SU1334342A1 - A.c.electric drive - Google Patents

Abstract

The invention relates to electrical engineering and can be used in machine tool industry for shifting machine tools. The aim of the invention is to simplify and improve accuracy. This goal is achieved by introducing into the block 3 tasks of data currents of the AC drive, two inverters 14 and 15, four three-input switches 16-19, three adders 20-22, reverser 23, counter 24, storage element 25, driver 26 commands. the registers 27 and 28, the converter 29 of the number of phases, the block of 30 EXCLUSIVE OR elements and the digital-analog converters 31 and 32. The introduction of these blocks provides the necessary coordinate transformations of the control signals of the phase currents from the rotating system to moving coordinate system using the same quarter of the period of the reference frequency. 1 il. 3 to (L

Description

11334342

the invention relates to electro and so and not you

for controlling the speed of one: night AC motors, and can be used, for example, in the machine tool industry to move the working parts of machine tools.

The purpose of the invention is to simplify and improve the accuracy of the electric drive of alternating current by reducing the torque pulsations in the whole range of rotational speed control.

The drawing shows the functional diagram of the AC drive.

The AC drive contains an asynchronous electric motor 1, the stator windings of which are connected to the outputs of an adjustable source of 2 phase currents connected by control inputs from the outputs of the DI unit of the 3 tasks of phase currents made to the inputs 4 and 5 of the stator current with voltage converter - frequency 6 and first and second digital-analog converters (D / A) 7 and 8, rotational speed sensor 9 mounted on the shaft of the induction motor set reactive current 10 , series-connected rotational frequency adjuster 11, comparison element 12 and rotational frequency regulator 13 whose output and output of reactive current adjuster 10 are connected respectively to inputs 4 and 5 for setting the active and reactive components of the stator current of the phase-current setting unit 3, while the input of the comparison element 12 is connected to the output of the rotational speed sensor 9.

In the AC drive additionally introduced two inverters 14 and. 15, four three-input keys 16–19, three adders 20–22, reverser 23, counter 24, memory element 25, command builder End of account 26, two registers 27 and 28, converter 29 number of phases, as well as a block of elements EXCLUSIVE OR 30 and digital to analog converters 31 and 32.

The inputs of the first and second inverters 14 and 15 form, respectively, inputs 4 and 5 for the tasks of the active and reactive composition: the stator current

five

0

five

0

five

0

five

0

five

currents. The output of the first inverter 14 is connected to the first inputs of the first and second power input switches 16 and 17, the second inputs of which are combined with the input of the first inverter 14.: The output of the second inverter 15 is connected to the first inputs of the third and fourth three-input switches 18 and 19, the second inputs of which are combined with input: house of the second inverter 15.

The analog inputs of digital-to-analog converters 7 and 8, 31 and 32 are connected to the outputs of the respective three-input keys 16-19. The outputs of the first and fourth digital-analog converters 7 and 32 are connected to the inputs of the first adder 20. The outputs of the second and third digital-analog converters 8 and 31 are connected to the inputs of the second adder 21. The outputs of the adders 20 and 21 are connected to the inputs of the converter 29 of the number of phases, the outputs of which form the outputs of the unit 3 setting the phase currents.

11 1-digital inputs of digital-to-analog converters 7 and 31, 8 and 32 are pairwise combined and connected respectively to the outputs of the first and second registers 27 and 28, the information inputs of which are connected to the outputs of the storage element 25. The clock inputs of the registers 27 and 28 are connected to the direct and inverter voltage-frequency inverter outputs 6.

The input of the first inverter 14 is combined with the first INPUT of the third adder 22, the second input of which is connected to the output of the rotational speed sensor 9. The output of the third adder 22 is connected to the input of the converter voltage - frequency bis by the input of the reverser 23, the output of which is connected to the input of the switching of the counting direction of the counter 24, the counting input of which is connected to the direct output of the voltage converter - frequency 6. The outputs of the counter 24 corresponding to the lowest and senior bits, respectively, are connected with the first inputs of the block of elements EXCLUSIVE OR 30 and the inputs of the command generator. Account termination 26.

