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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.
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.
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.
Aleksander Jakubowski,
Natalia Karkosińska-Brzozowska,
Krzysztof Karwowski,
Andrzej Wilk
Train run simulations, which focus on various power- and energy-oriented aspects, should reflect the losses in the electric powertrain. In general, the powertrain efficiency varies with respect to load and speed. Including this relation in simulation requires knowledge about detailed drivetrain parameters, which are often unavailable. This paper verifies the possibility to approximate the drivetrain efficiency in train run simulations by an equivalent constant that provides the same results of total energy usage. A case study of a suburban electric traction unit was selected to compare results of simulations carried out for different operating conditions including: route length, cruising speed and route inclination. The impact of replacing the variable efficiency with the equivalent constant on various outcomes of train run simulations was discussed and the limitations were formulated.
Aleksander Jakubowski,
Leszek Jarzębowicz
Tramwaje serii N8C są największą liczebnie grupą pojazdów szynowych we flocie GAiT. Zgodnie z informacjami pozyskanymi od przewoźnika, w ostatnim czasie zaobserwowano zwiększenie częstości występowania uszkodzeń silników trakcyjnych tych pojazdów widoczne zwłaszcza dla wozów stacjonujących w zajezdni Nowy Port. Celem wyjaśnienia przyczyny tego stanu rzeczy wykonano statystyczne badania rezystancji izolacji uzwojeń wszystkich silników pojazdów niezmodernizowanych stacjonujących w obu zajezdniach. Łącznie przebadano 52 pojazdy (104 silniki trakcyjne). Pozostałe wozy z tej serii przeszły ostatnio proces modernizacji (lub są w jego trakcie), w ramach którego silniki szeregowe prądu stałego są zastępowane silnikami indukcyjnymi.
Jacek Skibicki
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