Research On Buck Three-level DC Converter

Not only the switches suffer only the half of the input voltage but Three-Level(TL) converters are very suited for high input/output voltage and medium-to-high power dc-dc conversions, TL converters have been attracting more and more attentions. This thesis presents the derivation of all the dc-to-dc converters resulted from the two TL switch cells extracted from the derivation of HB TL converter. The block capacitor are proposed and applied to all dc/dc converters, thus a family of TL converters is derived. Besides the reduction of the voltage stress of the switches, by adopting proper control strategy, some TL converters have the TL waveforms across the filter, so the filter can be significantly reduced. And we proposed proper control strategy to solve the problem of balancing block capacitor voltage.Buck TL converter and Buck TL converter with input and output sharing the ground are taken as the examples to illustrate the operation of the TL converter. The operation of Buck TL converter and Buck TL converter with input and output sharing the ground are analyzed as well as parameter design and input/output characteristics.A 1000W prototype converter is built in the lab to verify the effectiveness of the proposed converter.