SU1515324A1 - Electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in the metallurgical and engineering industries. The aim of the invention is to improve the dynamic properties by improving speed. A three-input driver for control voltages 13 has been introduced into the electric drive. The inputs of the imaging unit 13 are connected respectively to the outputs of the torque regulator 8, the flux coupler 4, and the rotational speed sensor 7. The outputs of the driver 13 are connected to the control inputs of the converter 11 coordinates, which form the control signals of the frequency converter 2 in the stator circuit of an asynchronous short-circuited motor 1. Using the driver 13, the electromagnetic properties of the asynchronous motor 1 with the frequency converter 2 are taken into account and the necessary typical properties of the slave system are taken into account regulation. 3 il.

Description

SP

ate

with

tc

four

Phie.1

3

l 13 are connected to the control inputs of the converter of the 11 coordinates, which form the control signals of the frequency converter 2 in the circuit of the asynchronous short-circuited motor 1 torus.

The invention relates to electrical engineering, in particular, to adjustable AC drives with asynchronous short-circuited motors and direct frequency converters or frequency converters with pulse-width modulation, and can be used in a number of industries (metallurgical, engineering and other .) for frequency-controlled electric drives of high-speed mechanisms with increased demands on the accuracy of maintaining the set values of the torque or frequency of rotation and speed and in transient regimes.

The aim of the invention is to improve the dynamic properties by improving speed.

FIG. 1 shows a functional diagram of an electric drive with an asynchronous short-circuited motor; in fig. 2 is a functional diagram of a control voltage driver; in fig. 3 is a vector diagram of an asynchronous motor.

The electric drive contains an asynchronous motor 1 (Fig. 1) with a short-circuited rotor connected to the outputs of frequency converter 2, flow coupling setpoint generator 3 connected to one of the inputs of flow coupling controller A, connected to speed control 5, connected to one of the control inputs torus 6 speed, sensor 7 rotor speed of the induction motor 1, torque controller 8 connected by one input to the output of speed controller 6, sensors 9 and 10 of the current and stator phase voltage, respectively, block 11 rofessional coordinates and signal generating unit 12 inverse bonds with signals output torque and flux linkage harmonic functions, respectively connected to the other input torque regulator 8 of the controller 4 and the flux linkage to the supports

l 13 the electromagnetic properties of the asynchronous motor 1 with the 2 frequency converter are taken into account and compensated for, and the necessary typical properties of the slave control systems are introduced. S Il.

5 0 5

0

d 0

five

the inputs of the block 11 coordinate conversion. At the same time, the inputs of the feedback signal generation unit 12 are connected to the outputs of the sensors 9 and 10 of the current and voltage of the stator phases, and the outputs of the coordinate conversion unit 11 are connected to the control inputs of the frequency converter 2.

A three-input control voltage generator 13 (Fig. 2) is implemented in the electric drive; it is made with elements 14 and 15 divisions, multiplication elements 16–18, differentiation elements 19 and 20, nonlinear element 21 realizing the magnetization curve of induction motor 1, forcing link 22, proportional link 23, filter 24, adders 25-30, inverters 31 and 32.

The first input of the control voltage generator 13 is formed by the input of the divisible division element 14, the second input is the combined inputs of the divider of the division element 14, the nonlinear element 21 and adders 25 and 26, and the third input is one of the inputs of the adder 27, the other input of which is combined with the input of the multiplication element 16 and connected to the output of the division element 15. The output of the adder 27 is connected to the combined inputs of the multiplication elements 17 and 18, the output of the division element 14 is connected via a boost link 22 to the input of the divisible division element 15, via rvy inverter 31 to the input element 16 multiplying, to the input of adder 28 via a proportional member 23 to the joint between an input member 17. the multiplication and differentiation element 19, the output of which is connected to the second input of the adder 28, the third input of which is connected to the output of the multiplication element 18. The output of the multiplication element 16 is connected to the interconnected inputs of the adders 26 and 29. The output of the adder 26 through the filter 24 is connected to the input of the divider of the division element 15. Nonlinear output

one

element 21 is connected to the input of the adder 29, the output of which is connected to the interconnected inputs of adders 25 and 30. The output of the adder 25 is connected to the interconnected inputs of the multiplication element 18 and the differentiation element 20, the output of which is connected to the second input of the adder 30, whose third input through inverter 32 is connected to the output of multiplier 17. The first, second and third inputs of the control voltage generator 13 are connected respectively to the outputs of the torque controller 18, the flow coupling controller 4 and the rotational speed sensor 7. The outputs of the control voltage generator 13 formed by the outputs of the adders 28 and 30 are connected to corresponding control inputs of the coordinate conversion unit 11.

