Quasi-Resonant Converters-Topologies and Characteristics

In designing switching dc-dc converters, the effort to increase operating frequency to reduce weight, size, and cost of magnetic and filter elements is constantly hampered by higher switching stresses and switching losses. To overcome these obstacles, the concept of the "resonant switch" is proposed. By incorporating additional inductor and capacitor elements to shape the semiconductor switch's current waveform, a "zero-current switching" property can be realized. Based on the resonant switch technique, a new host of quasi-resonant converter circuits have been derived, which can be operated in the megahertz range.