JPH02273092A - Vector controller for induction motor - Google Patents

Abstract

PURPOSE:To compensate for secondary resistance fluctuation by calculating the secondary resistance fluctuation based on a detected secondary flux and a set value of primary current, and then carrying out secondary resistance compensation for the slip speed based on the secondary resistance fluctuation. CONSTITUTION:A voltage detector 20 detects three-phase primary voltage eu, ev, ew. A primary power source angle operating section 21 integrates output angular speed omega to obtain a primary power source angle theta. A three-phase/two- phase converting section 22 converts three-phase primary currents iu, iv, iw and three-phase primary voltages eu, ev, ew into two-phase (alpha, beta coordinate system) components. A flux observer 23 obtains an estimated value lambda2beta of secondary flux based on the primary currents i1alpha, i1beta and primary voltages e1alpha, e1beta. Secondary resistance fluctuation operating section 58 operates a secondary resistance fluctuation K. Thus, obtained secondary resistance fluctuation K is employed in slip angular speed operating section 8 where operation for compensating for the secondary resistance fluctuation is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a vector control device for an induction motor.

B0 Summary of the Invention The present invention includes a slip angular velocity calculation unit that calculates a slip angular velocity based on a primary current command value and a secondary time constant setting value based on an orthogonal two-axis coordinate system, and uses the calculated slip angular velocity to calculate a slip angular velocity. A secondary magnetic flux that outputs each axis component of a secondary magnetic flux estimated value by the seat system based on each axis component of the primary current and primary voltage in the coordinate system. and a secondary time constant correction unit that corrects the secondary time constant setting value based on the estimated secondary magnetic flux value in response to a change in secondary resistance; The estimating unit performs calculations by treating variables as each axis component in the coordinate system, and calculates a value based on the primary current, primary voltage, and feedback estimated secondary magnetic flux.
In addition to determining the rate of change of the primary current, the rate of change of the secondary magnetic flux is determined based on the primary current and the feedback estimated secondary magnetic flux value, and the The estimated value of the secondary magnetic flux is calculated, and the slip angular velocity calculation unit performs the calculation using the secondary time constant corrected by the secondary time constant correction unit, thereby compensating for the secondary resistance change. This is how it was done.

C1 Prior Art In general, in induction motors, a vector control method that controls a secondary magnetic flux and a secondary current orthogonal to the secondary magnetic flux in a non-interfering manner has been widely applied.

This vector control method handles current, magnetic flux, etc. as vectors, performs calculations, converts the calculation results into current command values, and controls the induction motor. In the case of a three-phase induction motor, vector components are calculated using an αβ coordinate system of two orthogonal axes that rotate at the same speed as the rotating magnetic field generated by the power source.

The vector control method has the advantage of providing coordination comparable to that of a DC motor.

D0 Problems to be Solved by the Invention However, the conventional vector control method has a problem in that the accuracy of torque characteristics is low.

One of the factors for this is a change in torque characteristics due to a change in secondary resistance. That is, the secondary resistance changes depending on the temperature. In the vector control method, the secondary resistance is used to calculate the sliding speed, so if a deviation occurs between the set value of the secondary resistance and the actual secondary resistance value, the generated torque will change.

SUMMARY OF THE INVENTION In view of these problems, it is an object of the present invention to provide an induction motor novector control device that can compensate for changes in secondary resistance.

21 Means for Solving the Problems In order to achieve the above object, the present invention provides a slip angular velocity calculation method based on a primary current command value and a secondary time constant setting value based on an orthogonal two-axis coordinate system. This device has an angular velocity calculating section and performs vector control of an induction motor using the calculated slip angular velocity, and takes the following measures.

(2) A secondary magnetic flux estimator is provided that outputs each axis component of a secondary magnetic flux estimated value based on the coordinate system based on each axis component of the primary current and primary voltage based on the coordinate system.

(2) A secondary time constant correction section is provided that corrects the secondary time constant setting value based on the estimated secondary magnetic flux value in response to a change in secondary resistance.

■ The secondary magnetic flux estimator performs calculations by treating variables as components of each axis in the coordinate system, and calculates the
In addition to determining the rate of change of the primary current, the rate of change of the secondary magnetic flux is determined based on the primary current and the feedback estimated secondary magnetic flux value, and the The next magnetic flux estimate shall be obtained.

