Sliding mode control for an induction machine submitted to large variations of mechanical configuration

In this paper, a variable structure control (VSC) algorithm with a time-varying switching surface is combined with an indirect field-oriented control in order to control the position of an induction machine shaft submitted to large variations of mechanical configuration such as inertia or load torque changes. The introduction of a time-varying switching surface guarantees the existence of a sliding mode since the beginning of the shaft motion without any chattering effects. Indeed, this moving switching surface allows the reaching phase elimination and the motor behaviour is insensitive to unknown mechanical configuration changes. The algorithm has been first tested in simulation and then implemented using a low-cost DSP platform combined with a numerical coprocessor. Finally, an advanced test bed is used in order to evaluate the tracking properties and the robustness capacities of the VSC law with variations of the mechanical configuration. Copyright (c) 2007 John Wiley & Sons, Ltd.