| With continuous enhancement of informationization and intelligence level of vehicle,more and more vehicular electronic devices are used in the vehicle.Therefore,higher requirements are put forward for the electromagnetic compatibility(EMC)design of vehicular electronic devices.On the one hand,the interference of various electronic equipment in the vehicle platform with the vehicular electronic devices is becoming more complicated.On the other hand,the development and application of artificially strong electromagnetic pulses(EMP)pose new challenges to the safety of vehicular electronic devices.Studying the complex electromagnetic environment effect of vehicular electronic devices is the premise of effective electromagnetic compatibility design,and it is very important to ensure the mobility and safety of vehicles.The thesis takes a civilian vehicle on with ultrashort wave radio and Beidou navigation system are carried as an example,the research is conducted by using numerical simulation and statistical method,focusing on four kinds of interference effects of vehicular electronic devices in complex electromagnetic environment: interference of vehicle electronic equipment with vehicular electronic devices,the mutual coupling interference between vehicular electronic devices,interference of vehicular electronic devices with vehicle electronic equipment as well as EMP interference.The aim is to carry out optimization of antenna layout and EMP protection design of vehicular electronic devices with reference of the analysis result,the main research content of the paper is as follows:(1)Analysis of EMC between vehicle electronic equipment and vehicular electronic devices.The mechanism of electromagnetic interference is analyzed from vehicle ignition systems and wiper motor circuit theory,the common mode conducted interference signals are extracted and vehicle system level EMC simulation model is established.Based on cable radiation emission model and the antenna model simulation the vehicle electromagnetic environment with coexistence of multiple interference sources,disturbed signal characteristics of VHF antenna and Beidou navigation antenna is analyzed when they are installed in different positions of the vehicle.The simulation results show that the amplitude of interference signals at ports of VHF antenna and Beidou navigation antenna can exceed the receiver sensitivity when ignition system and wiper motor which are not subjected to processing of electromagnetic compatibility are adopted in order.Disturbed extend can be effectively reduced by amplitude of interference signals.(2)Analyses of radiation characteristics of vehicular electronic devices and comprehensive layout of antennas.On basis of the calculation model of coupling between antennas and the theory of antenna radiation,the relationship among VHF antenna and Beidou navigation antenna’s coupling degree and antenna pattern distortion degree and their installation position is analyzed through simulation,and the statistical characteristics of vehicle cab field strength under excitation by high-power VHF antenna is also analyzed.Results show that by changing the antenna installation position,the antenna pattern distortion and the antenna coupling degree can be effectively reduced.Entire field strength distribution in driving cab complied with generalized extreme value(GEV)distribution under VHF antenna excitation,high value field strength complies with Generalized Pareto(GP)distribution,Peak Over Threshold(POT)model can be used to calculate maximum value of field strength of the cab.Finally,the ideal point sorting method is used to optimize the comprehensive layout of the antenna of the vehicular electronic devices’ antennas.(3)Analysis and protection of EMP effect on the front door of vehicular electronic devices.Establish the electromagnetic pulse irradiation model of the front door of the vehicular electronic devices.The disturbed signal characteristics of the VHF antenna port and the Beidou navigation antenna port under radiation of HEMP and HPM is analyzed through simulation.The statistical method is used to analyze the variation interval of the front door disturbed signal amplitude of the vehicular electronic devices when the HPM’s incoming parameters changed.Based on the simulation results,the front door protection circuit of the vehicular VHF radio is designed.The results show that the protection circuit has an insertion loss of 0.6dB,and has a suppression capability of 30 dB for continuous and high-voltage nanosecond EMP.Contribution and innovation are as follows:(1)An analysis method based on POT model to predict the maximum field strength of the vehicle cab is proposed.The method obtains the field strength samples of the cab through numerical software,fits the entire distribution of the field strength with the GEV distribution,and applies the POT model based on the GP distribution to study the statistical characteristics of the field strength and predict the maximum field strength.The results show that the entire field strength complies with GEV distribution when the VHF antenna with a frequency of 144 MHz and transmission power of 50 W excites at different installation positions.The deviation that GP distribution fits the high-value field strength is smaller.The POT model can be calculated when the VHF antenna excites in the upper left corner of the roof the maximum field strength of the cab is the smallest,and the maximum value of field strength is 194.8V/m.(2)The front door disturbance analysis method and electromagnetic compatibility design scheme of vehicular electronic devices under the action of multiple interference sources are proposed.The method is based on the radiation emission model of the vehicular electronic devices and the antenna radiation model,quantitatively analyzes the disturbed situation of the vehicular electronic devices in the coexistence of the interference between the vehicle electronic equipment and other vehicular electronic devices,and uses the ideal point sorting method to optimize antenna layout for vehicular electronic devices’ antenna according to the analysis result and taking various EMC indexes into account.The results show that when a variety of vehicle electronic equipment that are not processed by electromagnetic compatibility coexisting,the front door disturbed signal of the vehicular electronic devices exceeds its receiving sensitivity.The ideal point sorting method can evaluate performance of electromagnetic compatibility between the vehicle in regards of a plurality of electromagnetic compatibility indexes such as the disturbed signal of antenna of the vehicular electronic device,the coupling degree between the antennas,as well as the pattern distortion. |
