Generalised modelling and sliding mode control for n-cell cascade super-lift DC??DC converters

Positive output super-lift converters are a series of DC-DC topologies that can provide large-voltage transfer gains for various applications. Since all the circuits are featured with the single-switch operation, those complex control schemes for the multiple-switch operation are not applicable in these cases. In this study, both the mathematical modelling and the sliding mode (SM) control for super-lift converters have been explored. A reduced-order state-space modelling method is introduced, and a generalised linearised model is obtained. A new SM controller based on a new sliding surface is thus presented. The three conditions of SM control, existence condition, reaching condition and stability condition, are analysed, respectively. The triple-lift circuit of super-lift converters is taken as an example to validate the controller performance. The experimental results have good agreement with the theoretical analysis.