■ The slip angular velocity calculation unit shall perform calculations using the secondary time constant corrected by the secondary time constant correction unit.

21 action When the secondary resistance changes, the secondary magnetic flux is affected.

In other words, although the vector of the secondary magnetic flux should have only one axial component, it ends up having the other axial component.

According to the vector control device according to the present invention, the secondary magnetic flux is detected by the secondary magnetic flux detection section, and the secondary resistance change is calculated based on the detected secondary magnetic flux and the set primary current. Then, by performing secondary resistance compensation for the sliding speed based on the calculated secondary resistance change, it becomes possible to perform highly accurate compensation.

Moreover, since the secondary magnetic flux estimation section estimates the magnetic flux using a magnetic flux observer, an accurate secondary magnetic flux estimation value can be obtained even when the induction motor is operated at low speed. Furthermore, since the secondary magnetic flux estimated value is fed back and calculated, even if there is an initial error, it is possible to converge this error.

G. Embodiment In explaining a vector control device for an induction machine according to an embodiment of the present invention, vector control conditions will be explained.

First, the meanings of the symbols used in the explanation will be described.

e lil+ ” 1. α, β axis primary voltage!
1m+11 ... α, β axis primary current λ76. λ1
．． ... α, β-axis secondary magnetic flux ω0 ... Primary power supply angular velocity ω8 ω.

R,,R.

L In L *+ Slip angular velocity Rotor angular velocity 1st order, 2nd order resistance 1st order, 2nd order excitation inductance P... d/d The voltage equation of the induction motor is as follows. However, this formula is based on the orthogonal 2
Based on the axis (αβ axis) coordinate system.

...(1) The torque formula is as follows.

The conditions are as follows.

T-λ□i□-λ1811B...(2) However, λta=M I Ha+ L 21 taλ,,=Mi
□+L tlta ω8 = ω0-ωr ... (3) ... (4) ... - (5) ■ l 1a = -・λ, 7 ... (12) However, the quadratic time constant τ is It is as follows.

(13) When the secondary magnetic flux and secondary current are controlled to be orthogonal, the following results.

λ, 1=φf (constant) λ1. −〇 11#”O 1□=L ...(7) ...(8) ...(9) ...(lO) (1).

(lO) From the equation, vector control Therefore, in order to perform vector control, the slip angular velocity ω3
The condition is to control as shown in equation (11).

Next, the influence of the secondary resistance change on the secondary magnetic flux will be explained. In the following description, in order to distinguish between a set value and an actual value, "*" is added after the symbol indicating the set value.

The relational expression when the secondary time constant τ is different from the actual value of the motor is as follows from equation (1). However, τ
, * is the setting value of the secondary time constant, il, * is the current command value.

+, I** Here, the relationship between the set value τ, * of the secondary time constant and the true value τ is as follows.

In these equations (14) and (15), in the steady state P
=0. Also, if the inverter is a current control type, i
□*”” l Iag I 14*= 1□.

Therefore, equation (14)(t5) becomes as follows.

Assuming that the range of change in K is in a small range (-0, 25≦≦0゜25) and setting 2=0, from equations (18) and (19),
The secondary magnetic flux λ, 6 is as follows.

According to this equation (20), K is expressed as follows.

It becomes like this.

From equation (17), the secondary magnetic flux λ□ is λ2. if the following vector control conditions are satisfied. -0, so according to equation (21), =O.

From this equation (21), the following can be seen.

Magnetic flux current command i 1. *, Torque current command i 1, *so and the secondary magnetic flux λ7. If you know, Change in secondary resistance K can be calculated.

8, *.

1* is the setting value, so λ1. is required If so, Secondary resistance compensation can be performed.

From equation (23), □ is a measurement next, Calculation of secondary magnetic flux will be explained.

Because you can λ, 4゜ λ9. is estimated by the minimum dimension observer. By transforming equation (1), The following formula is obtained Set.

From Mr. Gopinath's method, An object like It will be done.

The server formula is obtained.

...(24) From the above, The minimum dimension observer is Ru.

Large-C(,,+I)y ...(30) however, ω.

U.

vl X is It is as follows.

however, U.

U.

vl.

■、Ha、 It is as follows Ru.

Also, large can be transformed as follows.

Expanding the observer equation, ω1. ω111g+e□
becomes as follows.

