Frequency Characteristics of LV Electric Apparatus From the Point of PLC

Data transmittion via electric power networkis a new trend at computer communication (PLC- PowerLine Communication). Main advantage – very spread andrealy existing potential transmitting network is rathercomplicated due to strong interferences and network highlyvariable impedance conditions. Therefore different lowvoltage nerwork configuratins and its frequenycytransmitting characterics are studied

Identifikacija parametara sinkronog stroja s permanentnim magnetima za proračun karakteristika opterećenja

Self reactance Xd in direct axis \u27d\u27 and self reactance Xq in quadrature axis \u27q\u27 influence the load characteristics of the permanent magnet machine. Their calculation methods are known. All calculations should be verified by measurements. Measurement with AC variable voltage and frequency source applied on stator winding is correct when eddy currents do not exist. Other methods evaluate the DC current decay after initial direct current was applied on the stator winding. Accuracy of these methods is lowered because of the numerical evaluation of current decay curve. Another method performs the measurement on the machine loaded as a motor. The load angle \u27beta\u27 is measured by a machine set of four machines. The accuracy is lowered by higher harmonics induced in no load in the helping synchronous machine. The load angle can be also obtained by geometrical construction of the vector diagram. In this paper the evaluation of the generator steady state regime of the machine is used. The generator works with different loads consisting of capacitance, inductance or arbitrary impedance or resistance. When the generator transfers from no load to load regime the rotor is shifting and the load angle changes. This angle is measured. The newly proposed measurement methods are simple in special cases of loads. Results of measurements and their experimental verification are published in the paper.Reaktancija Xd u uzdužnoj \u27d\u27 osi i reaktancija Xq u poprečnoj \u27q\u27 osi utječu na karakteristike opterećenja stroja s permanentnim magnetima. Metode za njihov izračun su poznate. Svaki izračun trebao bi se potvrditi mjerenjima. Mjerenje korištenjem izmjeničnog izvora s promjenjivim naponom i frekvencijom priključenim na statorske namote prikladno je kada nema vrtložnih struja. Druge metode procjenjuju opadanje istosmjerne struje nakon što je prethodno narinuta struja u uzdužnoj osi. Točnost ovih metoda umanjena je zbog numeričke evaluacije krivulje opadanja struje. Također se koristi i metoda koja vrši mjerenja na opterećenom stroju u motorskom režimu rada. Kut opterećenja \u27beta\u27 mjeri se korištenjem skupa od četiri stroja. Točnost je smanjena zbog induciranih viših harmonika u praznom hodu zbog pomoćnog sinkronog stroja. Kut opterećenja može se također dobiti geometrijskim pristupom iz faznog dijagrama. U ovom radu korištena je procjena u stacionarnom stanju uz generatorski režim rada. Generator je opterećen različitim trošilima koja uključuju kapacitivno, induktivno, otporno ili s proizvoljnom impedancijom. Prijelaznu pojavu generatora iz praznog hoda u opterećeni režim rada prati promjena rotorskih veličina i kuta opterećenja. Ovaj kut je moguće izmjeriti. Predložena metoda mjerenja jednostavna je uz posebne vrste opterećenja. U radu su prikazani rezultati mjerenja uz eksperimentalnu potvrdu metode

Region of the Southern Europe in geografical education

Diplomová práce se zabývá tématem regionu jižní Evropa ve výuce zeměpisu na druhém stupni základních škol. Je rozdělena do tří částí, z nichž první jsou teoretická východiska, která tvoří fyzickou a humánní geografii společně s vybranými problémy. Druhá část se věnuje didaktickým prostředkům, jako jsou metody a formy výuky, materiální prostředky a průřezová témata a postavení tématu v RVP a ŠVP. Třetí část obsahuje podklady k praktickému využití s plány jednotlivých hodin.The diploma thesis deals with the theme of the Southern Europe region in the teaching of geography at the second stage of primary schools.Thesis includes three parts, the first of which is theoretical review. It contains physical geohraphy and human geography together with selected problems. The second part focuses mainly on educational means, such as teaching forms and methods, material recourses and cross-cutting issues and the position of the topic at Framework Educational Programme for Basic Education and School Educational Programme. The third part involves materials for practical use with proposals of individual lessons

Electrical drive for compressor on turbocharged engine

Turbochargers are usually driven by turbine powered by exhausted gases. This conception is relatively simple but the compressor is not able to overcharge the compressed air or fuel-air mixture into the cylinder in the total revolution range and power regimes. Next disadvantage of turbine driven compressor is the low dynamic response of the turbine and compressor at quick fuel supply increase. There are two possible solutions. First - the “electrocharger”, that is the fully electric driven compressor can be used. Second - the hybrid driven charger is possible. Research of supercharging systems is one of activities of Josef Božek Research Centre of Engine and Automotive Technology on Faculties of Mechanical and Electrical Engineering at Czech Technical University in Prague. Part of this activity is research of electrical drive for the hybrid supercharging system especially from control point of view. Electric synchronous motor with permanent magnets was chosen as electric driving machine. Its robustness, high torque overload features, its small size and mass, high dynamical features and feasible high revolutions are promising for this implementation. Paper deals with torque control of high speed permanent magnet synchronous motor for driving compressor of supercharged combustion engines. Control structure which includes regimes with both full magnetic flux and flux weakening is described. Paper describes the research working place and presents test results achieved on 40 000 rev/min synchronous permanent magnet motor