JPH10174500A - Vector control inverter for induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid pulsation of output torque in the vicinity of rated r.p.m. of a motor. SOLUTION: Primary current of an induction motor 5, being driven through an inverter circuit is detected by a current detector 7 and divided into a torque component current detection value and an exciting component current detection value, and a primary current command value is divided into a torque component current command value and an exciting component current command value. In such a vector control inverter for controlling the induction motor 5, a flux command Φ2 * as a base of the exciting component current command, and the torque component current command Iq* are inputted individually and externally (torque command means 30/flux command means 31) in the form of command signal for controlling the output torque constantly regardless of the rotational speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector control inverter for controlling an induction motor.

[0002]

2. Description of the Related Art FIG. 7 shows a schematic configuration of a conventional vector control inverter device for driving and controlling an induction motor.

This vector control inverter device is composed of a rectifier circuit 2 composed of a diode or the like for obtaining a DC voltage from a three-phase AC power supply 1, a DC voltage smoothing filter 3, and a switching element such as a transistor. An inverter circuit 4 for controlling a current supplied to an induction motor 5 (hereinafter referred to as a motor); a speed command circuit 8 for providing a speed reference (command value) of the motor 5;
^* , The position detection value Xr detected by the position detector 6 connected to the motor 5 and the current detection values Iu, Iv, Iw of each phase detected by the current detector 7 are input and given to the motor 5 Phase primary voltage command values Vu ^* , Vv ^* , V
a vector control operation circuit 9 for calculating w ^*, and a pulse width modulation control circuit for generating a signal for turning on / off the switching element of the inverter circuit 4 based on the primary voltage command values Vu ^* , Vv ^* , Vw ^* (Hereinafter, referred to as a PWM circuit) 10.

[0004] The bias value of the magnetic flux command according to the detected current value of the torque is stored in a storage device 40 attached to the vector control operation circuit 9. Further, the output of the current detector 7 does not necessarily need to have all three phases, but detects any two phases, and the remaining 1 is obtained from the relationship of Iu + Iv + Iw = 0.
The phase current may be determined.

FIG. 8 shows an internal configuration of a vector control operation circuit 9 in a conventional vector control inverter device.

This vector control arithmetic circuit 9 is used for position detection.
The rotational speed ωr is obtained by differentiating the position detection value Xr from the heater 6.
And a finger from the speed command circuit 8.
Order price ωr^*And the rotation speed ω output by the rotation speed calculator 11
Amplify the deviation of r and torque command current value by PI control
Iq^*PI calculator 12 for outputting the current and the current detector 7
From the AC three-phase detection values Iu, Iv, Iw
Current Iq (current value of torque component detection) and Id (excitation component current
Current to convert to detected value), and three-phase to two-phase converter 13 and excitation
From the detected partial current value Id, the secondary magnetic flux value of the motor 5 Ф_TwoCalculate
Output from the secondary magnetic flux calculator 14 and the rotation speed calculator 11
Magnetic flux command value 応 じ according to the rotating speed ωr _Two ^*Calculate
Magnetic flux command calculator 15, magnetic flux command value Ф_Two ^*And secondary magnetic flux detection
Outgoing priceФ_TwoExcitation current by PI control
Command value Id^*And a secondary magnetic flux PI calculator 16 for calculating
Luc current command value Iq^*And the torque component current detection value Iq
Amplify the deviation and torque command voltage value Vq by PI control
^*, A torque component current PI calculator 17 for calculating
Flow command value Id^*Amplification of deviation between current and excitation current detection value Id
And the excitation component voltage command value Vd by PI control^*Calculate
An excitation component current PI calculator 18 is provided.

The vector control operation circuit 9 is provided with a secondary magnetic flux.
Secondary magnetic flux value output by arithmetic unit 14 _TwoAnd speed PI calculator
12 outputs the torque current command value Iq^*Tokara slide
Angular velocity θs^*And a slip angular velocity calculator 19 for calculating
Rotational angular velocity performance that calculates rotational angular velocity θr from rotational velocity ωr
The secondary magnetic flux value output by the calculator 20 and the secondary magnetic flux calculator 14
Ф_TwoAnd current command for torque output by speed PI calculator 12
Value Iq^*From the induced voltage compensation value Vqc of the torque divided voltage,
An induced voltage for calculating an induced voltage compensation value Vdc of the excitation component voltage
Including a pressure compensator 21 and a voltage two-phase to three-phase converter 22
I have.

