Research On Radiated EMI Prediction Technology Of Si/SiC Hybrid Device Inverter System Of Electric Vehicle

In recent years,with the increasing global warming,water pollution and air pollution,people are more and more aware of the importance of clean and environmental protection.Countries have advocated green travel,and the electric vehicle industry has ushered in a period of rapid development.However,unlike traditional fuel vehicles,which are mostly composed of Mechanical structural parts,there are many electronic equipment inside,which makes it more difficult for electric vehicles to realize electromagnetic compatibility than fuel vehicles.Taking the electric vehicle inverter system as an example,because it has the characteristics of high voltage,high power and high frequency,there are parasitic inductance,capacitance and other parameters.When the semiconductor high-frequency devices in the inverter are switched quickly,they will produce large dv/dt and di/dt.The parasitic parameters provide a propagation channel for these high-frequency interferences and threaten the EMC safety of the whole vehicle.Therefore,aiming at the prediction of electromagnetic radiated interference of Si/SiC hybrid device inverter system of electric vehicle,this paper carries out a series of theoretical research and technical analysis,and is committed to reducing the cost of electromagnetic compatibility design and development of electric vehicle.The main work of this paper includes:Firstly,the characteristics of Si IGBT and SiC MOSFET and the reasons for using Si/SiC hybrid devices are discussed respectively.The characteristics and parameters of Si/SiC hybrid devices are analyzed,the high-frequency circuit model of inverter circuit is established,and the high-frequency equivalent model of typical passive devices is analyzed.The parasitic parameters between hybrid devices and radiator are extracted by ANSYS Q3 D electromagnetic simulation software,and the established model is verified by simulation.Then,the electromagnetic interference mechanism of Si/SiC hybrid device and interconnected ribbon cable is analyzed,and the 3D model of hybrid device and interconnected ribbon cable is established in CST.The analysis method based on dipole antenna is proposed,the electromagnetic radiated interference of hybrid device pins is analyzed,the effects of different input parameters such as voltage,rise time and hold time on the electromagnetic radiated interference of hybrid devices are discussed,the far-field radiation diagram generated by hybrid devices is analyzed,and other device layout methods are discussed.For the interconnection ribbon cable composed of multiple cables,the multi wire model of the interconnection ribbon cable is simplified into one by using the equivalent cable bundle method,and compared with the original cable.The results show that the proposed method can better restore the distribution parameters of multiple wires.Finally,the radiation mechanism of the cable is studied,and it is determined that the large dv/dt caused by the rapid disconnection of the switching device is the main electromagnetic interference source of the inverter circuit system.The method of predicting the radiated interference path by analyzing the conducted electromagnetic interference path of the Si/SiC hybrid device inverter circuit system is proposed,and the equivalent circuit model of the power cable is established according to the transmission line theory.A complete 3D model is established in CST cable studio.The radiated interference electromagnetic field distribution of Si/SiC hybrid device inverter circuit system is calculated by field line circuit joint simulation method,and the test environment is constructed.The experimental verification is carried out.The measured data are in good agreement with the simulation results,which confirms the correctness of the proposed prediction method.