Modelling and analysis of switch-mode cascade converters with a single active switch

In recent years, the development of new technologies is requiring wider conversion ratios. A possible solution to this problem is to use n-conventional converters connected in cascade; however, a complex control circuitry is required. An alternative solution is to use an n-stage cascade converter with a single active switch. Nonlinear and linear models, using averaged model techniques, are given for a class of positive output cascade buck and boost converters. These converters use a single active switch. It is shown that the proposed linear models are globally asymptotically stable for any number of stages. The continuous-mode conditions are given with the corresponding design values for the voltage ripples of the capacitors and current ripples of the inductors. Therefore the need of having models for a class of DC-DC cascade converters is satisfied.