A Constant Frequency ZVS Modulation Scheme for Four-Switch Buck-Boost Converter With Optimal ZVS Conditions Based on BP Neural Network

The pseudocontinuous conduction mode (PCCM) four-switch buck-boost (FSBB) converter is widely used in applications with wide input and output voltage ranges. In this article, a constant frequency zero-voltage switching (ZVS) modulation scheme with minimized root mean square (rms) inductor current is proposed. The proposed constant frequency ZVS modulation scheme does not rely on data-heavy three-dimensional (3-D)/two-dimensional (2-D) look-up tables (LUTs) or require wide switching frequency variation. In addition, the accurate ZVS conditions of switches are derived through theoretical analysis, and approximated by using a back-propagation (BP) neural network, which allows simple and accurate calculation of ZVS conditions over wide operating ranges and facilitates the minimization of rms inductor current. Finally, a 300 W FSBB prototype is built to verify the proposed modulation scheme and the derived ZVS conditions.