JP2001120000A - Vector-control method for induction motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vector-control device and its method for induction motors that can be controlled, even in the state that an output voltage is fixed to the maximum value of a PWM inverter. SOLUTION: In a vector-control method of induction motors, by which the magnetic flux and torque of the induction motors is controlled via a power- converting device, torque current and magnetic flux current commands are calculated from torque and magnetic flux commands, when the voltage of the power-converting device is fixed to a given value. Then, a voltage vector command value is calculated from these torque current and magnetic flux current commands. A magnetic flux correcting value calculated from the difference between the magnitudes of this voltage vector command value and the voltage vector obtained, when the voltage of the power-converting device is fixed to a given value is added to the magnetic flux command.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector control method for an induction motor.

[0002]

2. Description of the Related Art FIG. 14 shows an example of a vector control operation section of a conventional vector control device for an induction motor using a voltage-type PWM inverter as a power converter. The vector control calculation unit 1 includes a vector control command value calculation unit 11, a d-axis current control unit 12, a q-axis current control unit 13, a slip frequency integration unit 14, a coordinate conversion unit 15, a triangular wave comparison unit 16, Consists of The vector control command value calculation unit 11 receives the magnetic flux command ΦRef and the torque command TorqRef,
By calculation, a magnetic flux current command IdRef, a torque current command IqRef, and a slip frequency command ωsRef are output. Magnetic flux current command IdRef and torque current command Iq
Ref is the I that is obtained by converting the load current into orthogonal dq axes.
The deviation is obtained by comparing d with Iq. The d-axis current control unit 12 controls the magnetic flux voltage command VdRef to make the deviation between the magnetic flux current command IdRef and the feedback value Id zero.
And output. The q-axis current control unit 13 obtains and outputs a torque voltage command VqRef that makes the deviation between the torque current command IqRef and the feedback value Iq zero.

The slip frequency integrator 14 receives a slip frequency command ωsRef and outputs the integrated value as a slip frequency phase θs. The coordinate converter 15 converts the magnetic flux voltage command VdRef and the torque voltage command VqRef into
Based on the sum of the slip frequency phase θs and the rotor phase θr, 2
And three-phase current control signals VuRef, VvR
ef and VvRef, and output. The triangular wave comparator 16 includes three-phase current control signals VuRef, VvRef
, VvRef and the triangular wave to perform pulse width modulation.

[0004]

Conventionally, in a vector control device of an induction motor using a voltage-type PWM inverter as a power converter, in order to control output torque and motor magnetic flux, the magnitude and frequency of the PWM voltage are respectively controlled. It must be variable. However, in order to reduce the capacity of the PWM inverter, it is necessary to make maximum use of the output voltage, and to allow the output voltage to have a margin in order to make the output voltage variable for vector control, PWM It is not preferable because the capacity of the inverter is increased.
Accordingly, it is an object of the present invention to provide a vector control method for an induction motor that can be controlled even when the output voltage is fixed at the maximum value of the PWM inverter.

[0005]

According to the present invention, there is provided a vector control method for an induction motor, wherein a torque current command and a magnetic flux current command are calculated from a torque command and a magnetic flux command. By calculating a voltage vector command value from the torque current command and the magnetic flux current command, and adding the angle of the voltage vector command value to the magnetic flux direction to the inverter voltage command phase, the current response speed can be increased. The vector control method for an induction motor according to claim 2 of the present invention calculates a torque current command and a magnetic flux current command from the torque command and the magnetic flux command when fixing the voltage of the power converter at a predetermined value. Calculate the voltage vector command value from the torque current command and the magnetic flux current command,
The output torque follows the command value by adding a magnetic flux correction value calculated from the difference between the magnitude of the voltage vector command value and the voltage vector when the voltage of the power converter is fixed at a predetermined value to the magnetic flux command. Can be.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1 to 4 show a first embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a configuration diagram of a vector control operation unit of a vector control device for an induction motor according to a first embodiment. The vector control operation unit 20 includes a vector control instruction operation unit 21, a voltage instruction operation unit 22, a polar coordinate conversion unit 23, a voltage fixing unit 24, a modulation factor operation unit 25, a magnetic flux correction value operation unit 26, a torque current The control unit 27 includes a slip frequency integrator 28 and a PWM voltage generator 29. In the vector control command value calculation unit 21, the magnetic flux command ΦRef
And a magnetic flux correction value ΔΦ which is an output of a magnetic flux correction value calculation unit 26 to be described later, and a torque command value TorqRef.
, Torque current command IqRef, slip frequency command ωs
Ref is output.

