Predictive control of induction motor drive with transformer

Abstract

This paper deals with the control of induction motor drive powered by 3-phase VSI with 3-phase output transformer. The drive configuration using transformer to adjust the voltage level from the converter is common for example in submersive pumps drives or in mining industry where the transmission line is limited to low voltage levels. Another field, where such drive configuration finds its place is in the testing facilities where the converter needs to cover wide portfolio of ac drives from medium voltage to low voltage range. The transformer together with usually long cables and difficult availability of the speed measurement strongly complicates the control design. A common control algorithms are based on open loop voltage per hertz techniques which are very simple and robust however they fails to provide high dynamic performance. In such a case FOC based algorithms may be used, which strongly increases the complexity of the cascade based control design, especially during motor startups, where high demanded torque may easily result in over-saturation of the transformer. In this paper we use popular version of the predictive control FCSMPC using complete model of the drive with the transformer. The resulting control algorithm is very simple and robust while provides high dynamics and effective solution to over-saturation of the transformer even in the low speed operation. The theoretical assumptions are validated by simulations.