Showing papers in "Przegląd Elektrotechniczny in 2009"

Supercapacitors: Alternative Energy Storage Systems

Abstract: The use of supercapacitors as energy storage systems is evaluated in this work. Supercapacitors are compared with other technologies such as compressed air, pumped hydro, superconductors and flywheels. This paper is focused on medium scale energy storage systems (applied to 100 kW photovoltaic generation plants). The supercapacitor is studied in detail, presenting these device structures, how they can be modeled, the balancing, their useful life and their principal applications. The overview is carried out after a detailed reference selection.

Superconducting Electrical Machines - State of the Art

Abstract: The paper contains a review of recent advancements in high temperature superconducting (HTS) machines. With the discovery of HTS cuprate-perovskite ceramic materials in 1986, the United States almost immediately resurrected interest in superconducting applications. The U.S. Department of Energy (DoE) and Defense Advanced Research Projects Agency (DARPA) have taken the lead in research and development of HTS electric machines and other HTS electric power applications. Recent developments in HTS electrical machines in Europe and Japan have been summarized too. The paper considers only those developments in HTS machines, which have been completed with working prototypes that passed laboratory tests. Fundamentals of superconductivity, HTS 1st generation (BSCCO) wires, 2nd generation (YBCO) wires and bulk HTS have been included.

T-source inverter

Abstract: Modern renewable generation systems and uninterruptible power supply (UPS) applications need smart and integrated power converters ensuring high efficiency of power conversion, reliability and low investment costs. The aim of the paper is to show the possibility of realization of buck-boost inverter similar to Z-source inverter but with use of high frequency transformer with low leakage inductance. Theoretical analysis as well simulation and experimental results are shown in the paper. Streszczenie. Uklady generowania i kondycjonowania energii wymagają zintegrowanych przeksztaltnikow energoelektronicznych o jak najwyzszej sprawności przetwarzania oraz niezawodności. Celem referatu jest pokazanie mozliwości realizacji ukladu podobnego do Z-falownika. Dlawiki czwornika wejściowego Z-falownika zastąpiono transformatorem impulsowym o malej indukcyjności rozproszenia i o zwartych zaciskach dolnych, ktory razem z jednym kondensatorem tworzy obwod wejściowy typu T. Pokazano analize teoretyczną nowego ukladu oraz wyniki badan.(Falownik typu T)

Reduction of the Microinstruction Length in the designing process of Microprogrammed Controllers

Abstract: The problem of the microinstruction length reduction is a very important part of the designing process of the microprogrammed controllers. Such a problem is NP-hard, therefore many various algorithms have been developed. Almost all proposed ideas are based on the traditional graph theory and its modifications (heuristics, stochastic, etc.). In the paper, we propose the method of microinstruction length reduction, where the hypergraph theory is applied. A hypergraph permits to store and reduce the information about the compatibility classes in comparison with traditional graphs. The microinstruction length reduction is reached thanks to the calculation of the dual hypergraph and computation of its minimum transversal (minimal vertices cover). All steps that are required in order to perform the microinstruction length reduction of microprogrammed controllers will be shown. The proposed method will be illustrated by way of example and compared with the traditional solution, based on the graph theory.

Stability Analysis of a Patched LQR Control System for Constrained Multi-Mass Electrical Drives

Abstract: In this paper we analyze a recently introduced protective predictive controller patch for motor drives with elastic transmission that are subject to physical and safety constraints on their variables The protective patch is obtained using invariant sets methodology and is used in combination with the classical LQR controller The easy implementation of the patch on-line allows the correction of the LQR control signal in order to suppress the violation of constraints in the future and thus avoid possibly dangerous and/or drive-harmful situations during the transients Since LQR controller itself in the absence of constraints guarantees stability of the control system, we show how the stability of the constrained control system with a controller composed of the combination of LQR and the protective patch may be confirmed

Digital signal acquisition and processing in FPGAs

Abstract: Rapid grow of FPGAs resources allows to include a whole system into a single FPGA chip. The system usually include soft-processors, limited on-chip memory, input-output interfaces, etc. The main advantage of FPGAs solution is, however, incorporation of dedicated hardware signal processing units such as signal filtering, FFT for which signal processing speed significantly surpasses DSP or general purpose processors. This paper presents an example of a whole system solution incorporating an FPGA and high-speed analog-digital converters. Streszczenie. Gwałtowny wzrost dostępnych zasobów układów FPGA pozwolił na integrację całego systemu w jednym układzie FPGA. Taki system z reguły zawiera soft-procesor, niewielką pamięć, interface’y wejścia wyjścia. Podstawową zaletą systemu opartego na układach FPGA jest możliwość dołączenia dedykowanych jednostek przetwarzania danych, umożliwiających np. filtrowanie sygnałów, obliczanie FFT. Dedykowane jednostki wykonują wybrane obliczenia dużo szybciej niż procesory DSP lub ogólnego przeznaczenia. Niniejszy artykuł przedstawia przykład właśnie takiego systemu składającego się układu FPGA i szybkich przetworników analog-cyfra. (Akwizycja i przetwarzanie sygnałów cyfrowych w układach FPGA)