JPH06335278A - Tuning of vector control inverter for induction motor - Google Patents

Abstract

PURPOSE:To provide a method for measuring a magnetic saturation characteristic, setting a compensation constant and measuring a mutual inductance (exciting inductance) and for tuning a vector controller of an induction motor which automatically decides the compensation value with a high accuracy. CONSTITUTION:A vector controller of an induction motor comprises a coefficient unit 509, an integrator 512, a function generator 513, a 2-phase/3-phase converter 506, a vector calculation unit 504, a vector rotation unit 505, a magnetic flux calculation unit 516, a speed detector 510, a magnetic flux command calculation unit 503, dividers 502, 508, a velocity controller 501, a magnetic flux controller 507, current controllers 517, 518, 519 and a magnetic flux command compensating unit 521. The magnetic flux controller 507 which performs I control for making zero the deviation DELTApsi2 between the magnetic flux command value psi2* and the detected magnetic flux psi2 is automatically controlled so that its output value is kept within the range of + or -0.5% of the magnetic flux command value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor vector control device, and more particularly to tuning of a vector control inverter.

[0002]

2. Description of the Related Art As a speed control of an induction motor, a slip frequency control method which is excellent in both responsiveness and accuracy is known. In particular, the primary current of the motor is divided into an exciting current and a torque current to control the secondary current. A vector control method has been implemented in which the magnetic flux and the torque current are controlled so as to be always orthogonal to each other so that a response equivalent to that of a DC motor can be obtained. FIG. 5 is a block diagram of a conventional induction motor servo system. This servo system modulates a voltage command of a converter section for converting AC to DC and a current controller output of each phase of U, V, W into a PWM signal using a thyristor or a switching element to generate an AC voltage. A voltage-type PWM inverter 401 including an inverter unit, an induction motor 402, an encoder 409 as a detector of a rotor electrical angular velocity (hereinafter abbreviated as velocity), and a current detector that detects a current flowing in each phase of U, V, and W. 406, 407, 408 and U,
Voltage detector 4 for detecting the voltage between each phase of V and W
05, a vector control device 413 for performing vector control, and a command generator 404.

FIG. 6 shows a vector controller 413 shown in FIG.
FIG. The vector controller 413 uses the coefficient unit 5
09, integrator 512, phase θ₁ ^*Input as exp (jθ
₁ ^*), That is, cos θ₁ ^*+ Jsinθ₁ ^*To generate
Number generator 513, direction of magnetic flux vector (hereinafter referred to as d-axis)
Component) in the direction orthogonal to that (hereinafter referred to as the q-axis)
With a vector of U, V, W phases of 120 degrees to each other
Two-phase / three-phase converter 506 for converting into a component having a difference direction
And γ = α + jβ for d-axis component α and q-axis component β
Cuttle, that is, amplitude | γ | = (α²+ Β² )^1/2, Phase t
an^-1A vector calculator 504 for calculating (β / α),
Vector γ and exp (jθ₁ ^*) As input and phase as θ₁ ^*+
tan^-1(Β / α) vector rotator 505
Primary voltage vector v obtained from the pressure detector 405₁ ,
And one obtained from the current detectors 406, 407, 408.
Next current vector i₁ Magnetic flux calculation unit 5 for detecting magnetic flux by
16, signal θ of encoder 409_r Calculate speed from
The speed detection unit 510 and the magnetic field weakening magnetic field depending on the speed value.
Bundle command calculation unit 503, dividers 502 and 508, command
Speed command ω commanded from generator 404_r ^*And speed detection value
ω _r The PI control that is provided to make the deviation of "0"
The speed controller 501 to perform and the magnetic flux command ψ₂ ^*Magnet detected as
Bundle ψ₂Deviation of (Δψ₂) Was set to "0"
Magnetic flux controller 507 for I control and each phase of U, V, W
Is set to zero the deviation of the command value of the primary current.
It consists of current controllers 517, 518, 519 for P control.
It Torque current command Iτ^* Is the output of the speed controller 501
Torque command T which is^*Is output by the magnetic flux command calculation unit 503.
A certain magnetic flux command ψ₂ ^*And the excitation current command Iψ^*Is a porcelain
Output of flux controller 507 and magnetic flux command ψ₂ ^* Porcelain with input
It is calculated as the sum of the outputs of the bundle command compensation unit 520.

Next, the operation of this vector control device will be described. The relationship between the voltage and current of the induction motor 402 is
It is expressed by the following equation in the static coordinate form.

