JP2005102467A - Variable speed controlling device for induction motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a variable speed controlling device that makes it possible to obtain good controlling performance with a fewer number of operations in an induction motor that is driven by a power converting device that outputs AC of variable voltage and variable frequency. <P>SOLUTION: The variable speed controlling device 15 is constituted of a frequency generating means 11, a torque computing means 16, a magnetic flux command value generating means 17, a current command value calculating means 18, and a current adjusting means 19. A primary current command value i<SB>1</SB><SP>*</SP>of the induction motor 2 is calculated on the basis of the torque computed value τ<SP>#</SP>of the motor 2 obtained by the torque computing means 16, and the secondary magnetic flux command value ψ<SB>2</SB><SP>*</SP>of the motor 2 from the magnetic flux command value generating means 17. The motor is controlled in such a way that the primary current detection value i<SB>1</SB>of the motor 2 follows the primary current command value i<SB>1</SB><SP>*</SP>. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a variable speed control device for an induction motor driven by a power converter that outputs AC power of variable voltage and variable frequency.

As a variable speed control device for driving an induction motor at a variable speed with AC power having a predetermined voltage and frequency, for example, as described in Patent Document 1 below, the ratio between the voltage and the frequency is constant. Using a method of applying an alternating voltage having a variable voltage and a variable frequency to the induction motor (hereinafter also referred to as a V / f ratio constant control method) and a current flowing through the induction motor in the same direction as the magnetic flux of the motor. There is a method using a so-called vector control method in which a component and a component orthogonal to the magnetic flux are decomposed and these current components are controlled independently. Further, in this vector control method, as described in Patent Document 2 below, an induction motor such as a pulse encoder is obtained by estimating and calculating the rotation speed of the induction motor inside the variable speed control device. There is a speed sensorless vector control method that eliminates the need for the speed sensor.
JP 2000-333500 A (Page 4, FIG. 1, etc.) Japanese Patent No. 3152058 (Page 4, FIG. 1 etc.)

  Problems in the above-described conventional variable speed control device for an induction motor will be described below with reference to the drawings.

FIG. 7 is a circuit configuration diagram of a variable speed control device for an induction motor using the V / f ratio constant control method. Reference numeral 1 denotes a primary voltage command value vector v ₁ ^* output by a voltage command value calculation means 13 described later ^. A power converter 10 such as an inverter that outputs an alternating voltage of each phase and supplies power to the induction motor 2 is a variable speed control device that controls the induction motor 2 via the power converter 1.

The variable speed control device 10 includes a frequency command value generating means 11 for generating a frequency command value ω ₁ ^* as a primary frequency of the induction motor 2, and the frequency command value ω ₁ ^{* up} to the base primary frequency of the induction motor 2. primary voltage amplitude command value of said motor proportional value to the command value | v ₁ ^* | outputted as, more frequency command value omega ₁ ^* primary voltage amplitude command value a constant value at | outputted as | v ₁ ^* V / f ratio calculation means 12 and voltage command value calculation means 13 for calculating and outputting the primary voltage command value vector v ₁ ^* of the induction motor 2 from the coefficient and the frequency command value ω ₁ ^* . .

When the induction motor 2 is controlled using the variable speed control device 10 shown in FIG. 7, the power conversion device 1 is used to output the AC voltage of each phase according to the primary voltage command value vector v ₁ ^*. The distortion of the AC voltage increases due to the dead time based on the PWM calculation, the forward voltage drop of the semiconductor elements constituting the power conversion device 1, the switching characteristics, the variation of the switching timing, and the like. There has been a problem that torque ripple and uneven rotation occur in the induction motor 2.

FIG. 8 is a circuit diagram of a variable speed control device for an induction motor using the speed sensorless vector control method. 4 is a three-phase AC voltage command value v _U ^* , output from a vector rotator 40 described later. A power conversion device such as an inverter that outputs an AC voltage of each phase according to v _V ^* and v _W ^{* and} supplies power to the induction motor 2, 5 is a current detection value i _U , i _V , i _W of each phase of the induction motor 2. A current detector 30 for obtaining a variable speed control device 30 controls the induction motor 2 via the power converter 4.

