Optimal Design of Complex Switched-Capacitor Converters Via Energy-Flow-Path Analysis

Many analytical methods of establishing accurate models of the switched-capacitor (SC) converters have been developed. These methods are applicable to simple low-order SC converters and can permit only a general efficiency calculation of SC converters. They do not provide analytical solutions that describe how individual electrical component in the circuit practically affects the SC converter at different frequencies. Such an analysis is important for the optimal design and realization of a complex (high-order) SC converter. This is particularly true for those SC converters which have more than two operating states. For complex SC converters, a constituent capacitor may have a profound effect on the converter's efficiency and is dependent on the configuration of the switches and the arrangement of the energy flow paths. In this paper, the relationship of the value of capacitors and the efficiency of complex SC converters is derived and investigated using an energy-flow-path analysis. Optimal design of SC converters can be achieved through a systematic component value selection by: 1) increasing the proportion of energy flow through the most efficient paths; and 2) increasing the efficiency of the paths that have a higher energy flow. The design of complex SC converters in terms of optimizing their power efficiency is discussed using an exponential SC converter as an illustration. The results of both calculation and experimental measurement show that the approach is effective.