SU1695483A1 - Asynchronous electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in electrical vibration drives of machines and mechanisms. The aim of the invention is to increase the efficiency of the reverse. The asynchronous electric drive contains a two-phase electric motor 1, a thyristor switch 2 with a control unit 3 and three capacitors 4-6. The control unit 3 generates control pulses with variable frequency and duty cycle. When key 2 is off, the current through the winding 8 of the electric motor flows through the circuit: capacitor 5 - winding 8 - capacitor 6, and with key 2 turned on - along the circuit; the winding 8 is a capacitor 4. Thus, the reverse of the electric motor is carried out by means of an anti-switching mode, which makes it possible to increase its reliability and increase its efficiency. 1 il.

Description

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The invention relates to electrical engineering and can be used in electric vibratory drives of machines and mechanisms.

The aim of the invention is to increase the efficiency of the reverse.

The drawing shows a structural diagram of the drive.

The asynchronous electric drive contains a two-phase asynchronous electric motor 1, a thyristor switch 2 with a control unit 3, the first 4, the second 5 and the third 6 capacitors. The first terminal of the first winding 7 of the electric motor 1 is connected to one output of the first capacitor 4 and the first terminal for connecting to a single-phase alternating voltage source, the second terminal of the first winding 7 of electric motor 1 is connected to a second terminal for connecting to a single-phase alternating voltage source, with the first the output of the thyristor switch 2 and one output of the second capacitor 5, the other output of which is connected to another output of the first capacitor 4 and the first output of the second winding 8 of the electric motor 1, the second output of which oedinen with the second terminal of the thyristor switch 2 and one terminal of the third capacitor 6, the other terminal of which is connected to one terminal of the first capacitor 4.

The drive works as follows.

The first 4, second 5 and third b capacitors and the thyristor switch 2 form a phase shifter. The winding 7 of the electric motor 1 is connected directly to the network, the current in it does not change its direction. The winding 8 of the electric motor 1 is included in the diagonal of the phase shifter, the direction of the current in it depends on the state of the thyristor switch 2. The control unit 3 generates pulses with variable frequency and duty cycle, opening the thyristor switch 2. With the nonconductive thyristor switch 2, current flows through the winding 8 : capacitor 5 - winding 8 - capacitor 6, and for conductive - along the circuit; winding 8 is capacitor 4. Thus, depending on the state of the thyristor switch 2, the current in winding 8 changes its direction. Capacitors 4-6 are selected based on the following conditions: the absolute value of the phase difference between the currents of the winding 7 and the winding 8 is approximately equal to

l / 2 radians in the open and closed state of the thyristor switch 2, which allows to obtain a circular rotating magnetic field during the reverse; the capacitors 4-6 must be such that reactive power is compensated for during the reverse process; when changing the capacitance of the capacitors 4-6 regulate the amount of current in the winding 8, this causes the necessary torque on the shaft

motor 1 and establishes the necessary relationship between clockwise and counterclockwise rotation.

In the thyristor switch 2, natural switching is used, which eliminates

shock currents and shock moments on the shaft, the electric motor 1, arising during the reverse, because at the time of the reverse the current in the winding 8 is zero.

The use of the proposed device for initiating the self-reverse of a two-phase asynchronous electric motor makes it possible to increase the efficiency of the reverse and increase the efficiency, since the most effective anti-switching mode is used for the reverse.

Claims (1)

The invention is an asynchronous electric drive containing a two-phase asynchronous electric motor, a thyristor switch with a control unit and the first capacitor, one output of which is connected to the first output of the first winding of the electric motor and the first terminal for connection to a single-phase a variable voltage source, another output of the first capacitor is connected to the first output of the second motor winding, characterized in that, in order to increase the efficiency of the reverse, The second and third capacitors are inserted into it, one output of the second capacitor is connected to the second output of the first motor winding, to the first output of the thyristor switch and to the second terminal for connecting to a single-phase AC source, another terminal of the second capacitor is connected to the first terminal of the second motor winding, the second terminal of which is connected to the second terminal thyristor key and one output of the third capacitor, the other output of which is connected to one output of the first capacitor.