JPH11151000A - Controller for induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a predetermined torque output by regulating the mutual inductance such that the difference of secondary flux outputted from first and second flux operating means becomes zero. SOLUTION: An induction motor controller comprises a first regulating means 9 which increases the output T2 if the instantaneous reactive power Q2>Q1 and decreases the output T2 if Q2<Q1 until Q1=Q2 is satisfied. The induction motor controller further comprises a first flux operating means 10 for determining a secondary flux f21 by receiving a primary current vector (i) and a primary voltage vector (v) from a current detecting means 4 and a voltage detecting means 6, and determining a secondary flux f22 by receiving the primary current vector (i) and a speed ωm from the current detecting means 4 and a speed detecting means 3. Output M from a second regulating means 12 is regulated such that the secondary fluxes f21, f22 from the first and second flux operating means 10, 11 will be equalized. According to the arrangement, a specified torque output can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling the torque of an induction motor, in which the secondary resistance or the secondary time constant of the induction motor or the mutual inductance varies according to operating conditions such as temperature and magnetic flux. By doing so, it is possible to suppress the deterioration of high-precision torque control accuracy.

[0002]

2. Description of the Related Art FIG. 3 shows an example of a block diagram of a conventional technique, which will be described below with reference to FIG. Power is supplied to the induction motor 2 by the power converter 1. Torque controller 5
Outputs a signal for controlling the power converter 1 so that the induction motor 2 outputs a predetermined torque. At that time, the torque controller 5 determines the primary current vector i of the induction motor 2 output from the current detection means 4, the rotation speed ωm of the induction motor 2 output from the speed detection means 3, and the secondary time constant of the induction motor 2. T2
Alternatively, the secondary resistance R2 and the mutual inductance M of the induction motor 2 are used.

[0003]

The conventional torque controller 5 uses the secondary time constant T2 or the secondary resistance R2 of the induction motor 2 and the mutual inductance M to control the torque of the induction motor. These values use values measured or designed before starting operation and are not changed during operation. However, since the secondary resistance R2 changes depending on the temperature of the induction motor 2, it fluctuates during operation. In addition, the secondary time constant T2 is represented by T2 = L2 / R2, and thus similarly varies during operation. Here, L2 is a secondary self inductance. Since the mutual inductance M changes with the magnetic flux density, if the magnitude of the magnetic flux changes, it changes accordingly. Therefore, the value of the secondary time constant T2 or the secondary resistance R2 or the mutual inductance M used in the torque controller may be different from the value of the induction motor 2 during operation. Then, since the torque controller 5 controls using the incorrect T2, R2, and M, a predetermined torque cannot be output from the induction motor 2.

To suppress the deterioration of the torque control accuracy due to the fluctuation of the secondary time constant or the secondary resistance, Japanese Patent Application Laid-Open No. 8-80 is disclosed.
No. 099, “Induction motor control device” (inventors Toshihiko Noguchi, Isao Takahashi, Yoichi Omori) has been reported. This is intended to compensate for the torque fluctuation due to the fluctuation of only the secondary time constant or the secondary resistance, but does not compensate for the fluctuation of the mutual inductance. In addition, since mutual inductance is used as a means for compensating the fluctuation of the secondary time constant or the secondary resistance, there remains a problem that the fluctuation of the secondary time constant or the secondary resistance is not normally compensated due to the fluctuation of the mutual inductance. ing. The present invention has been made in view of the above points, and aims to solve these disadvantages.
Even if the secondary time constant or secondary resistance fluctuates due to temperature, etc., or the mutual inductance fluctuates due to magnetic saturation, etc.,
It is an object of the present invention to provide a control device for an induction motor in which those values used in a torque controller can be set to correct values and a predetermined torque output can be obtained.

