SU1367123A1 - A.c. electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in the drives of the feeds of machine tools. The aim of the invention is to increase the speed by increasing the rate of change of the excitation current. This goal is achieved by connecting, in the AC drive, the output of the speed controller 19 to the second input of the field regulator 16. The output of the unit 10 for setting the longitudinal component of the stator voltage of the synchronous motor 1 is connected to the second input of the unit 9 for direct coordinate transformation. The power amplifier 4 in the electric drive is designed as a voltage inverter. Regulation is provided in the actuator. motor torque 1 due to a change in the excitation current with an increased desired rate of change in the excitation current. 1 il. with SS (L

Description

with a

Yu

00

eleven

The invention relates to electrical engineering, in particular to a controlled electric drive based on a synchronous motor with electromagnetic excitation and a voltage inverter, and can be used in systems and mechanisms with high dynamic requirements, for example, in feed drives of machine tools.

The aim of the invention is to increase the speed by increasing the rate of change of the excitation current.

The drawing shows the functional scheme of an AC drive.

The AC drive contains a synchronous motor 1 with phase windings 2 and 3 of the stator, connected to the output of the power amplifier 4, an angular position sensor 5 and a rotation frequency sensor 6 mounted on the shaft of the synchronous motor t, connected in series with the transverse current component 7 the stator and the regulator 8 of the transverse component of the stator current, the unit 9 is the direct coordinate transformation, the first input of which is connected to the output of the regulator 8 of the transverse component of the stator current, and the outputs are connected to the control The inputs of the MOHJHOCTH amplifier 4, the stator component set the longitudinal stator voltage component with two inputs, the inverse coordinate conversion unit I1 with the output of the transverse stator current component connected to another input of the stator regulator 8 and the first input block 10 sets the longitudinal stator voltage component, sensors 12 and 13 phase currents of the stator connected to the inputs of block 11 of the inverse coordinate transformation, exciter 14 connected to the excitation winding 15 of the synchronous motor 1, an excitation current regulator 16, the first input of which is connected to the output of the excitation current sensor 17, and an output to the control input of the exciter 14, the rotation speed setting unit 18 connected in series and the rotation frequency regulator 19. The outputs of the angular position flight dates 5 are connected to the reference inputs of the direct 9 and inverse 11 coordinate transform blocks

dinat, and the output of the rotation speed sensor b is connected to another input of the rotation speed controller 19 and to the second input of the block 1, setting the longitudinal stator voltage component,

In the AC drive, the output of the speed controller 19 is connected to the second input of the controller 16 of the field current, the output of the stator component of the longitudinal stator voltage 10 is connected to the second input of the block 9 direct conversion of the ordinates. Power amplifier 4 is implemented as a voltage inverter.

The block 9 of the direct coordinate transformation contains multipliers 20-2S and adders 24 and 25. The first inputs of the multipliers 20 and 22 are combined and form the first input of the block 9 of the direct coordinate transformation, the second input of which is formed by the combined inputs of the multipliers 21 and 23 The second inputs of the multipliers 20, 23 and 21, 22 are connected in pairs and form the reference inputs of the block 9 of the direct coordinate transformation. The outputs of the multipliers 20 and 21 are connected to the inputs of the adder 24, and the outputs of the multipliers 22 and 23 to the inputs of the adder 25, the output of which and the output of the adder 24 form the output of the block 9 of the direct coordinate transformation.

The block 11 of the inverse coordinate transformation contains multipliers 26 and 27 and the adder 28. The first and second inputs of the multipliers 26 and 27 form respectively the main and basic inputs of the block 11 inverse coordinate transform. The outputs of the multipliers 26 and 27 are connected to the inputs of the adder 28 5 whose output forms the output of the transverse component of the stator current of the block 11 of the inverse coordinate transformation,

Unit 10 of the task of the longitudinal component of the stator voltage contains sequentially connected multipliers 29 and inverting yci-30o

The synchronous motor 1 is a machine with not replicated poles or a motor with electromagnetic reduction, rotational frequency. The ANGULAR position sensor 5 can be implemented on the basis of a tick-cosine rotating transferor with an appropriate electronic circuit for processing its output information. The power amplifier 4 and exciter 14 can be implemented on the basis of transistor switches with relay current regulators.

The AC drive operates as follows (for example, take a non-pole synchronous motor 1).

In order to create a moment on the motor shaft, currents in the excitation winding f and in the core winding along the transverse q axis of the rotor are generated and not equal to zero. The torque of the engine is determined by the expression

M K-i

f4

Where

H

h

to the current in the field winding

transverse component

crust current;

constant coefficient

parameter dependent

engine

The regulation of the motor torque value can be carried out both by changing the magnitude of i, the nominal field current ir, in this case

t K.

-q, with H

K-i

di

Hdt

and by changing the value of i.

at the nominal value in this case

n

q, n

dM „To

dif:

Hmdt

As follows from expressions (2) and (3), the maximum rate of change of moment is determined by the maximum rate of change of current. The latter is determined in the first case by the inductance of the core winding on the transverse

rotor axis L,

winding excitation

in the second - induk-L,

The larger the values of L and

L year, the

lower permissible rate of change of current and, consequently, of the motor torque at a fixed value of the applied voltage.