The voltage two-phase to three-phase converter 22 outputs the torque component voltage command value Vq ^* and the excitation component voltage command value Vd ^* compensated by the induced voltage compensation values Vqc and Vdc, and outputs the slip angular velocity calculator 19. The deviation between the slip angular velocity θs ^{* to be performed} and the rotational angular velocity θr from the rotational angular velocity calculator 20 is input, and the torque component voltage command value Vq ^* and the excitation component voltage command value Vd are input.
^* Is converted into AC three-phase primary voltage commands Vu ^* , Vv ^* , Vw ^* .

In the above-described vector control by the inverter device, as shown in FIG. 9, the magnetic flux command value 以下₂ ^* is constant below the rated rotation speed of the motor, and above it is the square of the rotation speed. Changes in inverse proportion to. As shown in FIG. 10, the excitation component current command value Id ^* is constant below the rated rotation speed of the motor, and changes in inverse proportion to the square of the rotation speed above it. The torque current command value Iq ^* is a value proportional to the output torque of the motor, and there is no fixed pattern in the speed control by the configuration shown in FIG.

[0010] The torque generated by the motor can be expressed by the following equation.

That is, T = Pm · M · φ ₂ · _iqs / L ₂ ... Φ ₂ = M · _ids / (T ₂ · S + 1). Here, T is the torque generated by the motor, Pm is the pole pair of the motor, M is the mutual reactance, φ ₂ is the magnetic flux on the secondary winding side, _iqs is the torque component current, and L ₂ is the reactance of the secondary winding. , _Ids are excitation currents and S is a differential operator.

From the above equation, the torque T generated by the motor is given by
Is the excitation current i_dsAnd torque current i _qsIs proportional to the product of
You can see that. Also, from the equation, the secondary magnetic flux φ of the motor
_TwoIs the excitation current i_dsIt turns out that it is proportional to.

Further, since φ ₂ = M · _ids ... Steadily, T = Pm · M ₂ · _ids · _iqs / L ₂ ··· From the equation, the torque T generated by the motor is
It can be seen that it is proportional to the product of the exciting component current _ids and the torque component current _iqs .

Conventionally, when torque control is performed on the basis of the above equation, a fixed control characteristic pattern as shown in FIG. Only the current command value Iq ^* is given by an external speed command ωr ^* . The characteristic pattern of the exciting component current _ids at this time depends on the rotation speed of the motor, and has no relation to the feedback value of the torque component current.

[0015]

Since the conventional vector control type inverter device is configured as described above, for example, in the torque control for directly controlling the output torque of the motor by giving a torque command to the motor, Output torque from 0 speed to the maximum rotation speed of the motor
In the case of constant control at 0%, the excitation current command is given with the characteristics shown in FIG. 10 and the torque current command is given with the characteristics shown in FIG.

Therefore, at the rated rotational speed of the motor, the magnetic flux command changes abruptly, and due to the response delay of the current control loop determined by software inside the inverter device, at the rated rotational speed, as shown in FIG. There is a problem that the actual output torque T pulsates.

For this reason, for example, in the papermaking process, when feeding paper with a given tension applied to the paper, the rotation speed of the roll around which the paper is wound passes the rated rotation speed of the motor that drives the roller. In this case, there is a problem that the pulsation fluctuates, the tension fluctuates in accordance with the pulsation fluctuation, and the shape of the paper changes.

Further, since the magnetic flux command depends only on the rotation speed of the motor and has no relation to the feedback value of the current for the torque, an excessive current flows at a light load, the motor loss increases, and the efficiency decreases. There was also a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and uses a motor driven by torque control to avoid pulsation of output torque near the rated rotation speed of the motor. It is an object of the present invention to obtain a vector control inverter device for an induction motor, which can improve the quality of a product produced by the machine and improve the motor efficiency at light load.

[0020]

In order to achieve the above object, a vector control inverter device for an induction motor according to the present invention detects a primary current of the induction motor driven by the inverter circuit by a current detector. The primary current detection value by the current detector is divided into a torque component current detection value and an excitation component current detection value, and the primary current command value is divided into a torque component current command value and an excitation component current command value to induce the current. In a vector control inverter device that controls an electric motor, in order to control the output torque to be constant regardless of the rotation speed, a magnetic flux command as a source of an excitation component current command and a torque component current command are individually commanded from outside. It is input as a signal.

In the vector control inverter device for an induction motor according to the present invention, a magnetic flux command input from the outside,
Similarly, the torque output by the motor is controlled based on a torque current command externally input.

A vector control inverter device for an induction motor according to the present invention stores a bias value of a magnetic flux command according to a detected current value of a torque in a storage device attached to a vector operation circuit.