The second inputs of the block EXCLUSIVE OR 30 are connected to the direct outputs of the converter voltage - frequency 6. The outputs of the block of elements EXCLUSIVE OR 30 are connected

3133

with the inputs of the storage element 25. The first output of the command generator End of the account 26 is connected with the third inputs of the first and third keys 16 and 18, and the second output - with the third inputs of the second and fourth keys 17 and 19,

In the AC drive, frequency-current control was performed with coordinate transformation of the stator current components from a rotating orthogonal coordinate system X, Y to a fixed c. , is oriented relative to the stator of the asynchronous electric motor.

The AC drive works as follows.

Speed reference signal. The driver of the setting unit 11 is fed to the first input of the comparison element 12, to the second input of which a signal is output from the rotational speed sensor 9. The signal from the output of the noctynaeT comparison element 12 to the input of the rotational frequency controller 13, which forms a reference to the active component i of the stator current in the rotating coordinate system. A given current component i of the stator current is formed at the output of the reactive current setpoint 10. These tasks are received, respectively, at the inputs 4 and 5 of the block 3 of the assignment of phase currents.

The output of the rotational speed controller also comes from adder 22, where it is summed with the rotational frequency signal u.ii2: rotor, on, - coming from the output of sensor 9.

The output signal of the adder 22 is fed to the input of the converter for example

13 on

an hour

frequency is 6, which linearly converts this signal into direct and inverse pulse sequences whose frequency is proportional to the stator current frequency.

The impulses of the direct sequence are fed to the input of the counter 24, from the output of which the resulting 8-bit code of the signal a.) T is fed to the input of the block of the elements of the CCRIUS STII 30, the clock input associated with the output of the voltage converter - frequency 6,

At the output of block 30 with the frequency of the clock pulses, the direct code i) t and its inversion corresponding to the angle (|) alternately appear. Next, the angle code is fed to the inputs.

0

as ko-software device with wired

element 25,

used by

memorizing

in it is the binary code of the sine wave in

range of angles (O-TT). Insofar as

sin (-u), t) cosuj t,

then at the output of element 25, the numbers corresponding to sincO t and coscO, t appear alternately. They are rewritten into registers 28 and 27 for clocking pulses, which use the direct and inverse sequences of the output pulses of the voltage-frequency converter 6.

When occurrence of 1 in the 9th digit of the counter 24 from block 30, the inverse number code begins to arrive at the input of the storage element 25, which is necessary to form the second quarter of the sine wave and cosine wave in the range, i l

25 corner zone (, - - jT;,

Shaper 26 generates two commands. Account Termination, i.e. ending sine wave formation and ko30

sinusoids in the range of angles (O - Ji). For a sine wave, this command is the output of the 10th bit of counter 24, and for a cosine wave, the same command as for a sine wave, but shift

 .

35

chickpea

l to 2

From the outputs of the register 28, the sinusoid code is fed to the digital inputs of the D / A converters 8 and 32. From the outputs of the register 27, the other code of the sinusoids is fed to the digital inputs of the D / A converters 7 and 31. The analog inputs

the inputs of the D / A converter 7 and 8 are respectively supplied from the outputs of the keys 16 and 17. In this case, the switch 17 switches the signals from the output of the rotational frequency controller 13 and the inverter 14 through command 7. the end of the formation of the half-wave of the SINUSO1SCHCHY, and the key 16 - by the command of the end of the formation of the half-wave of the cosinusoid. Thus, at the outputs of the DAC 8 and 7 are formed

i, y sin u), t and iyCOScO t

55

The analog inputs of the D / A converters 31 and 32 are given signals from the keys 18 and 19, which are the output voltages of the reactive current setpoint 10 and the inverter 15 switched by the same commands. At the output of the DAC 32

and 31, the components i sin (jL) t and i cosu), t are formed.

