Low Inductance Laminated Busbar Design Method For SiC Devices Dynamic Test Platform

Silicon carbide(SiC)devices have excellent characteristics of high voltage,high temperature,and high frequency compared with silicon(Si)devices.The excellent performance of SiC devices makes them widely used in smart grid,aerospace,and power traction and so on.The dynamic characteristics of SiC devices are important to their modeling,power consumption evaluation,junction temperature prediction,and thermal design,which further affect the performance of power electronics de vices.In the dynamic characterization test platform of SiC devices,SiC devices are subjected to non-ideal electrical stresses during switching transients due to the presence of stray inductance in the commutation loop,which seriously affects the reliability and accuracy of the test.The laminated busbar is an effective means to reduce the stray inductance of the commutation loop.The capacitor is an important component of the platform,and the stray inductance of the laminated bus bar connecting the capacitor and other components is an important part of the stray inductance of the commutation loop.Therefore,how to effectively reduce the stray inductance of the laminated busbar is a key issue in the dynamic characteristic test of SiC devices.As the voltage and power levels of SiC devices continue to increase,capacitors need to be combined in series and parallel to meet test requirements,which increases the difficulty of busbar design.In this paper,the design of low-inductance laminated busbar with multi-capacitor series-parallel topology is investigated for the busbar of high-voltage high-power SiC device dynamic characterization test platform.First,the influence of stray inductance on the dynamic characteristics of SiC devices and the electromagnetic mechanism of the low stray inductance of the laminated busbar is analyzed.In addition,from the viewpoint of increasing the symmetry of current paths between busbars and the coupling degree of busbars,the influence of capacitor layout and terminal position on the stray inductance of busbars is analyzed,so a design method of laminated busbar for multi-capacitor series-parallel topology is proposed.The method improves the coupling degree between the busbar layers by constructing the reverse current path,thereby greatly reducing the stray inductance of the laminated busbar.In addition,the busbar has a compact structure and high space utilization.Second,in order to verify the effectiveness of the design method,the stray inductance of different busbar structures is extracted by simulation and actual measurement with finite element analysis software and impedance analyzer.In addition,a 400V/20A SiC device switching characteristics test platform is built,and the corresponding device turn-off voltage characteristics are obtained by using the test platform designed with different busbar structures.The simulation and experimental results show that the proposed design method can effectively reduce the stray inductance of the laminated busbar and has a good suppression effect on the devices turn-off voltage spikes.Finally,for the high-voltage and high-power SiC devices switching characteristics test platform,the proposed busbar design method is used to design a laminated busbar structure that meets both low stray inductance and high insulation requirements,taking into account the insulation requirements of the busbar.The main circuit,charge/discharge circuit and auxiliary circuit of the system are interconnected through the busbar structure,and an integrated integration method is designed.