SU1226598A1 - Method of braking induction motor - Google Patents

Abstract

The invention relates to electrical engineering and can be used in asynchronous electric drives with an active moment of static resistance on the motor shaft. The purpose of the invention is to reduce the braking time. The method reduces the loss in the engine during braking by decreasing the voltage during the reverse and controlling the direction of the active power on the stator of the engine. The braking efficiency is overcome at the initial stage of braking due to the reduction of the power consumption from the network and the constancy of the speed change over time. The increase in reliability is provided by limiting the electromagnetic field of the stator to the opposite direction of rotation, which increases the service life of the engine, mechanism, and transmission device. 1 il. i SL

Description

I

The invention relates to electrical engineering and can be used in asynchronous electric drives with an active moment of static resistance on the motor shaft, for example, in electric drives of lifting mechanization of hoisting-and-transport machines.

The purpose of the invention is to reduce the braking time.

The drawing shows a diagram of the device that implements the method of braking VIY induction motor.

The device contains an asynchronous motor, an automatic switch 2 in the motor power supply circuit, fuses.3, three contactors with coils 4-6 and contacts 7-17, the coil 18 of the direction of active power relay on the stator of the motor 1 is turned on, at the two phases of the stator winding, one contact 9 of the active power direction relay is connected between the contactor coil 5 and contact 17, which is connected via series-connected contacts 9 and 13 to one of the fuses 3 and to one of the outputs of contact 20 of the relay. neither active power, two triacs 21, cross-connected between, and, at the two phases of the stator winding of the electric motor, the unit of the control of triacs by one input through pin 11 is connected to the source of the driving voltage.

A switch-on button 23, which is shunted by contact 8, is connected to contact 20 via a disconnecting button 24, a contact 25 of a button 24 shunts a contact 13, another output of a button 23 via contacts 12 and 16 is connected to one output of a coil 4, another output of a contact 20 through contact 26 of a limit switch and series-connected contacts 10 and 14 are connected to one output of coil 6, other leads of coils 4-6 are combined and connected to another fuse, a torque sensor 27 mounted on the motor shaft is connected to one of the inputs of block 2B is summarized and, to the other input of which a predetermined voltage Ui is applied, the output of the unit 28 is connected to another input of the triac control unit 22.

The device works as follows.

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To start the engine, the automatic switch 2 is turned on, the button 23 is cleared, the coil 4 of the first contactor receives power

5 circuits: buttons 24 and 23, contacts 12 and -16z coil 4, and the contactor is activated, the power closing contacts 7 of the first contactor are activated; the stator winding of the motor 1 is connected to the mains, the engine 1 is started up and steady state, corresponding to the moment of static resistance M on the shaft and

t5 rotational speed

At the same time, the blocking contact 8 is closed, the button 23 is shunted, and the opening contacts 9 and 10 are opened 1 1, excluding the inclusion of the second and third contactors. The scheme is given in the initial state, preceding the beginning of the implementation of the method of braking an induction motor.

25 The method of braking an asynchronous DBH1_tel is performed as follows.

To transfer the motor 1 from the motor mode to the brake one, the shutdown button 24 is pressed, its break contact 25 of the power supply of coil 4 of the first contactor is opened and closed with a {b terminal contact in the power circuit of the coil 5 of the second contact.

Coil 4 loses power, the first contactor is disconnected, its power is disconnected: contacts 7 and the stator winding of the engine 1 are disconnected from the grid voltage, and the opening contacts 9 and 10 are closed. In this case, the coil 5 of the second contactor is energized by contacts 25,9,17 and 19, coil 5, the second contactor is activated, its closure contact 11 is closed and the input Uj of the triacs 21 is supplied with a signal Uj from the open or closed ci-icTEiM control reverse. Unit 22 begins to form control pulses on the triacs 21 at the corresponding control angle U and they open. The stator windings of the motor 1 are connected to the mains, and the phase alternation on the stator of the motor I is changed (for example, from A, B, C to C, B, A) 5 and as a result the motor 1 is switched to a deceleration braking mode.

