JPH09298900A - Speed sensor-less vector controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an uncontrollable condition for regeneration in a low speed range by limiting torque partial current at the maximum regeneratable torque. SOLUTION: In a speed sensor-less vector control method, he primary current of an induction motor 1 is detected to obtain the primary current detection value on the coordinate of a stator whose number of phase has been converted by a 3-phase-2- phase converter 14. The primary current detection value, the primary voltage command value of a motor on the stator coordinate, and a speed estimated value are inputted in one-dimensional magnetic flux observer. The secondary magnetic flux estimated value and the primary current estimated value in the stator coordinate are estimated, and a motor speed estimated value is calculated according to an adaptive adjusting expression for operating and estimating a speed Wr<ξ> of the motor 1, based on an estimated error signal obtained by comparing the primary current estimated value with the primary current detection value with a speed adaptive mechanism 7 to estimate the speed of the motor 1. A regenerative torque current limiter 10 is provided for a torque current command input part, and the limit value of the regenerative torque current limiter is called from a limiter table 11 to obtain operable torque partial current.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed sensorless vector control device which operates while limiting regenerative torque.

[0002]

2. Description of the Related Art A slip frequency control type vector control method has become popular as a high performance speed control method for induction motors.
A speed sensorless vector control method for controlling this without a speed sensor is known.

FIG. 3 shows a control system of a conventional speed sensorless vector controller for an induction motor, which estimates the actual speed of the induction motor by using a speed adaptive secondary magnetic flux observer.

First, the estimation of the motor speed (rotational angular frequency ω _r ) of the induction motor 1 will be described with reference to FIG.

The voltage equation of the induction motor 1 is given by the following equation (1) when it is represented by d-q axes for observing various quantities from the synchronous rotation coordinate system rotating at the power source angular frequency (ω ₀ ).

[0006]

[Equation 1]

However, v _1d , v _1q ... Primary excitation axis voltage, primary torque axis voltage (V) i _1d , i _{1q on} synchronous rotation coordinates (dq axes) synchronous rotation coordinates (dq axes) ) Above primary excitation axis current, primary torque axis current (A) λ _2d , λ _2q ... Secondary excitation axis magnetic flux on secondary rotation coordinate (dq axis), secondary torque axis magnetic flux (Wb) ω ₀ ………… Power supply angular frequency (rad / sec) ω _r ………… Motor speed (rotational angular frequency, rad / sec) ω _s ………… Slip angular frequency (rad / sec) R ₁ , R ₂ … 1 Next, secondary resistance (Ω) L ₁ , L ₂ … Primary, secondary inductance (H) M ………… Mutual (excitation) inductance (H) Lσ ………… Equivalent leakage inductance (H) (Lσ =
(L ₁ L ₂ −M ² ) / L ₂ ) s ………… Time fine molecule (d / dt) And power source angular frequency (ω ₀ ), motor speed (ω _r ),
Relationship slip angular frequency command value (omega _s ^*), and calculates the slip angular frequency command value (omega _s ^*) is represented by the following formula (2). ω ₀ = ω _r + ω _s ^* ω _s ^* = i _1b ^* / i _1a ^*・ τ ₂ …… (2) However, τ ₂ ………… Second-order time constant (τ ₂ = L ₂ / R ₂ ) Subscript (*): Indicates a command value or set value. Now, i _1d ^* = constant …………………………………………………………………………………………………………………………………………………………………………………… （………………………………………………………………………………………………………………………………………………………… of When the primary voltage command values (v _1d ^* , v _1q ^* ) of the synchronous rotation coordinate system (dq axes) are given by the following equation (4) which is a constitutive equation of the digital current controller 3, it becomes as follows.

[0008]

[Equation 2]

When the control is performed so as to satisfy the above equation (4), the primary current detection value i ₁ on the synchronous rotation coordinates (dq axes) is calculated.
^Indicates that the current flows according to the primary current command value i ₁ ^* (i _1d ^* , i _1q ^* ), and the secondary magnetic flux λ ₂ on the synchronous rotation coordinates (d-q axes).
(Λ _2d , λ _2q ) is kept at λ _2d = Mi _1d (constant), λ _2q = 0 …………………… (5).

As a result, the torque (T) of the induction motor 1
Is T = M / L ₂ · (λ _2d · i _1q −λ _2q · i _1d ) = M ² / L ₂ · (i _1d · i _1q ) ………………………… (6) , Secondary magnetic flux λ on synchronous rotation coordinates (d-q axes)
₂ (λ _2d , λ _2q ) and the secondary current i ₂ (i _2d , i _2q ) are non-interfering control vector control.

