Design And Realization Of High-frequency Buck PFC Converter Based On GaN Device

Power factor correction（Power Factor Correction,PFC）converters can eliminate the impact of harmonics generated by electrical equipment on the power grid.In the field of consumer electronics,power factor correction converters need to be reduced in size while maintaining high power and high efficiency.The most effective way to reduce the volume of that is to increase the switching frequency of the power switch.The thirdgeneration wide-bandgap semiconductor gallium nitride（GaN）material has the advantages of larger band gap,faster carrier saturation drift rate and smaller dielectric constant than silicon materials,which can meet the development of power semiconductors.It has gradually become a hot spot of research and application.As a power switch,GaN devices can make the switching frequency of the converter reach the MHz level,so that the converter has smaller conduction loss,smaller passive component volume and higher power density.In the field of low-voltage applications,the Buck power factor correction converter can directly provide a lower output voltage,and the stress of the power switching device is small,and the power switching device can realize zero current turn-on and no reverse recovery of the diode.Based on gallium nitride devices,this thesis designs a Buck power factor converter with the goal of achieving high operating frequency,high efficiency and high power factor.The main work is as follows:（1）Studying the ideal state output voltage model of Buck PFC converter in discontinuous current mode（DCM）,and analyzing the operating loss of each component in the operation of DCM Buck PFC converter,which is the non-ideal factor.Based on the ideal voltage model and non-ideal factors of the DCM Buck PFC converter,the non-ideal output voltage model of the DCM Buck PFC converter is established.Designing an algorithm to solve the control objective parameters through the non-ideal model.Two control strategies are designed by Using the algorithm of solving the control objective parameters.Analysing the power loss of GaN devices in high frequency power converters.（2）Designing the hardware parameters of the PFC converter based on the control strategy.Calculating the hardware parameters of each component of the power circuit.Designing the drive circuit and sampling circuit.To estimate the change of output voltage during the soft-start process,a soft-start algorithm of Buck PFC converter is designed.（3）Realizing the production of DCM Buck PFC converter.Testing the working parameters of the converter under the condition that the input voltage of 100Vac～240Vac and the load rate of 25Ω.The test results are consistent with the design analysis,When the operating frequency is 1MHz～1.2MHz,the output power of the converter is 100 W,the efficiency is greater than 90%,and the power factor is greater than 0.95.