Kwang-Hwa Liu

Resonant switches - Topologies and characteristics

In designing conventional switching converters, the effort to increase operating frequency in order 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 resonant switch was proposed. By incorporating additional Land C elements to shape device current and voltage waveforms, the desired zero-current switching property can be realized which enables converters to operate in the megahertz range.

Zero-voltage switching technique in DC/DC converters

A novel resonant switch operating under the principle of zero-voltage switching is presented. In contrast to the zero-current switching, this technique eliminates the switching loss and dv/dt noise due to the discharging of MOSFETs junction capacitances and the reverse recovery of diodes, and enables the converters to operate at yet higher frequencies.

Secondary-side resonance for high-frequency power conversion

A systematic approach is proposed that enables the use of the leakage inductance of the power transformer and a secondaryside capacitor to form a resonant tank for very high frequency power conversion. Several new quasi-resonant converter topologies based on this technique are derived.