Research On Shielding Effectiveness Of High Voltage Shielded Cables And Connectors For Electric Vehicle

The high-voltage connection system is one of the most important components in the electric vehicle electric drive system,including high-voltage shielded cables and high-voltage shielded connectors.The shielding effectiveness of the high-voltage connection system will directly affect the performance of the electromagnetic compatibility?Electromagnetic Compatibility,EMC?of the vehicle.However,at present,China's test standard for the shielding effectiveness of the high-voltage connection system of electric vehicles is not perfect,so it is necessary to study its test method.In addition,it is necessary to combine simulation technology as an effective auxiliary means to estimate the shielding effectiveness of the DUT through calculation.Therefore,this paper mainly studies the test method and simulation technology of the shielding effectiveness of the high-voltage connection system of electric vehicles.The main research results are as follows:?1?We can use the triax method and the wire injection method to test the transfer impedance of the high-voltage shielded cables of electric vehicles.The test principle of the tri-coaxial method and the line injection method is introduced in detail,and the results of the two tests are compared.The validity of the test value is verified.The connection system assembly can still be tested according to the triaxial method.The coaxial housing of the test equipment can be replaced with a larger box.In addition,a shield shell must be prepared to match the shielded cable and connector.For high-voltage connectors can be tested by the special three-coaxial method"tube-in-tube method".?2?An analytical optimization model of transfer impedance for high-voltage shielded cables with double-layer shielding?braid and aluminum foil?is proposed.Based on the analytic model of braided single-layer shielded cable,combined with the components of the transfer impedance characteristic curve of the shielded cable,considering the impact of the braided layer wrapped with aluminum foil,the DC resistance value increases,and the effect of the small hole inductance can be ignored An analytical optimization model of the transfer impedance of the double-layer shielded cable was further established,and the correctness of the optimization model was verified by comparison with the test results.?3?The electromagnetic simulation software HFSS was used to perform numerical calculations on the single-layer shielded and double-layer shielded cables,and the validity of the method was verified by comparison with the test results.The validity of the analytical model of the double-layer shielded cable is further verified.The addition of aluminum foil to the shield layer will increase the DC resistance value in the low frequency range,greatly reducing the transfer impedance value in the high frequency range,and the cable shielding effectiveness is improved.?4?An analytical model of the high-voltage connection system assembly of an electric vehicle is proposed.This method is based on the model of the high-voltage shielded cable.The additional contact resistance value₉(6?8?and the additional inductance value₉9)0)?8?are added.Generally,the internal contact resistance of a straight-plug interlocking elbow connector connected to a 35mm² shielded cable is usually 3⁵m?,and the additional inductance of the connector is 2.2nH.Compared with the assembly test results,the correctness of the model is verified.?5?The simulation of the transfer impedance value of the high-voltage connector can be performed by numerical analysis.The simplified connector electromagnetic simulation model is imported into HFSS for calculation.The validity of the method is verified by comparison with the test results.The cloud diagram shows the electromagnetic field distribution.It can be seen that there will be electromagnetic field leakage at the joints of the shield shell of the high-voltage connector,and the processing technology needs to be improved.