[0007]

(Equation 1) Here, M: mutual inductance L2: secondary inductance R2: secondary resistance In the voltage command calculator 22, the magnetic flux current command IdRef and the torque current command IqRef output from the vector control command value calculator 21 are input and the following equation is used. , A flux axis voltage command VdRef and a torque axis voltage command VqRef are obtained and output.

[0008]

(Equation 2) Here, R12: R1 + R2 * (M / L2) 2 R1: primary resistance, R2: secondary resistance L1: primary inductance, L2: secondary inductance M: mutual inductance σ: 1−M2 / (L1 * L2) ω1: Inverter angular frequency, ωr: rotor angular frequency In the polar coordinate converter 23, the magnetic flux direction voltage command VdRef and the torque direction voltage command VqRef output from the voltage command calculator 22 are input, and the voltage vector is calculated by the following equation. The magnitude | V | and the angle δ of the voltage vector with respect to the magnetic flux axis direction are output.

[0009]

(Equation 3) The voltage fixing unit 24 receives the voltage vector magnitude | V | and the voltage vector magnitude command value | V | Ref and the voltage fixing command Vfix, which are the outputs of the polar coordinate conversion unit 23, and receives the voltage fixing command Vfix. The magnitude | V | ′ of the new voltage vector is calculated and output according to When the magnitude | V | of the voltage vector exceeds a predetermined value, the voltage fixing unit 24 determines the command value | V | Ref of the magnitude of the voltage vector.
It works to fix to. Voltage fix command Vfix
Is "1" when the magnitude of the voltage vector is fixed to the command value | V | Ref, and is "0" when the magnitude of the voltage vector is not fixed to the command value | V | Ref.
When the voltage fixing command Vfix is 1, when the voltage fixing command Vfix is 1, | V | ′ = | V
When | Ref voltage fixing command Vfix is 0, | V | ′ =
| V | is output. The magnetic flux correction value calculator 26 will be described with reference to FIG. The magnetic flux correction value calculation unit 26 includes a voltage fixing unit 24
│V│ 'of the voltage vector output from the controller, the voltage vector angle 隆 output from the polar coordinate converter 23, and the torque axial voltage Vq output from the voltage command calculator 22
Using Ref and the inverter angular frequency ω1 as inputs, the magnetic flux correction value ΔΦ is calculated by the following calculation.

[0010]

(Equation 4) The torque current control unit 27 includes a vector control command value calculation unit 2
The slip frequency correction value Δωs is output by the proportional integral control represented by the following equation with the torque current command IqRef and the torque current actual value Iq output from 1 as inputs.

[0011]

(Equation 5) Here, s: differential operator Kp: proportional gain Ki: integral gain In the slip frequency integrator 28, the slip frequency command value ωsR output from the vector control command value calculator 21
The sum of ef and the slip frequency correction value Δωs output from the torque current control unit 27 is input, and the integrated value of the input is output as the slip frequency phase θs.

[0012]

(Equation 6) However, s: differential operator In the modulation rate calculation unit 25, the magnitude | V | ′ of the voltage vector output from the voltage fixing unit 24 and the DC link voltage Vdc of the PWM inverter are input, and the modulation rate is calculated by the following calculation. Calculate α.

[0013]

(Equation 7) The PWM voltage generator 29 will be described with reference to FIGS.
In the PWM voltage generator 29, the inverter phase θ1 which is the sum of the slip frequency phase θs output from the slip frequency integrator 28, the rotor phase θr, and the voltage vector angle δ output from the polar coordinate converter 23. The three-phase PWM voltage commands VuPWM, VvPWM, and VwPWM are output by the following calculation using the modulation factor α output from the modulation factor calculator 25 and the pulse mode command Pmode as inputs. The operation when the pulse mode command is 1 will be described. Using the input inverter phase θ1, UV
The inverter phases θu, θv, θw of each phase of W are calculated as in the following equation.

[0014]

(Equation 8) The U-phase inverter phase θu is input to the phase PWM voltage generator 31 and is calculated by the following equation to calculate the U-phase PWM voltage command VuP.
Output WM.

[0015]

(Equation 9) Similarly, the V-phase PWM voltage command VvPWM and the W-phase voltage command VwPWM are output by the phase PWM voltage generator 31 as follows.

[0016]

(Equation 10) The pulse waveform at this time is as shown in FIG. Next, the operation of the phase PWM voltage generator 31 when the pulse mode command is 3 will be described. The on / off phase θSW that varies with the modulation factor α according to the relationship between the on / off phase θSW of the PWM voltage and the modulation factor α that has been calculated and stored in advance.
Is used to calculate the phase PWM voltage. The modulation rate α and the on / off phase θSW of the PWM voltage are, for example, as follows.

[Equation 11] Then, by comparing the phase between θSW and the U-phase voltage phase θu, the U-phase PWM voltage command is obtained as follows.