In addition to changing the alternation of phases, and, consequently, changing the direction of rotation of the electromagnetic field of the stator, triacs 21 reduce the voltage U on the stator of the induction motor to a value at which the motor torque M is determined by the difference between the specified braking torque M. and the torque static

engine It also maintains the set braking torque, the constant acceleration of the rotor, the reduction of power consumption and the reduction of losses. Moreover, the reverse of the engine is mainly due to the active moment of static resistance. The coil 18 of the active power direction relay remains at

Go resistance M (| -M (- (U reverse, as with motor)

1M

If the moment of static resistance remains unchanged during the operation of the drive, then an open control system can be used to implement the method. At the same time, based on the known C and M,, the moment M ,, of the engine is determined and on the basis of its value and

press off because the direction of the active power does not change (from the mains to the engine). The second contactor, triggered, opens the opening contact 12 in the power supply circuit of the coil 4 of the first contactor, closes the closing contact 13, shunt the contact 25 of the shutdown button, and opens the contact 14 in the motor data circuit and calculates the power supply of the coil 6 of the third contact on the stator of the engine. By ra.

the value of the voltage is found as a result of the reverse, the speed of the driving voltage U. In the process of the engine 1, under the action of total braking, the value Ug may change (M + M) approaches the value, for example, as a function of time, 25 speeds (j, in order to maintain a constant engine torque.

If the moment of static resistance changes during the operation of the drive, or when braking is its direction, as the engine, then it is necessary for the implementor to switch to the regenerative mode of this method to apply closed braking. At the time of change management system. In order to control the active power in the process of stabilization, a sensor 27 of the engine of the engine 1 is installed on the coil 18 of the relay on the shaft of the engine 1, the output 35 of the active power is turned on, opens its breaker 19 in the power supply circuit of the coil 5 of the second contactor, de-energize it and

Life decreases and then changes sign to negative. At the same time, the active power consumed from the network is reduced to zero, and then the signal Irr is changed, which is fed to the first input of summation unit 28, to the second input of which a signal Uj, proportional to the specified braking torque M, is applied. In the summation block, they are subtracted (Uj - UDC), which corresponds to the operation M - M „M.

Thus, as a result, the 1st contact 20 in the power supply circuit of the coil 6 of the third contactor closes - the second contactor turns off, opens its contact 11, the control pulses are removed from the triacs 21, the last ones close and turn off

closes the 1st contact 20 in the power supply circuit of the coil 6 of the third contactor - the second contactor turns off, opens its contact 11, the control pulses are removed from the triacs 21, the last ones are closed and turn off

ka 28 signal U,

proportional

the hebraic summation of signals 45, the motor from the mains with a reduced voltage, and,, is determined at the output by a block. This opens the opening contact 14 and the coil 6 of the third contactor receives power through the circuit: contacts 20,26,10 and 14 and coil 6. The third contactor operates and closes its power contacts 15. The stator windings of the engine 1 are connected again to the network with a nominal voltage M motor 1. The signal U is fed to the lower input of block 22 and sets the required angle of control of the triacs and, therefore, the required voltage U on the stator of the motor 1. During braking, the specified braking torque M remains unchanged.

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phase alternation (with the opposite reverse direction) after the termination of braking by the rotation of the electromagnetic field

stator in relation to the motor mode). Engine 1 continues to fade. I is starting in the opposite direction, i.e. reverse

engine It also maintains the set braking torque, the constant acceleration of the rotor, the reduction of power consumption and the reduction of losses. Moreover, the reverse of the engine is mainly due to the active moment of static resistance. The coil 18 of the active power direction relay remains at

 as a result of the reverse, the speed of the engine 1 under the action of the total torque (M + M) approaches the value of the synchronous speed (j,

