JP3067681B2 - Variable speed control device for AC motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable speed control device for controlling an AC motor at a variable speed.

[0002]

2. Description of the Related Art In general, an induction motor is used as an AC motor. A terminal voltage of the induction motor shows a transient voltage expressed by a product of a differential term of a primary current and a leakage inductance of the induction motor. In the case of current control,
The above-described transient voltage is suppressed by a feedforward compensation method in which a product of a differential term of the current command value and a preset leakage inductance is calculated, and the calculation result is added to the voltage command value.

FIG. 14 is a block circuit diagram showing a conventional example of a variable speed control device for an induction motor in which a transient voltage is suppressed by feedforward compensation. In the conventional circuit shown in FIG. 14, the power converter 2 converts AC power supplied from the AC power supply 1 into AC power having a desired voltage and frequency, thereby causing the induction motor 3 to operate at a variable speed. That is, the U-phase current actual value i _U and the W-phase current actual value i _W detected by the current detector 4 are calculated by the first coordinate converter 5 as an arbitrary M-axis component M
Are decomposed into a T-axis current actual value I _T perpendicular to the M axis of the shaft current actual value I _M Toko. On the other hand, the command value generation circuit 7 outputs an M-axis current command value I _M ^* and a T-axis current command value I _T ^*.
The axis current adjuster 8 outputs a signal V _M ^** for making the deviation between the M axis current actual value I _M and the M axis current command value I _M ^* zero,
The T-axis current controller 9 also outputs a signal V _T ^** that makes the deviation between the T-axis current actual value _IT and the T-axis current command value I _T ^* zero. A respective axis current regulator output V _M ^** and V _T ^** as the voltage command value as it, when via the second coordinate converter 6 gives to the power converter 2, the transient voltage is generated as described above.

Therefore, the leakage inductance set value L ^* preset in the command value generation circuit 7, the above-described actual shaft current values I _M and I _T, and the respective axis current command values I _M ^* and I _T ^* are shown in FIG. Is input to the feed-forward compensation voltage calculation circuit 11 to calculate the feed-forward compensation voltage command values V _MF ^* and V _TF ^* for each axis. The M-axis compensation voltage adder 12 adds this V _MF ^* and the above-described M-axis current controller output V _M ^**, and uses the added result V _M ^* as the M-axis voltage command value in the second coordinate converter. Give to 6. Similarly, the T-axis compensation voltage adder 13 also adds the T-axis feed forward compensation voltage command value V _TF ^* and the T-axis current controller output V _T ^**, and outputs the added result V _T ^* to T.
It is given to the second coordinate converter 6 as a shaft voltage command value. Second coordinate converter 6 respective axes voltage command value V _M ^*, V _T ^* each phase voltage command value v _U ^*, v _V ^*, is converted into v _W ^* for controlling the power converter 2.

The calculations in the feedforward compensation voltage calculation circuit 11 and the respective axis compensation voltage adders 12 and 13 are summarized in the following equations (1) and (2). Here, p is a differential operator, and L ^* is a leakage inductance set value.

[0006]

[Number 1] _{^{V M * = V M ** +}} V MF * = V M ** + p · L * ·
I _M ^*

[0007]

[Number 2] _{^{V T * = V T ** +}} V TF * = V T ** + p · L * ·
I _T ^* Also, calculates the current actual value of the voltage actual value and the detected M axis induced voltage E _M ^* and T axis induced voltage of the induction motor by E _T ^* is the equation 3 and equation 4 below Is used. Here I _M, I _T is the axis current actual value, V _M and V _T is the axial voltage actual value, R ₁ ^* is the primary resistance set value of the motor, omega ₁ ^* is the frequency setting value.

[0008]

[Number 3] ^{_{E M * = V M -R 1}} * · I M -p · L * · I M
+ Ω ₁ ^* · L ^* · _IT

[0009]

[Number 4] ^{_{E T * = V T -R 1}} * · I T -p · L * · I T
^{_{-Ω 1 * · L * · I}} M voltage, as controlled by calculating the induced voltage from the current actual value, for example, the speed sensorless vector control according to "Kokoku No. 7-71400" Publication has been proposed.

[0010]

The M-axis voltage command value V _M ^*
And T-axis voltage command value V _T ^*, or M axis induced voltage E _M ^* and T axis induced voltage E _T ^* is calculated in accordance with the equations described above, but the calculation of a voltage drop due to the leakage inductance in the respective formulas include. Accordingly, if there is a difference between the leakage inductance set value L ^* used for the calculation of the voltage drop and the actual motor leakage inductance value, the calculation of the induced voltage and the feed of the current regulator in the conventional circuit described in FIG. An error will occur in the forward compensation. As a result, an error occurs in the control calculation of the electric motor such as the feedforward compensation, and a problem such as an inability to appropriately suppress the transient voltage occurs.

An object of the present invention is to provide a circuit which correctly calculates the leakage inductance of an AC motor and appropriately controls the motor using the calculated value of the leakage inductance.

