Digital Combination of Buck and Boost Converters to Control a Positive Buck–Boost Converter and Improve the Output Transients

A highly efficient and novel control strategy for improving the transients in the output voltage of a DC-DC positive buck-boost converter, required for low-power portable electronic applications, is presented in this paper. The proposed control technique can regulate the output voltage for variable input voltage, which is higher, lower, or equal to the output voltage. There are several existing solutions to these problems, and selecting the best approach involves a tradeoff among cost, efficiency, and output noise or ripple. In the proposed method, instead of instantaneous transition from buck to boost mode, intermediate combination modes consisting of several buck modes followed by several boost modes are utilized to distribute the voltage transients. This is unique of its kind from the point of view of improving the efficiency and ripple content in the output voltage. Theoretical considerations are presented. Simulation and experimental results are shown to prove the proposed theory.