Impact of Stray Load and Iron Losses on Vector Control of Small Induction Generators

This paper presents the analysis of detuning induced by the stray load and iron losses in vector-controlled self-excited induction generators (SEIGs). Previously, the stray load loss impact has been examined only for induction motors. Detuning in vector-controlled induction machines (IMs) is caused by a mismatch between the actual IM and the corresponding mathematical model. This usually implies disagreement between the actual and assumed values of IM parameters or between the actual and modeled phenomena. The detuning is characterized by a misalignment between the actual and reference flux vector (i.e., flux angle error) or by a non-unity ratio of actual to reference flux vector magnitudes (i.e., flux magnitude error). The presented analysis encompasses load torques up to the rated value and rotor flux values down to 50% of the rated value. For this purpose, an IM model is utilized in which the stray load and iron losses are modeled as variable with respect to the operating frequency, flux, and torque. The simulation model of the considered system is built in the MATLAB-Simulink. Three small IMs (1.5 kW) of different efficiency and rotor material have been considered.