The variable speed control device 30 includes a speed command value generating means 31 for generating a speed command value ω _r ^* of the induction motor 2, and the speed command value ωr * and the speed of the induction motor 2 derived by a speed estimation means 41 described later. A speed regulator 32 that performs an adjustment calculation that makes the deviation from the estimated value ω _r ^# zero and outputs the calculation result as a primary current command value i _1q ^* of the q-axis component of the induction motor 2, and a magnetic flux command value generation unit Current command value calculating means 34 for outputting the primary current command value i _1d ^* of the d-axis component of the induction motor 2 based on the secondary magnetic flux command value φ ₂ ^* of the induction motor 2 output by the 33, and the primary of the induction motor 2 A slip frequency calculating means 35 for calculating the slip frequency ω _s of the induction motor 2 from the current command value i _1q ^* and the primary current command value i _1d ^*, and adding the slip frequency ω _s and the estimated speed value ω _r ^# Then, this added value is used as the primary frequency command for the induction motor 2. omega ₁ ^* and adders 36 and output as an integration means 37 for outputting a phase angle command value obtained by the integral calculation of the primary frequency command value ω ₁ ^* θ ^*, the current detection obtained by the current detector 5 The values i _U , i _V , i _W are subjected to coordinate conversion based on the phase angle command value θ ^* , and the primary current detection value i _1d of the d-axis component of the induction motor 2 and the primary current detection value i _{1q of the} q-axis component The vector rotator 38 for obtaining the primary current command value i _1q ^* and the primary current command value i _1d ^*, and the adjustment calculation for making the deviation between the primary current detection value i _1d and the primary current detection value i _1q zero. The current adjusting means 39 for outputting these calculation results as the primary voltage command value v _1d ^* and the primary voltage command value v _1q ^* of the d-axis component of the induction motor 2, and the primary voltage command of the induction motor 2 Coordinate conversion between the value v _1d ^* and the primary voltage command value v _1q ^* based on the phase angle command value θ ^* And a vector rotator 40 for obtaining three-phase AC voltage command values v _U ^* , v _V ^* , and v _W ^* to the power converter 4, and the primary voltage command value v _1d ^* and the primary voltage command value v _1q ^*. Speed estimation means 41 for deriving a speed estimation value ω _r ^# of the induction motor 2 based on the primary current detection value i _1d and the primary current detection value i _1q .

  When the induction motor 2 is controlled using the variable speed control device 30 shown in FIG. 8, the power conversion device 1 that has become a problem in the variable speed control device 10 shown in FIG. The distortion of the output AC voltage is suppressed. As a result, torque ripple and rotation unevenness are reduced in the induction motor 2, but the amount of calculation such as the speed regulator 32, the slip frequency calculating means 35, and the speed estimating means 41 is large. The shift control device 30 had to have an expensive calculation function.

  Further, FIG. 9 is a circuit configuration diagram for simply performing current control in order to reduce the control amount that was a problem with the variable speed control device 30 shown in FIG. 8 described above.

In this variable speed control device 42, in addition to the magnetic flux command value generating means 33, the current command value calculating means 34, the integrating means 37, the vector rotator 38, the current adjusting means 39, and the vector rotator 40, as the primary frequency of the induction motor 2. The frequency command value generating means 43 for generating the frequency command value ω ₁ ^* is provided.

  When the induction motor 2 is controlled using the variable speed control device 42 shown in FIG. 9, there is a possibility that the control may be impossible due to a large torque output from the induction motor 2.

  An object of the present invention is to provide a variable speed control device for an induction motor that can suppress torque ripple and rotation unevenness of the induction motor with a smaller amount of computation while eliminating the above-described problems.

In a variable speed control device for an induction motor driven by a power converter that outputs AC power of variable voltage and variable frequency,
According to the first aspect of the present invention, there is provided torque calculation means for calculating a torque calculation value of the electric motor based on a primary frequency command value, a primary voltage command value, and a primary current detection value of the induction motor, and a secondary of the induction motor. Based on the magnetic flux command value, the primary frequency command value, and the torque calculation value, current command value calculation means for calculating the primary current command value of the electric motor, and a deviation between the primary current command value and the primary current detection value Current adjustment means for performing an adjustment calculation to zero and outputting a value based on the calculation result as the primary voltage command value, and outputting an AC voltage based on the primary voltage command value from the power converter. Features.

According to a second aspect of the present invention, in the variable speed control device,
Based on a primary frequency command value, a primary voltage command value, and a primary current detection value of the induction motor, torque calculation means for calculating a torque calculation value of the motor, and based on the secondary magnetic flux command value, the induction motor First current command value calculating means for calculating a first primary current command value; second current command value calculating means for calculating a second primary current command value of the induction motor based on the torque calculated value; A current for performing adjustment calculation to make the deviation between the first primary current command value and the second primary current command value and the primary current detection value zero, and outputting a value based on these calculation results as the primary voltage command value An AC voltage based on the adjusting means and the primary voltage command value is output from the power converter.