[0012]

To achieve the above object, a variable speed control device for an AC motor according to the present invention comprises a first coordinate conversion circuit for converting the current of an AC motor driven by AC power from a power converter. Where M axis current actual value and T orthogonal to this
The M-axis current controller outputs an M-axis voltage command value that makes the deviation between the M-axis current actual value and a separately set M-axis current command value zero, and outputs the T-axis current value. The controller outputs a T-axis voltage command value that makes a deviation between the T-axis current actual value and a separately set T-axis current command value zero, and the second coordinate conversion circuit outputs the M-axis voltage command value and the T-axis voltage command value. In a variable speed control device for an AC motor configured to control a power conversion device by converting a voltage command value into a phase voltage command value, a first invention includes an AC current signal output from a first AC signal generation circuit, The sum with the M-axis current command value is input to the M-axis current regulator instead of the M-axis current command value. On the other hand, the first leakage inductance calculation circuit inputs the AC current signal and the M-axis current actual value, calculates the leakage inductance of the AC motor, and stores the calculated leakage inductance value in the first memory circuit. Further, the first signal selector selects the operation value of the first leakage inductance operation circuit before the operation of the AC motor, and selects the data stored in the first memory circuit during the operation. The first differentiating circuit differentiates the sum of the AC current signal and the M-axis current command value or only the AC current signal, and the first multiplier calculates the differential operation value and the signal selected by the first signal selector ( Calculate the product with the calculated value of the leakage inductance or its memory value. An M-axis voltage command value is obtained by adding the change in the M-axis voltage command value, which is the result of the multiplication operation, to the output of the M-axis current regulator. The M-axis voltage command value is provided to the power converter via the second coordinate conversion circuit, and feedforward compensation for the voltage drop due to the leakage inductance is performed.

A second invention is an invention relating to the first leakage inductance calculation circuit according to the first invention. The M-axis voltage command value change ΔV _M ^* described in the first invention is:
This is the product of the differential value of the AC signal ΔI _M ^* and the leakage inductance calculation value L ^# output by the first leakage inductance calculation circuit. Therefore, if the differential operator is p, it is represented by the following Expression 5.

[0014]

ΔV _M ^* = p · L ^# · ΔI _M ^{* When the} AC motor is driven by the voltage-type power conversion device, the voltage command value and the actual voltage value match. Therefore, when ΔI _M is the change in the actual value of the M-axis current and L is the actual value of the leakage inductance, the following Expression 6 is established, and Expression 7 is obtained from Expressions 6 and 5.

[0015]

Equation 6 ΔV _M ^* = p · L · ΔI _M

[0016]

[Equation 7] _{^{p · L # · ΔI M *}} = p · L · ΔI M Therefore, M-axis current actual value variation ΔI _M is an AC signal ΔI _M ^*
By providing an arithmetic circuit to adjust the leakage inductance calculation value L ^# to match, it is possible to match the leakage inductance calculation value L ^# in the leakage inductance actual value L. Therefore, the following equation 8 is obtained from the amplitude information obtained by calculating the absolute value of the AC signal ΔI _M ^{* and} the amplitude information obtained by calculating the absolute value of the actual M-axis current value I _M.
By transforming, the following Expressions 9 and 10 are obtained.

[0017]

[Expression 8] p · L ^# · | ΔI _M ^* | = p · L · | ΔI _M |

[0018]

| ΔI _M | = (L ^# / L) · | ΔI _M ^* |

[0019]

| ΔI _M ^* | − | ΔI _M | = | ΔI _M ^* |
When {1- (L ^# / L)} L ^# > L, the result of Expression 10 is negative, and L ^# <L
In the case of, the result of Expression 10 is positive. Therefore, as shown in Expression 10, if the result obtained by subtracting the absolute value of ΔI _M from the absolute value of ΔI _M ^{* is used} as an error signal to obtain a value obtained by performing an integration operation or a proportional integration operation as a leakage inductance operation value L ^# , This operation value L ^# converges to the actual value L.

According to a third aspect of the present invention, even when a frequency component lower than the frequency is superimposed on the actual value of the M-axis current input to the first leakage inductance calculation circuit having the configuration described in the second aspect of the invention, In this invention, a correct leakage inductance calculation value L ^# is obtained, and the low frequency component described above is removed by passing the input actual M-axis current value through the first filter. Therefore, the absolute value of the M-axis current actual value I _M passing through the first filter is subtracted from the absolute value of the AC signal ΔI _M ^* as in the second invention described above, and the result of the subtraction is used as an error signal as an error signal. The value obtained by the integration operation is referred to as a leakage inductance operation value L ^# .

In the fourth invention, the first to third inventions are described.
A waveform output by the first AC current signal generation circuit according to any one of the aspects of the invention is an integrated waveform of a triangular wave. In a fifth aspect, the sum of the AC current signal output from the second AC signal generation circuit and the T-axis current command value is input to the T-axis current regulator instead of the T-axis current command value. On the other hand, the second leakage inductance calculation circuit calculates the leakage inductance of the AC motor by inputting the AC current signal and the T-axis current actual value, and stores the calculated leakage inductance value in the second memory circuit. Further, the second signal selector selects the operation value of the second leakage inductance operation circuit before the operation of the AC motor, and selects the data stored in the second memory circuit during the operation. The second differentiating circuit differentiates the sum of the AC current signal and the T-axis current command value or only the AC current signal, and the second multiplier calculates the differential operation value and the signal selected by the second signal selector ( Calculate the product with the calculated value of the leakage inductance or its memory value. A T-axis voltage command value can be obtained by adding the change in the T-axis voltage command value, which is the result of this multiplication operation, to the output of the T-axis current regulator. The T-axis voltage command value is provided to the power converter via the second coordinate conversion circuit, and feedforward compensation for a voltage drop due to leakage inductance is performed.

