Analogs and characteristics of compensated asynchronous machines with different numbers of phases

Аннотация

The disadvantages of three-phase asynchronous motors with short-circuited rotors, which are widely used in practice, are discussed. It is determined that the most significant disadvantage is consumption of two types of electric energy from a network: active energy for conversion into mechanical energy accompanied by inevitable heat losses and reactive energy that is not converted into other types of energy, but is expended on generation of the magnetic field required for electromechanical conversion of energy in an electrical machine. It is suggested to use internal capacitive compensation of reactive power to improve the technical and economic indices of asynchronous machines of both motors and generators. In addition, each phase winding of the asynchronous machine stator is divided into two parts equal in number of turns spatially shifted between each other in the core slots by an angle of 30°. These parts are connected according to the scheme of the rotary autotransformer to the electrical capacity at its output. The change of the spatial position of the stator windings leads to a change in time of the action of the phase angles of their electromotive force and, therefore, of currents and voltages without changing the introduced reactive impedances. Thus, the spatial coordinate of the electrical value is converted into the time coordinate in the electromagnetic circuit with a rotating magnetic field. The combination of this property of the stator windings in accordance with the rotary autotransformer with the action of the electrical capacity at its output creates the effect of internal capacitive compensation of reactive power in an asynchronous machine. The ability to use internal capacitive compensation of reactive power in single-phase asynchronous machines is considered. A method of calculation of the characteristics of compensated asynchronous machines taking into account the change of the magnetizing contour resistance is presented. The advantages of compensated asynchronous motors and compensated asynchronous generators are determined. Recommendations as to their effective practical use are given.