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Zurich, Switzerland

Bartholet M.T.,Celeroton AG | Nussbaumer T.,Levitronix GmbH | Kolar J.W.,ETH Zurich
IEEE Transactions on Industrial Electronics

The application of bearingless pump systems in cost-sensitive applications such as in the food, pharmaceutical, and biotechnology industries arises from the necessity of power electronics systems with reduced complexity and costs. In this paper, three different voltage-source inverter topologies are compared regarding their suitability for driving state-of-the-art two-phase bearingless motors. The comparison is based on performance indices such as the available drive voltage and/or pump power, number of required power electronics components, and level of compactness. © 2010 IEEE. Source

Krahenbuhl D.,Celeroton AG | Zwyssig C.,Celeroton AG | Kolar J.W.,ETH Zurich
IEEE Transactions on Industrial Electronics

Literature reports several future portable and distributed power supplies in the watt-to-kilowatt range based on rotating machinery equipped with a variable-speed permanent-magnet generator. In order to generate a constant direct-current output voltage, an ultracompact highly efficient low-power rectifier is required. A suitable concept, i.e., the half-controlled three-phase pulsewidth-modulation boost rectifier (HCBR), is analyzed in this paper. In previous literature, there is only limited information available, particularly concerning current stresses, common-mode characteristics, and operating principles. Therefore, the HCBR topology analysis is completed in this paper. Furthermore, a novel modulation scheme improving the power electronics efficiency is proposed using space-vector analysis. The integration into a compressed-air-to-electric-power system with a generator rotating at 350000 r/min is presented, and the measurements verify the theoretical results with an efficiency increase of 2% for the novel modulation scheme. © 2006 IEEE. Source

Casey M.,University of Stuttgart | Zwyssig C.,Celeroton AG | Robinson C.,PCA Engineers Ltd
Proceedings of the ASME Turbo Expo

The specific speed and specific diameter of radial, mixed and axial flow compressors can be plotted in a Cordier diagram, and the best compressors then lie in a relatively narrow band, known as the Cordier or Balje line. This line exhibits a distinctive s-shape, and it is shown in this paper that this is due to the variation of the centrifugal effect on the pressure rise of the different compressor types. A new equation for the Cordier line in the mixed flow region based on the pressure rise coefficient is developed and calibrated with data from mixed flow pumps and ventilators. Together with other empirical relationships for the expected efficiency as a function of the specific speed this provides some useful new guidelines for the preliminary design of mixed flow compressors. These guidelines are then examined by carrying out a preliminary design of a high-speed mixed-flow microcompressor that is analyzed using CFD and tested to justify the approach. © 2010 by ASME. Source

Dessornes O.,ONERA | Landais S.,ONERA | Valle R.,ONERA | Fourmaux A.,ONERA | And 3 more authors.
Journal of Engineering for Gas Turbines and Power

To reduce the size and weight of power generation machines for portable devices, several systems to replace the currently used heavy batteries are being investigated worldwide. As micro gas turbines are expected to offer the highest power density, several research groups launched programs to develop ultra micro gas turbines: IHI firm (Japan), PowerMEMS Consortium (Belgium). At Onera, a research program called DecaWatt is under development in order to realize a demonstrator of a micro gas turbine engine in the 50 to 100 Watts electrical power range. A single-stage gas turbine is currently being studied. First of all, a calculation of the overall efficiency of the micro gas turbine engine has been carried out according to the pressure ratio, the turbine inlet temperature, and the compressor and turbine efficiencies. With realistic hypotheses, we could obtain an overall efficiency of about 5% to 10%, which leads to around 200 W/kg when taking into account the mass of the micro gas turbine engine, its electronics, fuel and packaging. Moreover, the specific energy could be in the range 300 to 600 Wh/kg, which largely exceeds the performance of secondary batteries. To develop such a micro gas turbine engine, experimental and computational work focused on: (1) a 10-mm diameter centrifugal compressor, with the objective to obtain a pressure ratio of about 2.5; (2) a radial inflow turbine; (3) journal and thrust gas bearings (lobe bearings and spiral grooves) and their manufacturing; (4) a small combustor working with hydrogen or hydrocarbon gaseous fuel (propane); (5) a high rotation speed microgenerator; and (6) the choice of materials. Components of this tiny engine were tested prior to the test with all the parts assembled together. Tests of the generator at 700,000 rpm showed a very good efficiency of this component. In the same way, compressor testing was performed up to 500,000 rpm and showed that the nominal compression rate at the 840,000 rpm nominal speed should nearly be reached.©2014 by ASME. Source

Zwyssig C.,Celeroton AG
PCIM Europe Conference Proceedings

Emerging applications such as compact and efficient heat pumps, air conditioning and heating for future cars, medical surgical instruments and micro-machining spindles demand innovative, ultra-high-speed, high-power density electrical motors and drives. Celeroton, a spin-off company of the Power Electronics Laboratory of ETH Zurich, develops and produces such high-speed drive systems (motors, converters and turbocompressors) with rotational speeds up to 1 million revolutions per minute (rpm). An important factor in the interdisciplinary design of the drive system - and a major part of this paper - is the analysis of motorconverter interactions at ultra-high-speeds. The evaluation of the best power electronics topology depends on the machine type and design, and vice-versa are the losses in the machine influenced by the power electronics topology and modulation strategy. These insights are also applicable in other areas of extreme performance electrical drive systems. © VDE Verlag GMBH - Berlin. Source

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