A sixth invention is an invention relating to the second leakage inductance calculation circuit according to the fifth invention. The T-axis voltage command value change ΔV _T ^* described in the fifth invention is:
This is the product of the differential value of the AC signal ΔI _T ^* and the leakage inductance calculation value L ^# output by the second leakage inductance calculation circuit. Therefore, if the differential operator is p, the following equation 11
It is represented by

[0023]

Equation 11] _{^{ΔV T * = p · L #}} · ΔI T * by a voltage-source power converter when driving an AC motor, since coincides with voltage command value and a voltage actual value, the [Delta] I _T T-axis current actual value Assuming that the change and L are the actual values of the leakage inductance, Expression 12 is established, and Expression 13 is obtained from this and Expression 11.

[0024]

ΔV _T ^* = p · L · ΔI _T

[0025]

Equation 13] _{^{p · L # · ΔI T *}} = p · L · ΔI T Thus T-axis current actual value variation [Delta] I _T AC signal [Delta] I _T ^*
By providing an arithmetic circuit to adjust the leakage inductance calculation value L ^# to match, it is possible to match the leakage inductance calculation value L ^# in the leakage inductance actual value L. Therefore, the following Expression 14 is obtained from the amplitude information obtained by calculating the absolute value of the AC signal ΔI _T ^{* and} the amplitude information obtained by calculating the absolute value of the T-axis current actual value I _T. Equations 15 and 16 are obtained.

[0026]

[Expression 14] p · L ^# · | ΔI _T ^* | = p · L · | ΔI _T
|

[0027]

| ΔI _T | = (L ^# / L) · | ΔI _T ^* |

[0028]

| ΔI _T ^* | − | ΔI _T | = | ΔI _T ^* |
If {1- (L ^# / L)} L ^# > L, the result of Expression 16 is negative, and L ^# <L
In the case of, the result of Expression 16 is positive. Therefore, as shown in Expression 16, if the value obtained by performing the integral operation or the proportional integral operation on the result obtained by subtracting the absolute value of ΔI _T from the absolute value of ΔI _T ^* as an error signal is defined as the leakage inductance operation value L ^# , This operation value L ^# converges to the actual value L.

According to a seventh aspect of the present invention, even when a frequency component lower than the frequency is superimposed on the actual value of the T-axis current input to the second leakage inductance calculation circuit having the configuration described in the sixth aspect, In this invention, a correct leakage inductance calculation value L ^# is obtained, and the low frequency component described above is removed by passing the input actual value of the T-axis current through the second filter. Thus by subtracting the absolute value of the sixth invention as well as an AC signal [Delta] I _T ^* T-axis current passed through the second filter from the absolute value actual value I _T described above, the integral calculation or proportional to the subtraction result as an error signal The value obtained by the integration operation is referred to as a leakage inductance operation value L ^# .

According to an eighth aspect, in the fifth to seventh aspects,
According to another aspect of the present invention, the waveform output from the second AC current signal generating circuit according to any one of the aspects of the present invention is an integrated waveform of a triangular wave.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first invention is to provide a new addition value of an AC signal ΔI _M ^* output from a first AC signal generation circuit and an M-axis current command value I _M ^* output from a command value generation circuit. The AC signal ΔI _M ^* and the actual M-axis current value I _M are input to a first leakage inductance calculation circuit, and the leakage inductance calculation value L is given to the M-axis current controller as a current command value.
^# , And the calculation result is stored in the first memory circuit. The first signal selector selects either the leakage inductance calculation value L ^# or the leakage inductance set value L ^* stored in the first memory circuit. AC signal ΔI _M ^* obtained through the first differentiating circuit and M-axis current command value I _M
^The M-axis voltage command value change amount ΔV _M ^* is obtained by multiplying the addition value of ^* and the differential value of only the AC signal ΔI _M ^* by the value selected by the first signal selector in the first multiplier. . An M-axis voltage command value V _M ^* obtained by adding the M-axis voltage command value change ΔV _M ^* to V _M ^** output by the _M- axis current controller, and an output of the T-axis current controller. A certain T-axis voltage command value V _T ^* is input to the second coordinate converter, and each phase voltage command value v _U ^* , which is converted by the second coordinate converter,
v _V ^*, to control a power conversion device in v _W ^*.

According to a second aspect of the present invention, a first leakage inductance calculating circuit according to the first aspect of the present invention comprises a first amplitude calculating circuit,
An amplitude calculation circuit, a third adder, and a first adjustment circuit are provided, and the third adder is an M-axis obtained by the second amplitude calculation circuit from the absolute value of the AC signal ΔI _M ^* obtained by the first amplitude calculation circuit. The first adjusting circuit subtracts the absolute value of the current actual value I _M , and outputs the leakage inductance calculation value L ^# by the integration operation or the proportional integration operation by inputting the result of the subtraction.

The third invention has a configuration in which a first high-pass filter is added to the first leakage inductance calculation circuit described in the second invention, and the first high-pass filter is included in the actual M-axis current value I _M. Although the low amplitude component is removed and the second amplitude operation circuit inputs the actual M-axis current value I _{M from} which the low frequency component has been removed, the second amplitude arithmetic circuit is different from the second invention described above. This is the same as the second invention.

