JPH01202191A - Control system for induction motor - Google Patents

Abstract

PURPOSE:To prevent the instruction value error of a primary current vector due to the influence of an iron loss angle by obtaining the iron loss angle respon sive to a primary frequency from a memory. CONSTITUTION:An iron loss angle delta responsive to a primary angular frequency command omega1' is stored in an iron loss angle memory 10. A primary current vector calculator 11 obtains the value of the iron loss angle delta responsive to a primary frequency f1 from the memory 10, and obtains the magnitude ¦I1'¦ of a momentary primary current command and a phase command theta' by consider ing the angle delta. As a result, since the instruction value error of the primary current vector due to the influence of the angle delta can be prevented, an accurate vector control is performed even in a high speed range.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a vector control device that controls the speed and torque of an induction motor with high response, and is particularly suitable for a variable speed device that drives up to high speed (high frequency region). Regarding vector control methods.

[Prior art] Regarding the conventional vector control method for induction machines that takes iron loss resistance into consideration, please refer to IEE of Japan's Industrial Power and Electrical Application Study Group Material IE.
Discussed on pages 27-36 of A-87-10. This method is analyzed using a T-type equivalent circuit of an induction machine in which iron loss resistance r1 and mutual inductance M are connected in series, and the full angular frequency command and torque component current command are controlled as a function of iron loss resistance r y. The method is to do so.

[Problem to be solved by the invention]

The above-mentioned prior art is a method of controlling the slip angular frequency commands 03 and the torque component current command I- as a function of the iron loss resistance r, and cannot be controlled unless the iron loss resistance value r is always known. Also, iron loss resistance r.

Since r changes depending on the primary frequency, when applied to actual vector control, it is necessary to measure r, which poses a problem in that the control method becomes complicated.

Therefore, an object of the present invention is to perform accurate torque control (vector control) using a relatively simple method that takes iron loss into consideration even in a high-speed region where the primary frequency is high.

[Means to solve the problem]

The above purpose is to analyze a T-type equivalent circuit of an induction machine in which an iron loss resistance r and a mutual inductance M are connected in parallel, and to store in advance a pattern of an iron loss angle δ corresponding to the first layer wave number f1 in a memory. Considering the iron loss angle δ, the primary current vector I
This is accomplished by determining f. Specifically, when the excitation component current calculator 4 and the torque component current command It'' are given, the magnitude of the primary current 1■11* and the phase difference between the primary current vector If and the excitation component current vector E. Directive O*,
This is achieved by giving the edge angular frequency command ω3* according to the relationships of equations (1) to (3).

...(1) Note that the iron loss angle δ is 1 at no load when the slip frequency is zero.
This is the phase difference between the next current vector 11 and the current vector ■mo flowing through the mutual inductance.

In this way, the 1-hydraulic type controls the angular frequency command ω5 in the same way as conventional vector control, and the magnitude of the primary current 1
111 and the phase command O are controlled as a function of the iron loss angle δ.

[Effect]

In the case of an induction motor, the primary layer wave number f1 of the motor results in a relatively large iron loss angle δ. Therefore, the first layer wave number f
The value of the iron loss angle δ corresponding to 1 is obtained from the memory, and the primary current command vector is determined from equations (1) and (2), taking δ into account. As a result, due to the influence of iron loss angle δ, 1
Since command value errors in the next current vector can be prevented, accurate vector control can be achieved even in high-speed regions.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. Variable speed control of an induction motor 2 is performed by a power converter 1 such as an inverter. The speed controller 3 performs compensation so that the speed ω detected by the speed detector 4 matches the speed command ω-, and outputs the umbrella with a torque command 11. Further, the magnetic flux command generator 5 outputs a magnetic flux command Φ2 according to the speed, and in a low speed range, Φ2 is constant and constant torque control is performed, and in a high speed range, field weakening is performed to perform constant output control.

Further, the torque current calculator 6 calculates the equation (4) and outputs a torque component current command -.

Here, M is mutual inductance and L2 is secondary self-inductance. Next, the excitation component current calculator 7, for example, (5
) and outputs the excitation current command In''.

Here, r2 is the secondary resistance of the motor.

