ILE – Institut für Leistungselektronik
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Es wird auf die Unterschiede von trafobehafteten und trafolosen Wechselrichtern und die daraus resultierenden, wesentlichen Merkmale eingegangen. Die kapazitiven Umladeströme, hervorgerufen durch die im Solargenerator befindlichen Kapazitäten machen eine bipolare Taktung bei der H-Brücke oder eine andere Topologie notwendig. Daraus resultieren auch unterschiedliche Belastungen in den passiven Bauelementen. Hier wird im Wesentlichen auf die Zwischenkreisströme eingegangen.
In recent years the undisturbed electrical power supply became very important, because of the increasing automation (Schmidt, et al., 1995). A protected electrical power supply is possible by using a static uninterruptible power supply (UPS), because its electrical energy is stored in a DC-link intermediate circuit, connected with a battery. An important cost factor and power loss producer is the usually inserted line frequency output transformer. The elimination of the transformer causes a changing of the circuit topology and a rising of the DC-link voltage. It is possible to omit the transformer by connecting the ground wire of the load to the centre point of the DC-link capacitor. The DC-link voltage has to be higher than the sum of the peak value of the sinusoidal output voltage and the voltage drop of the output filter inductance at maximum load (e.g. U/sub d/= 800 V) (Patt, M, 2002). A second cost factor is the DC-link capacitor. Its reactive power capacity becomes bigger compared to conventional UPS because the low-frequency load current flows through the centre point of the DC-link capacitors. This is an essential and an expenditure property (F. Renken et al., 2002). The centre of the paper is the analysis of the DC-link capacitor current in different topologies. In the first part of the analysis the current-loading of a two and a three level voltage source inverter will be described. In the second part of the paper a three phase two-level and a three phase three level-inverter will be compared.
One main aspect in the development of uninterruptible power supplies (UPSs) is the elimination or the reduction of ferromagnetic components. In this paper, the effects of reducing ferromagnetic components is illustrated by the example of two different single phase UPS topologies. In the first part of the article, the transformer in a continuous mode UPS is eliminated, and in the second part of the contribution, the couple line inductance in a bidirectional UPS is replaced by different kinds of AC/AC converters. Several advantages and disadvantages of these two different UPS-topologies are discussed.
In FPGA applications low core voltages of 1 volt or below at high currents are increasingly getting important. This topic provides a guide for designing a highly reliable DC/DC converter of 1V, 15A.PCB layout consideration, 4 layers arrangement and proper grounding technique are based on a focus on reliability. Due
to use of an enhanced operation controller there is possibility to minimize diode conduction losses related to
the MOSFETs to absolute minimum dead-time,resulting in high efficiency.
With automobiles getting more and more electrified, there is a large number of different applications where dc/dc-converters have to be placed. In new electric vehicle concepts it is necessary to connect two different voltage levels with galvanic isolation and assure power transfer with high efficiency. The presented paper describes a new approach to improve the advantages of the well known phase shift zero voltage switching (ZVS) converter to meet efficiency and volume requirements.
This paper describes a bidirectional solar-battery- grid inverter, its principle and features as well as control functions and recent semiconductors which are used. The device is designed for smart grid applications, where the operator decides about a power and its direction for each active device. The proposed inverter is able to supply power grid by power and phase shift which are defined by superior logic. Or it can take required amount of power from the grid and store it in battery. Stored energy is used later for covering deficiency of solar energy. Solar cells are efficiently driven by MPP tracker and power balancing function ensures maximal usage of all sources.