According to a fourth aspect, the circuit is configured such that the waveform of the AC signal ΔI _M ^* output from the first AC signal generating circuit is a waveform obtained by integrating a triangular wave. According to a fifth aspect of the present invention, a T-axis current is obtained by adding an addition value of an AC signal ΔI _T ^* output from a second AC signal generation circuit and a T-axis current command value I _T ^* output from a command value generation circuit as a new current command value. To the controller,
The AC signal [Delta] I _T ^* a and T-axis current actual value I _T by entering into the second leakage inductance calculation circuit to calculates the leakage inductance calculation value L ^#, and stores the result of the calculation in the second memory circuit. The second signal selector selects either the leakage inductance calculation value L ^# or the leakage inductance set value L ^* stored in the second memory circuit. Second
Obtained via differential circuit AC signal [Delta] I _T ^* and T-axis current command value I _T ^* addition value or an AC signal between [Delta] I _T ^* and the value of the differential value and the second signal selector selects only the second By multiplying by the multiplier, the change amount of the T-axis voltage command value ΔV _T ^*
Is obtained. A T-axis voltage command value V _T ^* obtained by adding the T-axis voltage command value change ΔV _T ^* to V _T ^** output by the _T- axis current regulator, and an output of the M-axis current regulator. enter a certain M-axis voltage command value V _M ^* to a second coordinate converter, the phase voltage command values are converted by the second coordinate converter ^{_{v U *, v V *,}} v W * in the power converter Control.

According to a sixth aspect of the present invention, the second leakage inductance arithmetic circuit according to the fifth aspect of the present invention comprises a third amplitude arithmetic circuit,
The sixth adder comprises an amplitude calculation circuit, a sixth adder, and a second adjustment circuit. The sixth adder calculates a T-axis obtained by the fourth amplitude calculation circuit from the absolute value of the AC signal ΔI _T ^* obtained by the third amplitude calculation circuit. subtracting the absolute value of the current actual value I _T, the second adjustment circuit inputs the subtraction result, and outputs the leakage inductance calculation value L ^# by integration calculation or proportional integral operation.

[0036] A seventh invention is a configuration obtained by adding a second high-pass filter to the second leakage inductance calculation circuit described above in the sixth invention, the second high-pass filter is included in the T-axis current actual value I _T removing low frequency components, a fourth amplitude calculation circuit is where you enter the T-axis current actual value I _T to low-frequency components have been removed is different from the invention of the sixth described above, all other Part This is the same as the sixth invention.

According to an eighth aspect, the circuit is configured such that the waveform of the AC signal ΔI _T ^* output from the second AC signal generating circuit is a waveform obtained by integrating a triangular wave.

[0038]

FIG. 1 is a block circuit diagram showing a first embodiment of the present invention, and corresponds to claim 1. The AC power source 1, the power converter 2, Induction motor 3, current detector 4, first coordinate converter 5, second coordinate converter 6, command value generation circuit 7, M-axis current controller 8, and T
The names, applications, and functions of the shaft current controller 9 are the same as those in the case of the conventional circuit described above with reference to FIG.

The first AC signal generating circuit 21 generates an AC signal ΔI
_M ^*, and outputs the M-axis current command value I _M ^* output from the command value generation circuit 7 and the AC signal ΔI _M ^* to the first adder 27.
Enter The M-axis current command value I _M ^** obtained by the addition in the first adder 27 after adding the AC signal is an M-axis current controller together with the M-axis current actual value I _M instead of the M-axis current command value I _M ^* . 8 to output an M-axis current regulator output V _M ^** . Although first leakage inductance calculation circuit 22 inputs an alternating current signal [Delta] I _M ^* and M-axis current actual value I _M described above and outputs the leakage inductance calculation value L ^#, the leakage inductance calculation value L ^# first memory It is also stored in the circuit 23. Before the induction motor 3 operates, the first signal selector 26 selects the leakage inductance calculation value L ^# output from the first leakage inductance calculation circuit 22. If the induction motor 3 is operating, the first memory circuit 23 Select and output the leakage inductance set value L ^* to be stored. Although the first signal selector 26 has a configuration in which a signal is switched by a contact, the first signal selector 26 generally has a non-contact switching structure.

By inputting the M-axis current command value I _M ^** after addition of the AC signal to the first differentiating circuit 24, the differential value of I _M ^**
That is, a differential operation value of the AC signal ΔI _M ^* is obtained. The first multiplier 25 calculates the differential operation value and the leakage operation value L ^# or the set value L of the leakage inductance selected by the first signal selector 26.
^* M M-axis voltage command value change ΔV _M ^* (Equation 5)
See). The second adder 28 is an M-axis current controller 8
Outputs the output V _M ^** of Toko M-axis voltage command value change amount [Delta] V _M ^* and adding to the M-axis voltage command value V _M ^* to a second coordinate converter 6.

FIG. 2 is a block circuit diagram showing an application example of the first embodiment shown in FIG. 1. The application circuit of FIG. 2 inputs an AC signal ΔI _M ^* to a first differentiating circuit 24. What is different from the circuit of the first embodiment shown in FIG. 1 is that all other components are the same. Therefore, the description of the same part is omitted. The application circuit of FIG. 2 differentiates the AC signal ΔI _M ^*, and calculates the differential operation result and the leakage inductance operation value L ^#
Alternatively, the M-axis voltage command value V _M ^* shown in Expression 5 is obtained by multiplying by the set value L ^* .

FIG. 3 is a waveform diagram showing the waveforms of the signal input to the first adder and the signal output therefrom. FIG. 3 shows the waveform of the M-axis current command value I _M ^* input to the first adder 27. , FIG.
3 shows the waveform of the AC signal ΔI _M ^* input to the first adder 27, and FIG. 3 shows the waveform of the M-axis current command value I _M ^** after the addition of the AC signal output from the first adder 27. I have. That is, the M-axis current command value I after adding the output AC signal
_M ^** is because a DC component M-axis current command value I _M ^* is in the waveform is added to the AC signal [Delta] I _M ^*, differentiating the M-axis current command value I _M ^** after the AC signal added Even if the AC signal ΔI _M ^* is differentiated, the result of the differential operation is the same. Therefore, even if the M-axis current command value I _M ^** after the addition of the AC signal is input to the first differentiating circuit 24 (the first embodiment circuit of FIG. 1), the AC signal ΔI _M ^* is input (the application example of FIG. 2). Circuit), the same result is obtained.

