A Matlab/Simulink model for a prototype integrated starter alternator for automobiles

This paper concerns the development of a full dynamic model for a integrated starter alternator (ISA) employing an induction generator, for potential use in the future automobiles. The model includes a direct rotor flux oriented controlled (DFOC) induction machine drive, which is operated in both motoring and generating modes (i.e. starter and alternator modes). During the starting, the induction machine cranks the engine with high starting torque against the engine restoring torque. When the speed of the engine is increased to a certain value that ensures the complete starting of the engine, the control system changes the induction machine into the generation mode. In the generation mode, the power is input to the machine from the automotive engine which is modeled as an infinite source of torque. The DC bus voltage is maintained at 42 V. The operating speed of the modeled ISA can be varied, with field weakening starting at the machine base speed. The model successfully allows many operational aspects of the proposed ISA to be predicted, in particular the regulated DC voltage developed by the ISA during conditions of load dump step speed increase.