SU1246317A1 - Device for determining coordinates of induction motor in controlled-velocity electric drive - Google Patents

Abstract

This invention relates to electrical engineering and can be used in a controlled electric drive. The purpose of the invention is to simplify and improve the accuracy of the device for determining the coordinates of an asynchronous motor. The device contains an asynchronous motor (BP) I in an adjustable electric drive, a sensor (D) 2 stator phase currents, a current conversion unit 3, D 4 stator phase voltages, a voltage conversion unit. The block (B) 6 of the computation of the components of the rotor flow vector is connected to two elements of comparison 7, 8, two relay elements 9, 10. The block (B) AND the calculation of the components of the stator current vector is also connected to the driver of rotational speed signals BP 1 B & I is equipped with two additional comparison elements and a second pair of scale elements. The closed control system of the stator current vector components makes it possible to ensure high accuracy of determining such BP coordinates as the rotational speed and the rotor flow vector components of the rotor due to the absence of multiplication blocks and scale elements with a transfer coefficient depending on the active rotor resistance. 2 Il. SS (Л tsD 4 О5 СДЭ SI

Description

The invention relates to electrical engineering, namely, devices for determining the coordinates of an induction motor and can be used in a regulated asynchronous electric drive for general industrial purposes.

The purpose of the invention is to simplify and improve the accuracy of the device for determining the coordinates of an asynchronous motor.

FIG. 1 shows a functional diagram of the device for determining the coordinates of an asynchronous motor; in fig. 2 is a block diagram of the calculation of the components of the stator current vector.

A device for determining the coordinates of an asynchronous motor 1 (Fig. I) in an adjustable electric drive contains sensors of 2 stator phase currents connected by outputs to the inputs of current conversion unit 3, sensors of 4 stator phase voltages connected by outputs to inputs of voltage conversion unit 5, block 6 calculating the components of the rotor flow coupling vector, equipped with two pairs of inputs, two comparison elements 7 and 8, two relay elements 9 and 10, the block 11 calculating the stator current vector components, equipped with two pairs of inputs and shaper 12 logic signals of rotational speed of the asynchronous motor and the signal for matching the flow, equipped with two pairs of inputs and connected by outputs to the first pair of inputs of the calculator 6 components of the rotor flux vector of the coupling, the second pair of inputs of which are combined with the first inputs of the corresponding elements 7 and 8 comparisons and connected to the outputs of the current conversion unit 3. The outputs of the comparison elements 7 and 8 are connected to the inputs of the corresponding relay elements 9 and 10 connected by the outputs with the first pair of inputs of the specified logic driver 12, the second pair of inputs of which are phasewise connected to the first pair of stator current vector components and connected to the outputs of block 6 for calculating the components of the rotor flux linkage vector.

The outputs of the voltage conversion unit 5 are connected to the second pair of inputs of the calculation unit 11 of the stator current vector components, the outputs of which are connected to the second inputs of the comparison elements 7 and 8.

The calculating unit 11 of the stator current vector components is provided with two adders 13 and 14 (FIG. 2), two aperiodic links 15 and 16, and the first pair of main elements 17 and 18, whose inputs form the first pair of inputs of the stator current vector component . The outputs of the scale elements 17 and 18 are connected to one of the inputs of the adders 13 and 14, connected by outputs with

the inputs of the respective aperiodic links 1/3 15 and 16, and the other inputs of the adders 13 and 14 form the second pair of inputs of the block 11 for calculating the components of the stator current vector.

The calculating unit 11 is a component, their stator current vectors are additionally equipped with two elements 19 Ji 20 of comparison and a second pair of headband elements 2 and 22, whose inputs are connected respectively to the inputs of the first pair of scale elements 17 and 8. At the same time, the outputs of the second pair of meters. HI-Itable elements 21 and 22 are connected to one of the inputs of the respective comparison elements 19 and 20 connected by other inputs to the outputs of the corresponding aperiodic links 15 and 16, and the outputs of the comparison elements 19 and 20 form the outputs of the I 1 calculation unit. stator current stator.

A device for determining the coordinates in an asynchronous electric drive works as follows.

The current conversion unit 3 and the conversion and voltage unit 5 convert the phase currents and voltages from the outputs of the corresponding sensor 2 and 4 into the composition of the generalized current vectors Iscc, Up and voltage (Y, L p of the stator in the Cartesian system coordinates about :, r, motionless from 1-: single stator asynchronous motor 1.

In the outputs of the aperiodic links 15 and 16, in block 11 of the calculation of the components of the stator current vector, signals KJ, Ur are formed, which are a linear combination of the corresponding computational components of the stator current vector / ,, ti, / 45 and the rotor flux linkage (ifc, according to its following differential equations:

I JL.11 / o

I and. L.

Lm

X

40

Xij-fl “) J:

Lr

k. (t r ". - R (

L.LK - / 4G

L, LP.

d

where LS, LA, L,: t are the inductances of the stator, rotor and mutual inductance, respectively;

RS - stator resistance.

