SU1239824A1 - Induction electric drive with frequency-current control - Google Patents

Abstract

The invention relates to electrical engineering and can be used in systems with high accuracy requirements for controlling the speed (position) of the load. The purpose of the invention is to increase the accuracy of torque control of an induction motor. Asynchronous electric drive with frequency-current control contains asyn. Synchronous machine (AM) 1 with a squirrel-cage rotor, sensors of 2 phase currents and sensors of 3 phase voltages, controlled current source (IT) 4, block of 5 sensors of phase EMF. The shaper 6 phase flux couplings are made on the basis of aperiodic links 7 and is equipped with phase inputs 8 for setting the initial data. Task block 9 with outputs for torque and flux linkage tasks and coordinate conversion unit 12 are connected to control inputs for IT 4. Introduction of proportional-integral controller 17, nonlinear element 18, two adders 19 and 20, and additional coordinate conversion unit 21 ensures the maintenance flux linking with high accuracy, taking into account the actual magnetization curve, thereby improving the accuracy of torque control (rotational speed). 1 il. S (O

Description

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The invention relates to electrical equipment, namely, frequency-controlled electric drives, built on the basis of asynchronous machines with a short-circuited rotor, and can be used in systems with high rebates in speed control (position) of the load, such as feed drives and main drives. movement of machine tools. The purpose of the invention is to improve the accuracy of torque control of an asynchronous electric drive.

The drawing shows a functional scheme of an asynchronous electric drive with frequency-current control.

The circuit contains an asynchronous machine 1 with a squirrel-cage rotor, the stator windings of which through sensors 2 phase currents and sensors 3 phase voltages are connected to the outputs of a controlled source 4 currents, block 5 sensors of phase EMF connected by inputs to the outputs of sensors 2 and 3 phase currents and voltages, and outputs - to the inputs of the former 6 phase flux couplings, made on the basis of aperiodic links 7 and equipped with phase inputs 8 for setting the initial data, block 9 of tasks with outputs of torque and flux linkings, connected respectively with the first and second control inputs 10 and 11 of the main unit 12 of the coordinate conversion, the outputs of which are connected to the control inputs of the controlled source 4

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currents, the driver 13 of the reference voltage, equipped with phase outputs 14 and 15, connected to the reference inputs of the main unit 12 coordinate conversion, and amplitude output 16, while the inputs of the driver 13 of the reference voltage are connected to the outputs of the generator of 6 phase flux couplings.

A proportional-integral controller 17, a nonlinear element 18 with the characteristic of magnetization of the asynchronous machine 1, the first 19 and the second are introduced into the asynchronous electric drive.

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21 coordinate transformations, reference. the inputs of which are connected to the phase outputs 14 and 15 of the driver 13 of the reference voltage, and the outputs to the corresponding phase inputs 8 for

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the initial data of the driver of 6 phase linkages, wherein the control input of the proportional-integral controller 17, the input of the nonlinear element 18 and the first input of the first adder 19 are interconnected and connected to the task for linking the block of 9 tasks, the outputs of the proportional-integral controller 17 and nonlinear element 18 are connected respectively to the first and second inputs of the adder 20, the output of which is connected to the second control input 11 of the main unit 12 of the coordinate conversion, the second input of the first of the adder 19 is connected to the output of a proportional-invariant tegrsshnogo regulator 17, the output - to the control input of the complementary box 21, the coordinate conversion and yield 16 amplitudnm shaper 13 reference voltage connected to the input of the feedback proportional-integral regulator 17.

Asynchronous electric drive with frequency-current control works in the following way.

The stator windings of an asynchronous machine 1 with a squirrel cage rotor (in a two-phase drawing) are powered from a controlled source of 4 currents composed of phase voltage amplifiers covered by deep negative feedback currents of phase currents using sensors of 2 phase currents. Variable reference signals for phase currents are generated at the outputs of coordinate conversion unit 12, to the inputs of which constant signals b., Ug are received, corresponding to those for the stator component currents in a rotating orthogonal coordinate system connected to the flux linkage vector.

The reference signals necessary for coordinate transformations in the form of harmonic functions sinS2, t, cosSi t (circular frequency of stator current change) are obtained at outputs 14 and 15 of the driver 13 of the reference voltages by signals of phase loss couplings jH, coming from the outputs of the driver 6 phase flux couplings.

In each phase circuit of the former 6 phase flux coupler, there is an aperiodic link 7, which plays the role of an integrator corresponding to the phase EMF G.-, fy, coming from the output of the block Ь of the sensors of the EMF. Block 5 sensors of phase EMF produced by calculation of phase EMF according to information about phase currents 1l, i. and the voltage Vf, and, arriving from, the outputs of the sensors 2 and 3 phase currents and voltages. Phase EMFs can also be obtained at the outputs of special measuring windings installed on the stator of the asynchronous machine 1 (indicated by communication with the sensor unit 5 phase EMF is indicated by a dash).

The possibility of performing the integration operation of phase EMF using aperiodic links 7 in the entire frequency range, including zero, is associated with the need to feed additional signals corresponding to some initial data (initial values of phase flow couplings) to phase inputs 8 of the former 6 phase flow couplings.

