Research On Electromagnetic Compatibility Simulation And Optimal Layout Of Electronic System Interconnection Cables

Interconnection cables,as a type of transmission line,are the primary way to transfer energy and signals between the various functional modules in the electronic system.The cables play a critical role in electromagnetic compatibility(EMC)issues of electronic systems such as conducted emission(CE),radiated emission(RE),immunity,and signal integrity(SI).In this dissertation,the electromagnetic modeling of interconnected cables,the efficient calculation method of cable harness internal crosstalk,and the optimal routing technology under the maximum crosstalk constraint are carried out for the demand of EMC optimal layout of electronic system interconnected cables.The main contents and innovations of this dissertation are summarized in the following four aspects:1.For the problem that braided shielded coaxial cables are difficult to simulate,the internal and external transmission line(IETL)transfer matrix is proposed to represent the coupling relationship between the inner conductor and the shield of the coaxial cable.Starting from the multiconductor transmission line(MTL)equation,the IETL transfer matrix is derived based on the characteristics of coaxial cables with dual internal and external transmission lines and fixed transmission line port impedance.Using the IETL transfer matrix allows braided coaxial cables to be simplified to equivalent single wires for subsequent EMC simulations.In addition,the reactive field added method for calculating the near-field electric field is proposed based on the electric dipole method.By combining this method with the IETL transfer matrix,it is possible to analyze the near-field electric field radiation of coaxial cables.The comparison of simulation results and measurement results verifies that the proposed IETL transfer matrix can accurately reflect the EMC performance of coaxial cables and improve the efficiency of the simulations.2.For the problem that the crosstalk of cable harnesses containing coaxial cables are difficultly analyzed,equivalent cable bundle method(ECBM)that can reduce the complexity of cable harnesses is investigated.By simplifying the cables with similar characteristics in a cable harness into a single cable,the number of cables is greatly reduced.Introducing the IETL transfer matrix into the ECBM,this method is extended to the problem of crosstalk in cable harnesses containing coaxial cables.Different numerical methods are used to simulate and analyze the crosstalk of the internal and external transmission lines in the original cable bundle model,the equivalent single wire model,and the equivalent cable bundle model,and the simulation results are in good agreement.It is shown that the proposed method can accurately simulate the crosstalk of cable harnesses containing coaxial cable and improve the efficiency of the simulation.3.For the problem that the traditional cable routing method does not consider the crosstalk between cables,a new cable harness routing method based on the maximum crosstalk constraint is proposed in order to consider the crosstalk between cable branches to be at the routing stage.First,the closed expression of the crosstalk model is derived based on the MTL equation,and the low-frequency approximate crosstalk equations for single-ended signals and differential signals are derived.According to the characteristics of the crosstalk equations,the concept of maximum overlap length corresponding to the expected maximum crosstalk is proposed.Then,the method of generating connected graph and adjacency matrix in the design domain is investigated.And the escape graph is chosen as the connected map of the routing method.A variant of Dijkstra’s algorithm with the maximum overlap length as a constraint is proposed based on the traditional Dijkstra’s algorithm.The proposed method is applied to cable harness routing for single-ended signals and differential signals,respectively,and compared with the traditional method.In contrast,the layout results obtained by the routing method based on the maximum crosstalk constraint better meet the crosstalk constraint and layout requirements.4.To transform the structural model of an electronic system cable network into an electrical model that can be used for electromagnetic simulation,a layered modeling method based on connection tables is proposed.This method divides a cable network into five levels:cable harness,cable harness branch,cable,signal and signal port.The electrification parameters for each level are completely defined by supplementing the connection table with the necessary material parameters and cable database.Combining this layered method,a system-level cable network EMC simulation solution based on the extended development of electromagnetic simulation software is proposed to realize the electrical modeling and EMC simulation of cable networks.An cable harness electrical model is created in electromagnetic simulation software and crosstalk simulation is performed.The simulation results verify that the cable network electrical model obtained by the proposed modeling method can accurately reflect the EMC performance of the cable network.