Digital Model and Experimental Implementation of Suboptimal Control of Induction Motor

Abstract

This article examines a digital model of an induction motor (IM) speed control system using a thyristor voltage converter (TVC). The model, using timing diagrams, clearly demonstrates the feasibility of reducing the IM stator current at idle and under load conditions lower than the nominal value. This is particularly relevant for a wide range of mechanisms, such as pumping stations, water supply and wastewater disposal systems, lifting devices, conveyors, metal-cutting and woodworking machines, fans, and many others that, due to technological features, operate at less than full capacity or alternate between nominal and idle operation. The modeling results are confirmed by experimental studies with provided voltage and current oscillograms. It is shown that when operating at a suboptimal electromechanical characteristic, the IM power factor remains near the nominal value. Mathematical dependences of the TVC output voltage on the IM load are presented, allowing the motor to operate at a suboptimal electromechanical characteristic in terms of minimum stator current. Good agreement between the results of digital modeling and experimental studies was noted.