Bootstrap Capacitor Charge Control Method for GaN-based 4-Switch Buck-Boost Converter

This paper presents a wide input voltage buck-boost converter based on GaN semiconductors. The converter includes four GaN semiconductors and two bootstrap capacitors. The adaptive bootstrap capacitor charging (ABCC) technique is proposed to address the overcharging issue of the bootstrap capacitors, which is caused by the absence of an intrinsic body diode in GaN semiconductors. The maximum efficiency achieved was up to 96% in a load current range of 0 to 1.5 A. The proposed buck-boost converter has an input voltage range of 7 to 60 V and an output voltage range of 7 to 60 V. The switching frequency is up to 5 MHz.