[0005]

Means for achieving the object are as follows: 1) A voltage detecting means for detecting or estimating a primary voltage of an induction motor and converting it into a vector, and the current detecting means according to claim 1 First reactive power calculating means for calculating instantaneous reactive power by a cross product of a primary current vector output from the means and a primary voltage vector output from the voltage detecting means; a primary current vector and a speed output from the current and speed detecting means; Second reactive power calculating means for calculating instantaneous reactive power using a secondary resistance or a secondary time constant of the induction motor; and the first and second reactive power calculating means.
The secondary resistance or secondary time constant used in the second reactive power calculation means or the secondary resistance or secondary time constant used in the torque controller so that the difference in the reactive power of the output of the reactive power calculation means becomes zero. And a first magnetic flux for calculating a secondary magnetic flux of the induction motor by an integral operation using a primary current vector output from the current detecting means and a primary voltage vector output from the voltage detecting means. A calculating means, a primary current vector and a speed of the output of the current and speed detecting means,
A second magnetic flux calculating means for calculating a secondary magnetic flux of the induction motor using a mutual inductance of the induction motor; and a difference between magnitudes of secondary magnetic fluxes of outputs of the first and second magnetic flux calculating means is zero. A second adjusting means for adjusting the value of the mutual inductance used in the second magnetic flux calculating means and the value of the mutual inductance used in the torque controller.

2) A voltage detecting means for detecting or estimating a primary voltage of an induction motor and converting the voltage into a vector, a primary current vector output from the current detecting means and a primary voltage vector output from the voltage detecting means. First reactive power calculating means for calculating instantaneous reactive power by the cross product of the following, a primary current vector and speed of the output of the current and speed detecting means,
A third reactive power calculator for calculating instantaneous reactive power using the mutual inductance of the induction motor; and the third reactive power calculator so that a difference between reactive powers of outputs of the first and third reactive power calculators becomes zero. Third adjusting means for adjusting the value of the mutual inductance used in the reactive power calculating means and the value of the mutual inductance used in the torque controller; a primary current vector output from the current detecting means and a primary voltage output from the voltage detecting means; First magnetic flux calculating means for calculating the secondary magnetic flux of the induction motor by integral calculation using a vector, a primary current vector and speed of the output of the current and speed detecting means,
A third magnetic flux calculating means for calculating a secondary magnetic flux of the electric motor using a secondary resistance or a secondary time constant of the induction motor; and a magnitude of a secondary magnetic flux output from the first and third magnetic flux calculating means. And a fourth adjusting means for adjusting the secondary resistance or the secondary time constant used in the third magnetic flux calculating means or the secondary resistance or the secondary time constant used in the torque controller so that the difference between the second magnetic flux calculating means becomes zero. Things. Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing one embodiment of the first aspect of the present invention, and FIG. 2 is a block diagram showing one embodiment of the second aspect of the present invention. 1 and 2
In the above, the relationship among the power converter 1, the induction motor 2, the speed detecting means 3, the current detecting means 4, and the torque controller 5 is the same as in the prior art. The secondary time constant T2 and the mutual inductance M of the induction motor 2 used in the conventional torque controller 5 are the outputs of the first adjusting means 9 and the second adjusting means 12 in FIG. 4 adjustment means 16
And the output of the third adjusting means 14.

First, the remaining part in FIG. 1 will be described below. The first reactive power calculating means 7 receives the primary current vector i and the primary voltage vector v output from the current detecting means 4 and the voltage detecting means 6, and obtains Q1 = id * vq-iq * vd. The instantaneous reactive power Q1 is obtained by --- (1). Here, id and iq are components of the primary current vector i, and vd and vq are components of the primary voltage vector v. Second reactive power calculating means 8
Inputs the primary current vector i and the speed ωm of the outputs of the current detecting means 4 and the speed detecting means 3 and integrates f22 = (M / T2 * if22 / T2 + j * ωm * f22) dt ------ (2) The secondary magnetic flux vector f22 is obtained by the following. Here, M is the output of the second adjusting means 12, and T2 is the output of the first adjusting means 9.

Next, a primary magnetic flux vector f1 is obtained by f1 = M / L2 * f22 + (L1-M * M / L2) * i (3). Where L1, L
Reference numeral 2 denotes a primary and secondary self-inductance, respectively. After that, the instantaneous reactive power Q2 equivalent to the equation (1) is obtained by the following equation: Q2 = id * p (f1q) -iq * p (f1d)--------(4) Here, p () represents the time derivative in parentheses.
F1d and f1q are components of the primary magnetic flux vector f1. In the steady state, the instantaneous reactive power Q2 in equation (4)
Q2 = ω * ｛M / L2 * M / (1 + ωs * ωs * T2 * T2) -L1 + M * M / L2｝ * | i | * | i | ----------- It is expressed as Here, ω is an angular frequency and ωs is a slip angular frequency.

