A Uniform Nonlinear Control Method for DC-DC Converters with Fast Transient Response

Abstract

Much effort has been made to the switching surface control of buck converter. However, it remains a fundamental challenge to apply the same concepts and associated control techniques to converters with non-minimum-phase characteristics. A nonlinear control method for all basic dc-dc converters (i.e. buck converter, boost converter, buck-boost converter, Ćuk converter and SEPIC) is proposed by deriving a uniform switching surface. It retains the advantages of boundary control for buck converter with second-order switching surface. For example, the converters can reach steady state in two switching actions after being subjected to large-signal disturbances. The derivations are general-oriented and can determine the circuit variables needed in the switching function. The same controller is universally applicable to different converters operating in both continuous conduction and discontinuous conduction modes. The potential applications lie in power conversions which require fast response to line/load changes, such as the point of load (POL) converters in the distributed power conversion system, power conditioning stage of the conversion system supplied by renewable energy sources, and so on. Design procedures and performance of the proposed control method applied on a 190W 48/48V buck-boost converter prototype will presented and compared with theoretical predictions.