Research On High Frequency And High Efficiency LLC Resonant Converter Based On GaN Device

At present,high-efficiency,high-power-density converters have always been the goal pursued by the power supply industry.With the rapid development of semiconductor materials and technologies,this goal has been greatly promoted.LLC resonant converter is widely used in DC/DC because it can realize the zero-voltage switching(ZVS)of the primary-side power tube of the transformer and the zero-current switching(ZCS)of the secondary-side rectifier,However,in more high-frequency applications,the losses of the converter is still high.The third-generation wide bandgap semiconductor device gallium nitride(GaN)is favored by scholars for its excellent performance such as small size,high power density,fast switching speed,high temperature resistance,and no reverse recovery loss.Applying this device to LLC resonant converter will further improve the efficiency of the converter.This topic analyzes the switching process of GaN devices in LLC resonant converters based on GaN devices in detail.In order to reduce the influence of parasitic parameters of the loop,the wiring of the drive circuit and the power circuit is optimized,and the parasitics after improved wiring are extracted in Ansys Q3D parameter.The mathematical model of LLC resonant converter is established,and the influence of each parameter on the converter is analyzed in detail.In order to further improve the efficiency and power density of the converter,this topic uses a planar transformer,and uses Ansys Maxwell electromagnetic simulation software to build a model of the planar transformer.In the eddy current field simulation environment,its leakage inductance and other parameters are obtained,and the winding is assigned Carried out a simulation.The main circuit parameters of the LLC resonant converter are calculated,and then the LTspice circuit simulation software is used to simulate and verify,and the loss is calculated and compared and analyzed in detail.The results show that the efficiency and power density of LLC resonant converters based on GaN devices,planar transformers and synchronous rectification technology have been greatly improved.Finally,two experimental boards were produced in the laboratory,one using traditional Si MOSFET devices,traditional transformers and diode rectification,and the other is a 120W,1MHz experimental model using GaN devices,planar transformers and synchronous rectification technology.The experimental results show that the efficiency of the experimental model using GaN devices is 94.3%,and the power density is 92.3 w/in3,The efficiency is 11.25%higher than the traditional experimental board,and the power density is 76.6 w/in3 higher than the traditional experimental board,which further verifies the correctness and feasibility of this design.