[0005]

[Equation 1]

R: resistance of each phase L, M: self-inductance, mutual inductance l: total leakage inductance ω _r : velocity p: differential operator Subscript: primary and secondary Here, the circuit constants are shown in FIG. 7. It is a constant in an asymmetric T-type equivalent circuit. Further, the secondary interlinkage magnetic flux vector Ψ ₂ and the exciting current vector i ψ are expressed by the following equations. Ψ ₂ = M (i ₁ + i ₂ ) (2) i ψ = i ₁ + i ₂ (3) The expression (1) is expanded into the following expression using the expressions (2) and (3).

[0007] _{v 1 = (R 1 + lp} ) i 1 + pΨ 2 (4) 0 = R 2 i 2 + (p-jω r) Ψ 2 (5) Considering next on a rotating coordinate flux, the primary current The vector i ₁ and the secondary current vector i ₂ are expressed by the following equations. _{i 1 = (Iψ + jIτ)} Θ (6) i 2 = - (1 / R 2) {pψ 2 + j (ωψ-ω r) ψ 2} Θ (7) However, Θ = exp (jθψ), θψ: flux vector Angle. The calculation of the primary current vector i ₁ is performed according to the equation (6). In the calculation of the command corresponding to Iψ + jIτ in the formula (6), the vector calculator 504 and Θ are calculated by the function generator 513, and the linear calculator corresponding to the formula (6) is output from these two elements as the output of the vector rotator 505. The current command i ₁ ^* is required.

Further, the torque current command I τ ^* and the slip angular velocity command ω _s ^* are in the relationship of the following formula: ω _s ^* = R ₂ ^{* I} τ ^* / ψ ₂ (8) Using the divider 508 and the coefficient unit 509 is calculated, the angle Shitapusai the flux vector is in the following relationship _{θψ = ∫ωψdt = (ω r +} ω s *) / p (9) the speed detection value omega _r and an output of the speed detector 510 (8)
The sum of the slip angular velocity commands ω _s ^* obtained by the formula is used as the integrator 512.
Is obtained by integration. The primary current command i ₁ ^* , which is the output value of the vector rotator 505, is given by the two-phase / three-phase converter 50.
Converted into U, V, W phases by 6, and current detectors 406, 4
The respective difference from the current detection value of each phase detected by 07 and 408 is input to the current controllers 517, 518 and 519,
The result of P control is output as a voltage command value to the voltage source PWM inverter 401. The voltage between the U, V, and W phases is detected by the voltage detector 405, and is input to the magnetic flux calculator 516 together with the detected primary current value.

According to the equation (4), the voltage of the induction motor 402,
A motor flux formula Ψ ₂ = ∫ {v ₁ − (R ₁ ^* + l ^* p) i ₁ } dt (10) based on electric current is derived. Since the equation (10) is an integral calculation, the drift and the primary resistance value error are expanded at a low speed, and the initial position of the magnetic flux vector cannot be determined.
There is also a problem that the magnetic flux calculation value includes a compensation error of the primary parameter of the electric motor. Therefore, the magnetic flux calculation unit 51
Reference numeral 6 represents a value obtained by compensating the input primary current i ₁ with the primary resistance R ₁ ^* and the leakage inductance l ^*, and then based on the equation (10) in which the integral element of the motor magnetic flux is replaced with a primary delay element. The next interlinkage magnetic flux vector Ψ ₂ is obtained, ψ ₂ = | Ψ ₂ | is calculated, and the magnetic flux detection value ψ ₂ is output.

Next, the magnetic flux command compensator 520 is shown in FIG.
Will be described with reference to. From equations (2) and (3), there is a proportional relationship between the secondary interlinkage magnetic flux vector Ψ ₂ and the exciting current vector i ψ, but Ψ ₂ = Miψ (11) Field weakening control is performed. In this case, the equation (11) does not hold due to magnetic saturation of the iron core of the induction motor, and it is necessary to compensate for it. The magnetic flux command compensation unit 520 is provided to compensate for this magnetic saturation phenomenon, and as shown in FIG. 8, the field amount is 100% (rated), 75%, and 50%. , Has compensation coefficients A, B, and C that determine the magnitude of the exciting current command Iφ ^* , and the points 1, 2, 3 and the origin 0 are linearly approximated. In this way, the magnetic saturation characteristic of the induction motor 402 (ψ ₂ ^* and Aipusai ^* relationship)
Built in.