By the way, as is clear from the above equation (2).
If the speed sensor is not used, the slip angular frequency command
Value ω_s ^*Even if is set, the motor speed ω_rIs unknown
Power source angular frequency ω₀Can't decide
Is the power source angular frequency ω₀Synchronous rotation coordinate (d-
secondary magnetic flux λ on the q-axis)_Two(Λ_2d, Λ_2q) Is the above formula (5)
So that the power source angular frequency ω₀To control
Similarly, vector control of non-interference control is realized by
Can be That is, the same-dimensional magnetic flux observer 4
Speed adaptive secondary magnetic flux observer consisting of
Using synchronous rotation coordinates that satisfy the above equation (5)
Secondary magnetic flux λ on (dq axis)_Two(Λ_2d, Λ _2q)
The secondary magnetic flux estimated value λ_Two ^#(Λ_2d ^#, Λ_2q ^#) Based on
Motor speed ω_rEstimate (ω_r ^#)
Equation (2) (ω₀= Ω_r ^#+ Ω_s ^*) From the power angular frequency
Number ω₀And the power source angular frequency ω₀Due to digital current
Vector of decoupling control by controlling the controller 3
Control can be realized.

In the vector control system shown in FIG.
For conventional vector control method without speed sensor of induction motor
In addition, the actual speed of the induction motor 1 is not measured using a speed sensor.
The primary current of the induction motor 1 (phase current
Flow) i_u, I_v, I_w3 phase to 2 phase phase number converter 1
Primary power on the stator coordinates (a-b axis) converted in phase 4
Flow detection value i₁(I_1a, I_1b) Is obtained and this primary current detection value
i₁And the primary voltage finger of the motor on the stator coordinates (axis a-b)
Command v₁ ^*(V_1a ^*, V_1b ^*) And the estimated speed value ω _r ^#When
The same dimension magnetic flux observer 4 with
Secondary magnetic flux estimated value λ on coordinates (ab axis)_Two ^#(Λ_2a ^#,
λ_2b ^#) And the estimated primary current i₁ ^#(I_1a ^#, I_1b ^#)When
And the speed adaptation mechanism 7 estimates the primary current i₁ ^#
(I_1a ^#, I_1b ^#) And the primary current detection value i₁(I_1a,
i_1b) And the estimated error signal (i₁−i₁ ^#) Based on
Based on the adaptive adjustment law expressed by the following equation (7)
Degree estimate (ω_r ^#) Is calculated and estimated, and the speed of the induction motor 1 is calculated.
I am trying to detect.

Ω _r ^# = K _p (e _ia λ _2b ^# −e _ib λ _2a ^# ) + K _i ∫ (e _ia λ _2b ^# −e _ib λ _2a ^# ) dt (7) However, e _ia = i _1a −i _1a ^# : estimation error e _ib = i _1b −i _1b ^# : estimation error K _p : velocity estimation part proportional gain K _i : velocity estimation part integration gain Note that the same-dimensional secondary magnetic flux observer 4 and velocity adaptation mechanism are used. 7
For the speed sensorless vector control method of the induction motor 1 that estimates the actual speed of the induction motor by the speed adaptive secondary magnetic flux observer consisting of and, see "Journal of the Institute of Electrical Engineers of Japan, Volume 11, No. 11, 1991" (Kubota, Ozaki, Matsuse, Nakano: "Velocity sensorless direct vector control of induction motor using adaptive secondary magnetic flux observer").

A conventional speed sensorless vector control system for estimating the actual speed of the induction motor using the speed adaptive secondary magnetic flux observer will be described below.

The operation in FIG. 3 (control system configuration)
To explain, digital current in the current controller (ACR)
In the flow controller 3, 1 on the synchronous rotation coordinate (dq axis)
Next voltage command value v₁ ^*(V_1d ^*, V_1q ^*) Is the primary power
Flow command value i₁ ^*(I_1d ^*, I _1q ^*) And the primary current detection value i
₁(I_1d, I_1q) Are equal (i_1d ^*= I_1d, I_1q ^*= I
_1q) Is a conditional expression that enables decoupling control.
It is calculated by the above equation (4).

The primary voltage command value v ₁ ^* (v _1d ^* , v _1q ^* ) on the synchronous rotation coordinates (dq axes) is converted by the coordinate converter 9 to 1 on the stator coordinates (ab axes). Next voltage command value v ₁ ^* (v
_1a ^*, v after being converted to _1b ^*), 2-phase -3 is number of phases converted by the phase number of phases converter 15 three-phase phase of the primary voltage control command voltage v _u of the PWM control inverter 2, v _v , V _w to control the output voltage of each of the three phases of the PWM control inverter 2. As a result, the induction motor 1 is speed-controlled according to the desired motor speed command value (ω _r ^* ). In addition, synchronous rotation coordinates (d-q axes) that rotate at the power supply angular frequency ω ₀ ,
Stator coordinates (ab) fixed to the stator of the induction motor 1
The basic phase angle θ ₀ (θ ₀ = ω ₀ t) for generating the unit vector (sin θ ₀ , cos θ ₀ ) used in the coordinate converters 8 and 9 for conversion between You can ask in this way. That is, by the slip angular frequency calculator 5, as shown in the above equation (2), the synchronous rotation coordinates (dq axes)
The primary excitation axis current command value i _1d ^* , the primary torque axis current command value i _1q ^* , and the secondary time constant τ ₂ (= L of the induction motor 1
₂ / R ₂ ) Slip angular frequency command value (ω _s ^* ) and velocity adaptive secondary magnetic flux observer (4, 7)
The power source angular frequency (ω ₀ ) can be obtained from the estimated motor speed value (ω _r ^# ) estimated by

The secondary magnetic flux estimated value λ ₂ ^# on the stator coordinates (dq axes) estimated by the same-dimensional magnetic flux observer 4
(Λ _2d ^# , λ _2q ^# ) is taken into the control axis deviation compensation circuit 6, and the control axis deviation angular frequency correction value ω _rc is obtained. In this way, the actual speed can be accurately estimated and added to the slip angular frequency ω _s to obtain the power supply frequency ω _0, and vector control of decoupling control can be realized.

