Zero-Voltage-Switching Multi-Resonant Three Level Converters

Because the switches suffer only the half of the input voltage,the Three-Level (TL) converters have been attracting more and more attentions. This thesis proposes a family of zero-voltage-switching multi-resonant three-level dc/dc converters.A LCC multi-resonant (MR) network is added to the traditional three-level converters to realize ZVS. The unique arrangement of a multi-resonant network results in absorption of all major parasitic components hi the resonant circuit,such as transistor output capacitance,diode junction capacitance and transformer leakage inductance,which can eliminate parasitic oscillation in the converter. Compared with quasi-resonant,it can reduced transistor voltage stress and improved load range and stability in low frequency range. Because of the structure of three-level,transistor voltage stress and filter can be reduced significantly.Buck ZVS-MR-TL converter is taken as the examples to illustrate the operation of the ZVS-MR-TL converters. The operation of Buck ZVS-MR-TL converter is analyzed as well as parameter design,realization of Pulse-Frequency -Modulation (PFM) interleaved control and comparison between ZVS-MR converters and ZVS-MR-TL converters. A 1000W prototype converter is built in the lab to verify the effectiveness of the proposed converter.