The indicated initial values of phase flux couplings at the inputs 8 of the flux generator 6 of the phase flux linkages are established due to the action of normalized positive feedback circuits covering each of the phase aperiodic links 7 through the driver 13 of the reference voltages and the additional unit 21 coordinate transformations.

In this case, the amplitude of the initial phase flux linkages is determined by the signal h, which is outputted from the output of block 9 of tasks via the first adder 19 to the control input of the coordinate conversion unit 21, and the phases are arbitrary, but correspond to the two-phase signal system

The arbitrary values of the phase flux couplings obtained from the positive feedback chains determine arbitrary initial values of the signals at the reference inputs of the main coordinate conversion unit 12 and an arbitrary initial direction of the formed flux link vector in the asynchronous machine 1.

Since an asynchronous squirrel cage rotor machine 1 has phase-symmetric magnetic circuits, any initial position of the flux linkage vector can be taken as the initial one. Subsequently, when an input signal Ug arrives at input 10 of unit 12, which corresponds to the specification of torque M, an asynchronous machine 1 arises at the shaft, an instant leads to the rotation of the shaft and the occurrence of phase EMF fj . Phase flux linkages,,, at the outputs of the former 6 phase flux couplings are mainly determined by the action at its inputs of the phase EMF

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The signals at the phase inputs 8 are reduced to compensating for the active components of the output currents of the phase aperiodic links 7, which, under these 15 conditions, perform operations equivalent to integrating the phase EMFs.

In the electric drive, the magnetization curve of the magnetic circuit of an asynchronous machine 1 with a short 2Q closed rotor is taken into account due to the introduction of a nonlinear element 18, at the input of which a flux linkage signal V is received from the output of block 9.

The output signal of the nonlinear element 18 through the second adder 26 is fed to the input 11 of the coordinate conversion unit 12 (as an Up signal), which determines the magnitude of the component of magnetization in the stator current. Using the proportional-integral controller 17 introduced into the electric drive, the flow coupling is maintained at a predetermined level determined by the h signal. The feedback signal in the form of a real flow coupling module is fed to the regulator from the amplitude output 16 of the driver 13 of the reference voltages. If there is a mismatch between the set and the actual values of the flux coupling, the output signal of the proportional-integral controller 17, the component magnitude correction is determined: the magnetization current (i.e., the signal and through the adder 20) and the amplitude of phase couplings at the inputs 8 shaper 6 phase flux linkages (through the first adder 19 and additional

0 block 21 coordinate conversion). Thus, the introduction of an proportional-integral controller, a nonlinear element with the characteristic of magnetization of the asynchronous machine, two adders and an additional unit of coordinate conversion to an asynchronous electric drive with frequency-current control ensures that the flow coupling set in the electric drive is maintained with high accuracy, taking into account the real magnetization curve as in standby modes, as well as in the modes of rotation of the electric drive, due to which the accuracy of torque control (rotation speed nor) in comparison with the known solution,

Claims (1)

Invention Formula An asynchronous electric drive with frequency-current control, containing an asynchronous machine with a short-circuited rotor, the stator windings of which are connected to the outputs of the sensors of phase currents and connected to the outputs of the sensors of phase currents through sensors of phase currents and voltages through sensors of phase currents and voltages. voltages, and outputs - to the inputs of the phase coupler driver, made on the basis of aperiodic links; and supplied with phase inputs for setting initial data, a set of tasks with outputs of torque and flux linkages, associated with the first and second control inputs of the main unit of the coordinate transformer, the outputs of which are connected to the control inputs of the controlled source , the driver of the reference voltage, equipped with phase outputs connected to the reference inputs of the main unit of the coordinate conversion, and the amplitude output, while Editor A. Shandor Compiled by V. Tarasov Tehred O. Sopko Proofreader A. Obruchar Order 3406/55 Draw 631 VNIIPI State Committee (ZSSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Printing and production enterprise, Uzhgorod, st. Project, 4 the inputs of the driver of the reference voltages are connected; to the outputs of the driver of the phase flux linkages, which, in order to increase the accuracy of control of the moment, a proportional-integral controller is introduced into it, a non-linear element with the characteristic of a magnetized asynchronous machine with short-circuited a rotor, two adders and an additional coordinate conversion unit, the reference inputs of which are connected to the phase outputs of the reference voltage generator, and the outputs to the corresponding phase inputs for setting The initial data of the phase-flux coupling composer, while the control input of the proportional-integral controller, the input of the nonlinear element and the first input of the first adder are interconnected and connected to the output of the task linking flow of the task block, the outputs of the proportional-integral controller and the nonlinear element are connected respectively, to the first and second inputs of the second adder, the output of which is connected to the second control input of the main coordinate converting unit, the second input of the first summation The pa is connected to the output of the proportional-integral controller, the output is connected to the control input of the additional coordinate conversion unit, and the amplitude output of the voltage driver is connected to the feedback input of the proportional-integral controller. Subscription