Suchergebnisse

Photovoltaic applications have been developing and spreading rapidly in recent times. This paper describes the control strategy of the Voltage Source Inverter that is the important tail end of many photovoltaic applications.In order to supply the grid with a sinusoidal line current without harmonic distortion, the inverter is connected to the supply network via a L-C-L filter. The output current is controlled by the hysteresis controller. To improve the behaviors of the L-C-L filter, active damping of the filter is being used. This paper discusses controller design and simulation results.

This paper deals with the development of a matrix converter. Matrix converters belong to the category of direct frequency converters. A converter does not contain DC-link and the output voltage is provided by direct switching of voltage from the input phases. This is enabled by 9 bidirectional switches, which are provided by anti-serial connection of 18 IGBT transistors. The absence of a DC-link is great advantage of the matrix converter, but it also increases the requirements on the converter control. For this reason a new prototype of a matrix converter is being developed with sophisticated modern components (FPGA, Power PC) equipped in the control part of the converter. The converter will be used for testing new control algorithms and commutation methods.

The PWM rectifier is a very popular topic nowadays. With the expansion of electronics, conversion of electric parameters is also needed. For this purpose the side effects of passive rectifiers, e.g. production of harmonics and reactive power, must be taken into account. All these side effects fall away with the application of PWM rectifiers. This paper compares the differences between a phase angle controlled rectifier and a PWM rectifier.

THIS ARTICLE EXAMINES JAMES MADISON'S BELIEF THAT SUCCESSFUL REPUBLICAN GOVERNMENTS REQUIRE A SYSTEM OF ELECTIONS WHICH DISCOURAGES ELECTIONEERING AND FACILITATES THE SELECTION OF MEN OF "MERIT" AS REPRESENTATIVES.THE AUTHOR SUGGESTS THAT MADISON'S VISION OF THE "UNCORRUPT" ELECTION, ON WHICH HIS POLITICAL THEORY IS BASED, IS TIED TO HIS DESIRE TO SUSTAIN THE TRADITIONAL OR "HIERARCHICAL-DEFERENTIAL" STRUCTURE OF AMERICAN SOCIETY. THE FAILURE OF THE CONSTITUTION TO PREVENT THE EMERGENCE OF ELECTIONEERING IS, IN PART, DUE TO ITS BEING FOUNDED ON THE FALSE ASSUMPTION THAT AMERICAN SOCIAL STRUCTURE WOULD RETAIN ITS TRADITIONAL CHARACTER.