Unified modelling and dynamical analysis of current‐mode controlled single‐inductor dual‐output switching converter with ramp compensation

Abstract

Current-mode controlled single-inductor dual-output (SIDO) switching converters have three borders in wide-range parameter variations. Based on the slopes of inductor current during the power switches being turn-on or turn-off, a unified discrete-mapping model of current-mode controlled SIDO switching converters with ramp compensation is established in this study, which can be applied to three basic SIDO switching converters, i.e. buck type, boost type, and buck-boost type. Only six parameters appear in this model after non-dimensional analysis, from which the dynamical behaviours of SIDO switching converters in continuous conduction mode (CCM) and discontinuous conduction mode (DCM) can be effectively illustrated. The effect of ramp compensation is analysed in detail. By utilising the proposed unified model, two transition conditions and boundary equations of the converter are derived, where its operation state transits from stable period-1 to instability and operation mode shifts from CCM to DCM. The operation region with varied circuit parameters can be estimated and divided by the parameter-space map, which is significant for the design of circuit parameters and stability. Finally, taking a current-mode controlled SIDO boost converter as an example, its experimental results are carried out to validate the theoretic analysis and the non-dimensional unified model.