A study of the transient behavior of a 42 V prototype integrated starter alternator for sudden load changes

This paper presents the analysis of the transient behavior of a prototype 42 V integrated starter alternator (ISA) for sudden DC load changes. The developed prototype system includes a field oriented controlled (FOC) induction machine drive, which is operated in both motoring and generating modes (ie. starter and alternator modes). During starting, the induction machine cranks the engine, which is emulated using separately excited DC motor, with high starting torque. In the generation mode, the power is input to the ISA from emulated engine while the DC bus voltage is maintained at 42 V. The prototype ISA was subjected to various sudden load changes when it is running as a generator in order to observe the transients in the DC bus voltage, motor voltages, and currents and so on. In this paper, experimental results are presented with a view to understand the transient characteristics of the system for sudden load changes.