A third invention is the variable speed control device for an induction motor according to the second invention,
The current command value calculation means includes an integration means for obtaining a phase angle command value obtained by integrating the primary frequency command value, and a biaxial component orthogonal to the rotation coordinate based on the phase angle command value. A deviation between the first vector rotator that converts the first primary current command value and the first primary current command value and the second primary current command value and the primary current detection value that has been converted into two orthogonal biaxial components on rotation coordinates; A new current adjusting means for performing an adjustment calculation to zero and outputting a value based on these calculation results as a primary voltage command value of the orthogonal biaxial component on the rotational coordinate, and an orthogonal biaxial component on the rotational coordinate And a second vector rotator for converting the primary voltage command value into a three-phase AC voltage command value.

A fourth invention is the variable speed control device for the induction motor according to the second invention,
The current command value calculation means includes an integration means for obtaining a phase angle command value obtained by integrating the primary frequency command value, and the first primary current command value and the second primary current command value as the phase angle command value. A vector rotator for converting into orthogonal two-axis components on the static coordinates based on the three-phase / two-phase converter for converting the primary current detection value into two orthogonal axis components on the stationary coordinates; Adjustment calculation is performed to make the deviation between the primary current command value of the orthogonal two-axis component and the detected primary current value zero, and the value based on these calculation results is used as the primary voltage command value of the orthogonal two-axis component on the stationary coordinate It is characterized by comprising a new current adjusting means for outputting and a two-phase / three-phase converter for converting a primary voltage command value of orthogonal two-axis components on a stationary coordinate into a voltage command value of a three-phase alternating current.

A fifth invention is the variable speed control device for an induction motor according to the second invention,
The current command value calculation means includes an integration means for obtaining a phase angle command value obtained by integrating the primary frequency command value, and the first primary current command value and the second primary current command value as the phase angle command value. And a vector rotator that converts the current command value into a three-phase current command value, and an adjustment calculation that makes the deviation between the three-phase current command value and the primary current detection value zero, and values based on these calculation results are It comprises a new current adjusting means for outputting as a phase voltage command value.

A sixth invention is the variable speed control device for an induction motor according to the first invention,
V / f ratio calculation means for calculating a V / f (voltage / frequency) ratio based on a primary frequency command value of the induction motor, and a voltage command value based on the primary frequency command value and the V / f ratio Voltage command value calculating means, a switching signal generating means for generating a switching signal based on the primary frequency command value and the torque calculated value, an output of the voltage command value calculating means and an output of the current adjusting means. Switching means for switching and outputting based on the switching signal and outputting the output value as a new voltage command value is added.

A seventh invention is the variable speed control device for an induction motor according to the first or second invention,
The torque calculation means calculates a torque calculation value of the electric motor based on an active power calculation value of the induction motor.

An eighth invention is the variable speed control device for an induction motor according to the seventh invention,
The induction motor is operated in a no-load state, an active power calculation value obtained in this state is stored, and the torque calculation value is based on the stored value and an active power calculation value obtained during normal operation of the induction motor. Is calculated.

  According to the variable speed control device of the first to fifth aspects of the present invention, since the current of the motor is controlled so as to follow the current command value based on the torque calculation value of the induction motor, the conventional V / f ratio is constant. Compared with the control method, output AC voltage distortion caused by dead time based on PWM calculation of power converter, forward voltage drop of semiconductor elements constituting power converter, switching characteristics, switching timing variation, etc. Therefore, torque ripple and uneven rotation can be suppressed in the induction motor. At this time, the circuit configuration can be reduced with respect to the amount of calculation compared to the conventional vector control method, so that it can be implemented with an inexpensive variable speed control device. Furthermore, since the electric motor is controlled with a current command value based on the torque calculation value of the induction motor, the electric motor can be stably controlled even when the torque output from the induction motor is large.

  Further, according to the variable speed control device of the sixth aspect of the invention, a method of controlling the electric motor with a current command value based on the torque calculation value based on the torque calculation value of the induction motor and the primary frequency command value; Since the f ratio constant control method is switched, it is possible to reduce torque ripple and rotation unevenness at low speed and light load with a circuit configuration with less calculation amount, and also due to fluctuations in the electric constant when the induction motor is heavy loaded It is possible to provide a variable speed control device that is not affected by an increase in estimation error of the torque calculation value.

  Furthermore, according to the variable speed control device of the seventh and eighth inventions, the torque calculation value of the induction motor can be derived with a smaller calculation amount.

  FIG. 1 is a circuit diagram of a variable speed control device for an induction motor according to a first embodiment of the present invention. In this figure, components having the same functions as those of the conventional configuration shown in FIG. The description is omitted here.

