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Losses of capacitor run induction motor
Štaffa, Jiří ; Hájek, Vítězslav (referee) ; Mach, Martin (advisor)
This project deals with increasing efficiency of one phase induction motor with permanent split capacitor. We can whole thesis divide into two parts, the first one is basic and the second is interested in analysis and measurement. First part handles with construction of single phase induction motor, explanation of function principle, start and run of motor. Calculating of efficiency including type of losses, which reduce efficiency. Second part concerns analysis losses including moment load characteristic, motor measurement while rotor is locked, with no load operation, measuring mechanical and additional losses. Further there will be measured useful values for creation model for simulation (reactance of windings etc.). Than will be the model created in ANSYS Maxwell with module RMxprt. After analytic calculation in RMxprt and using Finite Element Method (FEM) load characteristics will be compared together. This comparison gives us information about accuracy of model for simulation. Simulation and measurement will be carried out on another engine with high quality ferromagnetic material used for magnetic circuit of motor. Further will be done simulation of motor with modifications shown in previous chapter for high efficiency.
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Electronic parts of small fotovoltaic power plant
Benda, Dušan ; Šťastný, Ladislav (referee) ; Bradáč, Zdeněk (advisor)
The thesis describes the design, implementation and subsequent testing of electronic circuits for usage in small photovoltaic power plants. It focused on the sub-power appliances, battery charging and monitoring of photovoltaic panels. Introduction of this work deals with selecting appropriate controllers for each subsystem and comparison of the proposed facilities with commercially available applications. A substantial part of the work describes the selected controller for each subsystem implemented and circuit design of the individual components of electronic systems in detail. For each subsystem are implemented measuring and comparing the results achieved.
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Design of cyclone separator for hot gas
Kadlík, Libor ; Milčák, Pavel (referee) ; Baláš, Marek (advisor)
This master’s thesis deals with separating of solid particles. The thesis is divided into three parts. In first part are described principles of separating solid particles from gas. In second part is designed optimal cyclone gas separator with high efficiency and are made technical drawings of components. Final part is focused on heat loss of designed cyclone gas separator and design of optimal insulation.
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Power supply system for mobile devices with high effiency
Vičar, Ondřej ; Kledrowetz, Vilém (referee) ; Brna, Jaroslav Rakušan, ENERGOKLASTR, Slavkov u (advisor)
This Master’s thesis is focused on design of voltage converter’s system operating with supply voltage of batteries. There are selected appropriate types of batteries, converter topologies and modes of their control. The specified output branches are systematically divided into three separate modules. Each module is designed in detail with focus on high efficiency. The modules are implemented and optimized. Parameter of final modules were measured and compared with correctness of design and theoretical assumptions.
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Gas Boiler for Local Natural Gas Combustion
Kozák, Ondřej ; Hudeček, Mirko (referee) ; Skála, Zdeněk (advisor)
This Master´s thesis deals with a thermal calculation and dimensional design of steam boiler for natural gas combustion with respect to the high efficiency of the boiler. It includes stoichiometric calculation and calculation of technical specifications of the boiler. Dimensions of combustion chamber are proposed. The crucial part of this thesis includes thermal calculation of designed heat-exchanging surfaces. The heat balance of the whole boiler is made to verify the results.
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Calculation of the optimum slip frequency with respect to the minimum losses of an induction motor
Prudík, Martin ; Huták, Petr (referee) ; Vorel, Pavel (advisor)
A mathematical model describing the calculation of the optimal slip frequency of an Induction Motor with squirrel-cage is proposed in this work. The derivation is done using a replace -network, and is designed for a wide range of speeds and torque. The requested torque, speed and constants of replacement network are the inputs of the optimization. Optimum slip frequency and corresponding line voltage are the outputs of this optimization. The results of the calcullations are presented using two asynchronous machines for different speed and torque.