In the vector control inverter device for an induction motor according to the present invention, the bias value of the magnetic flux command is set according to the detected current value for the torque.

The vector control inverter device for an induction motor according to the next invention is characterized in that the stored bias value of the magnetic flux command can be changed by a parameter setting device capable of changing a control constant inside the inverter. .

In the vector control inverter device for an induction motor according to the present invention, the stored bias value of the magnetic flux command can be changed by the parameter setting device.

The vector control inverter device for an induction motor according to the next invention is characterized in that the bias value of the stored magnetic flux command can be changed by an external setting signal.

In the vector control inverter device for an induction motor according to the present invention, the bias value of the stored magnetic flux command can be changed by an external setting signal.

The vector control inverter device for an induction motor according to the next invention is characterized in that the command signal or the setting signal is any one of a voltage signal, a current signal and a pulse signal.

In the vector control inverter device for an induction motor according to the present invention, the setting of the externally input magnetic flux command, the torque current command, or the bias value of the magnetic flux command is performed by any of a voltage signal, a current signal, and a pulse signal. .

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vector control inverter device for an induction motor according to the present invention will be described below in detail with reference to the accompanying drawings. In the embodiments of the present invention described below, portions having the same configurations as those of the above-described conventional example are denoted by the same reference numerals as those of the above-described conventional example, and description thereof will be omitted.

FIG. 1 shows the overall configuration of a vector control inverter device for an induction motor according to the present invention, and FIG. 2 shows the internal configuration of a vector control operation circuit. The vector control inverter device according to the present invention has a torque commanding means 30 for outputting a torque component current command and a magnetic flux commanding means 31 for outputting an excitation magnetic flux command separately. Each of them can be individually commanded from outside, and sets a torque current command and a magnetic flux command for controlling the output torque to be constant regardless of the rotation speed.

In this vector control inverter, it is important that the magnetic flux command, which is the source of the excitation current command, is input from the magnetic flux command means 31 as a command independent of the torque current command.

As a result, the secondary magnetic flux PI calculator 16
Apart from the torque current command, the deviation between the magnetic flux command value Ф ₂ ^* output from the magnetic flux command means 31 and the secondary magnetic flux detection value Ф ₂ is amplified to calculate the excitation current command value Id ^* by PI control, The torque component current PI calculator 17 is provided with the torque command means 3
A deviation between the torque component current command value Iq ^* output by the zero and the torque component current detection value Iq is amplified to calculate a torque component voltage command value Vq ^* by PI control.

Consider a case in which the output torque is controlled to be constant at 50% of the motor rating from 0 speed to the maximum rotation speed of the motor in the vector control inverter device configured as described above.

In the conventional inverter device, the magnetic flux command is shown in FIG. 9, the torque current command is shown in FIG. 11, and the output torque is shown in FIG. 12, whereas in the inverter device according to the present invention, the magnetic flux command is shown in FIG. 4 shows the torque current command, and FIG. 5 shows the output torque.

As shown in FIG. 3, a magnetic flux command is externally given as a voltage signal at a constant 50% irrespective of the rotation speed of the motor, and as shown in FIG. As shown in FIG. 5, the output torque of the motor is constant at 50% over the entire speed range without causing harmful pulsation, as shown in FIG. Will be kept.

The magnetic flux command includes a current signal,
Similarly, a pulse signal can be applied from the outside, and the signal form of the magnetic flux command is not limited to a voltage signal.

Further, as shown in FIG. 6, the feedback value for the torque current (the detected current value Iq for the torque).
However, when the motor rating is 100% or less, it is not necessary to increase the excitation to a value of 100% determined by the characteristics of the motor. Therefore, the magnetic flux command is reduced in proportion to the feedback value of the torque current.

The bias value Фb of the magnetic flux command when the feedback value for the torque current is 0 is stored inside the inverter device and can be changed by the parameter setting device 50 attached to the inverter device.

The bias value Δb can be externally changed by a setting signal such as a voltage signal, a current signal, or a pulse signal in accordance with the characteristics of each motor and the conditions of the machine to be controlled.

Thus, the inverter device can be connected to various command devices, and the versatility of the inverter device is improved.

[0042]

As will be understood from the above description, according to the vector control inverter device for an induction motor according to the present invention, the magnetic flux command is given by a command signal from the outside in addition to the torque current command. The output torque can be stably controlled irrespective of the rotation speed, and the quality of a product manufactured by a machine using the inverter device can be improved.

