SU1437989A1 - Induction motor control arrangement - Google Patents

Description

(21) 4178241 / 24-21

(22) 1/7/87

(46) 11/15/88. Bul No. 42 (75) V.G. Voghm nin

(53) 621.313 (088.8)

(56) USSR Copyright Certificate No. 746929, cl. H 03 K 17/56, 1977.

Author's certificate of the USSR No. 1173544, cl., L 03 K 17/56, 1984.

(54) DEVICE FOR CONTROLLING AN ASYNCHRONOUS ELECTRIC MOTOR

(57) The invention is intended to automatically reverse an asynchronous motor. The device for controlling an electric motor comprises a winding 1 of the first magnetic starter with contacts 6,

10, winding 3 of the second magnetic actuator with contacts 5.11, switching contact groups 8 and 13 of the first

and a second path switch, the first diode bridge 14 with an RC circuit 15, 16, a thyristor 17 and a threshold element 18 in the output diagonal. The introduction of a second diode bridge 19 with a KS circuit 20.21, a thyristor 22 and a threshold element 23 in the output diagonal, and connecting the input terminals of diode bridges 14 and 19 to the supply bus 4 through the contacts of the contact groups 8 and 13 of the path switches allows separate adjusting the stop time of the motor in extreme positions and reduce the number of contacts of magnetic starters used. To reduce the current flowing through the contact elements, use of triacs 27, 28 with resistors 29.30 in control circuits is provided. 1 hp ff, 2 ill.

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This invention relates to a pulsed technique designed to automatically reverse an asynchronous motor.

The purpose of the invention is to expand the field of use by providing, separately controlling the stopping time of an electric motor in extreme positions and increasing reliability by reducing the number of contact elements.

FIG. 1 shows a circuit diagram of the device; Fig. 2 shows a variant of control of the windings through the simistors.

The device (FIG. 1) contains a winding 1 of the first magnetic actuator, connected by its first output to the first supply bus 2 and the first output of the winding 3 of the second magnetic actuator,

The second output of winding 1 is connected to the second supply bus 4 through a series-connected disconnecting contacts 5 of the second magnetic actuator closing the contacts 6 of the first magnetic actuator, shunted by closing contacts 7 of the first control button, disconnecting contacts of the switching contact group 8 of the first track switch and disconnecting, pins 9 of the second control button. The second terminal of the winding 3 is connected to the contacts 9 through successively connected disconnecting contacts 10 of the first magnetic actuator, closing the contacts 11 of the second magnetic actuator, shunted 10

20

the diagonals of the bridges 14 and 19 are connected to the closing contacts of the contact groups 8 and 13, respectively, the second terminal of the second diagonal of the bridge 14 is connected to a common point of contacts 10 and 12, and the second terminal of the second diagonal of the bridge 19 is connected to a common point of contacts 5 and 7.

The device (Fig. 1} works as follows.

When the contacts 7 are closed, a supply voltage is applied to the winding 1 along the following circuit: bus 4, contacts 9, open contacts of group 8, contacts 7, contacts 5, winding 1, bus 2, Magnetic starter with winding 1 turns on. Its contact 6 closes and contact 10 opens. An electric motor (not shown) begins to rotate in the forward direction. Due to the contact 6, the magnetic starter with the winding 1 is held in the on state after the contacts 7 are opened. With the contact 10 the magnetic starter with the winding 1 breaks the power supply circuit of the winding 3, excluding the simultaneous operation of two magnetic starters.

When, under the action of the actuator driven by the electric motor, the contacts of group 8 take a position opposite to that shown in the drawing, winding 1 will be de-energized and the first starter will turn off. With

35. Through a resistor 24, a filter capacitor 25, a diode bridge .14, pins 10, a winding 3, a charge current of a capacitor 25 flows from which the threshold element is fed (single junction

25

thirty

popping contacts 12 of the third button-transistor) 18. The charging current of the control capacitors, and the opening contacts 12 of the switching contact group 13 of the second path switch. The first diagonal of the first diode 25 is significantly less than the current of the magnetic starter; therefore, the magnetic starter with winding 3 is turned off. Simultaneously through the bridge 14 between the outermost terminals, 45.or15 starts charging the condenser time of the first circuit from the relay 16 When the capacitor 16 of the charger 15 and the capacitor 16 is connected to the first thyristor 17, the input of which is connected to the output of the first threshold element 18 with a KS circuit 15, 16 at the 50th input, between the outermost leads of the second diode bridge 19 the second circuit of the resistor 20 and the capacitor 21 is connected to the second thyristor 22, the input of which 55 is connected to the output of the second threshold element 23 with an RC circuit 20, 21 at the input. First second

until the voltage of the transistor 18 is turned off, the latter is unlocked. The capacitor 16 through the opened transistor 18 is discharged to the control circuit of the thyristor 17, causing it to be unlocked. The discharge of the capacitor 16 through the resistor 26 to the control electrode of the thyristor 17 is carried out for several half-periods in the supply network (3-5 half-periods). During this time, bridge 14 is kept open and through it, along

the diagonals of the bridges 14 and 19 are connected to the closing contacts of the contact groups 8 and 13, respectively, the second terminal of the second diagonal of the bridge 14 is connected to a common point of contacts 10 and 12, and the second terminal of the second diagonal of the bridge 19 is connected to a common point of contacts 5 and 7.

