* 1. Ease of fabrication;
* 2. Relatively low cost;
* 3. Low power consumption;
* 4. Versatility of application;
* 5. High reliability in operation;
* 6. Possibility of connection into the network without power converters. The main disadvantages of IMs are the following:  
* 1. Significant power losses for heat, the possibility of overheating the motor;
* 2. Lack of stability in maintaining the set speed;
* 3. Low starting torque;
* 4. Considerable starting current;
* 5. Low power factor. A significant number of the disadvantages can be eliminated by feeding the IM from a static frequency converter. The main point is that the equipment that uses this type of motor must not have precise positioning [2]. For example, IMs are used in automated equipment drives of rolling and drawing machines in the metallurgical industry. IMs are used in all machine tools, machining centers, conveyors, crane equipment, centrifuges, industrial washing machines, etc. in the metalworking industry. IMs are used in mechanical assembly production: in drives of manipulators, conveyors, and compressors. IMs are used in mining: in drilling and excavator equipment. IMs are found in the domestic sphere of human activity: in hand-held electric tools, washing machines, pumps, extractors, fans, and other equipment [3]. Control in the coordinate system oriented by the calculated rotor flux vector (\(\psi_{\text{R}}\)) is called direct-field oriented control. Usually, systems with direct orientation also contain a flow stabilization loop. However, a simpler approach and another class of systems has emerged in which the rotor flux vector (\(\psi_{\text{R}}\)) is not evaluated, but its angle is calculated from the slip and velocity (or position) of the rotor. Such a system is called a system with indirect field orientation [4]. Such system do not contain a flow stabilization loop. In this case, it is believed that if the control actions on the motor are formed based on the condition of flow constancy, then if they are accurately implemented, the flow will be constant even without stabilization [5]. As practice has shown, this approach has justified itself due to a good ratio of accuracy and simplicity of regulation. A promising direction in the theory and practice of motor control is vector control. Its mathematical basis is differential equations describing IM equally correctly both in dynamics and in statics. Torque is obtained by controlling the amplitude and instantaneous phase of stator current vector or stator voltage vector. Vector control, contrary to scalar control, allows an assembly of highly dynamic and precise IMs, providing the highest speed and control precision [6]. There are many tasks where it is necessary to provide a given speed, and the described disadvantage becomes very relevant. In such cases, vector frequency control is used, in which the controller calculates the voltage needed to maintain torque, providing a stable frequency. In contrast to scalar mode, there is a \"smart\" control of rotor magnetic flux [7]. Vector control of IM is especially relevant at low frequencies--below 10 Hz, when the operating torque of the motor is dropping significantly. In addition, this method allows to keep stable speed (with predictable linear change) during acceleration. This is achieved by obtaining a high starting torque until the motor reaches steady mode [8]. It is also important that vector control saves energy (in some cases up to 60%), because most of the time the frequency converter sends exactly as much energy to the motor as necessary to maintain the set speed [9]. At present, the most perspective method of IM control is frequency regulation, which became possible due to the intensive development of power electronics element base and computer technology. Nowadays almost all controlled electric drives based on IMs are controlled by frequency converters (FC) [10].