According to the vector control inverter device for an induction motor according to the next invention, the bias value of the magnetic flux command is set in accordance with the detected current value of the torque, so that the motor current can be reduced in the case of a light load and the motor current can be reduced. Efficiency can be improved.

According to the vector control inverter device for an induction motor according to the next invention, since the stored bias value of the magnetic flux command can be changed by the parameter setting device, the degree of reduction of the motor current can be changed according to the characteristics of the motor and various machine conditions. They can be combined and can be used with any machine.

According to the vector control inverter device for an induction motor according to the next invention, the stored bias value of the magnetic flux command can be changed by an external setting signal, so that the degree of reduction of the motor current is determined by the characteristic of the motor. It can be adapted to various conditions of machines and machines, and can be used for all kinds of machines.

According to the vector control inverter apparatus for an induction motor according to the next invention, setting of a bias value of an externally input magnetic flux command, a torque component current command, or a magnetic flux command is performed, for example, by using a voltage signal for the purpose of low cost and versatility. In addition, since it is performed by either a current signal for the purpose of improving noise tolerance or a pulse signal for the purpose of improving control accuracy, the inverter device can be connected to various command devices, and the versatility of the inverter device is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a vector control inverter device for an induction motor according to the present invention.

FIG. 2 is a block diagram showing one embodiment of an internal configuration of a vector control operation circuit of the vector control inverter device for the induction motor according to the present invention.

FIG. 3 is a graph showing an example of a characteristic pattern of a magnetic flux command in the vector control inverter device for an induction motor according to the present invention.

FIG. 4 is a graph showing an example of a characteristic pattern of a torque current command in the vector control inverter device for an induction motor according to the present invention.

FIG. 5 is a graph showing an example of a characteristic pattern of an output torque in a vector control inverter device for an induction motor according to the present invention.

FIG. 6 is a graph showing an example of a magnetic flux command characteristic pattern in the vector control inverter device for an induction motor according to the present invention.

FIG. 7 is a block diagram showing the entire configuration of a conventional vector control inverter device for an induction motor.

FIG. 8 is a block diagram showing an internal configuration of a vector control operation circuit of a conventional vector control inverter device for an induction motor.

FIG. 9 is a graph showing an example of a characteristic pattern of a magnetic flux command in a conventional vector control inverter device for an induction motor.

FIG. 10 is a graph illustrating an example of a characteristic pattern of an excitation current command in a conventional vector control inverter device for an induction motor.

FIG. 11 is a graph showing an example of a characteristic pattern of a torque current command in a conventional vector control inverter device for an induction motor.

FIG. 12 is a graph showing an example of a characteristic pattern of an output torque in a conventional vector control inverter device for an induction motor.

[Explanation of symbols]

1 three-phase AC power supply, 2 rectifier circuit, 3 DC voltage smoothing filter, 4 inverter circuit, 5 induction motor, 6
Position detector, 7 Current detector, 9 Vector control arithmetic circuit, 10 Pulse width modulation control circuit, 11 Rotational speed arithmetic unit, 13 Current 3-phase to 2-phase converter, 14 Secondary magnetic flux arithmetic unit, 16 Secondary magnetic flux PI Calculator, 17 torque current PI
Calculator, 18 excitation current PI calculator, 19 slip angular velocity calculator, 20 rotation angular velocity calculator, 21 induced voltage compensator, 22 voltage 2 phase → 3 phase converter, 30 torque command means, 31 magnetic flux command means, 40 Storage device, 50 parameter setting device.

Claims (5)

[Claims] 1. A primary current of an induction motor driven by an inverter circuit is detected by a current detector, and a primary current detection value by the current detector is divided into a torque component current detection value and an excitation component current detection value. Then, in a vector control inverter device that controls the induction motor by dividing the primary current command value into a torque current command value and an excitation current command value, in order to control the output torque to be constant regardless of the rotation speed, A vector control inverter device for an induction motor, wherein a magnetic flux command as a source of an excitation component current command and a torque component current command are individually input as command signals from outside. 2. The vector control inverter device for an induction motor according to claim 1, wherein a bias value of a magnetic flux command according to the detected torque current value is stored. 3. The vector control inverter device for an induction motor according to claim 2, wherein the bias value of the stored magnetic flux command can be changed by a parameter setting device. 4. The vector control inverter device for an induction motor according to claim 2, wherein the bias value of the stored magnetic flux command can be changed by an external setting signal. 5. The vector of the induction motor according to claim 1, wherein the command signal or the setting signal is any one of a voltage signal, a current signal, and a pulse signal. Control inverter device.