Electromagnetic-thermal Multiphysics Coupling Analysis And Research Of High-power Inverter Laminated Busbar

With the continuous development of high-power power electronic converter devices,laminated busbars as the main connection parts between power electronic power devices,are getting more and more attention in problems such as loss of heat,electromagnetic characteristics,and stray parameters with high frequency and high power density working environment.This puts forward new requirements for the design of laminated busbars,that is,the temperature rise requirements of power devices need to be met,and the current density distribution and magnetic field distribution of laminated busbars also need to be considered.This paper analyzes the effects of different physical structures of laminated busbars on the electromagnetic characteristics of the busbars through simulation,and proposes an optimized busbar design method.Taking a high-power three-phase two-level inverter as an example,combining electromagnetic fields and steady-state heat transfer,to analysis and research the DC side laminated busbar with electromagnetic-thermal multiphysics coupling simulation.First of all,this paper carry out the theoretical analysis of the laminated busbar,and obtain the calculation method of the magnetic field and stray parameters of the laminated busbar,based on the theory of electromagnetic field.In this paper,the electromagnetic characteristics and stray parameters of laminated busbars in different frequency domains are simulated and analyzed,and the general law of the influence of frequency on the electromagnetic characteristics and stray parameters of busbars is obtained.Then this paper conducts electromagnetic simulation analysis on the different physical structures of the laminated busbars,and obtains the effects of different physical structures on the current density distribution,magnetic field distribution,stray inductance and equivalent resistance of the stacked busbars under different excitation frequencies.The method of optimizing the design of busbars and reducing the stray parameters of busbars is introduced.Secondly,this paper analyzes the heat transfer of the laminated busbars,obtains the calculation method of thermal loss and thermal resistance calculation model of the laminated busbars,and establishes the electromagnetic-thermal coupling calculation model of the laminated busbars.This paper takes the change of resistivity brought by the temperature rise of the laminated busbar as a reference factor,and proposes a twoway electromagnetic-thermal coupled simulation analysis method of the laminated busbar based on the finite element method.This method can effectively calculate the electromagnetic loss of the laminated busbar,and the temperature rise of the laminated busbar can be obtained by steady-state thermal analysis.Finally,taking the three-phase two-level inverter with 1.9MW and 900 A load current as an example,the DC busbar in the inverter is analyzed.Combined with the working principle and switching state of the three-phase two-level inverter,this paper analyzes the transient electromagnetic simulation of the trapezoidal wave current of the DC bus in the inverter.In this paper,the steady-state temperature rise of the DC busbar under normal working conditions is obtained through the steady-state thermal analysis simulation software for the DC busbar electromagnetic-thermal coupling analysis.This paper also simulates the temperature rise of the DC bus when the inverter has a shortterm overcurrent fault through simulation,and combines the above two points to verify the rationality of the DC bus design.This paper focuses on the electromagnetic characteristics,stray parameters,temperature rise and other factors of the high-power inverter laminated busbar,and carries out the electromagnetic and thermal coupling simulation analysis of the laminated busbar.A simulation verification method is proposed to optimize the design of the laminated busbar and verify the rationality of the laminated busbar design.The 200 k W three-phase two-level inverter is used as the experimental platform to verify the rationality of the electromagnetic-thermal coupling simulation.