Comparative analysis of on-line and off-line explicit solutions, applied in predictive direct current

This paper presents a comparative analysis of two Model Direct Predictive Controllers (MDPC), which are applied to the inner loop current control of a field-oriented control scheme for an ac drive. A model of the controlled system which includes the dynamics of the inverter (boolean and discrete) and also of the machine (continuous) is employed to predict the future stator currents for a pre-defined finite horizon. Using such information, a cost function is optimized to determine the value for the actuating variable. Such procedure is realized using an off-line as well as a on-line optimization methods. In this case, the predict control belongs to the group of direct control, therefore the actuating variables are the switching states [S_a S_b S _c] for the inverter.