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Control of power LED, using ATtiny
Sedláček, Michal ; Pust, Radim (referee) ; Zeman, Václav (advisor)
The bachelor thesis deals with designing DC/DC steep-down converter, intended to supply power LED from a lithium-ion batteries. Work on the preface introduces the reader to the functions and the requirements for the proposed facility. Steep-down converter is controlled by a microcontroller suitably selected from ATtiny family. In this work are gradually dismantled partial circuit solutions, from which is then compiled a complete circuit. Is analyzed in detail the proposal steep-down power circuit converter. Work also includes the program for microcontroller and PCB design for the final circuit solution. In conclusion, this work is carried out measurements on the sample the proposed facility.
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Switched Mode Power Supplies
Španěl, Petr ; Lettl,, Jiří (referee) ; Kadaník,, Petr (referee) ; Procházka, Petr (advisor)
This thesis deals with switched mode power supplies based on resonant principle to achieve high efficiency. Several ways of switched mode power supplies optimalisation are described as part of the work to achieve better efficiency. Priparily, the new generation of switching elements based on SiC and resonant topology are used to achieve significant switching loss minimization. The selected resonant topology is simualted in detail and then built with focus on high efficiency. The main content of the work consists in the design and realization of the switched mode power supply with selected control algorithms and their comparison. The problems associated with usage of new SiC MOSFET generation in TO-247-4L package are being solved within the design and implementation of the power source. To solve the main problems, new 3rd SiC MOSFET gate driver was developer for working with switching frequencies in hundreds of kHz and resisting very high voltage stress on the controlled transistor. The next part of the gate driver is the overcurrent protection. The overcurrent limit can be set easily by changing one component. This protection reacts very quickly in hundreds of nanoseconds, so it is capable of saving the converter even in branch failure and going to hard short circuit. The functional sample of the series resonant converter was built and revated in the work. The converter based on 3. Generation of SiC MOSFET transistors from Cree in a modern case TO-247-4L was built. For this inverter, it was also necessary to develop both the control scheme and the resonance frequency tracking to achieve accurate switching and thus achieve the use of the resonant principle of the converter to the maximum extent possible. The result of this work is up to 3 kW converter with adjustable output voltage while maintaining high efficiency up to 96%.
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Efficiency Improvement and Optimization of High Power Switching Converters
Martiš, Jan ; Dudrik,, Jaroslav (referee) ; Peroutka,, Zdeněk (referee) ; Vorel, Pavel (advisor)
This thesis focuses on optimization and increasing the efficiency of high-power DC/DC switching converters with transformer (switching power supplies). The work focuses mainly on using converters with flyback topology for high power, even though it is a common belief that this type of converter is not suitable for high power. This topology was selected because of potentially better achievable parameters, especially the efficiency, in comparison to a commonly used forward converter – in a flyback converter, losses are produced only in one magnetic component (transformer) in contrast to two components (transformer and inductor) in the forward converter. Compared to resonant and quasi-resonant converters, the flyback converter is easily controllable in the whole output voltage and current range. To make the flyback converter favorable for a high-power use, some innovative circuit modifications were made and modern semiconductor and passive components were used. Theoretical part of the work deals with efficiency optimization of the flyback converter, based on analytical solution. Operating parameters of the converter – switching frequency and parameters of the transformer (flux density and numbers of turns) are commonly only guessed or chosen from experience. The objective of this part is a mathematically exact determination of these parameters to achieve lowest total losses of the converter for given input parameters. In a certain case, it was possible to obtain the final solution analytically, in other cases the final solution step had to be done with a help of software. A prototype of a 12-kW switching power supply with a flyback converter was constructed to validate the proposed solutions and methods. The power supply fits into a space of only 33x33x16 cm. Modern semiconductors based on the silicon-carbide (SiC) technology (MOS-FET transistors and diodes) were used. After bringing the converter to a full-power operation, an efficiency of 96.8 % of the DC/DC converter was measured. High efficiency was obtained for a wide range of output parameters. A certain comparison with a forward converter with the same output parameters is done in the work. Not only from an efficiency point of view, the flyback converter seems very perspective.
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