Model development and research of a smooth start of the induction motor with two adjustable phases for a pump electric drive
Students Name: Maidan Roman Andriiovych
Qualification Level: magister
Speciality: Electrical Energetics, Electrical Engineering and Electromechanics
Institute: Institute of Power Engineering and Control Systems
Mode of Study: full
Academic Year: 2022-2023 н.р.
Language of Defence: ukrainian
Abstract: Soft start devices are simply necessary for all sectors of production, agricultural industry and even in the household sector. Soft start devices are necessary wherever there are asynchronous electric motors. A soft start device is an electrical device used with asynchronous electric motors that allows you to keep the motor parameters (current, voltage, etc.) within safe limits during start-up. Its use reduces starting currents, reduces the probability of motor overheating, eliminates jerks in mechanical drives, which ultimately increases the service life of the electric motor. The purpose of soft start devices is to control the process of starting, running and stopping electric motors. The main problems of asynchronous electric motors are: the impossibility of matching the motor torque with the load moment; high starting current. During start-up, the torque often reaches 150-200% in a fraction of a second, which can cause the drive kinematic circuit to fail. At the same time, the starting current can be 6-8 times greater than the nominal one, causing problems with the stability of the power supply. Soft starters avoid these problems by making engine acceleration and deceleration slower. This allows you to reduce starting currents and avoid jerks in the mechanical part of the drive or hydraulic shocks in pipes and valves at the time of starting and stopping the motors. The first section of the explanatory note discusses the advantages of using soft start devices. Special attention is paid to their technical characteristics and switching schemes. The first section of the explanatory note discusses the advantages of using soft start devices. Special attention is paid to their technical characteristics and switching schemes. Study object ? transient processes of regulating the voltage of the asynchronous electric drive of the pump. Scope of research ? transient processes in the asynchronous electric drive of the pump during start and braking in the case of voltage regulation in two phases with the help of thyristors. Goal of research: to analyze soft-start devices used for soft-starting and stopping of three-phase induction motors with short-circuited rotors. Analyze the advantages of using these devices. Develop a model of an electric drive of a smooth start of an asynchronous motor with a load in the form of a pump in MATLAB Simulink. Conduct research on the developed model of the pump drive in different operating modes, namely, starting the electric drive with different supply voltages, load moments, fixed and smooth opening angle of thyristors ?. In the second chapter, the theory of various methods of soft start of the electric motor and various methods of starting for the motor are considered. The third chapter deals with the basics of theoretical modelling of pumps and asynchronous machines when using the SimPowerSystems package. In the fourth chapter, a step-by-step implementation of the model of the electric drive of the soft-start pump with an asynchronous motor is carried out and the possibilities of each new stage of building the model in MATLAB Simulink are shown. In the fifth chapter, the study of the model of the electric drive for soft start of the pump with an asynchronous motor, namely the start of the electric drive with different supply voltages, load moments, simulated pump load, fixed and smooth thyristor opening angle ?, is carried out. Key words: asynchronous motor, pump, electric drive, soft start device, automation, mathematical model. References: 1. Zhijun Jiang, Xiaoling Huang and Na Lin, "Simulation study of heavy motor soft starter based on discrete variable frequency," 2009 4th International Conference on Computer Science & Education, 2009, pp. 560-563. 2. T. C. Mallick, S. Dhar and J. Khan, "Artificial neural network based soft-starter for induction motor," 2015 2nd International Conference on Electrical Information and Communication Technologies (EICT), 2015, pp. 228-233. 3. M. Rashevskaya, S. Yanchenko and S. Tsyruk, "Assessment of non-stationary harmonic distortion related to adjustable speed induction motor and soft starters," 2018 20th International Symposium on Electrical Apparatus and Technologies (SIELA), 2018, pp. 1-4. 4. A. M. Zyuzev, D. P. Stepanyuk and M. V. Bubnov, "Application of passive power filter with induction motor soft starter," 2016 2nd International Conference on Industrial Engineering, Applications and Manufacturing (ICIEAM), 2016, pp. 1-4.