Water for all : Proceedings of the 7th international scientific and professional conference Water for all

The 7th International Scientific and Professional Conference Water for all is organized to honour the World Water Day by the Josip Juraj Strossmayer University of Osijek, European Hygienic Engineering & Design Group (EHEDG), Danube Parks, Croatian Food Agency, Croatian Water, Faculty of Food Technology Osijek, Faculty of Agriculture in Osijek, Faculty of Civil Engineering Osijek, Josip Juraj Strossmayer University of Osijek Department of Biology, Josip Juraj Strossmayer University of Osijek Department of Chemistry, Nature Park “Kopački rit”, Osijek- Baranja County, Public Health Institute of the Osijek- Baranja County and „Vodovod-Osijek“ -water supply company in Osijek. The topic of World Water Day 2017 was "Wastewater" emphasizing the importance and influence of wastewater treatments on global environment. The international scientific and professional conference Water for all is a gathering of scientists and experts in the field of water management, including chemists, biologists, civil and agriculture engineers, with a goal to remind people about the significance of fresh water and to promote an interdisciplinary approach and sustainability for fresh water resource management. The Conference has been held since 2011. About 300 scientists and engineers submitted 95 abstracts to the 7th International Scientific and Professional Conference Water for all, out of which 33 was presented orally and 62 as posters. 47 full papers were accepted by the Scientific Committee. 38 full papers became the part of the this Proceedings while 9 papers were accepted for publication in Croatian Journal of Food Science and Technology and Electronic Journal of the Faculty of Civil Engineering Osijek - e-GFOS

High-order harmonics of the AC/DC converter, generated during the intermittent and continuous operation of GaN-HEMT power switches

<p>High electron mobility transistors (HEMT) have a growing application in the modern power converters. Gallium nitride (GaN) field effect transistors (FET) are particularly promising solutions for operation at very high switching frequencies. The aim of this paper is to examine the harmonic spectra of the high-frequency AC/DC power converter based on GaN HEMTs, tested both during its intermittent and continuous operation. Particular interest is dedicated to the effects of high order harmonics (above the 50th), not considered by international standards. Experiments were performed on the 4-kW, single-phase AC/DC converter, a power converter based on the bridgeless totem-pole power-factor correction (PFC) circuit. During the operation with minor load current (200 mA, being 2 % of the nominal output current), power converter operated in the intermittent mode, with bursts of control pulses succeeding the idle mode, when there were not pulses on the power switches. There was observed the great difference in the current total harmonic distortion (THDi) of the intermittent operation, comprising of these two modes. In the idle mode were dominant very-high order harmonics (one after the other, the 693rd, the 1384th and the 230th), with THDi being approximately 6.5 %. In a burst mode, the 3rd harmonic was dominant, while current distortion was very high, reaching THDi = 23 %. On the other hand, during the continuous operation with 70 % of the nominal load, only low-order harmonics became dominant, with THDi being less than 3.6 %.</p&gt