Rudenko M. Determining the parameters of electric drive with induction motor and taking into account the effect of current displacement

The dissertation is solved to date the actual scientific task of improving the accuracy of identification of electromagnetic parameters of induction motors in starting modes. The process of current displacement in the rotor of common induction motors is analyzed and the related with it phenomenon of increase of rotor resistance. As a result, polynomial expressions are obtained for the nonlinear parameters of the rotor circuit of a T-shaped equivalent circuit, namely active resistance and inductance, by approximating the graphs of their change when motor is starting. A mathematical apparatus for obtaining different types and kinds of pseudopolyharmonic signals has been developed with the use of reducing the initial signal period by the corresponding cutoff angles and the principle of axial symmetry, which allows to obtain the necessary harmonic composition for the formation of nonlinear identification equations of the instantaneous power balance using the energy method. Possibility and expediency of using energy storage devices in measuring and diagnostic complexes for post-repair tests of induction motors, which allow to obtain the necessary test signals of currents and voltages, which are close to the starting ones, even with a braked rotor and without the risk of isolation breakdown or its destruction and overheating is proved. This allows identify EMP of IM using the energy method in conditions close to the start of motor, in which the effect of displacement current has a greatest effect on the change of EMP of motor’s rotor. It is experimentally confirmed that based on the obtained polynomial dependences of active resistance and rotor inductance, and provided working out of the developed algorithm of operation of the identification system of EMP of IM, it is possible to improve accuracy of their determination during post-repair tests.