SU1396230A1 - Method of controlling induction motor by star-delta-star switching of its windings - Google Patents

Abstract

The invention relates to electrical engineering and can be used to regulate the loading of an electric motor in an electric drive of alternating current of general industrial mechanisms. The aim of the invention is to increase speed. Switching the phase windings 12 and 13 of the electric motor is carried out by alternately disconnecting the triacs 1, 2 and turning on the triacs 3-5, connecting to the lagging by 30 el. hail, sequence of linear stresses. Triac 1-5 is turned on at the moment of zero voltage difference on their outputs, which is controlled by zero-organs 7-10. The control switch 14 realizes the specified switching algorithm. The method allows to increase the speed when the motor switches from the star to the delta circuit and reduces the duration of the transition of the motor to a new operating characteristic. 1 il. i (L

Description

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The invention relates to electrical engineering and can be used to regulate the loading of an electric motor in AC drives of general industrial mechanisms.

The purpose of the invention is to increase speed.

The drawing shows a diagram of the device for the implementation of the proposed method: soba.

I According to the three-phase asynchronous motor control method, by switching its windings from star to triangle circuit and back switching from star to triangle circuit, one by one disconnects the ends of the winding phases from the obddey connection point and their connection to the beginning of the adjacent phases of the winding, and switching from the triangle scheme to the star circuit is carried out by alternately disconnecting the ends of the winding phases and connecting them to each other, and disconnecting the ends of the phases of the winding take place in transition of current in phases through zero, and their connection is carried out by the moment - Zero potential difference between the end of the connected winding phase and the corresponding connection point, to switch from the star to the delta circuit disconnect the end of the first phase of the winding (they turn it to the beginning of the third phase of the winding, then the end of the second phase is disconnected from the end of the third phase and connected to the patch of the third phase, the end of the third phase is connected to the beginning of the second phase and we get |; hem triangle, and switching from triangle in a star circuit disconnection start end of the first phase winding of the third iachala faz ob.motki, then the end of the second phase is disconnected from the start SW1 OH.

A device for implementing the method comprises triacs 1-5, in parallel with which zero-organs 6-10 are included, and a control unit. One pins of triacs 1 and 2 are connected to the beginnings of the first 11 and second 12 phase windings, respectively, and the other pins are interconnected and connected to the end of the third winding 13. Each of the triacs 3-5 is connected by one output to the corresponding end of one phase winding, and others to the corresponding beginning of the previous phase winding. One output of control unit 14 is connected to their; control voltage point Uy, and five other inputs to the outputs of the corresponding zero units 6-10. The outputs of the control unit 14 are connected to the inputs of the respective triacs 1-5. The device implements a method of controlling a three-phase asynchronous electric motor by switching its windings from a star to a delta circuit and back as follows.

In the absence of control signals, the triacs 1-5 are turned off, the phase windings 11-13 are disconnected and the motor is stationary.

5 Let the motor operate according to the star circuit, which corresponds to the on state of triacs 1 and 2.

When a control signal is applied for switching from the star circuit to the delta circuit, first disconnect the triac I and

 the moment of zero potential difference between the end of the first phase winding 11 and the beginning of the third phase winding 13 includes a triac 3, connecting the first phase winding 12 to a linear voltage of U5 U5. Then triac 2 is disconnected and at the time of zero potential difference between the end of the second phase winding 12 and the beginning of the first phase winding 11, the triac 4 is turned on, connecting the second winding 12 to a linear voltage

0 UBA. Further, at the time of zero potential difference between the end of the third phase winding 13 and the beginning of the second phase winding 12, the triac 5 is switched on, connecting the third phase winding 13 to the linear loading UCB and a triangle is obtained.

When switching the phase windings of an electric motor from a delta to a star circuit, first disconnect triac 3, then disconnect triac 4, and at the time of zero potential difference between the ends of the first 11 and second 12 phase windings turn on triac 1, connect the ends of these phase windings to each other. Turn off the triac biv moment of zero potential difference between the end of the third

5 windings 13 and the combined ends of the first 1 1 and second 12 phase windings include a triac 2, receiving a star circuit.

Claims (1)

Invention Formula  A three-phase asynchronous motor control method by switching its windings from a star to a delta circuit and back, in which switching from a star to a triangle circuit the gon is performed by alternately disconnecting the ends of the winding phases from the common connection point and connecting them to the beginnings of adjacent winding phases, and switching from the triangle to the star circuit is carried out by alternately disconnecting 0 ends of the phases of the winding and their connection to each other, all disconnections of the ends of the phases of the winding are carried out at the moment of current transition in the phases through zero, and their connection is carried out at the time of zero potential difference between the end of the connected phase of the winding and the corresponding point of its connection, characterized in that in order to increase speed for switching from star to circuit 1396230 34 triangle, turn off the end of the first phase of the star start off the end of the first windings from the ends of the two other phases and the sub-phase of the winding from the beginning of the third phase turn it on to the beginning of the third phase, winding, then turn off the end of the second phase the coils, then disconnect the end of the second phase from the beginning of the first phase and connect to the conza from the end of the third phase and connect the first phase, and the end of the third phase from the beginning of the first phase, end the third phase off from the beginning of the second phase and connect to the beginning of the second phase, and switch to the junction point of the first connection from the triangle to the second phase winding circuit.