That is, the variable speed control device 15 shown in FIG. 1 uses the primary frequency command value ω ₁ ^{* of} the induction motor 2 output from the frequency command value generating means 11 and the primary current detection value of the induction motor 2 obtained by the current detector 3. Based on i ₁ and a primary voltage command value vector v ₁ ^{* of} the induction motor 2 output from the current adjusting means 19 described later, a torque calculation means 16 for obtaining a torque calculation value τ ^# of the induction motor 2, and this torque calculation value Current command value calculation means 18 for deriving the primary current command value i ₁ ^* of the induction motor 2 from τ ^# and the secondary magnetic flux command value φ ₂ ^{* of} the induction motor 2 output from the magnetic flux command value generation means 17, and this primary An adjustment calculation is performed to make the deviation between the current command value i ₁ ^* and the primary current detection value i ₁ zero, and the primary voltage command value of the induction motor 2 based on the calculation result and the primary frequency command value ω ₁ ^*. Current adjuster that outputs vector v ₁ ^* And the stage 19.

In the torque calculation means 16 shown in FIG. 1, first, the primary voltage command value vector v ₁ ^* of the induction motor 2 and the primary current detection value i _{1 of the} motor are obtained by integrating the primary frequency command value ω ₁ ^*. Primary voltage command value v _1d ^* and primary current detection value i _1d and primary voltage command value v _1q ^* and primary current detection value i _1q of the d-axis component on the rotation coordinate based on the phase angle command value θ ^* After that, the following equation 1 is calculated to obtain the torque calculation value τ ^# of the induction motor 2.
[Equation 1]
τ ^# = (3/2) p (1 / ω ₁ ^* )
× {v _1d ^* · i _1d + v _1q ^* · i _1q −R ₁ (i _1d ² + i _1q ² )}
Here, p is the number of pole pairs of the induction motor 2, and R ₁ is the primary resistance in the T-1 type equivalent circuit of the induction motor 2.

The current command value calculation means 18 obtains the primary current command value i ₁ ^* of the induction motor 2 based on a constant value corresponding to the secondary magnetic flux command value φ ₂ ^* and a value proportional to the torque calculation value τ ^#. Yes.

That is, according to the variable speed control device 15 described above, the electric motor 2 follows the primary current / current command value i ₁ ^* based on the torque calculation value τ ^# of the induction motor 2 and the secondary magnetic flux command value φ ₂ ^*. Compared with the conventional constant V / f ratio control method, the dead time based on the PWM calculation of the power conversion device 1, the forward voltage drop of the semiconductor elements constituting the power conversion device 1, Distortion of the output AC voltage due to variations in switching characteristics, switching timing, and the like is reduced, and therefore torque ripple and rotation unevenness can be suppressed in the induction motor 2. At this time, the circuit configuration can be reduced with respect to the amount of calculation compared to the conventional vector control method, so that it can be implemented with an inexpensive variable speed control device. Furthermore, since the electric motor is controlled by the current command value i ₁ ^* based on the torque calculation value τ ^# of the induction motor 2, the electric motor can be stably controlled even when the torque output from the induction motor 2 is large. .

  FIG. 2 is a circuit diagram of a variable speed control device for an induction motor according to a second embodiment of the present invention. In this figure, components having the same functions as those in the embodiment shown in FIG. The description is omitted here.

  That is, the variable speed control device 21 shown in FIG. 2 replaces the current command value calculation means 18 and the current adjustment means 19 in the variable speed control device 15 shown in FIG. Two current command value calculating means 23 and current adjusting means 24 are provided.

The first current command value calculation means 22 outputs a constant value corresponding to the secondary magnetic flux command value φ ₂ ^* as the primary current command value i _1d ^* of the d-axis component of the induction motor 2, and the second current command The value calculation means 23 outputs a value proportional to the torque calculation value τ ^# as the primary current command value i _1q ^* of the q-axis component of the induction motor 2. Further, in the current adjusting means 24, the primary current command value i _1d ^*
And the primary current detection value i _1d and the q-axis component on the d-axis component on the rotation coordinate based on the phase angle command value θ ^* obtained by integrating the primary current command value i _1q ^* and the primary frequency command value ω ₁ ^*. The adjustment calculation is performed such that the deviation from the detected primary current value i _1q becomes zero, and the calculation result is output as the primary voltage command value vector v ₁ ^* of the induction motor 2.

That is, according to the variable speed control device 21 described above, the current of the motor is controlled so as to follow the current command value i _1q ^* of the q-axis component of the motor based on the torque calculation value τ ^# of the induction motor 2. Therefore, compared with the conventional V / f ratio constant control method, the dead time based on the PWM calculation of the power conversion device 1, the forward voltage drop of the semiconductor elements constituting the power conversion device 1, the switching characteristics, and the switching timing The distortion of the output AC voltage due to variations and the like is reduced, and therefore torque ripple and rotation unevenness can be suppressed in the induction motor. At this time, the circuit configuration can be reduced with respect to the amount of calculation compared to the conventional vector control method, so that it can be implemented with an inexpensive variable speed control device. Furthermore, since the electric motor is controlled with a current command value based on the torque calculation value of the induction motor, the electric motor can be stably controlled even when the torque output from the induction motor is large.