FIG. 4 is a block circuit diagram showing a second embodiment of the present invention.
9 shows a configuration of a leakage inductance calculation circuit, and corresponds to claim 2. In the circuit of the second embodiment shown in FIG. 4, the AC signal ΔI _M ^* is input to the first amplitude calculation circuit 31 constituted by an absolute value calculation circuit, and the absolute value of the AC signal ΔI _M ^* is obtained.
Similarly, the M-axis current actual value I _M is input to the second amplitude calculation circuit 32, and its absolute value is obtained. The third adder 33 subtracts the absolute value of the actual M-axis current value I _M from the absolute value of the AC signal ΔI _M ^* (that is, the operation of Expression 10). When input to the first adjusting circuit 34, the first adjusting circuit 34 outputs a calculated leakage inductance value L ^# equal to the actual leakage inductance value L.

When the power conversion device 2 performs pulse width modulation control or a delay in sampling current detection, the dead time t
Is present, the above equation 7 is expressed by the following equation 17.

[0045]

[Mathematical formula-see original document] p · L · ΔI _M = ε ^-st · p · L ^# · ΔI _M
^{* Even in} this case, the average value of the absolute value of the M-axis current actual value I _M is |
If I _M | _AV and the average absolute value of the M-axis current command value I _M ^* is represented as | I _M ^* | _AV , the relationship between the two is given by the following equation (18).

[0046]

| _IM | _AV = (L ^# / L) _.multidot.IM ^* | _AV That is, the calculation of the leakage inductance calculation value L ^# can be performed without being affected by the dead time t. FIG. 5 is a block circuit diagram showing a third embodiment of the present invention, and shows a configuration of a first leakage inductance calculation circuit described in the first embodiment circuit of FIG. Has a configuration in which the first high-pass filter 35 is added to the circuit of the second embodiment described above with reference to FIG. 4, so that the first amplitude operation circuit 31, the second amplitude operation circuit 32, the third adder 33, and the first Adjustment circuit 3
The description of the name, use, and function of No. 4 is omitted. In the circuit of the third embodiment, if the low-frequency component such as the DC component is included in the actual M-axis current value IM input to the first leakage inductance calculation circuit 22, the second current is used as it is.
Even if it inputs to 2, the correct amplitude information of the change cannot be obtained.
Therefore, the first high-pass filter 35 is added to remove the low-frequency component described above.

Although not shown, if a filter having the same function as that of the first high-pass filter 35 is provided at a stage preceding the first amplitude calculating circuit 31, a first adder may be provided instead of the AC signal ΔI _M ^* . It is also possible to input the M-axis current command value I _M ^** after the addition of the AC signal output by 27. FIG.
4 is a block circuit diagram showing a fourth embodiment of the present invention, and shows a configuration of the first AC signal generation circuit 21 described in the circuit of the first embodiment in FIG. First
The AC signal generating circuit 21 is composed of a triangular wave generating circuit 36 and an integrating circuit 37 to output an integrated waveform of a triangular wave. By adding the AC signal ΔI _M ^* of the waveform obtained in the circuit of the fourth embodiment to the M-axis current command value I _M ^* , the M-axis voltage command value V _M ^* can be made into a triangular waveform.

FIG. 7 is a waveform diagram showing the effect of the circuit of the fourth embodiment of FIG. 6, and FIG. 7 shows the waveform of the AC signal ΔI _M ^* ,
Figure 7 is a M-axis voltage command value V _M ^* of the waveform. FIG. 8 is a block circuit diagram showing a fifth embodiment of the present invention, which corresponds to claim 5, wherein an AC power supply 1, a power converter 2, an induction motor 3, The names, applications, and functions of the current detector 4, the first coordinate converter 5, the second coordinate converter 6, the command value generation circuit 7, the M-axis current controller 8, and the T-axis current controller 9 are shown in FIG. Since this is the same as the case of the conventional circuit described above, the description thereof is omitted.

The second AC signal generating circuit 41 outputs the AC signal ΔI
Outputs _T ^*, T axis current command value I _T ^* Toko AC signal [Delta] I _T ^* and the fourth adder 47 to the command value generating circuit 7 outputs
Enter Fourth adder T-axis current command value after the AC signal addition obtained by the addition in 47 I _T ^** is T-axis current command value I _T ^* T-axis current regulator together with the T-axis current actual value I _T instead of 9 to output a T-axis current regulator output V _T ^** . The second leakage inductance calculation circuit 42 outputs the above-described AC signal [Delta] I _T ^* and T-axis current actual value I _T leakage inductance calculation value inputs an L ^#, the leakage inductance calculation value L ^# the second memory It is also stored in the circuit 43. Before the induction motor 3 is operated, the second signal selector 46 selects the leakage inductance calculation value L ^# output from the second leakage inductance calculation circuit 42, and when the induction motor 3 is operating, the second memory circuit 43 Select and output the leakage inductance set value L ^* to be stored. Although the second signal selector 46 has a configuration in which a signal is switched by a contact, the second signal selector 46 generally has a non-contact switching structure. The T-axis current command value _IT ^** after adding the AC signal is
By inputting the signal to the differentiating circuit 44, a differential value of I _T ^** , that is, a differential operation value of the AC signal ΔI _T ^* is obtained. The second multiplier 45 calculates a change in the T-axis voltage command value ΔV _T ^* (Equation 11) which is a product of the differential operation value and the operation value L ^# or the set value L ^{* of} the leakage inductance selected by the second signal selector 46. See). The fifth adder 48 adds the output V _T ^** of the T-axis current controller 9 and the change ΔT _T ^* of the T-axis voltage command value to obtain the T-axis voltage command value V _T ^* in the second coordinate converter 6. Output to

