The doctoral dissertations of the former Helsinki University of Technology (TKK) and Aalto University Schools of Technology (CHEM, ELEC, ENG, SCI) published in electronic format are available in the electronic publications archive of Aalto University - Aaltodoc.
Aalto

Low-Power PFC and Forward Converters – Methods to Improve Performance

Vesa Tuomainen

Dissertation for the degree of Doctor of Science in Technology to be presented with due permission of the Department of Electrical and Communications Engineering for public examination and debate in Auditorium S4 at Helsinki University of Technology (Espoo, Finland) on the 4th of June, 2004, at 12 o'clock noon.

Overview in PDF format (ISBN 951-22-7099-4)   [1283 KB]
Dissertation is also available in print (ISBN 951-22-7098-6)

Abstract

The number of power electronic appliances is growing. Power electronic converters can be used to convert the ac line voltage to a dc voltage, and further through dc-dc conversion stages to desired dc voltages for different loads. This Thesis deals with three single-stage power factor correction converters and a forward type dc-dc converter.

Single-stage converters can be considered as low cost solutions for power factor correction. This is because only one active switching stage is used in the converters. Small signal and steady state analysis are performed for the dither converter. A resonant type snubber is analyzed for the BIFRED and BIBRED converters and a new type of clamp circuit is developed for the BIFRED converter.

The dc-dc conversion part of the Thesis deals with a forward converter with active clamp circuit and self-driven synchronous rectifiers. Resonant transition of the converter is analyzed in detail. Emphasis of the research is on improving the efficiency of the converter. Findings show that the minimization of the turn-on losses in the converter is not necessarily advantageous. The analysis is verified with a 3.4 V and 30 A prototype converter.

This thesis consists of an overview and of the following 8 publications:

  1. Tuomainen V. and Kyyrä J., 2002. Steady state analysis of modified dither converter. Proceedings of the 2002 Nordic Workshop on Power and Industrial Electronics (NORPIE 2002). Stockholm, Sweden, 12-14 August 2002, on CD-ROM.
  2. Tuomainen V. and Kyyrä J., 2003. Small signal analysis of dither converter with a tapped transformer. Proceedings of the 10th European Conference on Power Electronics and Applications (EPE 2003). Toulouse, France, 2-4 September 2003, on CD-ROM.
  3. Tuomainen V. and Kyyrä J., 2002. Analysis of a lossless snubber for BIFRED and BIBRED. Proceedings of the 10th International Power Electronics and Motion Control Conference (EPE-PEMC 2002). Cavtat & Dubrovnik, Croatia, 9-11 September 2002, on CD-ROM.
  4. Tuomainen V., 2003. A passive clamp circuit for BIFRED converter. Proceedings of the 18th Annual IEEE Applied Power Electronics Conference and Exposition (APEC'03). Miami Beach, Florida, USA, 9-13 February 2003, volume 2, pages 658-663.
  5. Tuomainen V. and Kyyrä J., 2002. Improved switching condition for a forward with active clamp. Proceedings of the 10th International Power Electronics and Motion Control Conference (EPE-PEMC 2002). Cavtat & Dubrovnik, Croatia, 9-11 September 2002, on CD-ROM.
  6. Tuomainen V. and Kyyrä J., 2002. Effect of the magnetization inductance on forward converter with active clamp. Proceedings of the 2002 Nordic Workshop on Power and Industrial Electronics (NORPIE 2002). Stockholm, Sweden, 12-14 August 2002, on CD-ROM.
  7. Tuomainen V. and Kyyrä J., 2003. Effect of resonant transition on efficiency of forward converter with active clamp and self-driven sr's. Proceedings of the 34th Annual IEEE Power Electronic Specialists Conference (PESC'03). Acapulco, Mexico, 15-19 June 2003, volume 3, pages 1333-1338. IEEE Transactions on Power Electronics, provisionally accepted for publication.
  8. Tuomainen V. and Kyyrä J., 2003. Design considerations of resonant transition forward converter with active clamp. Proceedings of the 10th European Conference on Power Electronics and Applications (EPE 2003). Toulouse, France, 2-4 September 2003, on CD-ROM.

Keywords: forward converter, single-stage converter, power factor correction, dc-dc conversion, active clamp circuit

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© 2004 Helsinki University of Technology

Last update 2011-05-26