Research On CRM Boost PFC Converter Based On GaN Device

In the consumer electronics arena,it is need for Power Factor Correction(PFC)converters to improve performance and reduce device size while maintaining high power factor.Increasing the switching frequency is the most important way to increase the power density of the PFC converter.In low-power applications,the commonly used form is the CRM Boost PFC converter.When the switching frequency of the converter is close to the MHz level,the switching loss of the conventional Si MOSFET increases sharply,resulting in a decrease in the overall efficiency of the converter.As a widebandgap semiconductor device,commercial products of gallium nitride(GaN)devices have become increasingly mature,enabling the realization of high-frequency CRM Boost PFC converters.At present,there are few researches on CRM Boost PFC converters using GaN devices as switching tubes.The existing researches at home and abroad have not fully considered the input current zero-crossing distortion rate brought by high-frequency operation,optimizing the driving circuit and control circuit.Firstly,the power factor correction principle of CRM Boost PFC converter based on GaN device is analyzed,and the static characteristics of Cascode GaN transistor and super junction Si device are analyzed and compared.The steady state analysis of the GaN device-based CRM Boost PFC converter is then carried out by establishing a mathematical model.Secondly,the main circuit of CRM Boost PFC converter based on GaN device is studied.According to the actual production requirements,the target parameters of the converter are determined,and the components are selected by deriving mathematical constraints.After analyzing the switching process of Cascode GaN transistor considering parasitic parameters,the method of increasing the driving resistance is used to improve the false turn-off phenomenon during the turn-on process,and the correctness of the theory is verified by simulation.Comparing the switching time and switching losses of Cascode GaN transistors and super-junction Si devices.The necessity of improving the zero-crossing distortion of the input current is analyzed by the high-frequency CRM Boost PFC converter.The zero-current distortion of the input current is suppressed by the strategy of improving the delay of the zero-current detection circuit.The correctness of the theoretical analysis is verified by simulation.Thirdly,the control circuit of CRM Boost PFC converter based on GaN device is studied,and a more accurate converter loss calculation model is established.The closed-loop transfer function is derived,the stability of the feedback loop is analyzed by Bode plot,and the feedback loop compensation is designed for high frequency conditions.In order to reduce the loss calculation error,the switching loss of the switch tube is calculated by the double pulse test simulation method,and the loss calculation model of each part of the converter is derived.Analyze the total efficiency of the converter and the proportion of each part of the loss,and compare the switching loss and the on-state loss when using the GaN device and the Si device.The PSpice simulation tool is used to build the main circuit and control circuit,and the simulation analyzes the converter's steady state time,power factor correction effect and output voltage ripple.Finally,a dual-pulse test platform based on Cascode GaN transistors and a CRM Boost PFC converter experimental platform are built.The dynamic characteristics and losses of GaN devices,control circuit performance,efficiency improvement and input current of CRM Boost PFC converters based on GaN devices Zero distortion suppression effect is verified.