[0017]

(Equation 12) Similarly, the V-phase PWM voltage command VvPWM and the W-phase voltage command VwPWM are output by the phase PWM voltage generator 31 as follows.

[0018]

(Equation 13) Similarly, in other pulse modes, a phase PWM voltage command is determined and output by comparing the PWM voltage on / off phase stored in correspondence with the modulation rate with each phase voltage phase. In the vector control device configured as described above, a torque current command and a magnetic flux current command are calculated from the magnetic flux command and the torque command, and a magnetic flux direction component voltage and a torque direction component voltage are calculated from the magnetic flux current command and the torque current command. The magnitude of the first voltage vector and the angle of the voltage vector with respect to the direction of the magnetic flux axis are computed from the flux direction component voltage and the torque direction component voltage, and the magnitude of the second voltage vector is fixed when the magnitude of the voltage vector is fixed. As a result, the magnitude of the predetermined fixed voltage vector is output, and the current response speed can be increased by adding the angle of the voltage vector to the slip frequency phase. The magnitude of the second voltage vector and the angle of the voltage vector can be increased. The magnitude of the second voltage vector is fixed to the magnitude of the fixed voltage vector from the torque component voltage and the inverter angular frequency. The error between the magnetic flux command calculating a flux correction value for correcting caused by the can be made to follow the output torque command value by adding the flux correction value to the magnetic flux instruction.

Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the vector control calculator 40 includes a vector control command value calculator 41, a voltage command calculator 22, a polar coordinate converter 23, and a modulation rate calculator 25.
And a torque current control unit 27 and a slip frequency integration unit 28
And a PWM voltage generator 29. In this configuration, a voltage command calculation unit 22, a polar coordinate conversion unit 23,
The operations of the modulation factor calculation unit 25, the torque current control unit 27, the slip frequency integration unit 28, and the PWM voltage generation unit 29 are the same as those in the first embodiment, and a description thereof will be omitted. In the vector control command value calculation unit 41, the magnetic flux command ΦRef
, Torque command TorqRef, and rotor angular frequency ω
r, voltage vector magnitude command value | V | Ref and voltage fixing command Vfix, and voltage fixing command Vf
The shaft current command IdRef, the torque current command IqRef, and the slip frequency command ωsRef are output by the following two calculation methods according to the value of ix. Voltage fixing command Vfi
x is when the magnitude of the voltage vector is fixed: Vf
ix = 1 When the magnitude of the voltage vector is not fixed: V
fix = 0. First, the voltage fixing command Vfix =
At the time of 1, the d-axis current command IdRef and the q-axis current command IqRe stored in advance using the torque command TorqRef, the voltage vector magnitude command | V | Ref, and the rotor angular frequency ωr as parameters.
f, outputs the slip frequency command ωsRef.

At this time, IdRef, IqRef
, ΩsRef must satisfy

[Equation 14] R12: R1 + R2 × (M / L2) 2 R1: Primary resistance, R2: Secondary resistance L1: Primary inductance, L2: Secondary inductance M: Mutual inductance σ: 1−M2 / (L1 × L2) ωr: Rotor It is the angular frequency. When the voltage fixation command Vfix = 0, the magnetic flux command ΦRef and the torque command value TorqR
With ef as an input, a magnetic flux current command IdRef, a torque current command IqRef, and a slip frequency command ωsRef are output by the following equation.

[0021]

(Equation 15) However, M: mutual inductance L2: secondary inductance R2: secondary resistance In the vector control device configured as described above, it is determined whether the magnetic flux command, the torque command, the rotor angular frequency, and the magnitude of the voltage vector are fixed. From the voltage fixing command to be determined and the magnitude of the predetermined fixed voltage vector, when fixing the magnitude of the voltage vector, the torque current command and the magnetic flux current command are based on the torque command, the rotor angular frequency, and the magnitude of the fixed voltage vector. And corrects the error from the magnetic flux command caused by being fixed to the magnitude of the fixed voltage vector, and causes the output torque to follow the command value. When the magnitude of the voltage vector is not fixed, the torque current command and the magnetic flux current command are calculated based on the magnetic flux command and the torque command. Further, a magnetic flux direction component voltage and a torque direction component voltage are calculated from the magnetic flux current command and the torque current command, and an angle of a voltage vector with respect to the magnetic flux axis direction is calculated from the magnetic flux direction component voltage and the torque direction component voltage. The current response speed can be increased by adding the angle of the vector to the slip frequency phase. Next, a third embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. In the third embodiment, the vector control calculation unit 50 includes a vector control command value calculation unit 21, a voltage command calculation unit 22, a polar coordinate conversion unit 23, a voltage fixing unit 24, a modulation factor calculation unit 25, a magnetic flux Correction value calculator 26
, The torque current control unit 53 and the slip frequency integration unit 28
A PWM voltage generator 29, a weighting coefficient calculator 54,
It comprises a d-axis current controller 55 and a q-axis current controller 56.

