Analysis Of Parasitic Inductance Of Laminated Busbars And Design Of Coupled Absorption Circuit

Wide band gap semiconductors,including silicon carbide(SiC)and gallium nitride(GaN)possess faster switching speed,allow engineers to develop higher power density systems compared to traditional Si technology.Silicon Carbide,in particular,has promising applications to the automotive,aerospace,and utilities industries among others.These widebandgap semiconductors are also increasingly used in high-power systems.However,highpower and high-speed switching speeds also impose stricter requirements on the design of parasitic parameters of current commutation loop.Laminated busbar are usually used in high-power systems to establish steady electrical and mechanical connections.They are important to ensure the reliability of the inverter in terms of fast switching and multi-device parallelism.They are an important part of the current commutation loop,so the analysis and research of its parasitic parameters is very necessary.Laminated busbar mainly reduce the overall inductance through mutual inductance cancellation.At present,researches on laminated busbars mainly focus on the influence of the current path on the parasitic inductance,and there is little research on the current distribution of the non-overlapping part of the busbar and the influence of electromagnetic fields on the parasitic inductance of this part.This paper focuses on the influence of the parasitic inductance of the laminated busbar on the voltage overshoot at the power devices.The current and magnetic field distribution of the laminated busbar is studied from the perspective of electromagnetic field.Based on circuit analyze,this paper first models the inverter current commutation loop and analyzed the effects of the parasitic resistance and parasitic inductance of the laminated busbar on the dynamic and static performance of the inverter.Then,the influence of parasitic parameters on busbar current sharing in the case of multiple devices in parallel is further analyzed.Based on two different current sharing ideas,laminated busbars are fabricated and the current sharing effects in the two modes are analyzed.Then,based on the electromagnetic field simulation,the relationship between the electromagnetic field and the parasitic inductance of the laminated busbar is analyzed.The laminated busbar is divided into several sections and electromagnetic field simulations are performed separately.The influence of the structure of each part of the laminated busbar on its parasitic inductance is researched,the concept of coupled absorption circuit is proposed.There is a strong coupling between the coupled absorption circuit and the laminated busbar.Only when the power device is turned on or off,the energy in the current commutation loop is transmitted to the coupled absorption circuit through the electromagnetic field,which suppresses the voltage overshoot on power device.This paper still analyzed the performance of the coupled absorption circuit from the perspective of circuit and electromagnetic field,and uses the NSGA-Ⅱ algorithm to optimize each parameter in the coupled absorption circuit.Finally,based on the simulation and analysis of the coupled absorption circuit,detailed design steps are proposed.According to the proposed design steps,the full-bridge inverter laminated busbar and the corresponding coupled absorption circuit are designed in the form of PCB.An experimental platform was set up to analyze the experimental results and waveforms.