A high efficiency resonant switched capacitor converter with continuous conversion ratio

A resonant switched capacitor converter with high efficiency over a wide and continuous conversion ratio is introduced. The efficiency of the topology depends primarily on the conduction losses and is decoupled, to a large extent, from the voltage conversion ratio. This is an advantage over classical switched capacitor converters in which the efficiency is strongly related to the conversion ratio. The operation principle applies three zero current switching (ZCS) states to charge, discharge and balance the remaining charge of the flying capacitor. This results in a Gyrator-behaved voltage-dependent current source with a wide voltage conversion ratio (smaller as well as greater than unity) as well as bidirectional power flow capabilities. The analytical expressions for conversion ratio and expected efficiency are provided and validated by simulation and experiments. The experimental verification of the converter demonstrates peak efficiency of 96%, and above 90% efficiency over a wide range of voltage gains and loading conditions. In addition, the system was found to be highly efficient at the extreme cases of both light and heavy loads.