Lyapunov-Function Based Control Strategy for Four-Switch Buck-Boost DC-DC Converters

Abstract

This paper presents a Lyapunov-function-based control strategy for four-switch buck-boost (FSBB) DC-DC converters. The inductor current control of FSBB is achieved by the Lyapunov-function-based control approach. The reference of the inductor current is obtained by a PI controller whose input is the error between the reference and measured values of FSBB output voltage. Since FSBB converter contains separate switches for buck and boost stages, separate control input equations are defined for each stage. As a consequence of controlling each stage by dedicated control input, the proposed control method does not need mode detection algorithm. Furthermore, the system stability is guaranteed by satisfying Lyapunov's stability condition. The effectiveness of the proposed method has been tested by Matlab simulations under load step, reference step and mode transitions for buck and boost modes. The results show that the proposed control method is capable of regulating the output voltage under all dynamic transition conditions.