Research on Switching Oscillation Suppression Strategies for Dual-Buck Symmetrical Half- Bridge Converter Using GaN HEMTs

GaN HEMTs' high voltage and high-frequency performance significantly enhance power amplifier output and efficiency. However, GaN HEMTs' at high switching frequencies, insufficient damping and parasitic parameters in power loops cause severe transient oscillations in switch voltages. These issues are the main causes of distortion in Dual-Buck Symmetrical Half-Bridge Converters (DBSHBC). This study establishes a unified terminal impedance model for GaN HEMTs and freewheeling diodes in DBSHBCs, revealing the oscillation suppression mechanism. To address low-frequency harmonic distortion caused by traditional DC-side high-frequency decoupling capacitors during oscillation suppression, this study investigates capacitor parameters and spatial layouts. A Bridge-Arm-Side C-RC Snubber Circuit Strategy is proposed to suppress oscillations. Experimental prototypes based on dual-pulse test principles validate the strategy's ability to maintain high-frequency oscillation suppression while eliminating low-frequency oscillations.