Research On Hybrid Full-bridge Three-level DC/DC Converter

High-frequency of power electronic switching devices has become trend of modern power electronics development. Meanwhile, Soft-switch is the key technology in high frequency and high power density development, as a hotspot of modern power electronics research.Three-Level DC-DC converter can reduce switch voltage stress. Switch to the use of parasitic capacitance and leakage transformers can be in a wide range of load within ZVS, reduce output filter size and the capacity and effectively improve converter efficiency .So three-level DC-DC converter has been thought much of in the world's experts and academics seriously. Just a dozen or so years, many topologies were put forward include half-bridge, full-bridge, hybrid full-bridge three-level DC-DC converters. It's also accompanied by a variety of modes of control there.In this paper, we firstly presents a basic three Hybrid full-bridge Three-Level DC-DC converter, a detailed analysis of its working principle. And the switch how to achieve ZVS, the loss of duty cycle and output filter inductance parameter design characteristics, are discussed. Then through the software modeling and simulation of Saber, we can verify that the theoretical analysis is correct. But, the oscillation of the resonant inductor and output rectifier diode junction capacitance, so as to make rectifier diodes produce peak voltage. To solve the above problem, and then we study a Hybrid full-Bridge three-level LLC resonant converter, which working principle, the energy transmission and the frequency characteristics are all been discussed.Finally, in view of the above two circuits, we respectively design a 600W experimental prototype to verify the validity of theoretical analysis. Experimental results are given for both circuits, noting the LLC resonant converter in the whole load can be achieved within the ZVS, and rectifier diode sub-zero current switching, the voltage stress of the output voltage twice.