METHOD FOR SMOOTH CONTROL OF ASYNCHRONOUS ELECTRIC MOTOR WITH SHORT-CIRCUITED ROTOR Russian patent published in 2005 - IPC

FIELD: electric engineering, applicable in various branches of industry, agriculture and housing.

SUBSTANCE: the method consists in the fact that a three-phase voltage is applied via three pairs of antiparallel connected thyristors to the stator windings of the asynchronous motor, and the control signals from the pulse-phase control system synchronized in the mains voltage are supplied to the control inputs of the thyristors, a signal in the form of voltage equivalent to the opening angle of the thyristor, whose value is preset in advance in each moment of time, is applied to the mains input. The instantaneous and acting values of the mains voltage and current in the stator windings of the asynchronous motor are measured, and at a deviation of them from the preset values the supply of the control signals to the thyristors is stopped. The additionally measured acting values of current in each period of the mains are estimated as the maximum, and as soon as the maximum is attained, it is memorized and the acting value of current of one of the phases is measured anew in each period of the mains, it is compared with the maximum value. At a deviation from the maximum value by the preset value a signal is formed for full opening of the thyristors and maintained for the period of operation of the asynchronous motor in the rated conditions.

EFFECT: eliminated oscillations of the phase currents, electromagnetic moment and rotation speed of the rotor in the thyristor converter - asynchronous motor system operating as part of the electric drive with a pump or ventilation load.

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