l, 1l7

The basis of the formation of these components of the stator current is the same quarter of the sinusoid, which ensures high accuracy of the transformations. The three-input keys 16-19 of the D / A converters 7 and 8, 31 and 32, as well as the adders 20 and 21, perform the coordinate transformations of the control signals from the rotating X, Y coordinate system to the d / 3 fixed system when frequency-controlled. The signals if, i obtained at the outputs i of the adders 20 and 21 are converted by means of the converter 29 of the number of phases into a three-phase system of control signals IQ, ig ,, i fed to the control inputs of the controlled source 2 phase currents, which form phase currents of the required frequency from them and amplitudes.

Thus, in the assumed AC drive, the necessary coordinate transformations of the phase current control signals from the rotating system to the fixed coordinate system are provided using the same quarter of the reference frequency period, thereby simplifying the structure of the electric drive and increasing the accuracy of shaping the control currents along the phase currents. compared with the famous electric, electric drive.

Claims (1)

Invention Formula An AC electric drive containing an asynchronous electric motor, the stator windings of which are connected to the outputs of an adjustable source of phase currents, connected by control inputs to the outputs of a phase current setting unit, which is filled with inputs for active and reactive components of the stator current, with a voltage converter - the frequency of both the first and second digital-to-analog converters, the rotational speed sensor mounted on the shaft of the induction motor, the reactive current setting device, Cpd nennye dial rotational speed, comparing the element and the rotational speed controller whose output setpoint and the reactive five current is connected respectively to the inputs for setting the active and reactive components of the stator current phase current setting block, while the other input of the reference element is connected to the rotational speed sensor input, characterized in that, to simplify and improve accuracy, the phase current setting unit additionally introduced the first and second inverters, the first, second, third and fourth three-input keys, the first, second and third adders, reverser, counter, storage element, driver - account count, first and second registers, a number of phases converter, as well as a block of EXCLUSIVE OR elements and a third and fourth digital-analog converters, while the inputs of the first and second inverters form respectively the inputs for the tasks of the active and reactive components of the caster of the phase setting block of the phase currents; the inputs of the first and second three-input switches, the second inputs of which are combined with the input of the first inverter, the output of the second inverter is connected to the first inputs of the third and fourth three-input lyuchey, second inputs of which are combined with the input of the second inverter, the analog inputs of analog converters connected to the outputs of respective keys trehvhodovyh, outputs of first and fourth digital to analog converters are connected to the The inputs of the first adder, the outputs of the second and third digital-to-analog converters are connected to the inputs of the second adder, the outputs of the first and second adders are connected to the converter inputs of the number of phases, the outputs of which form the outputs of the phase current reference unit, and the digital inputs of the first and third, second and fourth digital-analog converters are pairwise combined and connected respectively to the outputs of the first and second registers, the information inputs of which are connected to the output of the storage element, and clocking inputs of these registers are connected to the direct and inverse outputs of the converter voltage - frequency respectively, the first input of the inverter is integrated with the first input of the third five five 0 five -I1334342g an adder, the second input of which is a co-source OR, and the input is formed with the output of the frequency sensor; commands of the command end of the count, the second time, the output of the third sum of the co-input of the unit of the ICS unit (EE OR one with the input of the converter, is connected to direct output transform - frequency and with input of reverse voltage actuator - frequency, output, ra, the output of which is connected to the input block of the elements EXCLUSIVE OR connection- The switching of the counting direction is counted with the input of the storage element, the counting input of which is a, the first output of the driver with the direct output of the converter - | Q mand. The end of the counting is connected to voltage - frequency, the outputs are counted by the third inputs of the first and third keys, corresponding to the younger and old keys, and the second output - from the third ones ladies, are connected by the respective inputs of the second and fourth keys to the first input of the unit.