VIRTUAL MODEL OF THE SYSTEM "INDUCTION MOTOR - SOFTSTARTER WITH TWO CONTROLLED PHASES"

Abstract

One of the most commonly used start methods of induction motors  is starting by gradually increasing the supply voltage. At the same time, softstarters based on thyristors or triacs are used, which are cheaper in comparison with  frequency inverters based on IGBT - transistors. In turn, the disadvantage of this method of starting with significant reduction of the starting torque, so the possibility of using such starters for various executive mechanisms requires careful research. In the presence of a limitation of power source power, especially in wartime conditions, the problem of limitation of starting currents, especially in the case of using starters with two adjustable phases, is actual. To take into account the multiplicity of starting currents for different types of mechanisms, a mathematical model of the system " induction motor - softstarter with two controlled phases" was created. The model differs from the known ones by the possibility of limiting the power of the power supply network, the appearance of the mechanical characteristics of the executive mechanism and the starting moment at voltage ramp start mode. Transient processes in relative units for the possibility of estimating the multiplicity of starting currents to determine the required power of the autonomous power source are presented. To assess the adequacy of the mathematical model, a research stand with measuring of motor winding currents using a current transformer and a microprocessor device with an oscillography function was created. In the work, a comparative analysis of the results of modeling and experimental studies on a physical model is carried out, herewith the discrepancy of the results did not exceed 10%. It was determined that when using a soft-start device with two adjustable phases, even with small voltages, the current multiplicity is quite high and requires the use of a power source of greater power, but less than in the case of direct start. Formulated conclusions based on research results and recommendations for further reduction of starting currents.