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Synchronized voltage generation has already been considered in the context of pulse width modulation (PWM). References prove that synchronized PWM substantially decreases subharmonics in inverter output voltage when operating with low switching-to-fundamental frequency ratio. This paper identifies problems of unsynchronized voltage generation in electric drives under six-step inverter operation. Guidelines for the synchronization scheme were formulated, considering both minimization of voltage subharmonics and drive control properties. A comprehensive algorithm for adjusting the voltage update rate in six-step permanent magnet synchronous motor (PMSM) drive was presented. Superior properties of the synchronized six-step voltage generation were demonstrated by simulation and experiment for an exemplary 5-kW PMSM drive.
2019
Leszek Jarzębowicz,
Maciej Cisek
In this paper, results of the investigation on the performance of a small counter-rotating wind turbinehas been presented. Computational Fluid Dynamics methodshave been used forwind turbine simulations. Rotors representation were introduced into computational domain by means of Actuator Line Model. Influence of an axial distance of CRWTrotorshas been investigated. In all studied configurations rotors were counter-rotating with exactly the same rotational speed. Results of a study revealed noticeable increase in power coefficient for optimal configuration. Dynamic interactionbetween rotors has been investigated exposing significant interference in both torque and power in part of considered cases. Reasonable rotors distances, as well as rotors placements on tower’s sides have been proposed. Used calculation method has been foundto be appropriate for counter-rotating wind turbinesimulation.
2019
Michał Pacholczyk,
Krzysztof Blecharz,
Dariusz Karkosiński
This study proposes a new quasi-discrete approach to modelling the permanent magnet synchronous motor (PMSM). The quasi-discrete modelling reflects the impact of continuous rotor movement, which takes place during a control cycle, on the shape of motor current waveforms. This provides much improvement in current modelling accuracy under inverter low switching-to-fundamental frequency operation. The proposed approach may be used in predictive control to compute current at forthcoming instants or in classical control to improve precision of determining mean current feedback. The superior accuracy of the quasi-discrete model is confirmed by simulation and experiment for an exemplary PMSM drive operating at inverter switching frequency of 5 kHz and fundamental frequency reaching 400 Hz.
2019
Leszek Jarzębowicz
In the paper the essential assumptions regarding a research project implemented by a consortium of Gdansk University of Technology and Gdynia Maritime University are presented. The project has been commissioned by National Center of Research and Development with cooperation with Polish Railways (PKP Polskie Linie Kolejowe S.A.). The project is focused in implementation of modern measurement techniques using Global Navigation Positioning System GNSS, Inertial Navigation System INS and Mobile Laser Scanning MLS in a railway network management process. The precise aim of the research is both determine geometric parameters of a railway geometric layout as well as a railway vehicle movement trajectory. For this reason the innovative technique of mobile satellite measurements will be used. In the paper a synthetic description of the project together with the particular stages are presented. Also, a part of research which was realized in 2018 is shown. In the first stage, Gdansk University of Technology made a research of existing common methods for determining and assessing a track alignment, presented an idea of mobile investigation of track axis by the use of satellite measurements, took into consideration an issue of influence of dynamic behavior of the measurement vehicle on the accuracy of determined track positions by the use of GNSS/INS techniques and finally presented a technical project of measurement platform. Gdynia Maritime University made a query of GNSS/INS/MLS in measurements of track alignment, elaborated a scheme of measurement devices placement on the mobile measurement platform and studied possibilities of increasing accuracy for estimation a railway vehicle localization in relation to common techniques used by polish train operators.
2019
Andrzej Wilk,
Cezary Specht,
Władysław Koc,
Krzysztof Karwowski,
Piotr Chrostowski,
Jacek Szmagliński,
Paweł Dąbrowski,
Mariusz Specht,
Sławomir Judek,
Jacek Skibicki,
Marcin Skóra,
Sławomir Grulkowski
Rail transport is the most economical and energy-effective in the field of land transport, in particular electrified. In order to ensure efficient and reliable operation of electrified rail transport, the issues of monitoring and diagnostics of the traction infrastructure and vehicles are extremely important. The most critical point in the transmission of electric energy to the vehicle is the sliding contact of the current collector with the traction network. For this reason, work is currently being carried out on the possibility of monitoring the technical condition of current collectors at selected points of the railway lines, which makes it possible to detect the current collectors which do not work properly, and those in which the damage occurred after the train's departure. In order to make the diagnostic process at such point as complete as possible, it is necessary to develop new measurement methods and new applications for the existing methods. Evaluation of the technical condition of current collectors at the control point is carried out based on the analysis of displacements of the contact wire of the overhead contact line, caused by the impact of the current collector. The nature of these displacements, as well as the presence or absence of certain components provides the information on the correct adjustment of the current collector and the technical condition of its strips. Simultaneous measurement of vertical and horizontal displacements requires the application of innovative measurement techniques. The use of non-contact visual techniques for this purpose, which makes it possible to measure displacements in a two-dimensional plane using a fast 2D camera and advanced image analysis, is promising. This article presents the analysis of measurement uncertainty of visual measurement techniques for long distance measurements for application of electric traction element diagnostic and monitoring. The measurement verification at a laboratory test stand are also presented. The requirements concerning the measurement equipment have been determined and the factors affecting the uncertainty of the final measurement dependent on a given configuration of the stand have been specified.
2018
Jacek Skibicki
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