Modeling Techniques for the Simulation of a 42-Volt ISG Charging System

CAE modeling and simulation are of great value in the development of systems related to 42-volt technology. Simulation of subsystems that contain AC electric drives requires very small integration step sizes due to the high frequency switches and AC variables. These small step sizes create problems with lengthy computation times, especially in long duration simulation of automotive systems. Two alternative solutions to this problem without compromising accuracy are instead of detailed models to use either time-averaged (for switches) or dynamic phasor models (for both switches and AC machines). In this study, all three modeling methods (detailed, averaged, and dynamic phasors) are utilized and applied to an ISG (Integrated Starter Generator) charging system, and the results are compared. Three conditions are simulated; the transition from motoring (starting) to generating mode; the change of electrical loads; and a load dump. The results illustrate that averaged and dynamic phasor models provide accurate descriptions of the transients, with a significant improvement in CPU times compared to the detailed models.