Valtchev, S.,
"Super-resonant power converter operation in soft-switching mode",
Seminar of S.Valtchev on the new PhD thesis chapter, February, 1995.
AbstractThis new chapter of the PhD thesis was an addition to the presented already material at TU Sofia, Bulgaria. This was necessary to obtain the permission to prepare the thesis for its final version. Unfortunatelly this thesis was never presented but it served for the core to the presented in IST, Portugal, later on.
Valtchev, S.,
Series Resonant Power Converter for Contactless Energy Transfer with Improved Efficiency,
: UTL-IST (Portugal), TU Delft (the Netherlands), April, 2008.
AbstractThe development of more efficient power converters is the most important and challenging task for Power Electronics specialists. In the same time, many currently existing or yet to appear future applications require full mechanical independence between the transmitter and receiver of the electrical energy. This contactless form of energy transfer is the concern of the presented work. The work is based on the study of the Series Loaded Series Resonant converter which prove to be the best suitable for the contactless energy transfer. The work investigates the idealized Series Resonant Power Converter with the objective to find the best efficiency zones of operation. Generalized expressions obtained are original and useful. Based on the magnetic parameters of the loosely coupled transformer (magnetic link), the characteristics of the contactless power converter are described in approximated form. The approximation permits easier and faster calculation of the converter variables, thus predicting a shift of the maximum efficiency zone compared to the ideal converter case. The approximated form of the equations permitted to present a new instantaneous form of regulation which combines the frequency and pulse width modes which is free from the previously known defects. The method is based on calculating the energy portions supplied to the load during each half period. Measurements performed on industrial converters and on the laboratory experimental converter, confirm the predicted theoretically behaviour of the converter.
Valtchev, S., B. J. Klaassens, and M. van Wesenbeeck,
"Super?Resonant Converter with Switched Resonant Inductor with PFM?PWM Control,",
IEEE Transactions on Power Electronics, vol. 10, no. 6: IEEE, pp. 760–765, November, 1995.