The instantaneous reactive power Q1 in equation (1) is also Q1 = ω * ｛Mr / L2 * Mr / (1 + ωs * ωs * T2r * T2r) -L1 + Mr * Mr / L2｝ * | i | * | i | −−−−−−−− (6) Here, since Q1 is obtained from the detected voltage and current, it is considered that no error is included in the mutual inductance and the secondary time constant. Therefore, their actual values are expressed as Mr and T2r, respectively. Assuming that the mutual inductance M is made equal to the actual value Mr by the second adjusting means 12, when ω> 0, T is obtained from the equations (5) and (6).
It can be seen that there is a relationship of Q2 <Q1 when 2 <T2r and Q2 <Q1 when T2> T2r. Therefore, in the first adjusting means 9,
By inputting Q1 and Q2, if T2> Q1, T2 is increased, and if Q2 <Q1, T2 is reduced to perform Q2.
1 = Q2. Then, T2 = T2r, and a correct secondary time constant can be obtained.

In the first magnetic flux calculating means 10, the primary current vector i and the primary voltage vector v output from the current detecting means 4 and the voltage detecting means 6 are inputted, and f21 = ｛L2 / M * (v-R * i ) The secondary magnetic flux f21 is obtained from the integral of｝ dt-(L1 * L2 / M-M) * i-----------(7). Second magnetic flux calculation means 11
Then, the primary current vector i and the speed ωm of the outputs of the current detecting means 4 and the speed detecting means 3 are inputted, and the secondary magnetic flux vector f22 is obtained by the equation (2).

The second adjusting means 12 inputs the secondary magnetic flux vectors f21 and f22 output from the first magnetic flux calculating means 10 and the second magnetic flux calculating means 11 and adjusts M so that their magnitudes become equal. And output. In the steady state, f
The size of 22 is represented by | f22 | = M * M / (1 + ωs * ωs * T2 * T2) * | i | * | i | −−−−−−− (8) The same applies to the size of f21. | F21 | = Mr * Mr / (1 + ωs * ωs * T2r * T2r) * | i | * | i | −−−−−−−−−−− (9) Here, L2 = M + Lσ is expressed, and Lσ is very small as compared with M. Therefore, even if there is an error in M, (7)
Since the calculation error in the formula is very small, the actual values Mr and T2r are used for the mutual inductance and the secondary time constant.

Assuming that the second time constant T2 is made to coincide with the actual value T2r by the first adjusting means 9, (8),
From equation (9), when M <Mr, | f22 | <| f21 |, M>
It can be seen that there is a relationship of | f22 |> | f21 | in Mr. Therefore, in the second adjusting means 12, | f22 | <| f2
In the case of 1 |, M is increased, and in the case of | f22 |> | f21 |, M is decreased to | f22 | = | f21.
| Then, M = Mr, and a correct mutual inductance can be obtained. The torque is controlled by the torque controller 5 using the correct secondary time constant T2 and the mutual inductance M obtained from the first adjusting means 9 and the second adjusting means 12.

In the case of FIG. 2, the third reactive power calculating means 13 performs the same calculation as the second reactive power calculating means 8 and outputs it as Q3. The third adjusting means 14 adjusts M so that the reactive powers Q1 and Q3 become equal and outputs the result.
Specifically, if Q1> Q3, M is increased, and Q1 <Q
If 3, M is reduced. The third magnetic flux calculation means 15 performs the same calculation as that of the second magnetic flux calculation means and outputs it as f23. The fourth adjusting means 16 adjusts and outputs T2 such that the magnitudes of f21 and f23 are equal. Specifically, when | f23 | <| f21 |, T2 is reduced,
If | f23 |> | f21 |, T2 is increased. The torque is controlled by the torque controller 5 using the correct mutual inductance M and the secondary time constant T2 obtained from the third adjusting means 14 and the fourth adjusting means 16.

[0015]

As described above, according to the present invention, even if the secondary time constant or the secondary resistance fluctuates due to temperature or the like, or the mutual inductance fluctuates due to magnetic saturation or the like,
According to the present invention, since these values used in the torque controller can be set to correct values, a predetermined torque output can be obtained, which is extremely useful in practical use.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

FIG. 2 is a block diagram of an embodiment according to the second aspect of the present invention.