  FIG. 3 is a circuit diagram of a variable speed control device for an induction motor according to a third embodiment of the present invention. In this figure, the same function as that of the conventional configuration shown in FIGS. Are denoted by the same reference numerals, and the description thereof is omitted here.

  That is, the variable speed control device 45 shown in FIG. 3 includes the magnetic flux command value generating means 33, the integrating means 37, the vector rotator 38, the current adjusting means 39, the vector rotator 40, and the frequency command value generating means 43, First current command value calculating means 46, second current command value calculating means 47, and torque calculating means 48 are provided.

In this first current command value calculating means 46, a constant value corresponding to the secondary magnetic flux command value φ ₂ ^* of the induction motor 2 output from the magnetic flux command value generating means 33 is set to a primary current command value of the d-axis component of the induction motor 2. The first current command value i is output as i _1d ^* , and the second current command value calculation means 47 outputs a value proportional to a torque calculation value τ ^# output from a torque calculation means 41 described later to a primary current command value i of the q-axis component of the induction motor 2. Output as _1q ^* . Further, in the torque calculation means 48, the primary frequency command value ω ₁ ^* of the induction motor 2 output from the frequency command value generation means 43, the primary voltage command value v _1d ^* of the d-axis component of the induction motor 2 and the primary current detection value i. The torque calculation value τ ^# of the induction motor 2 is obtained from _1d , the primary voltage command value v _1q ^* of the q-axis component of the electric motor, and the primary current detection value i _1q according to the calculation of the equation (1).

That is, according to the variable speed control device 45 described above, the current of the motor is controlled so as to follow the current command value i _1q ^* of the q-axis component of the motor based on the torque calculation value τ ^# of the induction motor 2. Therefore, compared with the conventional V / f ratio constant control method, the dead time based on the PWM calculation of the power conversion device 4, the forward voltage drop of the semiconductor elements constituting the power conversion device 4, the switching characteristics, and the switching timing The distortion of the output AC voltage due to variations and the like is reduced, and therefore torque ripple and rotation unevenness can be suppressed in the induction motor. At this time, the circuit configuration can be reduced with respect to the amount of calculation compared to the conventional vector control method, so that it can be implemented with an inexpensive variable speed control device. Furthermore, since the electric motor is controlled with a current command value based on the torque calculation value of the induction motor, the electric motor can be stably controlled even when the torque output from the induction motor is large.

  FIG. 4 is a circuit diagram of a variable speed control device for an induction motor according to a fourth embodiment of the present invention. In this figure, components having the same functions as those of the embodiment shown in FIG. The description is omitted here.

  That is, the variable speed control device 50 shown in FIG. 4 includes magnetic flux command value generation means 33, integration means 37, frequency command value generation means 43, first current command value calculation means 46, and second current command value calculation means 47. In addition, a vector rotator 51, a three-phase / two-phase converter 52, a current adjusting unit 53, a torque calculating unit 54, and a two-phase / three-phase converter 55 are provided.

The variable speed control device 50 is different from the variable speed control device 45 shown in FIG. 3 in that the variable speed control device 45 has a d-axis component and a q-axis component that are decomposed into orthogonal dq axes on rotation coordinates. In contrast to the variable speed control of the induction motor 2 based on the control amount, the variable speed control device 50 controls each of the α axis component and β axis component which are decomposed into orthogonal α-β axes on a stationary coordinate. The induction motor 2 is subjected to variable speed control based on the above. At this time, in the torque calculation means 54, first, vα ^* , vβ ^* , iα, iβ as control amounts on orthogonal α-β axes are respectively represented as v _1d ^* , as control amounts on orthogonal dq axes. Each is divided into v _1q ^* , i _1d , and i _1q , and then the torque calculation value τ ^# of the induction motor 2 is obtained according to the calculation of the above equation (1).

  FIG. 5 is a circuit diagram of a variable speed control device for an induction motor according to a fifth embodiment of the present invention. In this figure, components having the same functions as those in the embodiment shown in FIG. The description is omitted here.

  In addition to the magnetic flux command value generating means 33, the integrating means 37, the frequency command value generating means 43, the first current command value calculating means 46, and the second current command value calculating means 47, the variable speed control device 57 shown in FIG. The vector rotator 58, the current adjusting means 59, and the torque calculating means 60 are provided.

