An alternative strategy for reducing mode transitions in a four-switch buck-boost converter

This paper presents an alternative method for improving the transient response exhibited by a four-switch buck-boost converter during its mode transitions. The proposed algorithm permits to determinate the combination of buck and boost cycles that has to be implemented in modes A and B to reduce the overshot and overmodulation on the output voltage. The so-called alpha and beta values are deduced by minimizing the mean-square error between the output voltage and the desired level. Nonlinear discrete-time models of buck and boost converters are used to predict the states of the circuit. Finally, three different options for assigning the duty cycles are considered. The performance of the converter is illustrated via numerical simulations.