Next, the slip angular frequency calculator 8 uses the calculation of equation (3) to output a slip angular frequency command ωs1.

Further, the adder 9 adds the slip angular frequency command ωS* and the rotational speed ω, and outputs the primary angular frequency command ω1*. Next, the iron loss angle memory 10 stores the primary angular frequency command ω
This is a memory in which the iron loss angle δ corresponding to 1 N is stored. Next, the primary current vector calculator 11 calculates equations (1) and (2), and the magnitude of the instantaneous primary current command l I 1
1*, phase (primary current vector and secondary flux linkage command Φ
2*) Outputs the command θ umbrella.

Next, the current command generator 12 performs (6), (7), (8)
Perform the formula to obtain the instantaneous three-phase current command i us, ivy, i
w” is output.

iu*==lItl*5in(ω is the book l t + θ
−) ... (6) iv*=l I
d*5in (Umbrella ω・t + 0 Shin-2/3
π)...(7) iw*=lId umbrella sin (ω1*・t+θ−−4/3
(π)...(8) Furthermore, the current control circuit 13 provides a three-phase PWM signal to the power converter 1 so that the actual current detected by the current detector 14 follows the current command.

In the frequency-controlled vector control described above, the main part of the present invention is to control the instantaneous primary current vector (LL
The point is that the slip frequency command obtained from equation (2) is determined from equation (3), and these will be described in detail below.

The equivalent circuit of a general induction motor considering iron loss is shown in FIG. 2, and the vector diagram of voltage and current is shown in FIG.

The secondary current I2, the secondary interlinkage magnetic flux Φ2, and the excitation component current ■1 are orthogonal to each other. In addition, the iron loss current vector Irm and the mutual inductance current vector ■mo are I o= I rm +
It is expressed as I who. Furthermore, the phase difference of I++O. Note that OL is the phase difference of the secondary leakage I2. Here, the excitation component current ■.

is the formula (9).

Im=■mo−cosθt”’
(9) Next, Δ■9 shown in Fig. 3 is I wro '
If sin is 01, equation (10) holds true from FIG. 3, so Δ■.

is the formula (11).

■mo: ΔIt= ■mo・ωt・M: ωlQz・
I2-(10)Δ■ consideration=-I z
(11) Note that ΔN takes a positive or negative value depending on the direction of I2.

Next, if the torque component current It=Iz+ΔIt, then (1
1) From equation 1. is the formula (12).

Also, since Δ■δ in FIG. 3 is 6−tanδ·cosθ, equation (13) is obtained by substituting equation (9).

ΔIA=1.・tanδ −(13
) As a result, the I2 direction component of the primary current vector E1 becomes 1
If it is 9, then equation (14) is obtained.

Iq=It+I-・tanδ...
(14) Next, consider the excitation component current vector direction component of work 1. 1. From FIG. 3, + becomes equation (15).

Id= Is −Two tan δ・sin et=
L+-Im-tanδ・tan Otz As a result, in the present invention, the magnitude command of the primary current IItl・
is -r-7present]2T, and is controlled by equation (1).

Also, since the phase command θ* is tan-1-, in equation (2), ■
d control.

Next, the slip angular frequency command ωS* will be explained. Equation (16) holds true from the equivalent circuit shown in FIG.

E so j CO5θt= I2
−(16) The left side is 111o・ωl−M−cosθt=
It becomes Ill・ω工・M.

ω2 I2 Therefore, both are equal and can be rearranged as Φ2=■,·M.

As a result, it can be seen that the slip angular frequency command ω3 rate can be controlled using equation (3). Next, the set value (pattern) of the iron loss angle δ, which is the content of the iron loss angle memory 0 shown in FIG. 1, will be explained using the vector diagram shown in FIG. 4. First, when operating in a no-load state (smooth S=O state) using the conventional vector control method with δ=O in the control block shown in Fig. 1, the voltage and current vector diagrams shown in Figs. 2 and 4 will be obtained. . Therefore, the magnitude of the primary voltage v1, the magnitude of the primary current generator 1, and the power factor angle ψ are measured. As a result, as shown in FIG. 4, the induced difference is determined in consideration of the primary impedance voltage drop and is taken as the iron loss angle δ. By this method, the primary angular frequency ω1
The iron loss angle memory 10 stores a pattern in which δ is actually measured by changing δ. Next, it is known that the change in the iron loss angle δ is proportional to the change in the primary layer wave number fl, and from the equivalent circuit shown in FIG. 2, W becomes the equation (17).

r discussion Further, vector control is magnetic flux Φ2 constant control.

