RU1833961C - Two-motor electric drive - Google Patents

Abstract

Usage: electric drives of a chain load-carrying conveyor with - .. asynchronous short-circuited electric motors, as well as twin-motor electric conveyor belts operating on a common load. SUMMARY OF THE INVENTION: A two-motor electric drive comprises a program start-up block 25, which controls a voltage converter 7, a periodic timer 17, an input connected to the output of a prestart alarm relay 1, a three-pin relay element 18, the input of which is connected to the output of a periodic timer 17, and the output contacts 19, 20, 21 are connected in parallel with the corresponding phases of the stator winding of the electric motor 9, which are connected in series with the corresponding phases of the stator winding of the electric 8. 2 rodvigatel yl. h yo

Description

The invention relates to electrical engineering, in particular to devices for controlling a twin-engine electric drive of a conveyor with asynchronous short-circuited electric motors. The device comprises a soft starter, a comparison unit, a voltage (frequency) converter, a tacho generator, a periodic timer with a three-pin relay element, and two squirrel-cage induction motors.

The aim of the invention is to increase the reliability and durability of the tractive organ by reducing the dynamic loads in it during the program start of the electric drive ahead of the inclusion of one of the motors relative to

the other in time, as well as a uniform distribution of loads between the electric drives and an increase in the reliability of the control system, reducing its cost by halving the number of voltage converters (frequency) and tachogenerators.

To achieve these goals, a time relay delaying the start of the second motor relative to the first one for the time required to select the kinematic gaps in the traction body is introduced into the electric motor control device containing a program start block, a comparison unit, a voltage (frequency) converter and a tachogenerator output contacts (proximity switches),

00

from

which the stator windings of the first motor are shunted, connected in series and respectively with the windings of the second motor and connected to the line voltage of the converter.

A device for controlling a twin-engine electric drive of the conveyor comprises a program start-up block 25, which includes a pre-alarm signaling relay 1, a low-speed operational amplifier 2, a rated speed operational amplifier 3, and diode separators 4 and 5, a speed controller operational amplifier 6, and a converter voltage (frequency 7), the load of which are two asynchronous squirrel-cage motors 8 and 9, stator windings 10, 11, 12 and 13, 14, 15 of which are connected in series and connected to the output of generator (frequency) 7. The tachogenerator 16 is connected to the speed controller 6.

Additional elements of the circuit are a p-type time relay 17, which provides a delay in turning on the second engine relative to the first one by the time required to select kinematically / h gaps in the traction organ by the first engine.

The output of the time relay 17 is connected to the control system of the relay element 18, power contacts (proximity switches) -19, 20, 21 of which are connected in parallel to the windings of the second motor and shunt the mx during the initial start-up period. Pre-start signaling is carried out by a call 22 connected to time relay 1 through an intermediate amplifier 23. Terminal 24 serves to supply voltage to set the speed of the moving organ.

The device operates as follows ..

At the moment of turning on the drive (to) (see Fig. 2), the time relay 1 turns on the pre-alarm signal 22, which alerts the operating personnel to turn on the conveyor, which lasts until time ti. 6B, the start-up alarm time ti is turned off and the low-speed operational amplifier 2 starts to run the start-up program, the time relay 17 is turned on, the control system of the power contacts 18 and contacts 19, 20 are activated. 21, closing, the windings 13, 14, 15 of the first motor are shunted .

The flame-increasing voltage from the converter 7 is applied to the windings 10, 11, 12 of the second motor 8 and it smoothly accelerates to a creeping speed equal to

0.15-0.2 of the nominal (the time period n - t2 in FIG. 2). This speed is set by the low-speed operational amplifier 2 and is provided by feedback in

speed. For a period of time from t2 to tz, the second engine 8, having a low rotational speed, selects kinematic gaps in the tractor body.

At time ta, the output signal

the time relay 17 disappears, the control system 18 opens the power contacts 19, 20, 21, and the windings 13, 14, 15 of the motor 9 are connected in series by the windings 10,11, 12 of the motor 8, which will cause start-up and acceleration

the first engine 9 to creep speed. This will make it possible to distribute the force of the genuine traction member between the two drives and eliminate its vibrations under the action of an elastic wave propagating along

head at start-up.

Over a period of time tz - t4, all sections of the tractive organ will move and over a period of time t4 - ts, the output voltage (frequency) of the inverter 7 will gradually increase, and both motors will smoothly accelerate to the rated speed.

In the device for controlling the twin-motor conveyor electric drive, the frequency of rotation of the electric motors is controlled by changing the voltage of the speed reference supplied to the input of the operational amplifier (terminal 24) of the speed controller G, which

can be carried out both manually and automatically, depending on a change in a technological parameter (e.g. temperature, etc.).

Even load distribution

between engines is carried out as follows.

Since their windings are connected in series, the same current flows through them. With an increase in load on any of.

5 motors of the rotor EMF decreases, the inductive and total resistance decreases, which leads to an increase in the current flowing through the windings. Consequently, the torque of the second engine will increase;

0 will take part of the total load and it will be evenly distributed between the engines automatically.

Compared with the prototype, the device uses cheaper and more

5 long-life squirrel-cage induction motors,

A voltage converter that is cheaper than a frequency converter can be used to control the speed.

The device makes it possible to smoothly start the conveyor according to a given program, which reduces the dynamic forces in the trading body and increases its service life.

The proposed circuit for turning on the electric motors allows evenly distributing the static and dynamic load between them, which is not provided for in the prototype.

Claims (1)

SUMMARY OF THE INVENTION A twin-motor drive containing two asynchronous motors, a program start block, equipped with a prestart alarm relay, the output of this block is connected to the first input of the speed controller connected to the input of an adjustable power supply, the outputs of which are connected to the phases of the stator winding of one of the asynchronous motors , on the rotor of which a speed sensor is installed, connected to the second input of the speed controller by an output, from ichayuschiys that, with In order to increase reliability and durability by reducing dynamic loads and simplification, a p-type time relay is introduced, an input connected to the output of the prestart alarm relay, a three-pin relay element, the input of which is connected to the output of the p-type time relay, and the output contacts are connected in parallel with the corresponding phases of the stator windings of another electric motor, which are connected in series with the corresponding phases of the stator winding of the first electric motor, moreover, adjustable chnik power supply is in the form a voltage converter, and the rotors of said electric motors are made short-circuited. 23 Figure 1 7 W to ° $ / MM 0 / f a is to  Ј tjf tj FIG. 2