In the automatic control system (ACS) of the electric drive, two closed control loops are formed: an external speed control loop with a speed control and an internal torque control loop. The required electromagnetic state of the motor is provided by the control loop of the induction motor. ATS synthesis was carried out on the basis of the theory of nonlinear multi-connected systems of subordinate regulation and taking into account the properties of an induction motor when powered by a direct frequency converter or frequency converter with pulse-width modulation as an object of regulation. A special feature of the SAR structure is the use of a rotating coordinate system oriented along the main flow of an induction motor.

The drive works as follows.

The flux linking reference signals (fe and rotational speeds and, engine 1, from outputs of setters 3 and 5, respectively, arrive at inputs of regulators A and 6, where they are compared with signals of actual values of flux coupling, Jj and rotation frequency U) feedback and speed sensor 7. The setpoint value of the asynchronous motor moment Sh1 from the output of the regulator 6 is fed to the input of the moment regulator 8, where

5324,

is compared with the signal of the actual value of the moment w, coming from the corresponding output of the block

5 12.

The formation in block 12 of the harmonic functions ainv, coa | - is carried out on the basis of the signals of the currents - Cho, b, c and voltages - Us „phases

e by relations (the notation used is generally accepted in the analytic theory of AC current; all variables and parameters, except time and constant time, are presented in 15 relative units):

   Vs -isp- «sp (1)

,

  V vV - T / b (2)

I

. f.

coa f --- (3)

V, / r d.iT subci.p () .Л.сГ, b, c-isaXc dt (5)

Sa,

  2- I- 3 S b 3 SC

isp

2 1 1 sd 3 Vsb 3 + scl

 sb-

(6)

(6a)

The values are determined with the help of operational amplifiers in integration mode 35 according to the formula (5).

The flow control and torque controllers 4 and 8 have transfer functions:

W (P)

one

(T + T P)

(7)

where T. is the time constant chosen according to the requirements for the electric drive and determining the speed 45 of the automatic control system.

The controllers ensure the equality of the moment and the flux linkage to their specified values in the established modes of operation of the electric drive.

The output signals of the torque regulator 8 (w ({), the flux linkage regulator 4 ((), the rotation speed sensor 7 (s)) are respectively fed to the 55 first to third inputs of the control voltage generator 13, at the output of which control signals p are generated frequency converter 2 based on the following equations.

describing the operation of an asynchronous short-circuited engine in the coordinate system J3, 1, oriented along the vector of the main engine flow, (Fig. 3):

Ug RF, -s, Vsc + rsispi (8) UsO + (xJKVsp + Tsis- (9) O Piy y rt + (10) 0 + Ws Vrp +; (11), o

CR isp + i.

  s-c r-o

1 rT -1 cc;

(12)

  f (i), (13)

 t cf, i.rt s6 (1-) 15

Vji + VpJ, Vrt i.-Xru) O5)

  I / H:

m

"G

(sixteen)

where Hz angles - and the speed of rotation

coordinate systems;

5 (Г the angular velocity of the arrest of the coordinate system relative to the rotor. With the help of the generator of 13 control voltages, the structure of which is composed in accordance with the block diagram of the asynchronous motor and frequency converter in the two-dimensional control circuit of the motor torque, the electromagnetic properties of the asynchronous motor are taken into account motor with a frequency converter and at the same time the required typical properties of the subordinate control systems (specified speed, standard character transients, etc.).

The signal m ' at the first input of the driver for control voltages 13 is converted into a signal using division element 14

  .

WH “- Mr-SG

(17

At the output of dividing element 15, a signal WSR is formed according to the ratio

s

 SR IiCltlLiPlkL, (18

 r $ (1

X r6

where W ,, (P) 1 1 + -; P Transmission function of boost 21.

At the output of the filter 24 with the transfer function W (P)

  (-b signal “i. according to the ratio

, gt; t; p- "7 -"

The non-linear element 21 represents the magnetization curve in the form

C D)

At the output of the proportional link 23 is formed with ignite

VsCfi Xsb. (20)

At the output of the adder 29, a signal is generated

    irfR (21) At the output of the adder 25, a signal is generated

V

Sfr

 iVrf., + isj, RXsi

(22)

At the outputs of the adders 28 and 30, control signals of the frequency converter 2 are generated according to the ratios:

I

   -K sfbR- (23) U, f, tR -), (24)

where K, is the voltage transfer coefficient of the frequency converter.

SS

 g S + g

g

g f, - resistance equivalent

frequency converter circuits.