FIG. 9 is a block circuit diagram showing an application example of the fifth embodiment shown in FIG. 8. The application circuit of FIG. 9 inputs an AC signal ΔI _T ^* to the second differentiating circuit 44. This is different from the circuit of the fifth embodiment shown in FIG. 8, but all other points are the same. Therefore, the description of the same part is omitted. The application example circuit of FIG. 9 differentiates the AC signal ΔI _T ^*, and calculates the differential operation result and the leakage inductance operation value L ^{#
Alternatively} , by multiplying by the set value L ^* , the T-axis voltage command value V _T ^* shown in Expression 11 is obtained.

FIG. 10 is a waveform diagram showing the waveforms of the signal input to the fourth adder and the signal output therefrom. FIG. 10 shows the waveform of the T-axis current command value I _T ^* input to the fourth adder 47. ,
FIG. 10 shows an AC signal ΔI _T ^* input to the fourth adder 47 ^.
10 shows the waveform of the T-axis current command value _IT ^** after the addition of the AC signal output from the fourth adder 47. Before the induction motor 3 operates, the T-axis current command value I _T ^* output from the command value generation circuit 7 is zero (FIG. 1).
0). Thus a fourth adder 47 T-axis current command value I _T ^** after the AC signal added to the output will AC signal [Delta] I _T ^* the same waveform. Therefore the AC signal differentiation result of T-axis current command value I _T ^** after the addition is also an AC signal [Delta] I _T ^* of the differential results are the same. Therefore, the T-axis current command value _IT ^** after the addition of the AC signal is input to the second differentiating circuit 44 (fifth embodiment circuit in FIG. 8).
Even when the AC signal ΔI _T ^* is input (application circuit of FIG. 9)
Even so, the same result is obtained.

FIG. 11 is a block circuit diagram showing a sixth embodiment of the present invention, and shows a configuration of a second leakage inductance calculation circuit described in the circuit of the fifth embodiment in FIG. Corresponding to In the circuit of the sixth embodiment shown in FIG. 11, the AC signal ΔI _T ^* is input to a third amplitude calculation circuit 51 constituted by an absolute value calculation circuit to determine the absolute value of the AC signal ΔI _T ^* . Similarly, the T-axis current actual value I _{T is} supplied to the fourth amplitude calculation circuit 52.
To find its absolute value. Since the sixth adder 53 subtracts the absolute value of the AC signal [Delta] I _T ^* of the absolute value from the T-axis current actual value I _T (i.e. calculation of Equation 16), the subtraction result in the integral calculator or a proportional-integral calculator Constituent second
When input to the adjustment circuit 54, the second adjustment circuit 54 outputs a leakage inductance calculation value L ^# equal to the leakage inductance actual value L.

When the power converter 2 performs the pulse width modulation control or the sampling delay of the current detection, the dead time t
Is present, the above equation 13 is expressed by the following equation 19.

[0054]

[Equation 19] p · L · ΔI _T = ε ^-st · p · L ^# · ΔI _T
^* The average value of the absolute value of the T axis current actual value I _T In this case |
Represents a _AV, T-axis current command value I _T ^* of the average of the absolute values | | I _T I _T ^* | expressed as _AV, relationship of both is the equation 20 below.

[0055]

| _IT | _AV = (L ^# / L). | _IT ^* | _{AV In} other words, the calculation of the leakage inductance calculation value L ^# can be performed without being affected by the dead time t. FIG. 12 is a block circuit diagram showing a seventh embodiment of the present invention, and shows a configuration of a second leakage inductance calculation circuit described in the circuit of the fifth embodiment in FIG. However, FIG.
Since the second high-pass filter 55 is added to the circuit of the sixth embodiment, the third amplitude calculation circuit 51 and the fourth
Descriptions of the names, applications, and functions of the amplitude calculation circuit 52, the sixth adder 53, and the second adjustment circuit 54 are omitted. This seventh
In the embodiment circuit, the low frequency components such as a DC component in the T-axis current actual value I _T is input to the second leakage inductance calculation circuit 42 is included, which was input as it is to the fourth amplitude calculation circuit 52 However, correct amplitude information for the change cannot be obtained. Therefore, the second high-pass filter 55 is added to remove the aforementioned low frequency components.

Although not shown, a fourth adder 47 is supplied to the third amplitude calculation circuit 51 instead of the AC signal ΔI _T ^*.
It is also possible to input the T-axis current command value I _T ^** after the addition of the AC signal output by. FIG. 13 is a block circuit diagram showing an eighth embodiment of the present invention, and shows a configuration of the second AC signal generating circuit 41 described in the circuit of the fifth embodiment in FIG. I do. Second AC signal generation circuit 41
Is composed of a triangular wave generating circuit 56 and an integrating circuit 57 to output an integrated waveform of a triangular wave. The T-axis voltage command value V _T ^* can be made into a triangular waveform by adding the T-axis current command value I _T ^* to the AC signal ΔI _T ^* having the waveform obtained in the circuit of the eighth embodiment. The waveform of the AC signal and the waveform of the voltage command value at this time are the same as those in FIG.

