ASYNCHRONOUS MOTOR WITH A HOLLOW PERFORATED ROTOR

Abstract

The paper presents a brief analysis of the conducted researches of the asynchronous executive motors and the induction motor, as well as the design of the asynchronous executive motor with a hollow perforated rotor. The basic relationships for determining the geometry of the rotor that directly influences the energy performance of the electric machine are also presented. The calculations to determine the geometry of the windows, located within a part of the active length of the stator package in the zone adjacent to the solid frontal area of the surface of the barrel from the side of its end face that is opposite to the bottom of the rotor barrel. In an asynchronous motor with a hollow perforated rotor improvement of energy performance (increase of maximum torque, efficiency and cosj of the engine) is achieved. These advantages are provided by the fact that the windows in the hollow rotor barrel are located within the part of the active length of the stator package in the zone adjacent to the solid frontal section of the rotor barrel surface on its end face that is opposite to the bottom of the barrel. In accordance with the design of the hollow rotor, the bottom of the barrel of one of the ends acts as superconducting short-circulating ring, therefore the ratio of increase in resistance (caused by the transverse edge effect) depends on the distribution of the rotor currents in the area adjacent to the solid frontal portion of the surface of the barrel on end that is opposite to the bottom of the barrel. In the analysis of current density distribution in a hollow rotor with the axial length L', all electric constant and geometric dimensions that are taken into account in the calculation are known values. Arbitrarily set constants are the primary currents and the rotational frequency of the rotor. With the rotation speed increase, due to the presence of the windows on one end face of the rotor and to the impact of the bottom of the barrel on the other one, the elementary currents of the rotor within the active length of the machine boring would be directed mainly in the axial direction, including the cases of comparatively small slippage that corresponds to the small frequency of the alternating magnetization of the rotor material. I. e. a certain part of the active surface of the rotor on the end that is opposite to the bottom of its barrel would not function as the frontal part of the winding while reducing the frequency of currents in the rotor material. This provides an increase in the active component of the rotor current that is proportional to the electromagnetic torque of the motor. Correspondingly, the frontal parts of equivalent winding of the hollow rotor (through which the currents do not generate torque) would not be spread at high rotational speeds to the area of the active length of the machine.