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An important role in the consumption of electric energy in urban transport are non-traction needs (auxiliaries), the main part of which is heating and air condition (HVAC). Auxiliaries are responsible for almost half of total energy consumption (normal weather conditions) and in the winter (or hot summer) it reaches up to 70% in daily scale. The reduction of energy used for non-traction needs is currently the main challenge related to the reduction of energy demand of means of transport. It is particularly important for battery vehicles, powered from an energy source with a very limited capacity. The article presents the analysis of the influence of air temperature on the energy consumption of electric traction carried out on the basis of the real data measurement analysis. The relation between the ambient temperature and the demand for heating power was determined quantitatively. The impact of traffic delays on auxiliaries energy consumption was analyzed and it was shown, that traffic congestion can result in 60% overall energy consumption increase. Presented researches also refer to the relationship between the bus charging cycle (night charging, opportunity fast charging) and the optimal value of energy consumption, which should be assumed for energy calculations. Depending on the charging mode, the differences can reach up to 50%. In the final part of the article, different methods of optimization of non-traction needs systems were compared.
2020
Mikołaj Bartłomiejczyk,
Robert Kołacz
The magnetizing inductance of the medium frequency transformer (MFT) impacts the performance of the isolated dc-dc power converters. The ferrite material is considered for high power transformers but it requires an assembly of type “I” cores resulting in a multi air gap structure of the magnetic core. The authors claim that the multiple air gaps are randomly distributed and that the average air gap length is unpredictable at the industrial design stage. As a consequence, the required effective magnetic permeability and the magnetizing inductance are difficult to achieve within reasonable error margins. This article presents the measurements of the equivalent B(H) and the equivalent magnetic permeability of two three-phase MFT prototypes. The measured equivalent B(H) is used in an FEM simulation and compared against a no load test of a 100 kW isolated dc-dc converter showing a good fit within a 10% error. Further analysis leads to the demonstration that the equivalent magnetic permeability and the average air gap length are nonlinear functions of the number of air gaps. The proposed exponential scaling function enables rapid estimation of the magnetizing inductance based on the ferrite material datasheet only.
2020
Piotr Dworakowski,
Andrzej Wilk,
Michał Michna,
Bruno Lefebvre,
Fabien Sixdenier,
Michel Mermet-Guyennet
The paper presents possible environmental, energy and economical gains implied by replacing conventional traction vehicles with independent powered electric multiple units (IPEMU) on partially electrified suburban railways. IPEMUs can operate in two modes of power supply – using overhead catenary or onboard battery storage. Appropriate computer simulations were carried out in the Matlab program, indicating the parameters of storage electric multiple units.
2020
Aleksander Jakubowski,
Natalia Karkosińska-Brzozowska,
Krzysztof Karwowski,
Andrzej Wilk
For many years, satellite systems have seen widespread use in a variety of technical applications, as well as in operations related to setting-out and the exploitation of track infrastructure. Their main applications include an inventory of the trackage course and detecting changes in its position. In both of these tasks, the most important element that determines the quality of an analyses is the high accuracy of the determinations being carried out. Satellite surveying techniques are not always sufficiently accurate, and in such cases, it is necessary to employ other land surveying methods to process surveying data. This article presents the authors’ considerations with regards to the possibility of applying one of the most common land surveying adjustment methods, the parametric method, to operations related to an inventory of tram infrastructure in Gdańsk. The results are based on surveys carried out during a surveying campaign in the autumn of 2018. The considerations presented in the article concern a small part of the research conducted under project No. POIR.04.01.01-00-0017/17 entitled “Development of an innovative method for determining the precise trajectory of a railborne vehicle” which is being implemented by a consortium of Gdansk University of Technology and Gdynia Maritime University.
2020
Krzysztof Czaplewski,
Cezary Specht,
Władysław Koc,
Andrzej Wilk,
Krzysztof Karwowski,
Paweł Dąbrowski,
Mariusz Specht,
Piotr Chrostowski,
Jacek Szmagliński
This article presents a nonlinear equivalent circuit model of an isolated dc-dc converter with a 3-phase medium frequency transformer. The model takes into account the magnetic cross saturation of the 3-phase core-type magnetic circuit. The model is suitable in detailed electromagnetic transient simulations of power systems involving isolated dc-dc converters. The model is developed using the Lagrange energy method. It involves a matrix of dynamic inductances containing a nonlinear term resulting from core magnetization and a linear term resulting from leakage flux. The model parameters are determined based on a series of magnetostatic finite element method simulations. This approach is convenient when applied to high power transformers offering a limited characterization effort, or if the transformer prototype does not exist. The experimental validation performed on a novel 3-phase MFT prototype in a 100kW 1.2kV 20kHz dual active bridge converter has proved the validity of the model and model parameters. The no-load steady-state and inrush tests and the full-load test show a very good fit between the simulated and experimentally measured waveforms. The comparison with a classical simplified model neglecting magnetic cross saturation shows a significant difference in the no-load inrush test.
2020
Piotr Dworakowski,
Andrzej Wilk,
Michał Michna,
Alexis Fouineau,
Martin Guillet
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