SU1259454A1 - Method of controlling three-phase induction electric motor by switching its windings from delta connection to star connection and vice versa - Google Patents

Abstract

The invention relates to electrical engineering and can be used to regulate the load of an AC motor of conventional mechanisms. The purpose of the invention is to improve the speed and reliability of motor operation. The method of controlling a three-phase asynchronous electric motor by switching its windings from the star to the delta and vice versa schemes is carried out when the current in the phases passes through zero, and the ends of each phase of the winding are connected when the potential of the connected winding phase is equal to the corresponding linear voltage network. A device that implements this method. contains triacs 1-5, in parallel with which are included the zero-organs 6-10 and the control unit 11. One input of the control unit 11 is connected to a source of control voltage, five other inputs - to the outputs of the corresponding zero-organs 6-10. The outputs of the control location 1 1 are connected to the inputs of the corresponding Siyistor 1-5. 1 il. VSL GCHD SP with 4:

Description

The invention relates to electrical engineering and can be used to regulate the loading of an AC motor of general industrial 5J mechanisms.

The purpose of the invention is to increase the speed and reliability of the motor.

The drawing shows a diagram of the device that implements the proposed method.

A method of controlling a three-phase asynchronous electric motor by switching its windings from a star to a delta and vice versa scheme is as follows.

First, disconnect the end of the first phase of the winding from the ends of the other two phases of the winding and connect it to the beginning of the second phase, then disconnect the end of the second phase from the end of the third phase and connect to the beginning of the third phase, end the third phase connect to the beginning of the first phase and get a triangle pattern. Switching from a delta to a star circuit is started by disconnecting the end of the first phase of the winding from the beginning of the second phase of the winding, then the end of the second phase is disconnected from the beginning of the third phase and connected to the end of the first phase, and the end of the third phase is disconnected from the beginning of the first phase and connected to the connection point the first and second phases, all of which are disconnected at the moment of the current passing in the phases through zero. In order to increase the speed and reliability of the electric motor, connecting the ends of each phase of the winding is carried out at the moment when the potential of the connected phase of the winding is equal to the corresponding linear voltage of the mains supply.

A device that implements the proposed method contains a simist, ores 1-5, in parallel with which are included the zero-organs 6-10 and the control unit 11. Some pins of triacs 1 and 2 are connected to the beginnings of the first and second phase windings 12 and 13, and the other pins are interconnected and connected to the end of the third winding 14.

Some pins of the triacs 3-5 are connected to the corresponding ends of one phase windings, and the other conclusions to the corresponding beginnings of the other phase windings. One input block

11 of the control is connected to the source of the control voltage U, five other inputs are connected to the outputs of the corresponding zero-organs 6-10. Outputs

the control unit 11 is connected to the inputs of the respective triacs 1-5.

The device works as follows.

In the absence of control signals, the triacs 1-5 are turned off, the windings 12-14 of the phases are disconnected and the motor is stationary.

Let the engine work according to the star scheme, which corresponds to the

to the condition of the simnstorov 1-2. When a control signal is applied for switching from a star to a delta circuit, the triac 1 is first disconnected and at the moment of equal values of the potential of phase A and the line voltage of the power supply Ug, the triac 3 is turned on, connecting the coil 12 to the linear voltage. Then disconnect the triac 2 and at the moment

equality of potential values of phase B (jf and linear voltage and include triac 4, connecting winding 13 to linear voltage. At the moment of equality of the values of phase potential Cf, 4 and linear voltage Odd include triac 5, obtaining a triangle circuit.

Claims (1)

Invention Formula A three-phase asynchronous motor control method by switching its windings from a star to a delta and reverse circuit, in which they first disconnect the end of the first phase of the winding from the ends of the other two phases of the winding and connect it to the beginning of the second phase, then disconnect the end of the second phase from the end. 45 of the third phase and connect to the beginning of the third phase, the end of the third phase is connected to the beginning of the first phase and get a triangle circuit, and switching from a triangle circuit to 50, the star circuit is started by disconnecting the end of the first phase of the winding from the beginning of the second phase of the winding, then the end of the second phase is disconnected from the beginning of the third phase and connected to the end 55 of the first phase, and the end of the third phase is disconnected from the beginning of the first phase and connected to the junction point of the first and second phases, all of which are disconnected in 312594544 the moment of current transition in phases through each of the winding phases is zero, which makes it possible, at the moment of equal potential, that, in order to increase the switchable phase of the winding, corresponding to the speed and reliability of the linear voltage of the supply motor network