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Diplomarbeit 2003 (DA03): Arbeits-Archiv
 
DA Ltt 03/2 - PFC Boost Converter with Soft-Switching
Studierende: Roger Brauchli, braucrog
  Dieter Tanner, tannedie

Betreuer: Jakob Lattmann, latj

The object of the Diploma Project was to develop a soft switched Power Factor Corrector (PFC)-booster. A hardware model of the booster had to be built as a prototype. Measurements had to be made on the prototype to assure that the required specifications of the PFC-booster were met. Schmidhauser AG, Romanshorn is developing a voltage-converter for a 15kW saw-drive. It is part of this project to develop a boost-converter for a DC voltage of 500V, the source of which is a three-phase 3x230V AC Voltage. Project specifications are that the power factor needs to be higher than 0.9. To realise this, it is necessary to use a PFC controller. The boost converter is controlled and regulated by the PFC-controller UC3855 The rectification is realised with a B6 three-phase-bridge, which makes it possible to reach a power factor of 0.95. This calculation was confirmed with measurements by the hardware. To reduce the size of the booster coil, a high switching frequency of 60 kHz had to be chosen. To reduce switching losses the booster was designed with soft-switching IGBTs. To reach that, the zero-voltage-switching (ZVS) method is applied. This mode has been chosen to prevent disturbances of the resonant circuit by the parasitical Drain-Source capacity of the IGBTs. Because of the soft-switching-methode the boost-converter has a much higher efficiency factor than a conventional boost converter with hard switched IGBTs. After extensive calculations, the boost converter was simulated with the simulation programme PLECS by Matlab. With this simulation the currents and voltages while switching the IGBT?s, could be plotted and by comparison, the measured results were confirmed. With these results the object of the Diploma Project has been achieved and furthermore we are able to make suggestions to improve and refine the PFC-boost-converter in order to develop a version for the industrial use.

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