[0018]

In the sensorless vector control described above, when powering in the low speed range, stable operation can be achieved by correcting various output voltage errors. In some cases, it may be out of control.
That is, the voltage v _1a input to the same-dimensional observer 4
^* , V _1b ^* is a command value, but since the voltage actually output to the induction motor 1 is a PWM waveform, this command value may differ due to dead time, quantization error, voltage drop in the main circuit element, etc. A voltage error occurs between the output value and the output value. In order to reduce these errors, the errors are reduced by dead time compensation or main circuit element voltage compensation, but the errors do not disappear. Here, since the voltage error is a small value, the ratio of the error voltage to the output voltage decreases,
There is no effect at high output voltage such as during power running / regeneration in high speed range and power running in low speed. However, during regeneration at low speed, the output voltage drops due to the output of a large regenerative torque, as illustrated in FIG. 2, which increases the influence of the error voltage. In other words, the ratio of the error voltage that can be used as the output voltage is reduced. When the observer 4 becomes large, it becomes impossible to estimate the magnetic flux and the current, and control becomes impossible.

It is an object of the present invention to provide a speed sensorless vector control device which avoids a control uncontrollable (driving) state even for regeneration in a low speed range.

[0020]

The present invention that achieves the above object has the following matters specifying the invention. (1) Of the vector control device for the induction motor, a speed sensorless vector for inputting the primary current detection value, the primary voltage command value, and the speed estimation value to obtain the speed estimation value by the same-dimensional magnetic flux observer and the speed adaptation mechanism. The control device is characterized in that it has means for limiting the current corresponding to the torque at the maximum regenerable torque. (2) In (1), the means for limiting the torque component current has a limiter at the torque component current input end, and the limiter is controlled by a table.

By providing the torque component current limiter, it is possible to suppress the torque component current which becomes inoperable.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Here, an example of an embodiment of the present invention will be described with reference to FIG. In FIG. 1, FIG.
The same parts as those of the above are denoted by the same reference numerals, and the description thereof will be omitted. In order to prevent the output voltage from being lowered to the extent that it becomes uncontrollable when a large regenerative torque is output, a command to limit the regenerative torque to operate may be given. Therefore, by setting the limit value of the regenerative torque and calculating with the controllable output voltage, it is possible to perform control that outputs the regenerative torque as much as possible and does not disable the control. In this case, the controllable output voltage can be expressed by the following equation [Equation 3] based on the voltage equation shown as the operable minimum output voltage.

(Equation 3)

In this case, the lowest operable voltage depends on the performance of the inverter 2. If the lowest operable voltage is 5 V in FIG. 2, in the example shown in FIG.
%, At 200 rpm, only 25% regenerative operation can be performed. Therefore, based on the above [Equation 3], the torque component current that is the maximum regenerative torque that can be operated is calculated by the estimated rotation speed, the motor constant, the voltage equation, the torque component current command, the minimum operable voltage, etc. Stable operation can be performed by issuing a regeneration command equal to or less than the regeneration torque.

To obtain the torque current, [Equation 3] is solved, but in order to obtain the solution of this quadratic equation, route calculation and calculation for coefficients are required.
C, which has high ability to perform these calculations for each control cycle,
PU is required. Therefore, the regenerative torque current limiter 10 is provided in the torque current command input unit, and the limit value of the regenerative torque current limiter is called from the limiter table 11 to obtain the torque current command that provides an operable voltage.

[0025]

As described above, according to the present invention, the operation in the sensorless vector control impossible region due to the decrease of the output voltage is performed by limiting the regenerative torque to the maximum reproducible torque calculated. It can be eliminated, and stable operation that does not prevent operation is possible.

[Brief description of drawings]

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

FIG. 2 is an output voltage characteristic diagram due to regeneration.

FIG. 3 is a block diagram of a conventional example.

[Explanation of symbols]

 10 Torque Current Limiter 11 Torque Current Limiter Table

Claims (2)

[Claims] 1. A vector controller for an induction motor, comprising:
In the speed sensorless vector control device that receives the primary current detection value, the primary voltage command value, and the speed estimation value to obtain the speed estimation value by the same-dimensional magnetic flux observer and the speed adaptation mechanism, the maximum torque that can be regenerated is the torque component. A speed sensorless vector control device comprising means for limiting an electric current. 2. The speed sensorless vector control device according to claim 1, wherein the means for limiting the torque component current comprises a limiter at the torque component current input end, and the limiter is controlled by a table. .