An on-line predictive system for steel wire straightening using genetic programming

Dimensional stability of forming processes is becoming more and more important in the modern production world. Especially when mass production is concerned, the technological system has to be reliable and accurate. Growing market demands are forcing production engineers towards process optimisation in order to achieve high machinery efficiency and reduce the production costs. An important precondition for improving the process chain is the prediction of process behaviour in advance. The paper is presenting the use of genetic programming to predict the wire geometry after forming. The results can be used as the basis for later optimisation of forming processes.     

Power calibrator using switched mode voltage source

The paper is focused on a sophisticated switched mode power supply with a pure sinusoidal output voltage waveform with frequency (40-65 Hz) and voltage range (30-500 V). In order to cope with stringent voltage (10.2%) and distortion constraint (THD<0.7%) in a modern calibration system, traditional inverter design with an output LC filter is upgraded with a feedback-feedforward control principle. The paper presents the voltage source topology, analyzes its steady-state response and gives its comprehensive evaluation. Using a simple sensor that is capable to detect a small voltage asymmetry at the presence of a high AC component (500 VRMS), the parasitic DC component is limited below 5 mV. Experimental results demonstrate exceptional voltage accuracy (<0.2%) and low total harmonic distortion (THD)     

High voltage pulse generation [electroporation]

A new topology of a high voltage source with a variable output pulse pattern and featuring an independent adjustment of the magnitude, repetition frequency and pulse duration is presented. The power stage of the source consists of eight individual unipolar sources that can be arbitrarily connected in series to obtain the desired output voltage pulse of several amps and with extremely high du/dt     

Synchronization of active power filter current reference to thenetwork

This paper presents an improved method of current reference determination for a parallel active power filter. To insure sinusoidal line currents, thus reducing reactive power, an integrative method of reference calculation is applied. As a result, satisfactory response of line current to the load change is achieved. One of the major problems, the synchronization to the net voltage, is also considered. Classical solution is based on zero-cross detection of line voltage. Since this approach is very sensitive to the voltage distortions, a new method is suggested, relying on voltage fundamental harmonic calculation. These ideas were tested on a three-phase active power filter, controlled by 32-bit microcontroller     

Active power filter for nonlinear AC loads

This paper describes an active power filter for nonlinear AC loads with the power part carried out in the bridge connection. A theoretical approach to the implementation of the current reference is given for this original solution of the serial active filter. The paper also provides experimental results of the filter application on two specific nonlinear loads, i.e., on the ohmic load, fed over a pair of antiparallel thyristors, and on the accumulator feeder     

Extending the low-speed operation range of PM Generator in automotive applications using novel AC-DC converter control

This paper outlines a case study on an integrated starter-generator-torque-booster (ISGtB) for a hybrid propulsion system, with a particular focus on the generator operation in the low-speed range. The propulsion system consists of an internal combustion (IC) engine and a brushless dc machine and is intended to drive a street scooter. The complex functionality of the ISGtB, some outstanding characteristics of modern IC engines, stringent demands on the generated supply voltage, and operational principle of the selected electrical machine are the reasons for our research on the generator operation. An ac-dc converter and its control are proposed. By utilizing MOSFET transistor reverse conduction characteristics, the idea of synchronous rectification, and the principle of boost switching conversion, several improvements in the generator characteristics are accomplished. The proposed solution, enabling each of the three-phase converter legs to operate as an autonomous boost converter with synchronously driven upper transistors instead of using body diodes, extends the generator operation range below the nominal rotational speed and offers simple yet efficient energy flow control.     

Tie-line data for aqueous mixtures of butyric acid with isobutyl acetate at various temperatures

Experimental liquid-liquid equilibrium (LLE) data for the system of (water+butyric acid+iso-butyl acetate) were obtained at T=(298.2, 303.2, 308.2, and 313.2) K and atmospheric pressure. This ternary system exhibits type-1 behavior of LLE. The experimental tie-line data were correlated using the UNIQUAC and NRTL models. The reliability of the experimental tie-line data was determined by applying the Othmer-Tobias and Hand correlations. Distribution coefficients and separation factors were calculated over the immiscibility regions.     

Parallel active power filter for single- and three-phase non-linear loads

Contents A parallel active power filter for non-linear loads, its signal processing unit for single-and three-phase application, control principle and power stages are described. The filter current reference determination method, which provides reduction of the fundamental displacement reactive power and non-active distortion power for variable non-linear loads, is based on the combined analogue and digital signal processing. First, the load current is filtered by a precision analogue circuit. Further calculation of the filter current references in a single-and three-phase application is accomplished by microcontrollers. The implemented discrete-time triggering method and selected reactive elements in the filter's power stage provide fast response of the actual filter current to its reference. The results, obtained from experimental circuits, illustrate the active filter performance in steady state and during load current transients.

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Paralleles aktives Leistungsfilter für einund dreiphasige nichtlineare Last

Übersicht Im Rahmen dieser Arbeit wird ein paralleles, aktives Leistungsfilter vorgestellt, welches eine nichtlineare Last in ein-oder dreiphasiger Ausführung speist. Das hierbei eingesetzte Verfahren zur Regelung der Filterströme, das Mikroprozessorsystem zur Realisierung dieser Regelung und die leistungselektronischen Stellglieder werden beschrieben. Durch eine geeignete Methode zur Generierung eines Filterstromsollwerts auf Basis analoger und digitaler Signalverarbeitung soll die Grund-und Oberschwingungsblindleistung vermindert werden. Zunächst wird der Laststrom unter Verwendung einer hochgenauen Analogschaltung gefiltert. Die weitere Berechnung des Filterstromsollwerts erfolgt mit Hilfe eines Mikroprozessors. Die Regelung des Filterstroms nach dem Prinzip der zeitdiskreten Schaltzustandsänderung, die Elemente des Leistungsfilters sowie die im leistungselektronischen Stellglied eingesetzten Leistungshalbleiter ermöglichen ein schnelles Einregeln des Filterstroms auf dessen Sollwert. Die Ergebnisse aus Messungen in Versuchsschaltungen zeigen das Verhalten des Filters im stationären Zustand und bei transienten Vorgängen im Verlauf des Laststroms.