・Q++ MRz -Akira -Sagi
.

ωr−[−elil, λta (iJJtn”(
R+”(t, 7”RJbaLllL* Lx, Qlt M-assemble-L#ω
o I Ia]” [-e re”-ωrλ
2#--λtsL, Lt Lt
'薖lRi'()'RJ I +s+L*ωolljt +1(M I +-1tj+ω8i□
...(36) Lt 1 crystal MRt-M -Mω1-[-〇1
m]λ! r-ω mountain-”IR++)”Rtl i
raLllLx Lt, Q□ M -MR, -shi#ωo I
+a]"["-e +-child-ωrλ! α□λ!
βL, L, L,' + (R1÷(-)LI + +, +L, ω0iljL.

+”L(Mi,,-foot,6)+ω8e1.
...(87) Shi! λ,, -ω, +Q++ i +'a +Lt I I
a −(38)λvs−(t
)t +12y+ I Ia +Qtx! +s
-(39) In this way, the primary current 11. .

IIs and the estimated value of the secondary magnetic flux λ21. from the primary voltage e1m+e15. λ2. can be found.

In this embodiment, the estimated value λ2 of the secondary magnetic flux. Find λ1
．． - Perform secondary resistance compensation by manipulating K so that it becomes -〇. This will be explained in detail below.

FIG. 1 shows a vector control system of a current controlled inverter according to this embodiment. In the same figure, the formula in the block indicates a transfer function.

1 is a motor. The speed detector 2 detects the speed of the motor l (rotor angular velocity), and the speed calculation unit 3 converts the detection output of the speed detector 2 into a rotor angular velocity ω.

Then, the subtraction unit 4 calculates the speed setting ω input from the outside.
, * and rotor angular velocity ω, to find the deviation,
The speed amplifier 5 converts the output of the subtraction unit 4 into a β-axis primary current command (torque current command) Irp*.

The current calculation unit 6 receives an α-axis primary current command (excitation current command) i+J input from the outside and a torque current command 11.
Determine the primary current command rI from *. In the phase calculation section 7,
Similarly, the excitation current command 114* and the torque current command i
Find the phase φ from , , *.

In the slip angular velocity calculation unit 8, the excitation current command 17.
* and torque current command 11. *Slip angular velocity ω
, find. The adder 9 adds the rotor angular velocity ω and the slip angular velocity ω to obtain the output angular velocity ω.

In the sin function calculation unit 10, the phase φ and the output angular velocity ω
5in (ωt+φ) and sin (ωt+φ−2
/3π). The D/A converter 11 obtains current commands 1u* and Iv* from the primary current command 11* and the output of the sine function calculation unit 10.

Also, the current detector 12 detects the primary current! U,! v+iw
is detected, and the subtraction units 13-1 and 13-2 calculate the respective deviations between the current commands t+J, Iv* and the primary currents 1u, Iv. This deviation is calculated as current amplifier 14-1.1
Perform proportional integration using 4-2 to obtain 1. & Voltage command eJ, ev*
seek. Furthermore, the adder 15-1 and the inverter 15
-2, the primary voltage command euJeJ is added and the primary voltage command e is obtained. Find *.

The primary voltage command obtained in this way e u*+ e J
.

eJ by the comparator 16, the triangular wave generation circuit 17
control signals U, V, and W of the base drive 18 are obtained.

The base drive 18 generates a gate signal based on the control signals U, V, and W, and based on this gate signal, PW
An M (pulse width modulation) inverter 19 controls the supply of primary power to the motor 1 .

In addition to the above circuit configuration, this embodiment has a configuration that corrects the function used in the calculation of the slip angular velocity calculation section 8.

First, the voltage detector 20 detects the three-phase primary voltages eU and ev.
, ew is detected. Further, the primary power source angle calculating section 21 integrates the output angular velocity ω to determine the primary power source angle θ.

In the 3-phase/2-phase converter 22, the 3-phase primary current lu,! v
, Iw and three-phase primary voltages eu, ev+e8 are each converted into two-phase (αβ axis coordinate system).

The magnetic flux observer 23 uses the primary current 1+a+Il+5 and the primary voltage e1°, el to calculate the estimated secondary magnetic flux value λ3. seek.