A vector control command value calculation unit 21, a voltage command calculation unit 22, a polar coordinate conversion unit 23, and a voltage fixing unit 24
The operations of the modulation factor calculator 25, the magnetic flux correction value calculator 26, the slip frequency integrator 28, and the PWM voltage generator 29 are the same as those of the first embodiment, and therefore the description is omitted. The weight coefficient calculator 54 will be described with reference to FIG. The weight coefficient calculation unit 54 includes a control mode switching determination unit 57 and a change rate limit unit 58. Control mode switching determination unit 57
, The absolute value | ω1 of the inverter angular frequency ω1
|, The control mode Cmo is determined by the following condition determination.
Output de. The control mode is C for constant voltage control.
When mode = 0 and variable voltage control, Cmode = 1. When the current control mode is Cmode = 0,

(Equation 16) Becomes When the current control mode is Cmode = 1,

[Equation 17] Becomes

However, it is assumed that ωCHG1 ≦ ωCHG2.
The change rate limit unit 58 receives the control mode Cmode output from the control mode switching determination unit 57 as input, and outputs a value that limits the rising and falling speeds of Cmode as the weight coefficient K1. The weight coefficient K2 falls and rises according to the rise and fall speed of the weight coefficient K1. When the control mode Cmode changes from 0 to 1 at t = 0, assuming that the limit value of the change rate is a, the weight coefficients K1 and K2 change as follows.

[0024]

(Equation 18) Similarly, when the control mode Cmode changes from 1 to 0 at t = 0,

[Equation 19] In the d-axis current control unit 55, the weight coefficient K1 output from the weight coefficient calculation unit 54 is subtracted from the magnetic flux current command value IdRef output from the vector control command value calculation unit 21 by subtracting the actual magnetic flux current value Id. The multiplied value is input, and the magnetic flux direction voltage correction value ΔVd is output by proportional integral control represented by the following equation.

[0025]

(Equation 20) Here, s: differential operator Gp: proportional gain, Gi: integral gain The output ΔVd of the d-axis current controller 55 is calculated by the voltage command calculator 2
2 is added to the magnetic flux direction voltage command VdRef output from the control unit 2 and is input to the polar coordinate conversion unit 23 as a new magnetic flux direction voltage command VdRef. In the q-axis current control unit 56, the weight coefficient K1 output from the weight coefficient calculation unit 54 is subtracted from the torque current command value IqRef output from the vector control command value calculation unit 21 by subtracting the actual torque current value Iq. The multiplied value is input, and a torque direction voltage correction value ΔVq is output by proportional integral control represented by the following equation.

[0026]

(Equation 21) Here, s: differential operator Gp: proportional gain, Gi: integral gain The output ΔVq of the q-axis current control unit 56 is calculated by the voltage command calculation unit 2
2 is added to the torque direction voltage command VqRef output from the second unit 2 and is input to the polar coordinate conversion unit 23 as a new torque direction voltage command VqRef. The torque current control unit 53 multiplies a value obtained by subtracting the actual torque current value Iq from the torque current command value IqRef output from the vector control command value calculation unit 21 by the weight coefficient K2 output from the weight coefficient calculation unit 54. The slip frequency correction value Δωs is output by the proportional integral control represented by the following equation.

[0027]

(Equation 22) However, s: differential operator Kp: proportional gain, Ki: integral gain In the vector control device configured as described above, the weight is gradually changed at the time of transition between the variable voltage control and the fixed voltage control, so that the variable voltage control is performed. And the transition to the fixed voltage control can be performed smoothly. Next, a fourth embodiment of the present invention will be described with reference to FIG. The fourth embodiment is similar to the first embodiment.
The second embodiment is the same as the first embodiment except that the input and calculation of the magnetic flux correction value calculation unit 26 of the second embodiment are different. The vector control operation unit 60 according to the fourth embodiment includes a vector control command value operation unit 21, a voltage command operation unit 22, and a polar coordinate conversion unit 23.
, A voltage fixing unit 24, a modulation factor calculation unit 25, a magnetic flux correction value calculation unit 61, a torque current control unit 27, a slip frequency integration unit 28, and a PWM voltage generation unit 29.
In the magnetic flux correction value calculation unit 61, the magnitude | V | of the voltage vector output from the polar coordinate conversion unit 23 and the magnitude | V | ′ of the voltage vector output from the voltage fixing unit 24
And the inverter angular frequency ω1 as inputs, and outputs a magnetic flux correction value ΔΦ by the following calculation.

