| Press-Pack IGBT is the core device of the flexible DC transmission system.Compared with the traditional IGBT,Press-Pack IGBT is more suitable for high voltage DC transmission system,and its reliability directly affects the property of the flexible DC transmission system.The Press-Pack IGBT keeps the internal components electrically and mechanically connected through external pressure.Its own structure,internal layout of the module,processing errors,and thermal stress during operation may cause uneven temperature distribution in parallel module and weak points on single chip,which greatly affect the reliability of its devices.Therefore,it is of great significance to study the thermal management of the Press-Pack IGBT module,explore the main factors affecting the heat dissipation and optimize the heat dissipation design.The paper mainly focuses on the following topics.First,study the structure and working process of single-chip Press-Pack IGBT,then explore the main factors affecting the heat dissipation of Press-Pack IGBT.According to the structure of the single-chip Press-Pack IGBT,a finite element model of the singlechip Press-Pack IGBT is constructed in the COMSOL software platform through the contact thermal resistance and contact resistance empirical formula,and a simplified thermal resistance model of Press-Pack IGBT is proposed.Through simulation analysis,the current distribution,stress distribution and temperature distribution of the single-chip Press-Pack IGBT are studied,and the weak links of the chip are analyzed.According to the simplified thermal resistance model,the bottleneck affecting the heat dissipation of the Press-Pack IGBT device is studied,and it is convinced contact thermal resistance is an important link that affects its heat transfer performance.Secondly,the microscopic morphology of the contact interface of the Press-Pack IGBT device and its influence on the contact thermal resistance are deeply studied,and the improved thermal resistance model of the device is proposed and verified by experiments.At first,analyze the mechanism of contact thermal resistance.Using Monte Carlo method to model the micro morphology of the contact interface,and constructing contact thermal resistance of Press-Pack IGBT by simulating the rough peak height of the contact interface and the actual contact area.Then,a parallel module model of two chips in parallel is established on the basis of the Press-Pack IGBT model,and the validity of the model is verified by experimental data.Finally,a method that using graphene is proposed to improve the heat dissipation performance of Press-Pack IGBT modules and design an optimized heat dissipation solution.At first,the mechanism of the graphene layer enhancing the heat conduction of the contact interface is studied.Then analyze the influence of the graphene layer on the longitudinal thermal resistance of the contact interface and the influence of the high thermal conductivity in the graphene plane on the temperature distribution of the chip surface.By comparing the improvement effect of graphene layer on the weak point of the single chip of Press-Pack IGBT module and the uneven temperature distribution of the parallel chip,an optimized design plan for the heat dissipation of the graphene layer in Press-Pack IGBT is proposed. |
