Vestnik of Samara State Technical University. Technical Sciences SeriesVestnik of Samara State Technical University. Technical Sciences Series1991-85422712-8938Samara State Technical University61170Original ArticleAsynchronous motor rotation speed observerStarikovAlexander V.<p>Dr. Sci. Techn., Professor, head of the department</p>info@eco-vector.comStrizhakovaElena V.<p>Ph.D. Techn., Associate Professor</p>info@eco-vector.comBelyaevaOlga S.<p>Postgraduate Student</p>info@eco-vector.comKareem AltaheAbbas A.<p>Postgraduate Student</p>info@eco-vector.comSamara State Technical UniversityUlyanovsk State Technical University151220202841551661702202117022021Copyright © 2020, Samara State Technical University2020<p class="a"><span lang="EN-US">The paper is devoted to the mathematical foundations of creating sensorless speed stabilization systems for induction motors with scalar control. There are many applications of AC electric drives where scalar control is required, and the use of speed sensors is impossible for technical or economic reasons. Most modern observers of the asynchronous motor speed are intended for electric drives with vector control and are based on solving differential equations using Kalman filters or an adaptive model of an asynchronous motor. The paper discusses a new approach to creating a speed observer, based on solving the algebraic equation of the induction motor mechanical characteristics. The change in the rotor speed of the motor under the influence of the load torque and the variation of the stator voltage is analyzed. A coefficient connecting the speed of an induction motor with voltage is introduced. It is shown that its value depends on the initial conditions and the moment of loading. The nonlinear relationship between the torque developed by the motor and the stator current is taken into account. As a result, the analytical relationship is found that connects the speed of an induction motor with the effective values of the stator voltage and current and the frequency of these values. An assessment of the adequacy of the obtained formula for calculating the induction motor speed in a scalar frequency control system is carried out. The results of field experiments are presented, which show that the maximum error in calculating the speed from the found analytical dependence does not exceed 4.3%. It is concluded that the use of the formula obtained is essential in the asynchronous motor speed observer of the electric drive with scalar control.</span></p>AC electric drivespeed observerinduction motorscalar frequency controlэлектропривод переменного токанаблюдатель скоростиасинхронный двигательскалярное частотное управление[Anuchin A.S. Control systems for electric drives. Moscow: Publishing house MEI, 2015. 373 p.][Kalachev Yu.N. State observers in a vector drive. Moscow, 2015. 80 p.][Pankratov V.V., Kotin D.A. Synthesis of adaptive algorithms for calculating the speed of an asynchro-nous electric drive based on the second Lyapunov method. Electricity. No. 8. 2007. Pp. 48–53.][Vdovin V.V. Adaptive Coordinate Estimator Algorithms sensorless AC drives with an extended control range: Dis…. Cand. tech. Sciences. Novosibirsk: Novosibirsk State Technical University, 2014. 244 p.][Vinogradov A.B., Kolodin I.Yu. Sensorless asynchronous electric drive with an adaptive vector control system. Electricity. No. 2. 2007. Pp. 44–50.][Langraf S.V., Glazyrin A.S. Application of the Kalman filter in a torque asynchronous electric drive with vector sensorless control. News of higher educational institutions. Electromechanics. No. 6. 2009. Pp. 61–64.][Langraf S.V., Glazyrin A.S., Afanasyev K.S. The use of the Luenberger observer for the synthesis of vector sensorless asynchronous electric drives. News of higher educational institutions. Electrome-chanics. No. 6. 2011. Pp. 57–62.][Afanasyev K.S., Glazyrin A.S. Identification of the speed of the asynchronous electric motor of the laboratory stand using the Kalman filter and the Luenberger observer. Electrotechnical complexes and control systems. No. 4 (28). 2012. Pp. 66–69.][Kovchin S.A., Sabini Yu.A. Electric drive theory. St. Petersburg: Energoatomizdat, 1994. 496 p.][Klyuchev V.I. Theory of electric drive. Moscow: Energoatomizdat, 2001. 704 p.][Onishchenko G.B. Electric drive. Moscow: RAAS, 2003. – 320 p.][Terekhov V.M., Osipov O.I. Control systems for electric drives. Moscow: Academy, 2005. 300 p.][Mikhailov O.P. Automated electric drive of machine tools and industrial robots. Moscow: Mechanical engineering, 1990. 304 p.][Sokolovsky G.G. AC electric drives with frequency regulation. Moscow: Academy, 2006. 265 p.][Starikov A.V., Lisin S.L., Tabachnikova T.V., Kosorlukov I.A., Belyaeva O.S. Linearized mathematical model of a submersible induction motor. Bulletin of the Samara State Technical University. Series. “Engineering sciences”, 4(64). 2019. Samara: SSTU. Pp. 155–167.]