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Description
An electric drive based on the wound rotor induction motor (WRIM) needs to be optimized. The inclusion of additional resistances in the WRIM rotor circuit is used not only to regulate the motor current and torque during startup, but also to control the rotor speed. The efficiency of an induction drive can be increased by optimally selecting the parameters of the rheostat resistances and the programmable switching law of the starting rheostat sections. To do this, it is necessary to develop programs for numerical analysis of their operation both during startup and cargo movement. The paper deals with the problem of calculating the parameters of the starting rheostat of an induction motor with a phase rotor.
Mathematical models for analyzing the starting modes of an electric drive based on an WRIM have been developed, which allow choosing the numerical values of the resistances of the rheostat sections and their number, based on the starting conditions and the constraints that must be met during the starting process, to carry out mathematical modeling of the starting modes of the electric drive in order to verify the designed solutions. The calculation is based on an advanced mathematical model of the motor (in the form of differential equations of state) developed on the basis of (representational vectors of currents, voltages and fluxes) circuit theory, which takes into account the saturation of the magnetic circuit and the differential method of calculating static characteristics. Electromagnetic processes in the motor are described by a system of nonlinear differential equations of electrical equilibrium, composed in a fixed three-phase coordinate system or transformed to orthogonal x, y coordinates, which is solved by the continuation method by parameter in combination with the iterative Newton's method. The mathematical model of the WRIM uses real magnetization curves calculated on the basis of the geometry of the magnetic circuit and motor winding data, which makes it possible to adequately account for saturation and ensures the accuracy of the calculation results. Mathematical models created on the basis of the proposed calculation algorithm can be used to design regulated asynchronous electric drives based on WRIM and their control systems in order to form the necessary starting characteristics and control algorithms of electric drive systems based on WRIM.
