High-frequency off-line power conversion using zero-voltage-switching quasi-resonant and multiresonant techniques

Abstract

The characteristics and limitations of the half-bridge zerovoltage-switched (ZVS) quasi-resonant converters (QRC's) are described. A novel multiresonant switch concept is proposed for the halfbridge topology to improve the ZVS QRC's load range. Experimental results for 300-V 75-W zero-voltage-switched quasi-resonant and multiresonant converters operating in the frequency range of 2 MHz to 8 MHz are presented.

DC analysis of half-bridge zero-voltage-switched multiresonant converter

“…12 and 13 for the same input-voltage range (same and M,,,,,) and the same load range (same 1;;' and I ; ; ) , the frequency range (f::,'i$Fii) of the converter becomes narrower as X c increases. On the other hand, the peak primary current also increases as X c increases, since it is given as [4]:…”

Development of Multiresonant ZVS High‐Frequency Inverter

“…The switching loss can be reduced by these soft switching circuits, but problems involving the settings of the load range arise, owing to limits on the soft switching region due to the relation between the load circuit constants and the operating frequency. In order to address such problems, investigations of soft switching circuits using multiresonant circuits, which are little affected by the load impedance, have been performed .…”

“…The load circuit configuration of the full‐bridge multiresonant ZVS high‐frequency inverter described in the present paper is similar to that of the half‐bridge type. However, conventional multiresonant circuits are made multiresonant primarily for the purpose of assuring soft switching over a wide operating range, while in contrast, the objective of the multiresonant circuit proposed in this paper is to reduce the conduction loss accompanying higher outputs and larger currents, and to reduce the switching loss resulting from multiresonant design by using the fewest possible circuit elements. However, the dead time settings required to achieve the above objective have a greater effect on the load circuit constants, the capacitance ratio, and the relationship to the output operating frequency than in a conventional series resonant ZVS inverter.…”

Design, construction and control of a quasi-resonant SMPS working at 2 MHz.

“…Besides that, they cannot handle short-circuiting at the output terminals. Multi-resonant tanks combine the advantages of both of these low order resonant tanks, by employing more elements in the resonant tank [9]. The LLC-type converter appeared to have the best behaviour and is being designed in this project.…”