Simulation research of EMI on automotive ignition system

Ignition system is the critical electromagnetic interference (EMI) source in automotive, the conducted EMI caused by the transient voltage of primary circuit will attack the accumulator and interfere the ECU or other electronic devices by power cord; The high frequency spark noise caused by spark plug broken down will produce. In this paper, the changing of ignition coil voltage and current is analyzed when ignition switch is closed and open respectively, and the discharged circuit model of spark plug is set up, the electric field distribution in automotive is calculated while the high-voltage wire is regarded as an unipole antenna. Results indicate that using damped wire and adding spark plug resistance can suppress the spark noise.