A Soft-Switched Asymmetric Flying-Capacitor Boost Converter With Synchronous Rectification

The multilevel flying-capacitor boost converter was analyzed for asymmetric voltage operation-this permits loss optimization that takes advantage of different voltage class MOSFETs. A cost-motivated design of a suitable zero-voltage zero-current switching snubber is then developed that permits a great reduction of the inductor size. With the proposed snubber, synchronous rectification operation is compared to that of diode boost, with a particular attention to the contribution of nonlinear MOSFET parasitics. Experimental results from a 2-kW/30-kHz prototype justify the effectiveness of this solution with a conversion efficiency around 99% ± 0.1% for a wide load range.