Research On Totem-pole Bridgeless Boost PFC Converter Based On GaN Devices

The air conditioning compressor drive system pursues higher efficiency.GaN power device and totem-pole bridgeless Boost PFC converter can effectively improve the efficiency of air conditioning compressor drive system.However,there are still technical difficulties in the bridgeless Boost PFC converter based on GaN power devices where GaN power devices have extremely high switching speed and low safe driving voltage range.If the driving circuit is improperly designed,serious voltage and current shock will occur.At the same time,the input current waveform of the bridgeless Boost PFC converter will be greatly distorted under light load.In this paper,the problems mentioned above are studied and corresponding solutions are given,so as to promote the practical application of GaN power devices in higher power situations and realize the bridgeless PFC converter with high power factor in the full power range.Firstly,an optimized design method of GaN power device driver module is studied.By analyzing the equivalent circuit of the drive system,the cause of the output current oscillation is found from the perspective of the system damping ratio.A damping resistor is added to suppress the oscillation.Then the drain-source turn-off overvoltage and the gate-source crosstalk voltage are proposed.The generation mechanism was analyzed separately,and the drive system was optimized by adding buffer circuits,reducing the turn-off resistance,and adding anti-parallel diodes.A double-pulse experimental platform for GaN power devices was built,and the effectiveness of the optimized design method was verified through experiments.Then,by establishing a small-signal model of the PFC converter control system and time-domain mathematical derivation,the four causes of current waveform distortion under light-load conditions of the bridgeless PFC converter are analyzed and summarized.At the same time,combining theoretical results with actual experimental waveforms,the influence of current loop bandwidth,different operating modes,EMI filter capacitors,and the resonance of PFC inductance with input capacitor on current waveform distortion are studied.The main influencing factors are studied and solved.Therewith,an average current control strategy based on inductor current sampling correction and duty cycle feedforward is proposed.By adding the inductor current sampling correction link,the inductor current sampling under DCM is corrected to the actual inductor current average value.Also,the duty cycle feedforward link is added to the traditional average current control strategy to form a feedback and feedforward composite PFC control system so that only a single current regulator can achieve a bridgeless PFC converter with a high power factor in the full power range.Finally,a GaN HEMT totem-pole bridgeless PFC converter prototype with rated power of 2k W using Renesas RX62 T as the main control chip was developed.An air-conditioning compressor experimental platform was built.On this platform,the proposed PFC control strategy and the developed GaN HEMT drive module are verified,and the efficiency comparison is made.