FIG. 2 shows details of the magnetic flux observer. Transfer element 24
~45 and addition/subtraction units 46~57, (36)~(3
9) Perform the calculation shown in the formula to obtain the secondary magnetic flux quasi-planted λ3. seek.

The secondary resistance change calculating section 58 performs the calculation shown in equation (21) to obtain the secondary resistance change K.

By using the thus obtained secondary resistance change K, the slip angular velocity calculation unit 8 calculates the 2
Compensate for changes in resistance.

Next, a modification of the secondary resistance change calculating section will be described.

As shown in FIG. 3, the secondary resistance change calculating section 58 is composed of a subtracting section 59 and a proportional-integral amplifier 60. This secondary resistance change calculation section 58 uses equation (21) to calculate 2
Estimated magnetic flux λ3. Instead of finding the secondary resistance change K from the estimated secondary magnetic flux λ1. and secondary magnetic flux command λ1. The secondary resistance change K is corrected by taking the deviation of * and proportionally integrating this deviation. In the figure,
K is a conversion gain, S is an operator, and T is a time constant.

According to this aspect, there is an advantage that the secondary resistance change K can be determined in a short time by simple calculation.

In addition, when calculating the secondary magnetic flux λ2d+λ,9,
1 instead of primary voltage eu, ev+ew (detected value)
An embodiment using the next voltage commands eυ*, ev*, and ew* can also be adopted. In this case, the 3-phase/2-phase converter 2
1, the primary voltage 1o from the voltage detector 2o.

l v) Instead of I and l, the primary voltage command e u *+ e v from the current amplifier 14 and the adder 15
*+e w* is converted into two-phase, and the secondary magnetic flux calculation unit 22
The configuration may be such that the output is output to .

As described in detail of the H1 invention, in the vector control device for an induction motor according to the present invention, the secondary magnetic flux is estimated by the secondary magnetic flux estimation section, and the secondary magnetic flux is calculated based on the secondary magnetic flux estimated value and the set primary current. Calculate the next resistance change.

Then, it becomes possible to perform secondary resistance compensation for the sliding speed based on the calculated secondary resistance change amount, and there is an advantage that robust control can be performed.

Further, since secondary resistance compensation can be performed by calculating the secondary magnetic flux estimated value and the secondary resistance change, there is an advantage that the calculation section can be simplified.

Furthermore, since the secondary magnetic flux estimator estimates the magnetic flux using a magnetic flux observer, it has the advantage of being able to accurately estimate the magnetic flux. In other words, it is possible to obtain an accurate secondary magnetic flux estimate even when the induction motor is operating at low speed, and since the secondary magnetic flux estimate is fed back and calculated, even if there is an initial error, it is possible to converge this error. becomes.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the circuit configuration of a vector control system according to an embodiment of the present invention, Fig. 2 is a block diagram showing details of the magnetic flux observer, and Fig. 3 is a modification of the secondary resistance change calculation section. FIG. 1. Motor, 8.
...Slip angular velocity calculation unit, 21...Primary power source angle calculation unit, 22...3-phase/2-phase conversion unit, 23...Secondary magnetic flux observer, 58...Secondary resistance change calculation unit. 2 people outside

Claims (1)

[Claims] (1) It has a slip angular velocity calculation unit that calculates the slip angular velocity based on the primary current command value and the secondary time constant setting value based on the orthogonal two-axis coordinate system, and uses the calculated slip angular velocity to vector the induction motor. In the control device, a secondary magnetic flux estimator is provided that outputs each axis component of a secondary magnetic flux estimated value according to the coordinate system based on each axis component of the primary current and primary voltage according to the coordinate system, and A secondary time constant correction section is provided that corrects the secondary time constant setting value based on the secondary magnetic flux estimation value in response to a change in secondary resistance, and the secondary magnetic flux estimating section adjusts a variable. Calculations are performed by handling each axis component in the coordinate system, and the calculation is performed based on the primary current, primary voltage, and feedback secondary magnetic flux estimated value.
In addition to determining the rate of change of the primary current, the rate of change of the secondary magnetic flux is determined based on the primary current and the feedback estimated secondary magnetic flux value, and the A vector control device for an induction motor, characterized in that a first-order magnetic flux estimated value is obtained, and the slip angular velocity calculation section performs the calculation using a second-order time constant corrected by a second-order time constant correction section. .