Since the vector control is performed as described above, conventionally, the mutual inductance (excitation inductance) and the magnetic saturation characteristic of the induction motor to be controlled have been obtained from the design value or the measured value of the motor.

[0012]

In the above-mentioned conventional technique, there is a problem that calculation and measurement from the design value of the induction motor is troublesome and accurate measurement is difficult. Therefore, the present invention is a method of tuning an induction motor vector control device capable of accurately and automatically measuring the mutual inductance (excitation inductance) which is a constant of the induction motor and the magnetic saturation characteristic and setting the compensation coefficient thereof. The purpose is to provide.

[0013]

A vector control tuning method for an induction motor according to the present invention comprises an induction motor using an inverter as a drive power source, an inverter for generating an AC current having a predetermined frequency and phase as an inverter output, and Vector control having a magnetic flux calculator for calculating a motor magnetic flux from the current and voltage applied to the induction motor, a magnetic flux command compensator for compensating the magnetic flux command, and a controller for controlling the frequency and phase of the output current of the inverter. In the apparatus, in the method of tuning a vector control inverter, which is operated in a state in which the induction motor is operated without a load and the primary resistance and the leakage inductance that are obtained in advance are compensated, at least the rated field amount of the induction motor is set. for,
Alternatively, in the case of performing field weakening control, the motor magnetic flux value detected by the magnetic flux calculation unit for each of a plurality of predetermined field amounts in addition to the rated field amount becomes equal to the respective magnetic flux command value. Thus, there is a procedure for automatically measuring and setting the compensation coefficient of the magnetic flux command compensator.

[0014]

[Function] When a magnetic flux feedback loop is provided to set the magnetic flux deviation (Δψ ₂ ) to "0" and integral control is performed, the magnetic flux deviation (Δψ ₂ ) is "0" in a steady state.
Becomes The exciting current command value at this time is the magnitude of the exciting current required to generate the magnetic flux having the magnitude of the output of the magnetic flux command computing unit. Therefore, if the magnetic flux control output becomes zero (that is, all of the necessary exciting current commands become the magnetic flux command compensator output), if the compensation coefficient of the magnetic flux compensator is adjusted by several field weakening factors, As a result, the magnetic saturation of the induction motor can be known.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a flow chart of a first embodiment of a method for tuning a vector control inverter for an induction motor according to the present invention, and FIG. 3 is a block diagram of a servo system for an induction motor to which the method for tuning a vector control inverter shown in FIG. 1 is applied. FIG. 4 is a detailed diagram of the vector control device 403 shown in FIG. The difference from the prior art of the present invention is that the compensation coefficient in the magnetic flux command compensating unit 520 is changed according to the output of the magnetic flux control unit 507. The changing procedure is the magnetic flux detection value and the magnetic flux command. The compensating coefficient of the magnetic flux command compensating section 521 is tuned according to the algorithm shown in FIG. 1 by a comparator that compares the value with an adder and a subtracter that adds and subtracts the compensating coefficient according to the instruction of the comparator.
Thereby, the output of the magnetic flux controller 507 is automatically reduced to the range of the predetermined difference.

First, the compensation coefficient A is set so that the output of the magnetic flux controller 507 becomes "0" in a steady state by operating at a rotational speed at which 100% field or rated field is obtained (step 11).
To change. That is, the output of the magnetic flux controller 507 is detected (step 12), and if the output is positive, the compensation coefficient A
Is increased (step 13), and if it is negative, the compensation coefficient A is decreased (step 14). In this adjustment, the output of the magnetic flux controller 507 is within ± 0.5% of the output value of the magnetic flux command compensator 521. Next, the field amount is 7
Operate at rotational speeds of 5% and 50% (step 15
And 19), the compensation coefficients B and C are changed so that the output of the magnetic flux controller 507 becomes "0" in the steady state. That is, the output of the magnetic flux controller 507 is detected (steps 16 and 20), and if the output is positive, the respective compensation coefficients B and C are increased (steps 17 and 2).
1), in the case of minus, each compensation coefficient is reduced (steps 18 and 22). In this case, the procedure for changing the compensation coefficient and the adjustment conditions are the same as in the case of 100% field. With the above operation, the mutual inductance (exciting inductance) and magnetic saturation characteristics of the induction motor can be automatically measured and set as the values of the compensation coefficients A, B, and C of the magnetic flux command compensation unit 520.