FIG. 3 is a block diagram of an example of the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power converter 2 Induction motor 3 Speed detecting means 4 Current detecting means 5 Torque controller 6 Voltage detecting means 7 First reactive power calculating means 8 Second reactive power calculating means 9 First adjusting means 10 First magnetic flux calculating means 11 2 magnetic flux calculating means 12 second adjusting means 13 third reactive power calculating means 14 third adjusting means 15 third magnetic flux calculating means 16 fourth adjusting means

Claims (2)

[Claims] 1. A power converter for outputting a variable frequency / variable voltage alternating current, an induction motor driven by the power converter, speed detection means for detecting the speed of the induction motor, and a primary motor for the induction motor. A current detecting means for detecting a current and converting the vector, and a power converter for controlling an output torque of the induction motor by inputting a speed of an output of the speed detecting means and a primary current vector of an output of the current detecting means. A control device for an induction motor, comprising: a torque controller for outputting a signal for controlling a motor to the power converter; a voltage detection means for detecting or estimating a primary voltage of the induction motor and converting the voltage into a vector; First reactive power calculating means for calculating an instantaneous reactive power by a cross product of a primary current vector of the output of the voltage detecting means and a primary voltage vector of the output of the voltage detecting means; Second reactive power calculating means for calculating instantaneous reactive power using the primary current vector and speed of the output of the degree detecting means, and the secondary resistance or secondary time constant of the induction motor; and the first and second reactive power calculating means. The secondary resistance or the secondary time constant used in the second reactive power calculating means or the secondary resistance or the secondary time constant used in the torque controller is adjusted so that the difference in the reactive power of the output of the power calculating means becomes zero. First
Adjusting means; first magnetic flux calculating means for calculating a secondary magnetic flux of the induction motor by integral calculation using a primary current vector output from the current detecting means and a primary voltage vector output from the voltage detecting means; A second magnetic flux calculating means for calculating a secondary magnetic flux of the induction motor using a primary current vector and a speed of an output of the current and speed detecting means and a mutual inductance of the induction motor; and the first and second magnetic flux calculating means A second adjusting means for adjusting the value of the mutual inductance used in the second magnetic flux calculating means and the value of the mutual inductance used in the torque controller so that the difference in the magnitude of the secondary magnetic flux output from the means becomes zero. A control device for an induction motor, comprising: 2. A power converter for outputting a variable frequency / variable voltage alternating current, an induction motor driven by the power converter, speed detection means for detecting the speed of the induction motor, and a primary motor for the induction motor. A current detecting means for detecting a current and converting the vector, and a power converter for controlling an output torque of the induction motor by inputting a speed of an output of the speed detecting means and a primary current vector of an output of the current detecting means. A control device for an induction motor, comprising: a torque controller for outputting a signal for controlling a motor to the power converter; a voltage detection means for detecting or estimating a primary voltage of the induction motor and converting the voltage into a vector; First reactive power calculating means for calculating an instantaneous reactive power by a cross product of a primary current vector of the output of the voltage detecting means and a primary voltage vector of the output of the voltage detecting means; Third reactive power calculating means for calculating the instantaneous reactive power using the primary current vector and speed of the output of the degree detecting means and the mutual inductance of the induction motor, and the output of the first and third reactive power calculating means. Third adjusting means for adjusting the value of the mutual inductance used in the third reactive power calculating means or the value of the mutual inductance used in the torque controller so that the difference in the reactive power becomes zero, and the output of the current detecting means. First magnetic flux calculating means for calculating a secondary magnetic flux of the induction motor by integral calculation using a primary current vector and a primary voltage vector output from the voltage detecting means, and a primary current vector output from the current and speed detecting means Magnetic flux calculating means for calculating a secondary magnetic flux of the induction motor using a secondary resistance or a secondary time constant of the induction motor; The secondary resistance or the secondary time constant used in the third magnetic flux calculating means or the secondary resistance or the secondary time constant used in the torque controller is set so that the difference in the magnitude of the secondary magnetic flux output from the means becomes zero. A control device for an induction motor, comprising: a fourth adjusting means for adjusting.