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Was für die sogenannte weiße Ware passt, muss sich auch für andere
Anwendungen in der Industrie eignen. Überzeugt von diesem Ansatz, kooperieren die Hochschule Kempten und ein Unternehmen für drahtlose Sensorsysteme eng miteinander, um ein kabelloses Sensorsystem weiterzuentwickeln.
Ziel des gemeinsam von Pro-micron und der Hochschule Kempten durchgeführten Projekts ist die Weiterentwicklung eines kabellosen Sensorsystems, das seit Jahren im automatisierten Garprozess in der weissen Ware zum Einsatz kommt. Das System dient zur Messung der Rotortemperatur von Elektromotoren in Großserienanwendungen. Denkbar sind somit nicht nur Anwendungen in Konvektomaten, sondern in sämtlichen Bereichen, in denen eine ausgeklügelte Temperaturmessung zu besseren Antriebseigenschaften führt. Somit liegt der Mehrwert entsprechender Temperatursignale zur Steuerung elektrischer Maschinen auf der Hand und kann erhebliche Vorteile aufweisen. Auslastung, Effizienz und Drehmomentengenauigkeit sowie ein zuverlässiger Übertemperaturschutz sind nur einige Beispiele für die Vielzahl von Vorzügen, welche sich aus der Rotortemperaturmessung ergeben.
Active phase shifting method incorporates change in phase and amplitude of fundamental primary inverter output and secondary rectifier input voltages of a resonant DC/DC converter. This paper
presents implementation of this method on four basic topologies of resonant tank configurations or
compensation circuits of a resonant converter. Smooth variation of input power along with Zero Voltage Switching (ZVS) regions both on primary and secondary side have been observed for different configurations. Equations for input power as a function of the phase angles, switching
frequency, input and output voltage amplitudes and the values of the reactive components have been derived. The results are verified with simulations of all the configurations and practical setup for one of the best configuration for IPT systems.
In inductive power transfer systems a smooth variation of input power can be achieved by using a controlled rectifier. The power can be changed by varying the fundamental amplitude of the primary and secondary voltages along with the phase angle between them. The paper shows how the input power is controlled and under what circumstances Zero Voltage Switching (ZVS) is lost on primary and secondary side of the system.
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.
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.
Transformers are used when galvanically isolated energy transfer, i.e. according to the European standard EN61558, is necessary. Traditional
transformers are bulky and consist 80% of copper and iron. Since the 1960s the demand for refined copper has increased by 250% from 5 mil tons to 20 mil tons. Due to the increasing high demand of copper a continuous price increase in the next years is expected. To guarantee the availability of copper for the next decades and to counteract the expected price increase, it is essential to find resource friendly alternatives. Compared to a three stage power conversion system a one stage AC-AC converter based on a dual-active-bridge (DAB) converter does not incorporate electrolytic capacitors in the power path. The elimination of electrolytic capacitors makes it possible to reduce size and weight and reduce the amount of needed copper, without
sacrificing lifetime. The functionality of the one stage system is ensured with ohmic loads. The problem arises, when non ohmic loads are connected and the converter enters reactive power operation, which produces a highly nonlinear shape of the control parameter. Therefore an extremely dynamic control scheme is essential in order to keep track of the control parameter. Furthermore, due to the low capacitance on the output of the converter, the power stage is highly unstable. It is therefore essential to design and implement a control scheme with high dynamics and robustness. In this paper the drawbacks of an AC-AC DAB converter under reactive power operation are described. Furthermore a current mode control scheme is presented. Firstly the transfer functions of the control stages are measured and afterwards a current mode controller is implemented and optimized. Lastly the newly designed current mode controller is compared to a voltage mode control scheme and it is shown, that the bandwidth is increased. Therefore the proposed control scheme enhances the reactive power operation of a one stage AC-AC converter.