FREQUENCY-PARAMETRIC CONTROL SYSTEM OF AN ASYNCHRONOUS ELECTRIC DRIVE WITH AN OBSERVER OF THE ANGLE BETWEEN THE VECTORS OF THE STATOR CURRENT AND THE MAGNETIZATION CURRENT

In industry, especially metallurgy, a large number of previously installed electric drives based on an asynchronous motor with a phase rotor with uneconomical parametric control systems are used, the advantage of which is the possibility of removing part of the sliding energy from the rotor circuit, and the ability to obtain an increased inrush current multiplicity. The use of frequency converters in such an electric drive allows you to adjust the speed of rotation of the stator field and maintain sliding and losses in the rotor circuit at a minimum level. However, when the rotor windings are shorted, the multiplicity of the starting torque decreases. Additional possibilities for maintaining an increased starting torque of an asynchronous motor with a phase rotor with frequency control are provided by the inclusion of a frequency-dependent active-inductive resistance (IR) in the rotor circuit. In this case, the electric drive will be frequency-parametric. Using an observer of the mutual position of the stator and rotor current vectors, working on the basis of processing the measured signals of instantaneous values of the stator and rotor currents, allows you to build a scalar control system with stator current correction, bringing the operation of the electric drive to the mode with minimal losses in the motor windings.