MHz Resonant DC-DC Converters with First Cycle Control
Faster dynamic response and higher power density are the major achievements obtained by increasing the switching frequency of power supplies. However, switching frequencies are limited by topology, control, semiconductor materials, and packaging methods. To address these issues, the thesis first proposes a new quasi-resonant converter topology reduces the switching components’ voltage stress to half, and nearly eliminates the switching losses in quasi-resonant converters specifically under on-off control strategy. The second major thesis achievement is the introduction of the first cycle control method that enhances the performance of the so-called ‘on-off’ control method. This method suffers from overvoltage stress and the hard-switching power losses in on-off transients. The proposed first cycle control method substantially alleviates the voltage stress and switching losses. This achievement makes better use of the switches, and paves the way to further increase the on-off rate. Final contribution is the proposed (ZVT) cell that is introduced to have a fully ZVS on-off control. Simple structure, low number of components, and avoidance of inductive components in the cell are advantages of the circuit. Higher modulation frequency, lower input and output filter sizes, and faster dynamic responses are the benefits of this method. The zero voltage switching operation of all semiconductor components allows the designer to increase the modulation frequency without any significant drop in the overall efficiency.