The coordinate conversion unit 12 generates the frequency converter control signals 2, sequentially implementing the conversion of the rotation of the coordinates to the angle and the transition from the two-phase coordinate system o, l to the three-phase relationship:

U.cos y - U. “inj-; T- + U., ccos, j

and.

(25)

 - I and. —And ,;

one

V3

(26)

- 2 So (2

The operations carried out by the differentiation elements 19, 20 are performed with the necessary accuracy, since the signals m, tpj, filtered, are sent to the input of the driver of control voltages.

Blocks 11 and 12 are realized with the help of standard elements of functional devices for AC electric drives UBSR-A - phase converters 3/2, phase converters 2/3, vector analyzer, coordinate conversion unit. The remaining elements of the system can be implemented directly by the equations describing their operation, by means of regulation techniques (large-scale adders, integrators, nonlinear functional converters, differential and multiplying-dividing elements, etc.) from typical controls of the UBSR-AI series ..

The efficiency of the proposed device was tested by simulating the processes in the electric drive on a digital computer. The asynchronous motor was simulated using the complete system of differential equations, and the control system was modeled by the equations corresponding to those shown in FIG. 1 and 2 structures.

The calculation of transient processes showed that the dynamic properties of the proposed electric drive over the entire range of operating speeds and loads are close to the typical properties of the subordinate control systems: the processes of moment and speed are close to typical processes

subordinate automatic control systems; in dynamics, given modes are maintained with satisfactory accuracy.

Thus, the introduction into the electric drive with an induction motor of a control voltage driver equipped with elements of division, multiplication, differentiation, nonlinear element, boosting and proportional links, filter, adders and inverters allowed, in contrast to the known solutions, to sufficiently take into account the properties object of regulation (ASD with frequency converter).

Due to this, high dynamic performance of the proposed electric drive with an asynchronous motor is achieved, which makes it possible to use it for working machines with a highly dynamic mode of operation, on which DC direct current drives are traditionally used (main drives and main rolling mill mechanisms). , vehicles, etc.).

Claims (1)

Invention Formula Electric drive containing an asynchronous motor with a short-circuited rotor connected to the outputs of the frequency converter, flow master Q 0 5 0 five 0 50 five a coupling connected to one of the inputs of the regulator of coupling, a speed setting device connected by an output to one of the inputs of a speed regulator, to another input of which the output of a rotor speed sensor of a specified asynchronous motor is connected, a torque regulator connected by one input to the output of the speed regulator, current and voltage sensors of the stator phases, the coordinate conversion unit and the shaping unit — feedback signals with the outputs of the torque, flux coupler and functions connected respectively to another input of the torque controller, another input of the flux linkage regulator and to the reference inputs of the coordinate conversion unit, while the inputs of the feedback signal generating unit are connected to the outputs of the current sensor and stator phase voltage, and the outputs of the coordinate transformer connected to the control inputs of the frequency converter, characterized in that, in order to improve the dynamic properties by increasing the speed, a three-input driver control is introduced x voltages made with two elements of division, three elements of multiplication, two elements of differentiation, nonlinear element that implements the magnetization curve of the induction motor, boosting and proportional links, filter, six adders, two inverters, with the first input of the control voltage generator formed by the input of the divisible first division element, the second input is formed by the combined inputs of the divider of the first division element of the specified nonlinear element and the first inputs of the first O and the second adders, the third input of the control voltage generator is formed by one of the inputs of the third adder, the other input of which is combined with one input of the first multiplication element and connected to the output of the second division element, and the output of the third adder is connected to the combined first inputs of the second and third elements multiplying, the output of the first division element is connected to the first input of the fourth adder, through a boosting link to the input of the divisible second element by the first inverter to the second input of the first multiplication element and through a proportional link to the second input of the second multiplication element connected between the bob and the input of the first differentiation element whose output is connected to the second input of the fourth adder, the third input of which is connected to the output the third multiplication element, the output of the first multiplication element is connected to the combined second inputs of the second and fifth adders, the output of the second adder through the filter is connected to the input of the divider in the second element of the division, the output of the specified nonlinear element is connected to the first input of the fifth adder, the output of which is connected to the combined second and first inputs of the first and sixth adders, respectively, the output of the first adder is connected to the second input of the third multiplication element and the second differentiation element, the output of which is connected to the second input of the sixth adder, the third input of which through the second inverter is connected to the output of the second multiplication element the control voltage driver is connected respectively to the outputs of the torque controller, flow controller and rotation speed sensor, and the controller outputs their voltages derived outputs of the fourth and sixth adders are connected to respective control inputs of the block preobrazoaani coordinates. FIG. 2  - fj Fi.Z