[0028]

(Equation 23) The operations in the other components are the same as in the first embodiment.
In the vector control device configured as described above, a torque current command and a magnetic flux current command are calculated from the magnetic flux command and the torque command, and a magnetic flux direction component voltage and a torque direction component voltage are calculated from the magnetic flux current command and the torque current command. The magnitude of the first voltage vector and the angle of the voltage vector with respect to the direction of the magnetic flux axis are computed from the flux direction component voltage and the torque direction component voltage, and the magnitude of the second voltage vector is fixed when the magnitude of the voltage vector is fixed. The magnitude of the first voltage vector and the magnitude of the second voltage vector can be increased by outputting the magnitude of a predetermined fixed voltage vector and adding the angle of the voltage vector to the slip frequency phase. From the magnitude of the second voltage vector is fixed to the magnitude of the fixed voltage vector. Calculating a magnetic flux correction value for correcting, it is possible to follow the output torque command value by adding the flux correction value to the magnetic flux instruction. A fifth embodiment of the present invention will be described with reference to FIGS. FIG. 9 shows the fifth
It is a block diagram of the vector control calculation part of the vector control apparatus of the induction motor of the Example of FIG.

The vector control calculator 70 includes a vector control command calculator 21, a voltage command calculator 71, a polar coordinate converter 23, a voltage fixing unit 24, a modulation factor calculator 25, and a magnetic flux correction value calculator 72. , A torque current control unit 73, a slip frequency integration unit 74, and a PWM voltage generation unit 75. In the vector control command value calculation unit 21, the magnetic flux command Φ
The sum of Ref and a magnetic flux correction value ΔΦ output from a magnetic flux correction value calculation unit 72 described later, and a torque command value TorqRef
And the magnetic flux current command IdR is calculated by the following equation.
ef, a torque current command IqRef, and a slip frequency command ωsRef.

[0030]

(Equation 24) Here, M: mutual inductance L2: secondary inductance R2: secondary resistance In the voltage command calculation unit 71, the magnetic flux current command IdRef and the torque current command IqRef output from the vector control command value calculation unit 21 are input and the following equation is used. , A flux axis voltage command VdRef and a torque axis voltage command VqRef are obtained and output.

[0031]

(Equation 25) The polar coordinate conversion unit 23 receives the magnetic flux direction voltage command VdRef and the torque direction voltage command VqRef output from the voltage command calculation unit 71 as inputs, and calculates the voltage vector magnitude | V | The angle δ with respect to the axial direction is output.

[0032]

(Equation 26) The voltage fixing unit 24 receives the voltage vector magnitude | V | and the voltage vector magnitude command value | V | Ref and the voltage fixing command Vfix, which are the outputs of the polar coordinate conversion unit 23, and receives the voltage fixing command Vfix. The magnitude | V | ′ of the new voltage vector is calculated and output according to When the magnitude | V | of the voltage vector exceeds a predetermined value, the voltage fixing unit 24 determines the command value | V | Ref of the magnitude of the voltage vector.
It works to fix to. Voltage fix command Vfix
Is "1" when the magnitude of the voltage vector is fixed to the command value | V | Ref, and is "0" when the magnitude of the voltage vector is not fixed to the command value | V | Ref.
When the voltage fixing command Vfix is 1, the voltage fixing unit 24 determines that | V | '= | according to the value of the voltage fixing command Vfix.
When | V | Ref voltage fixing command Vfix is 0, | V | ′
= | V | is output. The magnetic flux correction value calculation unit 72 calculates the magnitude | V | ′ of the voltage vector output from the voltage fixing unit 24.
And the magnitude | V | of the voltage vector output from the polar coordinate conversion unit 23 as an input, and the magnetic flux correction value Δ
Calculate Φ.

[0033]

[Equation 27] Here, s: differential operator Gp: proportional gain Gi: integral gain The torque current control unit 73 is a vector control command value calculation unit 2
With the torque current command IqRef and torque current actual value Iq output from 1 as inputs, a magnetic flux angle correction value Δθr is output by proportional integral control represented by the following equation.

[0034]

[Equation 28] Here, s: differential operator Kp: proportional gain Ki: integral gain In the slip frequency integrator 74, the slip frequency command value ωsR output from the vector control command value calculator 21
ef is input, and the integrated value of the input is output as the slip frequency phase θs.

[0035]

(Equation 29) However, s: differential operator In the modulation rate calculation unit 25, the magnitude | V | ′ of the voltage vector output from the voltage fixing unit 24 and the DC link voltage Vdc of the PWM inverter are input, and the modulation rate is calculated by the following calculation. Calculate α.