Further, a case will be described in which the induction motor is applied only when adjusting the mutual inductance (exciting inductance) that needs to be adjusted even when the induction motor is used only in the constant torque region. FIG. 2 is a flowchart of the second embodiment of the method for tuning the vector control inverter of the induction motor of the present invention. In the second embodiment, similarly to the first embodiment, the numerical value of the compensation coefficient is changed so that the output of the magnetic flux controller 507 falls within a predetermined value range close to 0 by the comparator, adder and subtractor. The coefficient unit 522 is provided instead of the magnetic flux command compensation unit 521. Next, the operation of the second embodiment will be described. First, operation is performed at a rotational speed that provides a rated field, that is, 100% field (step 31), and the numerical value of the coefficient unit 522 is changed so that the output of the magnetic flux control unit 507 becomes "0" in a steady state. That is, the magnetic flux controller 507
Output in a predetermined range, for example, the magnetic flux command value and the coefficient unit 522.
Within 0.5% of the product of the values of and, it is determined whether the value is within the range (step 32). If it is larger, the value of the coefficient unit 522 is increased (step 33). The value of is reduced (step 34), and the operation of setting it within the range of ± 0.5% is automatically performed.

Further, the slip frequency vector control with the speed detector has been described, but the same can be applied to the case without the speed detector or to the other vector control method if the magnitude of the magnetic flux is controlled. Further, in FIG. 8, the origin 0 and the points 1, 2, and 3 are interpolated by a straight line, but may be interpolated by, for example, a quadratic curve or more.

[0019]

As described above, according to the present invention, the mutual inductance (exciting inductance) of the induction motor and the compensation coefficient for compensating for the magnetic saturation phenomenon are automatically adjusted, so that a troublesome setting of the motor constant can be easily performed. Since it can be performed within the range of, the control accuracy is improved, and the flux control loop is not required during normal operation after the end of auto-tuning, and the expensive voltage detector can be removed.
There is also an effect that the cost of the vector control inverter can be reduced.

[Brief description of drawings]

FIG. 1 is a flowchart of a first embodiment of a vector control inverter chewing method for an induction motor according to the present invention.

FIG. 2 is a flowchart of a second embodiment of the chewing method for the vector control inverter of the induction motor of the present invention.

FIG. 3 is a block diagram of an induction motor servo system to which the vector control inverter chewing method shown in FIG. 1 is applied.

FIG. 4 is a detailed diagram of the vector control device 403 shown in FIG.

FIG. 5 is a block diagram of a conventional induction motor servo system.

FIG. 6 is a detailed view of the vector control device 413 shown in FIG.

FIG. 7 is an equivalent circuit showing the circuit constants of the induction motor.

8 is a diagram showing a relationship between a field amount and a compensation coefficient of a magnetic flux command compensation section 520 shown in FIG.

FIG. 9 is a detailed diagram of the vector control device according to the second embodiment of the present invention.

[Explanation of symbols]

 401 Voltage type PWM inverter 402 Induction motor 403, 413 Vector controller 404 Command generator 405 Voltage detector 406, 407, 408 Current detector 409 Encoder 501 Speed controller 502 Divider 503 Flux command calculator 504 Vector calculator 505 Vector rotator 506 Two-phase / three-phase converter 507 Flux control unit 508 Divider 509 Coefficient unit 510 Speed detection unit 512 Integrator 513 Function generator 516 Flux calculation unit 517, 518, 519 Current controller 520, 521 Flux command Compensator 522 Coefficient unit

Claims (1)

[Claims] 1. An induction motor that uses an inverter as a drive power source, an inverter that generates an AC current having a predetermined frequency and phase as an inverter output, and a magnetic flux calculation that calculates a motor magnetic flux from a current and a voltage applied to the induction motor. Part, a magnetic flux command compensating part for compensating the magnetic flux command, and a vector controller having a controller for controlling the frequency and phase of the output current of the inverter, the induction motor is operated without load, and is obtained in advance. In the tuning method of the vector control inverter performed while compensating the primary resistance and the leakage inductance, at least the rated field amount of the induction motor, or when performing the field weakening control, the rated field Motor flux detected by the magnetic flux calculation unit for each of a plurality of predetermined field amounts in addition to the amount There were measured automatically compensating coefficient of the magnetic flux command compensator to be equal to each of the magnetic flux command value, and the vector control inverter method tuning and setting.