[0057]

According to the first and fifth aspects of the present invention, the feedforward compensation of current control and the calculation of the induced voltage are performed by using the leakage inductance calculation value obtained before the start of the operation of the AC motor. Even when the wiring length of the electric wire connecting the AC motor is changed, or when the value of the leakage inductance fluctuates due to a winding change repair of the AC motor or replacement of the motor, the calculation of the motor torque or the magnetic flux is performed. Alternatively, an effect that the control can be appropriately performed is obtained.

According to the second or sixth aspect of the present invention, using the M-axis or T-axis current command value to which the AC signal is added and the actual M-axis or T-axis current value, the comparison between the amplitude values of the two is omitted. Since the inductance is identified, it is possible to obtain the effect that the leakage inductance can be identified without being affected by the delay time in the current control. In the third or seventh invention, even when a DC component such as an offset is superimposed on the actual value of the M-axis or T-axis current, the DC component is removed using a high-pass filter. The effect of accurately calculating the inductance is obtained.

According to the fourth or eighth aspect of the present invention, a triangular wave integrated waveform is adopted as an AC signal to be added to the current command value, and leakage inductance is identified using this waveform, whereby the voltage command value becomes a triangular wave. Become. Therefore, the quantization error can be reduced, and the effect that the leakage inductance can be identified without imposing an extra burden on the power converter is obtained.

Further, according to the fifth and sixth aspects of the present invention, since there is no DC bias component in the T-axis current command value, there is obtained an effect that leakage inductance can be identified without being affected by magnetic saturation.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a block circuit diagram showing an application example of the first embodiment shown in FIG.

FIG. 3 is a waveform chart showing waveforms of a signal input to a first adder and a signal output therefrom;

FIG. 4 is a block circuit diagram showing a second embodiment of the present invention.

FIG. 5 is a block circuit diagram showing a third embodiment of the present invention.

FIG. 6 is a block circuit diagram showing a fourth embodiment of the present invention.

FIG. 7 is a waveform chart showing the effect of the circuit of the fourth embodiment of FIG. 6;

FIG. 8 is a block circuit diagram showing a fifth embodiment of the present invention.

9 is a block circuit diagram showing an application example of the fifth embodiment shown in FIG.

FIG. 10 is a waveform chart showing waveforms of a signal input to a fourth adder and a signal output therefrom.

FIG. 11 is a block circuit diagram showing a sixth embodiment of the present invention.

FIG. 12 is a block circuit diagram showing a seventh embodiment of the present invention.

FIG. 13 is a block circuit diagram showing an eighth embodiment of the present invention.

FIG. 14 is a block circuit diagram showing a conventional example of a variable speed control device for an induction motor in which a transient voltage is suppressed by feedforward compensation.

[Explanation of symbols]

5 first coordinate converter, 6 second coordinate converter, 7 command value generation circuit, 8 M-axis current adjuster, 9 T-axis current adjuster,
11: feedforward compensation voltage calculation circuit, 21: first AC signal generation circuit, 22: first leakage inductance calculation circuit, 23: first memory circuit, 24: first differentiation circuit, 25: first multiplier, 26 ... A first signal selector, 27 ...
First adder, 28 second adder, 31 first amplitude calculator, 32 second amplitude calculator, 33 third adder, 34
... First adjustment circuit, 35 ... First high-pass filter, 36 ...
Triangular wave generation circuit, 37 integration circuit, 41 second AC signal generation circuit, 42 second leakage inductance calculation circuit, 4
3, a second memory circuit, 44, a second differentiating circuit, 45, a second multiplier, 46, a second signal selector, 47, a fourth adder,
48 a fifth adder, 51 a third amplitude arithmetic circuit, 52 a fourth amplitude arithmetic circuit, 53 a sixth adder, 54 a second adjustment circuit, 55 a second high-pass filter, 56 a triangular wave generating circuit, 57: integrating circuit, _IM , _IT : actual value of each axis current, I
_M ^*, I _T ^* ... Each axis current ^{_{value, I M **, I T **}} ... each axis current command value after the AC signal addition, ΔI _M, ΔI _T ... each axis actual current variation, [Delta] I _M ^* , ΔI _T ^* ... AC signal, L ...
Leakage inductance actual value, L ^# ... leakage inductance calculation value, L ^* ... leakage inductance set value, V _M, V _T
… Each axis voltage actual value, V _M ^* , V _T ^* … Each axis voltage command value,
V _M ^** , V _T ^** ... output of each axis current controller, ΔV _M , ΔV _T
… Change in each axis voltage command value

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-1-308187 (JP, A) JP-A-9-285198 (JP, A) JP-A-6-273496 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00

Claims (8)