Since E-o/fx is controlled to be constant, E so ”
The impedance of mutual inductance M connected in parallel with f 1 iron loss resistance r yo changes in proportion to fl,
Since Emo"ft, I+mo is constant. On the other hand.

The current I- flowing through the iron loss resistor r1 side becomes, and as the primary layer wave number J1 increases, the curve shown in FIG. 4 increases, and the iron loss angle δ increases.

For example, high speed spindle etc. 30,000 rpm (ft=500H)
z) When driving, etc., δ may be 15° to 206°,
Becomes relatively large.

According to the present embodiment described above, the iron loss angle δ is taken into account even in the high speed (high frequency) region, and (1) and (2) are achieved.

Vector control is performed based on equation (3), which has the effect of allowing accurate torque control (vector control). In this example, 1 is shown in FIG. 1 for ease of understanding.
The explanation has been made with the memory 1o storing the iron loss angle δ corresponding to the next angular frequency command ω1*, but if the value of tan δ corresponding to ω1* is stored in the memory, equations (1) and (2) can be This has the effect of making calculations even faster. Furthermore, since the ω1 umbrella and the speed ω are almost the same, δ or tanδ corresponding to the speed ω may be stored instead of ω1*.

Next, another embodiment applied to a voltage control type vector control device is shown in FIG. 1 is a primary voltage vector calculator 15 instead of the primary current vector calculator 11, a voltage command generator 16 instead of the current command generator 12, a current control circuit 13, and a current detector 14. This is a point in which the gate signal generator 17 is constructed as shown in FIG. The other parts perform the same operations as in FIG. Details of the voltage command generator 16 and the primary voltage vector calculator 15 are shown in FIG. 6, and a vector diagram of voltage and current is shown in FIG. The knee Iq* calculator 18 calculates d of the primary current vector 11 command based on ``yIt'' using equations (15) and (14).
The axis component Ial and the nine components Iq* are determined. Next, the d-axis component vd* and the q-axis component Vq'' of the primary voltage vector v1 are expressed as equations (18) and (19) from the vector diagram in FIG.
This process is performed by a Vd'Vq'' computing unit.

Vdt: -ωtl'Q2 I z umbrella +I d*' r
t Iq “ω1 umbrella-QL=-ω1 umbrella・Q 2・
It*+Ia*-rt Iq*・ωxshin・Q
I...(18) Vq umbrella "Im umbrella・ωt*'M+Iq umbrella j r1+ω1*
・*・Qx'Iq"...(19) Next, the voltage command generator 16 performs (20), (21),
The calculation shown in equation (22) is performed and three-phase voltage commands are output.

vu umbrella = Vdt"+Vq*" ・sin ω
1 umbrella・t・=(20)vvumbrella=J ball'
dl12+-\n', *"-5in (ω 1 umbrella・
t-2/3 π)...(21) vw""9s'q*" ・5in(ω1 umbrella・t
-4/ 3 π)...(22) Also in the voltage control type vector control described above, considering the iron loss angle δ, (14), (15), (18)
.

The primary voltage vector (1) is determined from equation (19), which has the effect of enabling accurate torque control even in the high-speed region.

Next, in another embodiment, the primary assembly pressure is set such that the excitation current command I matches the excitation current detected value, and the torque current detection value matches the 1 torque current command I. vector v1
As an example of application to a vector control device for controlling the primary current vector E1, FIG. 8 shows a method for controlling the primary voltage vector. The different parts from FIG. 5 are the actual currents iυ, iv
.

iw is detected, the excitation current and torque current detector 20 detects the actual I-, It, and these values are subtracted by the subtractor 21a.
, 21b with the command values I-, It*, respectively,
Proportional + integral compensators 22a, 22 so that the deviation becomes zero
Compensation is performed in step b, and the d-q axis component Va '' * V q '' of the primary assembly pressure vector v1 is output.

This is how the primary voltage is controlled.