The variable speed control device 57 is different from the variable speed control device 45 shown in FIG. 3 in that the variable speed control device 45 has a d-axis component and a q-axis component that are decomposed into orthogonal dq axes on rotation coordinates. While the induction motor 2 is controlled at a variable speed based on the control amount, the variable speed control device 57 performs induction based on the control amounts decomposed into the U phase, the V phase, and the W phase as three-phase alternating current. That is, the motor 2 is controlled at a variable speed. At this time, in the torque calculation means 60, first, v _U ^* , v _V ^* , v _W ^* , i _U , i _V , and i _W as control amounts of the U phase, V phase, and W phase are orthogonally crossed d−. It is decomposed into v _1d ^* , v _1q ^* , i _1d , and i _1q as control quantities on the q axis, and then a torque calculation value τ ^# of the induction motor 2 is obtained according to the calculation of the above equation (1). .

  FIG. 6 is a circuit diagram of a variable speed control device for an induction motor according to a sixth embodiment of the present invention. In this figure, the configuration of the embodiment shown in FIG. 1 and the configuration of the conventional example shown in FIG. Components having the same function are denoted by the same reference numerals, and description thereof is omitted here.

  That is, the variable speed control device 26 shown in FIG. 6 includes frequency command value generation means 11, V / f calculation means 12, voltage command value calculation means 13, torque calculation means 16, magnetic flux command value generation means 17, current command value calculation. In addition to the means 18 and the current adjusting means 19, a switching signal generating means 27 and a switching means 28 are provided.

  As is clear from the circuit configuration of FIG. 6, the variable speed control device 26 has newly added the control function of the variable speed control device 15 shown in FIG. 1 and the control function of the variable speed control device 10 shown in FIG. The induction motor 2 is subjected to variable speed control by switching by means of the switching signal generating means 27 and the switching means 28 provided in FIG.

That is, in the switching signal generation means 27, the induction motor 2 is in the low speed region from the primary frequency command value ω ₁ ^* of the induction motor 2 from the frequency command value generation means 11 and the torque calculation value τ ^# from the torque calculation means 16. In the light and low load state, the output of the switching means 28 is the current adjusting means 19 side output, and when the state of the motor is other than the above, the switching signal that the output of the switching means 28 is the voltage command value calculating means 13 side output Operates to emit.

According to this variable speed control device 26, the method of controlling the induction motor 2 with the current command value based on the torque calculation value τ ^# according to the speed and load state of the induction motor 2, and the conventional constant V / f ratio control Since the induction motor 2 is controlled at a variable speed by switching the method, torque ripple and rotation unevenness at low speed and light load can be reduced with a circuit configuration with a smaller amount of calculation, and the electric power of the induction motor 2 can be reduced when the load is heavy. It is possible to provide a variable speed control device that is not affected by an increase in the estimation error of the torque calculation value τ ^# caused by the constant fluctuation.

  FIG. 10 is a circuit diagram of a variable speed control device for an induction motor according to a seventh embodiment of the present invention. In this figure, components having the same functions as those in the embodiment shown in FIG. The description is omitted here.

  That is, the variable speed control device 61 shown in FIG. 10 includes either a torque calculation means 62 or a torque calculation means 63 instead of the torque calculation means 16 in the variable speed control device 15 shown in FIG.

  FIG. 11 is a detailed circuit configuration diagram of the torque calculation means 62, which comprises an active power calculation means 62a, a no-load active power setting means 62b, an addition calculation means 62c, and a division calculation means 62d. The calculation operation in the torque calculation means 62 will be described below.

In the active power calculation means 62a, first, a phase angle command obtained by integrating the primary frequency command value ω ₁ ^* of the primary voltage command value vector v ₁ ^* of the induction motor 2 and the primary current detection value i _{1 of the} motor. The primary voltage command value v _1d ^* and primary current detection value i _1d of the d-axis component on the rotation coordinate based on the value θ ^* are decomposed into the primary voltage command value v _1q ^* and primary current detection value i _{1q of the} q-axis component. Thereafter, the calculation of the following formula 2 is performed to obtain the active power calculation value P ^# of the induction motor 2.
[Equation 2]
P ^# = 3 · (v _1d ^* · i _1d + v _1q ^* · i _1q )
The no-load active power setting means 62b measures an active power value generated by the induction motor 2 during no-load operation by experiments or the like, and sets and outputs this measured value as P ₀ ^* .

Therefore, the torque calculation value τ ^## of the induction motor 2 that is the calculation result of the division calculation means 62d is expressed by the following equation (3).
[Equation 3]
_{^{τ ## = (P # -P 0}} *) / ω 1 *
FIG. 12 is a detailed circuit diagram of the torque calculation means 63. The difference between the torque calculation means 63 and the torque calculation means 62 shown in FIG. 11 is that the no-load active power setting means 62b is replaced with a no-load active power setting means 62b. The power storage means 63a is provided.

That is, in the variable speed control device 61 using the torque calculation means 63, the induction motor 2 is preliminarily tested in a no-load state, and the active power value calculated by the active power calculation means 62a at this time is used as the no-load active power. Since the stored value is taken in and stored in the storage means 63a and this stored value is set as P ₀ ^* and is output during normal operation of the induction motor 2, the active power value during no-load operation of the induction motor 2 is set more appropriately. Is possible.