In the electric drive under consideration, the problem of increasing the required

oh

th

ten

15

20

thirty

35

40

45

50

th

25

rate of change of the excitation current dif / dt.

The signal La at the output of the transistor stator component 7 sets the constant value of the last one at the input of the controller 8. The regulator 8 based on the information about the required current i and real i (generates at its output a reference signal of the transverse component of the root voltage Ut. The value of ut is converted by the block 9 of the direct transformation of coordinates into the signals of setting the phase voltages I and A for the amplifier 4 power, as a result, currents i and 2 flow through the phases 2 and 3. The sensors 12 and 13 phase currents determine the values of these currents, and based on This information is determined by the block 11 of the inverse coordinate transformation, the transverse component of the crust current i (s which is fed to another input of the current regulator 8. At the output of the task block 10, a signal is generated that is proportional to the product of the rotation frequency of the rotor of the synchronous motor 1, via the sensor 6 rotational speed, and the transverse component of the stator current io, taken from the output of the block 11 inverse coordinate transformation. This signal sets the longitudinal component of the voltage from the tator.

 In this case, the regulation of the moment of 1 EG is made by changing the excitation current i. The torque setting signal is the output signal of the speed regulator 19, the input of which is supplied with the reference signal from the output of block 18 and a signal proportional to the rotor speed of the motor 1 s in the encoder code 6. The output signal of the regulator 19 sets the excitation current i, and therefore and the engine torque in accordance with the expression (1). The current i is controlled by the exciter current regulator 16 and the driver 14.

In the electric drive under consideration, the transverse component of the current i о gg is set constant, and the torque is controlled by controlling the excitation current.

The required value of the transverse with the remaining core current forms-.

one

With the corresponding setting of the transverse component of the core voltage IL, and the longitudinal component Uo is formed proportional to the product of the rotational speed and current.

Let us show that in this case a high rate of change of the excitation current is provided, and consequently, a high rate of change of the moment as compared with the limestone device.

The equations describing the electromagnetic processes of a synchronous motor in the rotor axes d and q are

.l. 5r- 5r-- -iv

 (+ wLi ,, +;

H -

23

- i. -f

When choosing a source of supply voltage, a much greater voltage drop across the active resistance, equation (9) can be replaced by approximation

, - Z

IT t -ii-n- I dt L-Lf

(ten)

For existing synchronous machines, the magnitude of the magnetic coupling coefficient is

t 2

V o q

h L-Lj

With this in mind, the expression (u)

we get

(five)

25

thirty

35

t- th - (, - ("

de i.ij is the transverse and longitudinal component of the root tone;

R, rA - active resistances of the phase of the core winding and the field winding;

L - self-inductance, the root winding;

Lr. - self-inductance of the excitation winding;

L - mutual inductance

Tp

between the core winding and the field winding; U) engine rotor speed;

1 "is the current in the field winding; U- - voltage on the winding

arousal; and, and, are the longitudinal and transverse components of the voltage applied to the root winding.

Since the voltage U forms- 50. In the electric drive by the expression y -LoLia (7), from expression 4 we have

40

45

 -H L

0 (8)

did. di

----- + L -j-From expressions (6 and (.7 T we get

2;

tm r dif ,, L hi.

g (9)

,., „

(AND)

five

five

0

five

0

0

five

Thus, the realization in the AC drive of a synchronous motor control from the side of the field winding and the execution of a ratio (7) equivalent to the location on the stator of a short-circuited circuit along the longitudinal axis of the rotor provides, in comparison with the known solution, an increase in the rate of change of the excitation current, and therefore speed about 10 times.

Claims (1)

Invention Formula An AC electric drive containing a synchronous motor connected to the output of a power amplifier, an angular position sensor and a rotational speed sensor mounted on the shaft of a synchronous motor, are connected in series to set the transverse stator current component and stator cross current regulator, block direct coordinate transformation, the first input of which is connected to the output of the regulator of the transverse component of the stator current, and the outputs are connected to the control inputs of the power amplifier, the unit for setting the longitudinal component of the stator voltage with two inputs, the block of the inverse coordinate transformation with the output of the transverse component guide stator current connected to another input of transverse component regulator sticking TOKffi stator, and to the first input of the stator longitudinal supply voltage unit of the stator, stator phase current sensors connected by outputs to the inputs of the reverse coordinate conversion unit, exciter connected by output to the excitation winding of the synchronous motor, the regulator of the excitation current, the first input of which is connected to the output of the excitation current sensor, and the output to the control input of the exciters, serially connected. rotational speed controllers and rotational speed regulator, while the outputs of the angular position sensor are connected to the reference inputs of the unit direct and inverse coordinate transformations, and the output of the rotational speed sensor is connected to another input of the rotational speed regulator and to the second input of the task setting unit of the longitudinal component voltage of the stator; in order to increase speed by increasing the rate of change excitation current, the output of the speed regulator is connected to the second input of the excitation current regulator, the output of the stator component of the stator voltage is connected to the second input of the direct coordinate conversion unit, and the power amplifier is filled as a voltage inverter.