The features of this embodiment will be described below. The conventional method is ■.

=Id, It=Iq, but the iron loss angle δ
When becomes larger, Ia becomes larger, and It and Iq no longer match. Therefore, this method corrects the iron loss angle δ and
, It is accurately detected and vector control is performed based on this. Next, a detailed block diagram of the exciting current and torque current detector 20 is shown in FIG. By the conventional Id Iq calculator 23, (23).

(24) is performed to detect the d-q axis components of the primary current detection value.

I, 1: i a・cosω 1 t +
i βl5inω1 umbrella・shi・(23)Iq=
-iI-sinωi*・t+iβ'CO8(11t*”
=(24) However, im=iu, iβ= (i u
-i w)/ JTj.

Next, from equations (14) and (15), 1. , It becomes equations (25) and (26), and the I-It calculator 24 calculates accurate excitation current distribution construction and torque component current I by considering the iron loss angle δ from Ia and Iq.
t is detected.

Further, since δ is about 20° at most, considering that jan''δ is small, I− and Ir can be approximated by equations (27) and (28).

It4Iq Ia・tan δ --- (28) As mentioned above, in the other embodiment shown in FIG. The primary voltage vector is determined based on this, which has the effect of allowing accurate torque control (vector control).

Next, FIG. 10 shows another embodiment applied to a general-purpose inverter without a speed sensor. The excitation current/torque current detector 20 shown in FIG. 9 detects the actual torque current It. Also, engineering.

The estimated slip angle frequency value 2 is obtained by multiplying the detected value by a proportional gain 25. Next, the speed command value ω- is added to the adder 26
and add it up to get the primary angular frequency command ω1*, which is 1■11umbrella/
The magnitude of the primary voltage corresponding to ωII is determined to be 1V11 via the ω111 pattern memory 27. As described above, in the embodiment shown in FIG. 10, the slip angular frequency ωS can be accurately corrected by considering the iron loss angle δ from the motor current, and there is an effect that accurate torque control can be performed even in a high-speed region.

〔Effect of the invention〕

According to the present invention, in consideration of the iron loss angle δ, in the current control type vector control, the instantaneous primary current vector is
), is determined accurately from equation (2). In addition, in voltage control type vector control, the primary voltage vector is (18)
, is accurately determined from equation (19), and it is possible to prevent the axis misalignment of the magnetic flux axis due to the iron loss angle δ, which increases as the primary frequency increases, so accurate torque control (vector control) is possible even in the high-speed region. There is. Furthermore, the iron loss angle δ corresponding to the primary frequency is stored in the memory in advance, and δ can be directly obtained from the memory according to the primary frequency, which makes it a very simple control method and is very practical. It has the effect of saying.

[Brief explanation of the drawing]

FIG. 1 is a control block diagram showing one embodiment of the present invention, and FIG.
The figure is a general T-type equivalent circuit diagram of an induction motor, Figure 3 is a vector diagram of the motor voltage and current in Figure 2, Figure 4 is an explanatory diagram of the means for determining the iron loss angle δ, and Figure 5 is a voltage FIG. 6 is a detailed block diagram of the voltage vector calculator in FIG. 5, FIG. 7 is a detailed explanatory diagram of the primary voltage vector, and FIG. 8 is a general block diagram showing another embodiment applied to a control type. 1. −
■, Overall block diagram of another embodiment using closed loop control, Figure 9 is a detailed block diagram of the excitation current and torque current detector in Figure 8, Figure 10 is another embodiment applied to a general-purpose inverter. FIG. 1...Power converter, 2...Induction motor, 3...
Speed controller, 5... Magnetic flux command generator, 6... Torque component current calculator, 7... Excitation component current calculator, 8... Slip angle frequency calculator, 10... Iron loss angle Memory, 11.
...Primary current vector calculator, 12...Current command generator, 13...Current control circuit, 15...Primary voltage vector calculator, 16...Voltage command generator, 18... I
d"Iq" computing unit, 19...Vd"-Vq" computing unit, 20...exciting current, torque current detector, 24...
I-It operator, 27...second tea 30 (υnokai↑+
(b) rEJ□Gint7゜Hisashi, Figure 9

Claims (1)