The device (Fig. 1} works as follows.

When the contacts 7 are closed, winding 1 is supplied with the supply voltage through the circuit: bus 4, contacts 9, disconnecting contacts of group 8, contacts 7, contacts 5, winding 1, bus 2, Magnetic starter with winding 1 is turned on. Its contact 6 closes and contact 10 opens. An electric motor (not shown) begins to rotate in the forward direction. Due to the contact 6, the magnetic starter with the winding 1 is held in the on state after the contacts 7 are opened. With the contact 10 the magnetic starter with the winding 1 breaks the power supply circuit of the winding 3, excluding the simultaneous operation of two magnetic starters.

When, under the action of the actuator driven by the electric motor, the contacts of group 8 take a position opposite to that shown in the drawing, winding 1 will be de-energized and the first starter will turn off. With

This. Through a resistor 24, a filter capacitor 25, a diode bridge .14, contacts 10, a winding 3, a charge current of a capacitor 25 flows, from which a threshold element is fed (single junction

transistor) 18. The charge current of the capacitor 25 is significantly less than the response current of the magnetic starter, therefore the magnetic starter with winding 3 is turned off. Simultaneously, the capacitor 16 is charged through the resistor 15 or the capacitor 16 to charge before the unlocking voltage of the transistor 18, the latter is unlocked. The capacitor 16 through the opened transistor 18 is discharged to the control circuit of the thyristor 17, causing it to be unlocked. The discharge of the capacitor 16 through the resistor 26 to the control electrode of the thyristor 17 is carried out for several half-periods in the supply network (3-5 half-periods). During this time, the bridge 14 is kept open and through it, in series with it the included contacts 10 and the winding 3, a current flows causing the second magnetic starter to be turned on, which, by means of its power contacts, switches the motor on reverse rotation. At the same time, contact 11 is closed and contact 5 is opened, thereby preventing the magnetic starter with winding 1 to operate.

When switching the contact group 13 in the same way as described, the magnetic starter with winding 3 is de-energized, and winding 1 is connected to bus 4 via diode bridge 19, contacts 5 are connected, contact 5 closes and contact 6 opens. Through a time delay determined by the charge time of the capacitor 21 to the threshold voltage of the single junction transistor 23, the thyristor 22 is opened, ensuring the inclusion of a magnetic starter with a winding 1,

In the future, the operation of the circuit is repeated.

The device is switched off by opening the contacts 9. To reduce the current flowing through the contact elements, the control unit of the asynchronous motor can be configured as shown in FIG. 2, while triacs 27 and 28 are used with limiting resistors 29, 30 in control circuitry.

Claims (1)

The device of FIG. 2 operates in a manner similar to that of FIG. 1, with the difference that the respective triacs are initially turned on, and then the windings 1 and 3 of the magnetic starters are energized. Invention Formula 1, An asynchronous motor control device comprising a winding of a first magnetic starter connected by its first output to a first terminal of a winding of a first magnetic starter and a first power supply and connected by a second terminal (H1Ohm to the second power line through sequentially connected disconnecting contacts of the second magnetic starter, the closing block contacts of the first magnetic starter, which are bridged by the closing contacts of the first control button, the breaking contacts of the switching contact g uppy first track intersection switch and opening contacts of the second control button, the second terminal of the winding of the second magnetic actuator is connected to the opening contacts of the second control button through the series-connected disconnecting contacts of the first magnetic actuator, closing the contacts of the second magnetic actuator0 five 0 cycles of the third control button, and the opening contacts of the switching contact group of the second path switch, the first diode bridge, the first threshold element with the time specifying the first RC circuit on the input, the first thyristor included in the first diagonal of the first diode bridge between the outermost leads of the first RC circuit and connected by its input to the output of the first threshold element, characterized in that, in order to expand the area of use and increase reliability, a second diode bridge is introduced, the second threshold element with time a second thyristor connected to the first diagonal of the second diode bridge between the outermost leads of the second RC circuit and connected to the output of the second threshold element with its input; the groups of the first and second path switches, respectively, the second output of the second diagonal of the first diode bridge is connected to the common point of the opening contacts of the first magnetic starter and the closure the third control button and the second output of the second diagonal of the second diode bridge is connected to the common point of the opening contacts of the second magnetic actuator and the closing contacts of the first control button, 2, The device according to claim 1, characterized in that it contains two triacs and two resistors connected in series with the input triacs of the triacs in the circuit connecting the second winding terminals of the magnetic starters to the second power bus, and the anodes of the triacs are connected to the second power bus via the disconnecting contacts acts of the second control button. five 0 five 0 SIL 7