A new concept, the multi level voltage/current reinjection ac/dc conversion, is described in this thesis. Novel voltage and current source converter configurations, based on voltage and current reinjection concepts are proposed. These converter configurations are thoroughly analyzed in their ac and dc system sides. The fundamentals of the reinjection concept is discussed briefly, which lead to the derivation of the ideal reinjection waveform for complete harmonic cancellation and approximations for practical implementation. The concept of multi level voltage reinjection VSC is demonstrated through two types of configurations, based on standard 12-pulse parallel and series connected VSC modified with reinjection bridges and transformers. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. The multi level current reinjection CSC is also described using two configurations based on standard 12-pulse parallel and series connected CSC modified with associated reinjection circuitry. Firing control strategies and steady state waveform analysis are presented and verified by EMTDC simulations. Taking the advantage of zero current switching in the main bridge valves, achieved through multi level current reinjection, an advanced multi level current reinjection scheme, consisting thyristor main bridges and self-commutated reinjection circuitry is proposed. This hybrid scheme effectively incorporates self-commutated capability into a conventional thyristor converter. The ability of the main bridge valves to commutate without the assistance of a turn-off pulse or line commutating voltage under the zero current condition is explained and verified by EMTDC simulations. Finally, the applications of the MLCR-CSC are discussed in terms of a back to back HVDC link and a long distance HVDC transmission system. The power and control structures and closed loop control strategies are presented. Dynamic simulation is carried out on PSCAD/EMTDC to demonstrate the two systems ability to respond to varying active and reactive power operating conditions.

Ce mémoire présente une solution de conversion d’énergie permettant de couplerdeux sources de tension électrique similaire à dimensionnement réduit. Appliqué à un système de stockage hybridé puissance/énergie pour véhicule électrique, cette solution présente un compromis de coût de production, de masse et de rendement énergétique meilleur que celui des hacheurs classiques. Nous proposons en réponse à cette problématique l’utilisation d’une source de courant contrôlée placée en série avec les deux sources de tension pour réaliser leur couplage. Une structure de convertisseur permettant ce couplage est étudiée, puis comparée à une structure classique, et enfin réalisée au travers d’un démonstrateur à échelle de tension réduite afin de mettre en évidence ses avantages et inconvénients / This thesis deals with the development of a power conversion solution, allowing for the coupling of two similar voltage sources. Applied to a combined battery storage sys-tem power/energy for electric vehicles, the proposed solution presents a compromise between production costs, mass and energy performance, providing a better solution than those currently in existence. As such, the two voltage sources are coupled in series with a controlled current source. A structure of the converter allowing the coupling is studied and compared to a classic structure. Finally a demonstrator on a reduced voltage scale has been realized and shows advantages of this converter solution.

This thesis deals with design of evaluation platform for integrated circuit NCV78934, which is designed to control LED headlights in automotive industry. The theory concerning the current regulation of buck converter, schematic design, PCB design and software design are also included in the thesis. Finally the measured data and testing procedures of the designed evaluation platform are discussed.

This thesis deals with design and use synthetic circuit elements with higher-order immittance with controlled current sources to implement the frequency filters. Controlled current sources which are derived from the voltage variations are presented. They are current follower, current invertor and current operational amplifier. Low-pass and high-pass filter which are used synthetic elements are simulated on computer. The influence of real properities of active elements and passive elements tolerances on filter functionality is investigated. Selected circuit of frequency filter is realized and measured the frequency characteristic.

The aim of this work is to clarify the function of the vocal cords and get familiarized with their investigative methods. In this work we find possible solutions to the peripheral device to illuminate the rapidly vibrating vocal cords using an LED that is less energy exacting than conventional halogen lamps. Then there are solved the problems of processing, signal filtering and finding the natural frequency of vibration of the vocal cords.

The aim of my master’s thesis is the design of the LED lighting system for breeding and growing purposes as replacement for the classical high-pressure sodium lamps and other sources of light used today. The whole system can be controlled locally by buttons or remotely by web server using Ethernet interface. LEDs are powered by five-channel step-down converter with current feedback. Converters are controlled by pulse width modulation generated by microcontroller.

Master’s thesis is focused on design of digitally controllable power-supply for generating current pulses with nominal level (few amperes), adjustable rising slope and time of duration. Device uses voltage controlled current source. Control voltage is generated by digital to analog converter. Computer simulations are accomplished for designed electronic circuit and measurement of prototype is done as well.

Goal of this semestral thesis is to design power converter which is to be used for measurement. The converter consists of two forward converters in push-pull topology. The converter is to behave as a constant current source with maximum open-circuit voltage of 1000V. Maximum current is 5A. The current range is split into three sub-ranges, to meet the strict requirements on ripple current. The range of currents is 0-5A. The operating frequency of converter is 34KHz. The converter will be charged using two portable electric generators with output voltage 230V.

This thesis contains an introduction to anatomy and physiology of the skin highlighting its barrier function. The barrier function of the skin enables it to separate internal organism from external environment. thermore, the electrical properties of the skin are described and possibilities of skin conductance measurement are discussed. The thesis presents a design of a device for the skin conductance measurement as the method of evaluation for barrier function. Alternating current is used for measurement during iontophoresis for evaluation of skin conductance. Circuit design and circuit board are included with a list of parts. The designed device was realized and in the end it was tested and the results were discussed.

In the master's thesis, there has been described and explained the principle of operation of the second generation coherence controlled holographic microscope (CCHM2) designed at the Brno University of Technology. There has also been listed theoretical description of the operation of the optical trap, together with the calculation of the forces acting on it, ways of measuring the stiffness of the optical trap and the principle of~creating a time-shared optical traps. The optical tweezers forming a separate module connectable to CCHM2 was designed. Simulation and optimization of parameters of the optical system, mechanical design, manufacturing documentation, current source to power the laser diode which allows to control the diode output power by the controller card connected to the PC was designed. The galvano-optics mirror angle is controlled by the PC card too. The optical tweezer has been designed, manufactured and tested in conjunction with the CCHM2.