[0036]

[Equation 30] The PWM voltage generator 75 will be described with reference to FIG. PW
In the M voltage generation section 75, the slip frequency integration section 74
, The magnetic flux angle correction value Δθr output from the torque current controller 73, the rotor phase θr, and the voltage vector angle δ output from the polar coordinate converter 23. Inverter phase θ1
, The modulation rate α output from the modulation rate calculator 25, and the pulse mode command Pmode, and
Phase PWM voltage commands VuPWM, VvPWM, VwP
Output WM. The operation when the pulse mode command is 1 will be described. Using the input inverter phase θ1, the inverter phases θu, θv, θw of each UVW phase are used.
Is calculated as in the following equation.

[0037]

(Equation 31) The U-phase inverter phase θu is input to the phase PWM voltage generator 31 and is calculated by the following equation to calculate the U-phase PWM voltage command VuP.
Output WM.

[0038]

(Equation 32) Similarly, the V-phase PWM voltage command VvPWM and the W-phase voltage command VwPWM are output by the phase PWM voltage generator 31 as follows.

[0039]

[Equation 33] Next, the operation of the phase PWM voltage generator 31 when the pulse mode command is 3 will be described. The on / off phase θS that varies depending on the modulation factor α according to the relationship between the on / off phase θSW of the PWM voltage and the modulation factor α that has been calculated and stored in advance.
The phase PWM voltage is calculated using W. Modulation rate α and PWM
The voltage on / off phase θSW is, for example, as follows.

(Equation 34) Then, by comparing the phase between θSW and the U-phase voltage phase θu, the U-phase PWM voltage command is obtained as follows.

[0040]

(Equation 35) Similarly, the V-phase PWM voltage command VvPWM and the W-phase voltage command VwPWM are output by the phase PWM voltage generator 31 as follows.

[0041]

[Equation 36] Similarly, in other pulse modes, a phase PWM voltage command is determined and output by comparing the PWM voltage on / off phase stored in correspondence with the modulation rate with each phase voltage phase. In the vector control device configured as described above, a torque current command and a magnetic flux current command are calculated from the magnetic flux command and the torque command, and a magnetic flux direction component voltage and a torque direction component voltage are calculated from the magnetic flux current command and the torque current command. The magnitude of the first voltage vector and the angle of the voltage vector with respect to the direction of the magnetic flux axis are computed from the flux direction component voltage and the torque direction component voltage, and the magnitude of the second voltage vector is fixed when the magnitude of the voltage vector is fixed. As a result, the magnitude of a predetermined fixed voltage vector is output, and the current response speed can be increased by adding the angle of the voltage vector to the rotor rotation angle phase. The magnitude of the second voltage vector and the voltage vector The magnitude of the second voltage vector is fixed to the magnitude of the fixed voltage vector from the angle of the torque direction component voltage and the inverter angular frequency. It is the error between the magnetic flux command calculating a flux correction value for correcting caused by the can be made to follow the output torque command value by adding the flux correction value to the magnetic flux instruction.

A sixth embodiment of the present invention will be described with reference to FIG. FIG. 11 is a configuration diagram of a vector control operation unit of the vector control device for an induction motor according to the sixth embodiment. The vector control operation unit 80 includes a vector control instruction operation unit 81
, A voltage command calculator 71, a polar coordinate converter 23, a voltage fixing unit 24, a modulation factor calculator 25, and a magnetic flux correction value calculator 7.
2, a secondary resistance correction value calculation unit 82, a slip frequency integration unit 74, and a PWM voltage generation unit 75. In this configuration, the voltage command calculator 71 and the polar coordinate converter 2
3, the voltage fixing unit 24, the modulation factor calculating unit 25, the magnetic flux correction value calculating unit 72, the slip frequency integrator 74, and the PWM voltage generator 75 are the same as those in the fifth embodiment.
Description is omitted. In the vector control command value calculation unit 81,
The sum of the magnetic flux command ΦRef and the magnetic flux correction value ΔΦ output from the magnetic flux correction value calculation unit 72, and the torque command value TorqRe
The magnetic flux current command IdRef and the torque current command Iq are calculated by the following equations using f and a secondary resistance correction value ΔR2, which is an output of a secondary resistance correction value calculation unit 82 described later, as inputs.
Ref and the slip frequency command ωsRef are output.

[0043]

(37) Here, M: mutual inductance L2: secondary inductance R2: secondary resistance The secondary resistance correction value calculator 82 receives the torque current command IqRef and the torque current actual value Iq output from the vector control command value calculator 81 as inputs. The secondary resistance correction value ΔR2 is output by the proportional integral control represented by the following equation.

