Simulation And Experiment Research On Electromagnetic Interference Of Automobile Ignition System

With the rapid development of the automobile industry and electronic technology, a growing number of electronic devices are used to enhance the automotive comfort and safety, while at the same time the electromagnetic compatibility (EMC) issues of the vehicle's electrical system have become increasingly prominent. The strongest electromagnetic interference (EMI) of the car is from ignition system; therefore, the research on it has important theoretical significance and the value of the enginer.Based on in-depth study of automobile ignition system, author analyzed the working principle of their influence on electromagnetic harassment, calculated the ignition current and the electronic field distribution inside automobile. And the conclusions listed as follow:â‘ Established an equivalent model of ignition system's primary circuit, and analyzed the current and voltage changes of the ignition switch from the closure to the process of ignition coils in, and thus gained its conducted interference characteristics and at the same time got the corresponding methods to transient voltage suppression.â‘¡Established an equivalent model of the secondary loop based on the distributed capacitance discharge of spark plug, simulating the spark current when the spark plug broken-down. And then calculated the electronic field distribution while making the high-voltage wires as a monopole antenna, and compared the environmental impact of the car produced by high-voltage wire whih changing location, the length, working frequency, terminal load impedance.The results show that the length and working frequency of high-voltage wire closely related the noise distribution. And adding load resistor to the terminal can suppress the noise effectively.â‘¢Deeply study the Chinese standards of the automobile EMC test, according to GB-18655, designed ignition system testing programs, and finished actual measurement to get the ignition system waveform, electromagnetic radiation on the vehicle, and electromagnetic radiation on receivers used on board vehicles produced by ignition system, meanwhile, compared the results of shielding high-voltage wires with enwind tinfoil.â‘£Analyzing the experimental data, and compared with the calculated spark current in the equivalent model to prove the correctness of the model. Provide a reference to further improve the model and design other experiments. This paper systematically analyzes EMI characteristics of the ignition system, calculating the impact of the ignition system on the electromagnetic environment inside of automobile, and provides reference for ignition system electromagnetic compatibility design.