[Claims] 1. In a control device for variable speed control of an induction motor, the phase difference between the primary current vector ■_1 and the current vector ■_mo flowing through the mutual inductance M when the slip frequency of the induction motor is zero is expressed as A vector control method for an induction motor characterized in that the magnitude and phase of a primary current vector or a primary voltage vector are controlled in consideration of an iron loss angle δ, where the loss angle is δ. 2. In the vector control method described in claim 1, an excitation component current command I_m* which is the secondary flux linkage direction of the primary current (d-axis direction) and an excitation component current command I_m* which is perpendicular to this (q-axis direction)
Based on the output obtained by adding each correction amount according to the iron loss angle δ to the torque component current command I_t*, calculate the d/q axis components of the primary current vector command or primary voltage vector command, and based on this, A vector control method for an induction motor characterized by controlling the magnitude and phase of a primary current vector or a primary voltage vector. 3. The magnitude of the primary current vector ■_1 according to claim 1 or 2 |I_1|* and the phase difference command θ* between the primary current vector ■_1 and the excitation component current vector ■_m
and the slip angular frequency command ωs* of the induction motor. ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ωs * = (r_2/L_2)・(M/Φ_2*)・I_
t* [L_2 is secondary self-inductance, l_2 is secondary leakage inductance, M is mutual inductance, r_2 is secondary resistance, Φ_2* is secondary flux linkage command] Current control characterized by being given by the following relationship. Vector control method for type induction motors. 4. In the vector control device for an induction motor considering the iron loss angle δ as described in claim 3, the secondary leakage inductance is approximated as zero, and the magnitude of the primary current vector ■_1 |I_1|*, Phase command θ* and slip angle frequency command ωs* are |I_1|*=■[I_m*+(I_t*+I_m*・
tan δ)^2] θ*=tan^-^1 [(I_t*+
I_m*・tanδ)/I_m]ω_s*=(r_2/
A vector control method for a current control type induction motor characterized by applying the following relationship: L_2)・(M/Φ_2*)・I_t*. 5. In the slip frequency control type vector control device that takes into account the iron loss angle δ as set forth in claim 1 or 2, the secondary linkage magnetic flux direction component of the primary voltage vector command of the induction motor is V_d*, The direction component perpendicular to this is V_q*
Then, V_d*=I_d*・r_1−ω_1*・l_2・(M
/L_2)・I_t*−I_q*・ω_1*・l_1V
＿q*=I_q*・r_1+ω_1*・l_1・I_d
*+ω_1*, M・I_m* [However, I_d*=I_
m*-tanδ・I_t*・(l_2/L_2), I_
q*=I_t*+I_m*·tan δ, and ω_1* is the primary angular frequency command. ] A vector control method for a voltage control type induction motor characterized by controlling a primary voltage vector given in the following relationship. 6. In the slip frequency control type vector control device considering the iron loss angle δ as described in claim 1 or 2, the secondary flux linkage component of the primary current vector of the induction motor is 1_d, and this and If the orthogonal component is I_q, then the excitation component current I_m and the torque component current I_t are ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Approximate formula I_m≒I_d-tanδ・(l_2/L_2)・I_
q) I_t=[I_q-I_d・tanδ]/[1+t
an^2δ・(l_2)/(L_2)] Approximate formula I_t≒I_q−I_d・tanδ It is detected by the following relationship, and the excitation current command I_m* matches the excitation current detection value I_m, and the torque component current command I_t* 1 of the induction motor so that the torque component current I_t matches
A vector control method for an induction motor characterized by controlling a primary voltage vector or a primary current vector. 7. In claim 6, a value proportional to the torque component current detection value I_t obtained by the torque component current detection method is used as the estimated slip angle frequency ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼
▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ and the speed command ω
A control method for an induction motor, characterized in that a primary voltage of the induction motor is controlled in response to a primary angular frequency command ω_1* obtained by adding _r*. 8. The iron loss angle δ described in any one of claims 1 to 6 is the primary angular frequency command ω_1* of the induction motor.
A control method for an induction motor, characterized in that an iron loss angle δ is stored in a memory in advance as a function of ω_1*, and an iron loss angle δ is determined according to a primary angular frequency command ω_1*.