[0044]

(38) However, s: differential operator Kp: proportional gain Ki: integral gain In the vector control device configured as described above, the torque current command and the magnetic flux current command are calculated from the magnetic flux command and the torque command, and the magnetic flux current command and the torque are calculated. The magnetic flux direction component voltage and the torque direction component voltage are calculated from the current command, and the magnitude of the first voltage vector and the angle of the voltage vector with respect to the magnetic flux axis direction are calculated from the flux direction component voltage and the torque direction component voltage. When the magnitude of the vector is fixed, the magnitude of the predetermined fixed voltage vector is output as the magnitude of the second voltage vector, and the current response speed is increased by adding the angle of the voltage vector to the rotor rotation angle phase. From the magnitude of the second voltage vector, the angle of the voltage vector, the torque direction component voltage, and the inverter angular frequency, A magnetic flux correction value for correcting an error with a magnetic flux command caused by fixing the magnitude of the second voltage vector to the magnitude of the fixed voltage vector is calculated, and the magnetic flux correction value is added to the magnetic flux command to thereby obtain an output torque. Can follow the command value. Next, a seventh embodiment of the present invention will be described with reference to FIGS. In the seventh embodiment, the vector control calculation unit 90 includes a vector control command value calculation unit 21, a voltage command calculation unit 71, a polar coordinate conversion unit 23, a voltage fixing unit 24, a modulation rate calculation unit 25,
Magnetic flux correction value calculation section 72, torque current control section 91, slip frequency integration section 74, PWM voltage generation section 75, weight coefficient calculation section 92, d-axis current control section 93, q-axis current control section 94 It is composed of

The vector control command value calculator 21, the voltage command calculator 71, the polar coordinate converter 23, and the voltage fixing unit 24
The operations of the modulation factor calculation unit 25, the magnetic flux correction value calculation unit 72, the slip frequency integration unit 74, and the PWM voltage generation unit 75 are the same as those in the fifth embodiment, and a description thereof will be omitted. The weight coefficient calculator 92 will be described with reference to FIG. The weight coefficient calculation unit 92 includes a control mode switching determination unit 95 and a change rate limit unit 96. Control mode switching determination section 9
5, the absolute value | ω1 of the inverter angular frequency ω1
|, The control mode Cmo is determined by the following condition determination.
Output de. The control mode is C for constant voltage control.
When mode = 0 and variable voltage control, Cmode = 1. When the current control mode is Cmode = 0,

[Equation 39] Becomes When the current control mode is Cmode = 1,

(Equation 40) Becomes

However, it is assumed that ωCHG1 ≦ ωCHG2.
The change rate limit section 96 receives the control mode Cmode output from the control mode switching determination section 95 as an input, and outputs a value that limits the rising and falling speeds of Cmode as a weight coefficient K1. The weight coefficient K2 falls and rises according to the rise and fall speed of the weight coefficient K1. When the control mode Cmode changes from 0 to 1 at t = 0, assuming that the limit value of the change rate is a, the weighting coefficients K1 and K2 change as follows.

[0047]

[Equation 41]

(Equation 42) In the d-axis current controller 93, the weight coefficient K1 output from the weight coefficient calculator 92 is subtracted from the magnetic flux current command value IdRef output from the vector control command value calculator 21 by subtracting the magnetic flux current actual value Id. The multiplied value is input, and the magnetic flux direction voltage correction value ΔVd is output by proportional integral control represented by the following equation.

[0048]

[Equation 43] Here, s: differential operator Gp: proportional gain, Gi: integral gain The output ΔVd of the d-axis current control unit 93 is calculated by the voltage command calculation unit 7
This is added to the magnetic flux direction voltage command VdRef output from 1 and input to the polar coordinate converter 23 as a new magnetic flux direction voltage command VdRef. The q-axis current control unit 94 calculates the torque current actual value Iq from the torque current instruction value IqRef output from the vector control instruction value calculation unit 21.
Is subtracted by the weight coefficient K1 output from the weight coefficient calculation unit 92, and a torque direction voltage correction value ΔVq is output by proportional integral control represented by the following equation.

[0049]

[Equation 44] Here, s: differential operator Gp: proportional gain, Gi: integral gain The output ΔVq of the q-axis current control unit 94 is calculated by the voltage command calculation unit 7
This is added to the torque direction voltage command VqRef output from 1 and input to the polar coordinate conversion unit 23 as a new torque direction voltage command VqRef. In torque current control section 91, a value obtained by subtracting actual torque current value Iq from torque current command value IqRef output from vector control command value calculation section 21 is multiplied by weight coefficient K2 output from weight coefficient calculation section 92. Then, the magnetic flux angle correction value Δθr is output by proportional integral control represented by the following equation.