The projections of the calculated stator current vector /. ,, / Д at the outputs of the comparison elements 17 and 18 are determined by the equations

/ G y / bj L p, -1 tr

) R

/ LR, - / p

LiLa-l n

Rf ,.

The projections of the calculated no-clutch rotor vector of α-f / ha are formed in

block 6, which implements the following differential equations:

d, iG I RK-Ln ,, „, -, - Ф« i +

+)

1 ..... And, |, f L G) .Л I

. -. xj,; fp | -i7; / sp + +

+,

where - the active resistance of the rotor; Q speed of asynchronous

engine;

fj, is fictitious.

The magnitude Q and p, modulated in time, lia by the output of the logic driver 12, play the role of control actions in the control loop.

The average value of Q determines the speed of rotation of the shaft of the induction motor 1. In the installation mode of the device, when its free movement is completed, the average value J is zero. The values of Q and q create such a vector for controlling the motion of the device so that the tracking of the stator current vector is carried out in all modes of operation of a real asynchronous motor.

The components of the stator current vector / s, / s obtained at the output of the current conversion unit 3, and the AV components formed at the outputs of the unit 11, are compared with the help of the comparison elements 7 and 8. Comparison results affect the relay elements 9 and 10, from the output of which they receive pulse signals that determine the sign of the mismatch. These pulsed signals are distributed in the driver 12 of the logic signals to BbixOxW, on which the signals O, C are set depending on the p. / Burning of the flux linkage vector on plane a, (3 so that the signs of the error of the derivatives of the stator current components are always negative, t . e. that in each channel feedback is negative at any time.

The signal distribution algorithm is determined based on the fact that the signals C (i vary with frequency much more than the voltage and current of the induction motor in the variable-frequency drive. In addition, the high switching frequency ensures a small free movement of the system.

The signals О, | 1 are formed according to the following logic functions:

,., & 5 ,, & 5l /. .&& 5 ,, .. & S ,, - ,, & 5l / in

-54-, & 5, - ,, ,, ,, & S., & S, ff .;

Q, &, & & &

& S &, & & &

, &,

0

five

0 s

about 5

0

Where

five

5y. s / g - "(vl; (:),

5 ... f ....);

5v / a - s / g-n (7., - / 4), sign {,, l,}.

The closed control system of the stator current vector components implemented in the device ensures high accuracy of determining such asynchronous motor coordinates, such as the rotation speed Q and the rotor flux-coupling vector components f a, flr due to the absence of multiplication units and massive elements. with a transmission coefficient depending on the active resistance of the rotor.

Thus, the introduction into the calculator of the stator current vector components of two adders, two aperiodic links, two comparison elements and two pairs of scale elements in the device determines the coordinates of the asynchronous motor (rotation speed, components of the rotor flux linkage vector) with high accuracy in comparison with the known solution.

Claims (1)

Invention Formula A device for determining the coordinates of an armature motor in an adjustable electric drive, comprising sensors of stator phase currents connected by outputs to inputs of a current conversion unit, sensors of phase stator voltages connected by outputs to inputs of a voltage conversion unit, a rotor flux coupling vector components, equipped with two pairs of inputs, two comparison elements, two relay elements, a stator current vector component calculation unit equipped with two pairs of inputs, and a log generator of the rotational speed of the asynchronous motor and the signal for the misalignment of the flow coupling, equipped with two pairs of inputs and connected to the first pair of inputs b, of the calculation of the components of the rotor flux vector, the second pair of inputs of which are combined with the first inputs of the corresponding comparison elements and connected to the outputs of the current conversion unit, while the outputs of the comparison elements are connected to the inputs of the corresponding relay elements connected by the outputs with the first pair of inputs specified Logic signal generator, the second pair of inputs of which is phase-wise combined with the first pair of inputs of the calculator of the stator current vector components and connected to the outputs of the calculator of the rotor flux-coupling vector components, the outputs of the voltage conversion unit are connected to the second pair of inputs of the current vector component of the calculator a stator, the outputs of which are connected to the second inputs of the respective elements of the comparison, and the block for calculating the components of the stator current vector is equipped with two adders, VUM aperiodic link means and the first pair of scaling elements, the inputs of which form the first pair of inputs calculating unit constituting the stator current vector, the outputs of said masschtabnyh elements connected to one input of respective adders connected R five the outputs with the inputs of the corresponding aperiodic links, and the other inputs of the adders form the second pair of inputs of the calculator of the stator current vector components, characterized in that, in order to simplify and improve the accuracy, the calculator of the stator current vector components is equipped with two additional comparison elements and a second pair scaled elements, the inputs of which are connected respectively to the inputs of the first pair of scaled elements, while the outputs of the second pair of scale elements are connected to one of the inputs according to comparing stvuyuschih additional elements connected to other inputs to the outputs of the respective aperiodic links, and outputs the comparison elements form additional calculating unit outputs constituting the stator current vector. -one .2