Analysis And Design Of Half Bridge Circuit Based On GaN HEMT

Advanced power semiconductor devices are the most powerful driving force in energy conversion technology.Gallium nitride(GaN)material has shown several times higher in terms of insulation breakdown field strength,saturation drift speed,thermal conductivity,bandgap width and other characteristics when compared with the current silicon(Si)materials,and it is more suitable for high frequency,high efficiency,high power density applications.To this end,take the GaN device E-HEMT GS66516T from GaN System as the basis and develop its application research from the following aspects:(1)Develop the driving circuit analysis and design of GaN devices.Based on the characteristics of GaN device fast switching speed,the driving circuit is discussed in terms of resistance selection,Miller effect control,isolation and driving delay.Then,the driving circuit suitable for GaN device is designed.(2)The layout analysis of the GaN device when forming the half bridge circuit is carried out,and the PCB layout with small stray inductance arise from commutation circuit is designed.In order to accurately evaluate the effect of layout stray inductance on the performance of GaN devices,the stray inductance parameter extraction was carried out by finite element analysis,and substituted into the simulation model for verification.(3)The thermal analysis of the half-bridge circuit was carried out.Based on the traditional segmented linear loss model,a simplified method of calculating the loss of GaN devices is proposed.The scheme calculates the power loss of the device based on the parameters of the GaN device and the stray inductance value.The three-dimensional finite element model including GaN device,PCB board and heatsink is established in the next,and the thermal performance of the half-bridge circuit is evaluated by thermal simulation with the calculated power loss value.In order to fully verify the above analysis and design,this study has established the experimental prototype according to the design result,and has carried on the double pulse performance test and the power running test.The design of the half-bridge circuit size is only55×40mm~2,removed additional buffer circuit when work in the 400V input,1.5kW power conditions.The heatsink volume is only 28×28×14mm~3,and the conversion power density up to 500W/in~3.The experimental results prove the validity of the above design scheme.