[0050]

[Equation 45] Here, s: differential operator Kp: proportional gain, Ki: integral gain In the vector control device configured as described above, a torque current command and a magnetic flux current command are calculated from the magnetic flux command and the torque command, and the magnetic flux current command is calculated. Calculate the magnetic flux direction component voltage and the torque direction component voltage from the torque current command, calculate the magnitude of the first voltage vector and the angle of the voltage vector with respect to the magnetic flux axis direction from the magnetic flux direction component voltage and the torque direction component voltage, When fixing the magnitude of the voltage vector, the magnitude of the predetermined fixed voltage vector is output as the magnitude of the second voltage vector, and the current response speed is increased by adding the angle of the voltage vector to the rotor rotation angle phase. From the magnitude of the second voltage vector, the angle of the voltage vector, the torque direction component voltage, and the inverter angular frequency. A magnetic flux correction value for correcting an error with a magnetic flux command caused by fixing the magnitude of the second voltage vector to the magnitude of the fixed voltage vector is calculated, and the magnetic flux correction value is added to the magnetic flux command to thereby obtain an output torque. Can follow the command value. In addition, by gradually changing the weight at the transition between the variable voltage control and the fixed voltage control, the transition between the variable voltage control and the fixed voltage control can be smoothly performed.

[0051]

According to the vector control method for an induction motor according to the first aspect of the present invention, a torque current command and a magnetic flux current command are calculated from a torque command and a magnetic flux command. By calculating the voltage vector command value from the above and adding the angle of the voltage vector command value to the magnetic flux direction to the inverter voltage command phase, the current response speed can be increased. The vector control method for an induction motor according to claim 2 of the present invention calculates a torque current command and a magnetic flux current command from the torque command and the magnetic flux command when fixing the voltage of the power converter at a predetermined value,
A voltage vector command value is calculated from the torque current command and the magnetic flux current command, and a magnetic flux correction calculated from a difference between the magnitude of the voltage vector command value and the voltage vector when the voltage of the power converter is fixed at a predetermined value. By adding the value to the magnetic flux command, the output torque can follow the command value.

[Brief description of the drawings]

FIG. 1 is a functional block diagram of a vector control operation unit according to a first embodiment.

FIG. 2 is a functional block diagram of a magnetic flux correction value calculation unit according to the first embodiment.

FIG. 3 is a functional block diagram of a PWM voltage generator according to the first embodiment.

FIG. 4 is a pulse waveform chart in the first embodiment.

FIG. 5 is a functional block diagram of a vector control operation unit according to a second embodiment.

FIG. 6 is a functional block diagram of a vector control operation unit according to a third embodiment.

FIG. 7 is a functional block diagram of a weight coefficient calculating unit according to a third embodiment.

FIG. 8 is a functional block diagram of a vector control operation unit according to a fourth embodiment.

FIG. 9 is a functional block diagram of a vector control operation unit according to a fifth embodiment.

FIG. 10 is a functional block diagram of a PWM voltage generator according to a fifth embodiment.

FIG. 11 is a functional block diagram of a vector control operation unit according to a sixth embodiment.

FIG. 12 is a functional block diagram of a vector control operation unit according to a seventh embodiment.

FIG. 13 is a functional block diagram of a weight coefficient calculating unit according to a seventh embodiment.

FIG. 14 is a functional block diagram of a vector control operation unit of a conventional induction motor.

[Explanation of symbols]

20, 40, 50, 60, 70, 80, 90,... Vector control operation unit 21, 81, vector control command value operation unit 22, 71, voltage command operation unit 23, polar coordinate conversion unit 24, voltage fixing unit 25, modulation Ratio calculation units 26, 72 ... magnetic flux correction value calculation units 27, 53, 73, 91 ... torque current control units 28, 74 ... slip frequency integration units 29, 75 ... PWM voltage generation units 54, 92 ... weight coefficient calculation units 55, 93: d-axis current controller 56, 94: q-axis current controller 82: secondary resistance correction value calculator

Claims (2)

[Claims] In an induction motor vector control method for controlling the magnetic flux and torque of an induction motor via a power converter, a torque current command and a magnetic flux current command are calculated from a torque command and a magnetic flux command. A vector control method for an induction motor, comprising: calculating a voltage vector command value from a current command and a magnetic flux current command; and adding an angle of the voltage vector command value to a magnetic flux direction to an inverter voltage command phase. 2. A vector control method of an induction motor for controlling a magnetic flux and a torque of an induction motor via a power converter, wherein when the voltage of the power converter is fixed at a predetermined value, a torque command and a magnetic flux command are used. From the torque current command and the magnetic flux current command, calculate the voltage vector command value from the torque current command and the magnetic flux current command, and fix the magnitude of the voltage vector command value and the voltage of the power converter at a predetermined value. A vector control method for an induction motor, characterized in that a magnetic flux correction value calculated from a difference from a voltage vector at the time of performing the control is added to the magnetic flux command.