SU1206940A1 - Device for controlling three-phase induction motor - Google Patents

Description

I

The invention relates to 93 electro technology and can be used in drives of lifting mechanisms and passalir elevators.

The purpose of the invention is to expand the range of regulation.

The drawing shows a device diagram.

A device for controlling a single-speed three-phase asynchronous electric motor 1 with a short-circuited rotor contains a thyristor voltage regulator 2 that controls the inputs of which are connected to the unit 3 of the pulse phase control system, the intensity setting 4 and the rotation frequency sensor 5, the outputs of which connected to the inputs of the speed control block b, a contactor reverser 7 connected by the input to the block of 8 commands; power switching element 9, two triangular thyristor switches 10 and 11 with a control unit 12, a frequency division unit 13, a switch unit 14, a three-phase transformer with one primary winding 15 and two secondary windings 16 and 17c with different transformation ratios.

The device works in the following way.

From the command block 8 is included) TC convator reverser 7, power switching element 9, unit 4 intensity,

The intensity setting unit through, the speed control unit 6 and the pulse phase control system unit 3 includes a thyristor voltage regulator 2, which performs controlled acceleration of the motor with a given acceleration intensity setting unit, the acceleration of the motor is corrected

5 rotational speed through the regulator

6 speeds.

When the motor is decelerated (decelerated), the command block 8 is given a signal to turn off the power switch element 9 and turn on the frequency dividing system composed of frequency dividing blocks 13 and control 12, triangular thyristor switches 10 and II

2069402

16 and 17 three-phase step-down transformer.

The secondary windings of the transformer have different transformation ratios 5, which allows modulating the dividing frequency voltages with a significantly improved harmonic composition. Thus, the stator winding of the motor I is given a lower frequency voltage, and the motor is slowed down in a mode of generator braking, and the intensity of the slowdown is determined accordingly by means of blocks 4,5,6 and 3 thyristor regulator 2 voltage

At the end of the braking process

2Q engine can go into positioning mode (tune up), on. An example is if braking is performed when lifting an unbalanced load, and at the moment of command

25 exact stop from the block 8 includes a relay element in the switching unit 14, which with its contacts in the control unit 12 forms the operation of only one thyristor

, “In the triangular thyristor switches at O and 11, At the same time, in the stator winding

a short-time constant current is applied and the motor with dynamic braking is stopped.

The use of electric braking in the electric drive reduces the energy losses in the electric motor.

The use in the electric drive of the positioning mode (fine-tuning) at low speed, which is very insignificant in time (if there is a speed sensor in the control system) and practically does not affect the lift performance, makes it possible to simplify the drive control system, for example , sensors along the way and controllers along the way, current sensors and current regulators are excluded from the control system, the control logic is simplified, the system can be made of relatively simple analog elements and s.

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ABOUT

Compiled by E Peremyslova Editor N.Pushnenkova Tehred.M.NadKorrektor V.But ha

Order 8732/58 Circulation - Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Branch gash Patent, Uzhgorod, st. Project, 4

Claims (1)

DEVICE FOR CONTROL OF A THREE-PHASE ASYNCHRONOUS ELECTRIC MOTOR with a short-circuited rotor, containing a thyristor voltage regulator, the control inputs of which are connected to a pulse-phase control system unit, an intensity regulator and a speed sensor, the outputs of which are connected to the inputs of the speed control unit, the output of which is connected to pulse-phase control, contactor reverser in the phases of the stator winding of the electric motor, connected by an input to a command block, and an output with a thyristor voltage regulator, the output of which is connected through the power switching elements to the phases of the stator winding of the electric motor, one of the outputs of the command block is connected to an intensity adjuster, characterized in that, in order to expand the control range, two triangular thyristor switches with a control unit are introduced into it , a switching unit and a three-phase transformer with one primary and two secondary windings with different transformation ratios, one secondary winding of a three-phase transformer connected to the stator winding of the motor g by its beginnings, the other ends, triangular thyristor switches are connected to opposite terminals of the secondary windings of the three-phase transformer, the second and third outputs of the command block through the frequency division unit and the switching unit are respectively connected to the inputs of the control unit of the triangular thyristor switches, the primary winding a three-phase transformer with one terminal connected between the thyristor voltage regulator and power switching elements, its other output dy combined.