Comprehensive Modeling of Automotive Ignition Systems

This paper presents a comprehensive approach to improve the analysis and design process of automotive ignition coils. The delivered voltage and energy of the coil to the spark plug load are the two essential requirements placed on a coil design. The prediction of these two quantities, derived from the simulated transient secondary current and voltage, is fundamental to the design process and allows early assessment of design robustness. With only the data required for electromagnetic finite element analysis (FEA), including material loss data, the magnetic and electrostatic interactions among the coil laminations and windings can be modeled. These field computations are converted to equivalent circuit elements employed in a systems model. The systems model allows the calculation of requisite transient signals. This approach is highly flexible and gives fast simulations. Good agreement was obtained between the test data and the simulation results in both the time-domain and the frequency-domain.