Characterization Of Strong Electromagnetic Interference Mechanism Of Flexible Direct Converter Valve Module

Due to the rapid development of power electronic science and technology,power electronic equipment is also developing vigorously towards high frequency,high capacity range and high output power.At present,due to the generation of a large number of parasitic parameters,a large voltage EMI difference will be formed during the turn-on and switching of the high-power switching element IGBT,which will not only affect the normal operation of the flexible DC power transmission converter valve sub-module,but also increase the According to the generation of equipment operation.Through the research on the use of IGBT sub-module equipment,this paper systematically analyzes the common mode output voltage of the IGBT single-tube Buck and the synchronous Buck circuit,and uses the circuit simplification equivalent method to analyze the equipment use characteristics of the flexible DC converter valve.The common mode current problem of the converter valve sub-module in the switching power supply is established,and a mathematical model is established to estimate the change rule of the common mode current of the sub-module.The validity of the model is verified by comparing the model with the theoretical results.The main findings and conclusions of this paper are as follows:(1)Based on the IGBT single-tube Buck circuit and principle,the parasitic parameter distribution in the sub-module system is analyzed.By establishing the equivalent model of the common mode loop,it is obtained that the scale of the common mode current Icm increases with the value of Uce(S).Increase,and expand with the increase of the parasitic capacitor Cps of the primary and secondary sides of the drive;introduce the influence of the parasitic parameters between the bypass switch and the power supply and the drive board,and obtain the increase of the value of the parasitic capacitance Cd of the drive board to the ground The expansion also increases with the increase of the equivalent capacitance of Cc and Cs,but decreases with the increase of the value of the IGBT’s collector and emitter parasitic inductances Lc2 and Le2.(2)Use the electronic simulation and circuit simulation obtained in the model to carry out a combined simulation,and analyze and simulate the transient magnetic field and electrostatic field of the high-power IGBT.The combined simulation of state and magnetism shows that the magnetic field strength in the central part of the inner layer of the IGBT is weak,which verifies that the electromagnetic interference problem is mostly concentrated around the collector of the inner layer of the IGBT.(3)Build a 3D simulation model to simulate the electromagnetic interference phenomenon in the sub-module.After comparing the simulation results,due to the large current density on the wire at the IGBT collector cathode,it is obtained that the collector cathode part forms a stronger magnetic field distribution than other places.law,which confirms the theory.This paper provides the necessary theoretical basis for the layout design of the modular flexible DC converter valve and the parameter selection of its components through theoretical calculation and modeling and simulation research.