Therefore, according to the variable speed control device 61, the motor of the induction motor 2 is tracked so as to follow the primary current / current command value i ₁ ^* based on the torque calculation value τ ^## of the induction motor 2 and the secondary magnetic flux command value φ ₂ ^* . Compared with the conventional V / f ratio constant control method for controlling the primary current, the dead time based on the PWM calculation of the power conversion device 1, the forward voltage drop of the semiconductor elements constituting the power conversion device 1, Distortion of the output AC voltage due to variations in switching characteristics, switching timing, and the like is reduced, and therefore torque ripple and rotation unevenness can be suppressed in the induction motor 2.

Further, since the electric motor is controlled with the current command value i ₁ ^* based on the torque calculation value τ ^## of the induction motor 2, the electric motor can be stably controlled even when the torque output from the induction motor 2 is large. it can.

  FIG. 13 is a circuit diagram of a variable speed control device for an induction motor according to an eighth embodiment of the present invention. In this figure, components having the same functions as those in the embodiment shown in FIG. The description is omitted here.

  That is, the variable speed control device 64 shown in FIG. 13 includes either the torque calculation means 62 or the torque calculation means 63 in place of the torque calculation means 16 in the variable speed control device 26 shown in FIG.

According to the variable speed control device 64, the method of controlling the induction motor 2 with the current command value based on the torque calculation value τ ^## according to the speed and load state of the induction motor 2, and the conventional constant V / f ratio. Since the induction motor 2 is controlled at a variable speed by switching the control method, torque ripple and rotation unevenness at low speed and light load can be reduced with a circuit configuration with less calculation amount, and when the induction motor 2 is heavy loaded, It is possible to provide a variable speed control device that is not affected by an increase in the estimation error of the torque calculation value τ ^## resulting from the fluctuation of the electrical constant.

In particular, in the variable speed control device 64 using the torque calculation means 63, the induction motor 2 is previously tested in a no-load state, and the active power value calculated by the active power calculation means 62a at this time is used as the no-load active power. Since the stored value is taken in and stored in the storage means 63a and this stored value is set as P ₀ ^* and is output during normal operation of the induction motor 2, the active power value during no-load operation of the induction motor 2 is set more appropriately. Is possible.

The circuit block diagram of the variable speed control apparatus of the induction motor which shows 1st Example of this invention The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 2nd Example of this invention The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 3rd Example of this invention The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 4th Example of this invention The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 5th Example of this invention The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 6th Example of this invention Circuit diagram of variable speed control device for induction motor showing conventional example The circuit block diagram of the variable speed control apparatus of the induction motor which shows the prior art example different from FIG. FIG. 7 is a circuit configuration diagram of a variable speed control device for an induction motor showing a conventional example different from FIGS. The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 7th Example of this invention Partial detailed circuit configuration diagram of FIG. Partial detailed circuit configuration diagram of FIG. The circuit block diagram of the variable speed control apparatus of the induction motor which shows the 8th Example of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Power converter device, 2 ... Induction motor, 3 ... Current detector, 4 ... Power converter device, 5 ... Current detector, 10 ... Variable speed control device, 11 ... Frequency command value generation means, 12 ... V / f ratio Calculation means, 13 ... Voltage command value calculation means, 15 ... Variable speed control device, 16 ... Torque calculation means, 17 ... Magnetic flux command value generation means, 18 ... Current command value calculation means, 19 ... Current adjustment means, 21 ... Variable speed Control device, 22 ... first current command value calculating means, 23 ... second current command value calculating means, 24 ... current adjusting means, 26 ... variable speed control device, 27 ... switching signal generating means, 29 ... switching means, 30 ... Variable speed control device, 31 ... speed command value generating means, 32 ... speed regulator, 33 ... magnetic flux command value generating means, 34 ... current command value calculating means, 35 ... slip frequency calculating means, 36 ... addition calculator, 37 ... Integration means, 38 ... vector rotator, DESCRIPTION OF SYMBOLS 9 ... Current adjustment means, 40 ... Vector rotator, 41 ... Speed estimation means, 42 ... Variable speed control apparatus, 43 ... Frequency command value generation means, 45 ... Variable speed control apparatus, 46 ... First current command value calculation means, 47 ... second current command value calculating means, 48 ... torque calculating means, 50 ... variable speed control device, 51 ... vector rotator, 52 ... three-phase / two-phase converter, 53 ... current adjusting means, 54 ... torque calculating means , 55 ... 2-phase / 3-phase converter, 57 ... variable speed controller, 58 ... vector rotator, 59 ... current adjusting means, 60 ... torque calculating means, 61 ... variable speed control apparatus, 62, 63 ... torque calculating means 64 ... Variable speed control device.