It has its own direction, since the motor goes into regenerative braking mode. At the moment of changing the direction of the active power on the engine of the engine 1, the coil 18 of the relay of the direction of the active power turns on, opens its disconnecting contact 19 in the power supply circuit of the coil 5 of the second contactor, de-energizes it, and

Life decreases and then changes sign to negative. At the same time, the power consumed from the network is reduced to zero, and then changing the closure of the 1st contact 20 in the power supply circuit of the coil 6 of the third contactor — the second contactor turns off, opens its contact 11, removes the control pulses from the triacs 21, closes it and turns off

mains motor with low voltage. This opens the opening contact 14 and the coil 6 of the third contactor receives power through the circuit: contacts 20,26,10 and 14 and coil 6. The third contactor operates and closes its power contacts 15. The stator windings of the engine 1 are connected again to the network with a nominal voltage 45

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with the same reverse and alternate speed, recovering energy. braking in the supply network. The transient process ends when the motor torque is equal to the moment of static resistance,. When the regenerative braking time expires, the disconnecting contact 26 of the limit switch opens, the coil 6 of the third contactor loses power, the third contactor opens, disconnects the power contacts 15, the engine 1 is disconnected from the network and switched to a speed reduction mode, for example, by activating brake electromagnets.

The proposed method of braking is also used when powering an induction motor from a semiconductor converter. Its use in comparison with the known methods provides a number of advantages. The losses in the engine during braking are significantly reduced by decreasing the voltage during reversal and controlling the direction of the active power on the stator of the engine. Braking efficiency increases at the initial stage of braking.

The method of braking an asynchronous electric motor, in which the alternation of phases of the lateral winding is made, after which the motor is disconnected from the power source, due to the fact that, in order to reduce the braking time, the torque on the motor shaft is compared with a given value and in the case of inequality of moments simultaneously with a change in the alternation of phases of the stator winding, the voltage on the stator of the electric motor decreases to the value at which the result of comparison of the moment on the motor shaft desired torque becomes zero, active power control direction to a hundred torus and when changing its sign increased voltage across the stator to the new by reducing consumption of electricity from the network and persistence changes 30minalnogo value, whereupon The relative velocity or time. The key to the motor increases from the source - reliability, as power is limited.

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shots of the electromagnetic moment of the engine when the electromagnetic field of the stator is switched to the opposite direction of rotation, which increases the service life of the engine, mechanism and transmission device.

Formula and from “bretheni

The braking method of the asynchronous electric motor, in which the alternation of the phases of the lateral winding is made, after which the motor is disconnected from the power source, due to the fact that, in order to reduce the braking time, the torque on the motor shaft is compared to a given value in the case of inequality of moments simultaneously with a change in the alternation of phases of the stator winding reduces the voltage on the stator of the electric motor to the value at which the result of comparing the moment on the motor shaft and of a given moment becomes equal to zero, control the direction of active power on the stator and, when its sign changes, increase the voltage on the stator to the nominal value, after which the motor is disconnected from the power source.

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VNShShI Order 2144/56 Circulation 631 Subscription Proizv.-polygr. pr-tie, Uzhgorod, st. Project, 4

Claims (1)

Claim A method of braking an asynchronous electric motor, in which the phase sequence of the stator winding is changed, then the motor is disconnected from the power source, about t ~ 15, characterized in that, in order to reduce the braking time, the moment on the motor shaft is determined, compare it with the set value and in case inequalities of moments simultaneously with a change in the phase rotation of the stator winding reduce the voltage at the stator electronically, losses in the motor during braking are reduced due to a decrease in voltage during reverse and ntrolya direction of active power to the motor stator. The efficiency of braking at the initial stage of braking is increased due to the reduction of electric energy consumption from the network and the constancy of the change in speed over time. The motor rises to a value at which the result of comparing the moment on the motor shaft and the set moment becomes zero, control the direction of the active power on the stator and, when its sign changes, increase the voltage on the stator to the nominal value, after which the electric motor is disconnected from the source of reliability, since nutrition.