Optimization of the stator voltage pattern in the sliding mode controlled induction motor drive

This article addresses the optimization of output voltage pattern of the voltage source inverter, which feeds an induction motor drive under the control in the d-q frame and variable structure. Used are the Lyapunov method for the sliding mode condition and hierarchical control with distinguished control stages, i.e. the sliding is established, and the sliding is preserved. For each stage, strategies selecting inverter switching states are proposed. This assures sliding like motion within the neighbourhood of prescribed intersection of switching lines. Neighbourhood is determined with two time-discrete hysteresis controllers. The proposed modulations are tested by simulations which confirm expected improvement over the known reference example. It is all well within real-time capabilities of contemporary microprocessor technology