(57) [Claims] 1. An AC motor operating with AC power from a power converter is decomposed into an actual M-axis current value as an arbitrary M-axis component and an actual T-axis current value as a T-axis component orthogonal thereto. A first coordinate conversion circuit for outputting the M-axis current command value and a T-axis current command value orthogonal to the M-axis current command value; a M-axis current command value and the M-axis current actual value; And an M-axis current controller that outputs an M-axis voltage command value that makes the deviation of the T-axis current zero, and a T-axis voltage controller that outputs a T-axis voltage command value that makes the deviation between the T-axis current command value and the T-axis current actual value zero. A shaft current controller, and a second coordinate conversion circuit that receives the M-axis voltage command value and the T-axis voltage command value and outputs a phase voltage command value,
In the variable speed control device for an AC motor configured to control the power converter with each phase voltage command value, a first AC signal generation circuit for generating an AC current signal, the AC current signal and the M-axis current command value And a first adder for inputting a calculation result of the sum of the AC current signal to the M-axis current adjuster instead of the M-axis current command value, and inputting the AC current signal and the M-axis current actual value to output the AC motor. A first leakage inductance calculation circuit for calculating a leakage inductance component of
A first memory circuit for storing the calculated value of the leakage inductance;
A first signal selector for selecting one of the memory circuit storage data, a first differentiator for calculating an output value of the first adder or a differential value of the AC current signal; A first multiplier for calculating a product of the signal selected by the signal selector, and a calculation result of a sum of a result of the multiplication calculation and an output of the M-axis current regulator as an M-axis voltage command value, the second coordinate conversion A second adder to be provided to a circuit, wherein the first signal selector is configured to switch the first signal before the operation of the AC motor.
A variable speed control device for an AC motor, wherein a calculation value of a leakage inductance calculation circuit is selected, and data stored in the first memory circuit is selected during operation. 2. The variable speed control device for an AC motor according to claim 1, wherein said first leakage inductance calculation circuit calculates a first amplitude calculation circuit for calculating an amplitude of an input AC current signal, and an input M-axis. A second amplitude calculation circuit for calculating the amplitude of the actual current value, a third adder for subtracting the output of the second amplitude calculation circuit from the output of the first amplitude calculation circuit, and a calculation result of the third adder A variable speed control device for an AC motor, comprising: a first adjustment circuit for inputting an integration operation or a proportional integration operation, and using an output of the first adjustment circuit as a leakage inductance operation value. 3. The variable speed control device for an AC motor according to claim 1, wherein the first leakage inductance calculation circuit calculates a first amplitude calculation circuit for calculating an amplitude of an input AC current signal, and an input M-axis. A first filter for removing a frequency component lower than the frequency of the actual current value, a second amplitude arithmetic circuit for calculating the amplitude of the actual M-axis current value passing through the first filter, and an output of the first amplitude arithmetic circuit A third adder for subtracting the output of the second amplitude calculation circuit from the first and a first adjustment circuit for inputting the calculation result of the third adder and performing an integration calculation or a proportional integration calculation. A variable speed control device for an AC motor, wherein an output is a calculated value of a leakage inductance. 4. The variable speed control device for an AC motor according to claim 1, wherein said first AC current signal generating circuit outputs a triangular integrated waveform. Variable speed control device for an AC motor. 5. An M-axis current actual value which is an arbitrary M-axis component and a T-axis current actual value which is a T-axis component orthogonal to the current of an AC motor driven by AC power from the power converter. A first coordinate conversion circuit for outputting the M-axis current command value and a T-axis current command value orthogonal to the M-axis current command value; a M-axis current command value and the M-axis current actual value; And an M-axis current controller that outputs an M-axis voltage command value that makes the deviation of the T-axis current zero, and a T-axis voltage controller that outputs a T-axis voltage command value that makes the deviation between the T-axis current command value and the T-axis current actual value zero. A shaft current controller, and a second coordinate conversion circuit that receives the M-axis voltage command value and the T-axis voltage command value and outputs a phase voltage command value,
In the variable speed control device for an AC motor configured to control the power converter with each phase voltage command value, a second AC signal generation circuit for generating an AC current signal, the AC current signal and the T-axis current command value And a fourth adder for inputting the result of the calculation of the sum of the AC current signal and the T-axis current actual value to the T-axis current adjuster instead of the T-axis current command value. A second leakage inductance calculation circuit for calculating the leakage inductance of
A second memory circuit for storing the calculated value of the leakage inductance;
A second signal selector for selecting one of the memory circuit storage data, a second differentiating circuit for calculating an output value of the fourth adder or a differential value of the AC current signal; A second multiplier for calculating a product of the signal selected by the signal selector, and a second coordinate conversion using a result of the sum of the result of the multiplication operation and the output of the T-axis current regulator as a T-axis voltage command value A fifth adder to be provided to the circuit, wherein the second signal selector selects the second adder before operating the AC motor.
A variable speed control device for an AC motor, wherein a calculation value of a leakage inductance calculation circuit is selected, and data stored in the second memory circuit is selected during operation. 6. The variable speed control device for an AC motor according to claim 5, wherein the second leakage inductance calculation circuit calculates a amplitude of an input AC current signal, and a T-axis input. A fourth amplitude calculation circuit for calculating the amplitude of the actual current value, a sixth adder for subtracting the output of the fourth amplitude calculation circuit from the output of the third amplitude calculation circuit, and a calculation result of the sixth adder A variable speed control device for an AC motor, comprising: a second adjustment circuit for performing an integration operation or a proportional integration operation upon input, and using an output of the second adjustment circuit as a leakage inductance identification value. 7. The variable speed control device for an AC motor according to claim 5, wherein the second leakage inductance calculation circuit calculates a amplitude of an input AC current signal, and a T-axis input. A second filter for removing a frequency component lower than the frequency of the actual current value, a fourth amplitude arithmetic circuit for calculating the amplitude of the actual T-axis current value passing through the second filter, and an output of the third amplitude arithmetic circuit A sixth adder for subtracting the output of the fourth amplitude arithmetic circuit from the input signal, and a second adjusting circuit for inputting the operation result of the sixth adder and performing an integration operation or a proportional integration operation. A variable speed control device for an AC motor, wherein an output is a calculated value of a leakage inductance. 8. The variable speed control device for an AC motor according to claim 5, wherein the second AC current signal generating circuit outputs a triangular integrated waveform. Variable speed control device for an AC motor.