasibility of the algorithm, the proposed method is verified in a virtual simulation platform. Simulation result illustrates that the proposed algorithm is efficient and feasible.
Practical implications
The proposed method can provide guidance on load power supply when the civil aircraft is under abnormal power supply situation.
Originality/value
An optimal load management scheme is proposed by considering different requirements of the loads in different flight phase and the current total power supply.
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A.B. Schwartz, S. Malick and J.R. Friesen
THE experimental determination of the moment of inertia of a body is frequently required to confirm a calculated value or to eliminate the tedious work involved in the…
Abstract
THE experimental determination of the moment of inertia of a body is frequently required to confirm a calculated value or to eliminate the tedious work involved in the calculation. This is normally done by integrating the body into a vibrating system, such as a pendulum.
Dmitri Vinnikov and Juhan Laugis
The paper presents the findings of an R&D project connected to the development of 50 kW auxiliary power supply for the high‐voltage DC‐fed commuter trains. The aim was to…
Abstract
Purpose
The paper presents the findings of an R&D project connected to the development of 50 kW auxiliary power supply for the high‐voltage DC‐fed commuter trains. The aim was to introduce a new generation power converter utilizing high‐voltage insulated gate bibolar transistor (IGBT) modules, which can outpace the predecessors in terms of efficiency and power density, i.e. to provide more power for smaller volumetric space.
Design/methodology/approach
For development of the proposed converter, mathematical analysis and computer simulations were used. The software intended for simulations is Ansoft Simplorer, which is a mixed‐technology simulator for electrical, electromechanical, power electronic systems and drive applications. For the verification of theoretical results the full‐scale laboratory prototype of the proposed converter was developed and tested.
Findings
Thanks to increased switching frequency and current‐doubler rectifier (CDR) implemented in the proposed converter, the power dissipation of the isolation transformer was reduced by 30 percent as compared to earlier designs. Moreover, the 27 and 24 percent reductions in rectifier and inductor losses, respectively, led to approximately 1 percent efficiency rise of the proposed converter in comparison with its predecessors. Also, the proposed three‐level topology outpaces the two‐level one by more than 20 percent in terms of power density.
Practical implications
The proposed converter topology is aimed for the high‐voltage DC trains. With small modifications it also can be used in trams, trolleybuses as well as in some industrial applications.
Originality/value
The paper presents the novel DC/DC converter topology with 3.3 kV IGBT‐based three‐level neutral point clamped inverter, high‐frequency isolation transformer and the CDR.
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Zhenxing Ren, Daowu Yang, Jun Liu, Yong Ma, Zhongtang Huo and Shaochang Zheng
The purpose of the paper was to design an anti-corrosion system that combined conductive coatings with cathodic protection for a 500-kV substation ground grid, and provide a basis…
Abstract
Purpose
The purpose of the paper was to design an anti-corrosion system that combined conductive coatings with cathodic protection for a 500-kV substation ground grid, and provide a basis for the anti-corrosion construction of the installation.
Design/methodology/approach
The study took the Shaoguan 500-kV substation grounding grid as the research object. The anti-corrosion performance of KV conductive coatings on grounding metal was researched. In parallel, the alkalinity of substation soil was evaluated according to the German DIN50929 Standard, and the combined protection system comprising conductive coatings and impressed current cathodic protection was designed.
Findings
KV conductive coatings, that have resistance to acids, alkalis and salts, can effectively slow down the corrosion rate of the grounding grid. The investigation also provided the outline design, installation, construction requirements and monitoring methods for the 500-kV substation grounding grid.
Originality/value
This report contains some guiding significance for anti-corrosion engineering of 500-kV substation grounding grids.
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Yu Luo, Zewei Fang, Juzhi Guo, Hao Lu and Juan Li
This paper aims to improve the scene sense of a virtual scene, the welding model of a virtual reality system of riser automatic equipment was constructed using Unity3D and UG…
Abstract
Purpose
This paper aims to improve the scene sense of a virtual scene, the welding model of a virtual reality system of riser automatic equipment was constructed using Unity3D and UG software, which mainly included a welding car, welding guide rail, welding power supply, virtual camera and other equipment and the model was rendered.
Design/methodology/approach
The human-computer interaction page and simulation test of the system was produced using the user interface GUI system for creating a human-computer interaction scene. The operator could capture the welding status of the physical equipment accurately and in real-time so the virtual reality technology was very suitable for the remote monitoring operation integrated with the welding system.
Findings
Human-computer interaction design and collision detection were realized. In addition, the system simulation experiment was accomplished. With the continuous improvement and development of virtual reality technology real-time virtual simulation and monitoring, technology will become the main development trend.
Research limitations/implications
Based on virtual reality, the monitoring system can capture the operation status of physical welding equipment in real-time and accurately, which is very suitable for remote monitoring operation integrated with the welding system and also conducive to improving the monitoring level of the welding process.
Practical implications
This technology is time-saving and money-saving, for the operators do not have to be in a real welding environment and therefore they can get away from dangerous places. Consequently, it can avoid unnecessary injuries and problems.
Social implications
This technology can replace people to enter the dangerous and extreme environment to carry out welding operation, so it becomes the most effective means of nuclear power plant maintenance, space structure construction and marine engineering construction. In addition, it is time-saving and money-saving.
Originality/value
With the rapid development of virtual reality technology in recent years, it is a new research direction to apply virtual reality technology to the remote welding operation. This technology is different from the traditional way of welding for the operators can stay away from the welding scene especially some dangerous places.
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