Claims (8)

In a variable speed control device for an induction motor driven by a power converter that outputs AC power of variable voltage and variable frequency,
Torque calculation means for calculating a torque calculation value of the electric motor based on a primary frequency command value, a primary voltage command value, and a primary current detection value of the induction motor;
Current command value calculation means for calculating a primary current command value of the motor based on the secondary magnetic flux command value of the induction motor and the primary frequency command value and torque calculation value;
An adjustment calculation that makes a deviation between the primary current command value and the primary current detection value zero, and a current adjustment unit that outputs a value based on the calculation result as the primary voltage command value;
A variable speed control device for an induction motor, wherein an AC voltage based on the primary voltage command value is output from the power converter. In a variable speed control device for an induction motor driven by a power converter that outputs AC power of variable voltage and variable frequency,
Torque calculation means for calculating a torque calculation value of the electric motor based on a primary frequency command value, a primary voltage command value, and a primary current detection value of the induction motor;
First current command value calculating means for calculating a first primary current command value of the induction motor based on the secondary magnetic flux command value;
Second current command value calculation means for calculating a second primary current command value of the induction motor based on the torque calculation value;
An adjustment calculation is performed to make the deviation between the first primary current command value and the second primary current command value and the primary current detection value zero, and a value based on these calculation results is output as the primary voltage command value. Current adjusting means;
A variable speed control device for an induction motor, wherein an AC voltage based on the primary voltage command value is output from the power converter. In the variable speed control device for an induction motor according to claim 2,
The current command value calculation means includes
Integrating means for obtaining a phase angle command value obtained by integrating the primary frequency command value;
A first vector rotator that converts the primary current detection value into a two-axis component orthogonal to rotation coordinates based on the phase angle command value;
An adjustment calculation is performed to make a deviation between the first primary current command value and the second primary current command value and the detected primary current value converted into the two-axis components orthogonal to each other on the rotation coordinate to be zero. A new current adjusting means for outputting a value based on the result as a primary voltage command value of two orthogonal axis components on the rotation coordinate;
A variable speed control device for an induction motor, comprising: a second vector rotator for converting the primary voltage command value of two orthogonal axis components on rotation coordinates into a three-phase AC voltage command value. In the variable speed control device for an induction motor according to claim 2,
The current command value calculation means includes
Integrating means for obtaining a phase angle command value obtained by integrating the primary frequency command value;
A vector rotator that converts the first primary current command value and the second primary current command value into orthogonal biaxial components on a stationary coordinate based on the phase angle command value;
A three-phase / two-phase converter that converts the primary current detection value into two orthogonal axes on a stationary coordinate;
An adjustment calculation is performed to make the deviation between the primary current command value of the orthogonal two-axis component on the stationary coordinate and the detected primary current zero, and the value based on these calculation results is the primary of the orthogonal two-axis component on the stationary coordinate A new current adjusting means for outputting as a voltage command value;
A variable speed control device for an induction motor comprising a two-phase / three-phase converter for converting a primary voltage command value of orthogonal two-axis components on a stationary coordinate into a voltage command value of a three-phase alternating current. In the variable speed control device for an induction motor according to claim 2,
The current command value calculation means includes
Integrating means for obtaining a phase angle command value obtained by integrating the primary frequency command value;
A vector rotator that converts the first primary current command value and the second primary current command value into a three-phase current command value based on the phase angle command value;
It comprises a new current adjusting means for performing an adjustment calculation for making the deviation between the three-phase current command value and the detected primary current value zero and outputting a value based on these calculation results as a three-phase voltage command value. A variable speed control device for an induction motor. The variable speed control device for an induction motor according to claim 1,
V / f ratio calculating means for calculating a V / f (voltage / frequency) ratio based on a primary frequency command value of the induction motor;
Voltage command value calculating means for calculating a voltage command value based on the primary frequency command value and the V / f ratio;
Switching signal generating means for generating a switching signal based on the primary frequency command value and the torque calculation value;
The output of the voltage command value calculation means and the output of the current adjustment means are switched based on the switching signal and output, and switching means for outputting the output value as a new voltage command value is added. Variable speed control device for induction motor. In the variable speed control device for an induction motor according to claim 1 or 2,
The torque calculation means includes
A variable speed control device for an induction motor, wherein a torque calculation value of the motor is calculated based on an active power calculation value of the induction motor. The variable speed control device for an induction motor according to claim 7,
The induction motor is operated in a no-load state, an active power calculation value obtained in this state is stored, and the torque calculation value is based on the stored value and an active power calculation value obtained during normal operation of the induction motor. A variable speed control device for an induction motor, characterized in that

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