JP2009213331A - Controller for induction motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the change of an exciting inductance and the change of a secondary leakage inductance in the axial direction of torque, when a load is applied to an induction motor. <P>SOLUTION: Exciting inductance/secondary leakage inductance estimating means 300 estimates the exciting inductance Mγ, taking into consideration the magnetic saturation of an exciting axis and the secondary leakage inductance l<SB>r</SB>δ in the axial direction of torque, based on the observed value of an input and output of the induction motor 40, when the induction motor 40 is operated, on the basis of a primary frequency determined so that the magnetic flux of an air gap in the axial direction of torque is zero. Torque current command value forming means 135, while taking into consideration the exciting inductance Mγ, forms a torque current command value P00 from an exciting current command value P1 and a torque command value P2. An axial shift compensator 165 takes into consideration the secondary leakage inductance l<SB>r</SB>δ, in the axial direction of torque to calculate a primary frequency compensating value P20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an induction motor control apparatus, and is particularly suitable for application to a method for variable speed control of an induction motor by vector control.

Induction motors are widely used as power sources for consumer and industrial machines because the number of revolutions determined by the number of poles and frequency is almost constant, the structure is simple and robust, and they have excellent safety and environmental resistance and high cost performance. ing. In a power source such as a fan or a pump, variable speed operation is utilized as a means for saving energy, and V / F control and vector control are mainly used as control methods for performing variable speed. Here, in the V / F control, the configuration is simple and the adjustment is easy. On the other hand, since it is the open loop control, there is a restriction that the control responsiveness cannot be improved. On the other hand, in the vector control, by changing the current phase in addition to the slip frequency control, the magnetic flux can be made invariant with respect to a transient load fluctuation, and a high-speed response can be obtained.
For example, Patent Document 1 discloses a control device for an induction motor based on slip frequency vector control using a shaft misalignment compensation technique.

FIG. 3 is a block diagram showing a schematic configuration of a control device for an induction motor based on slip frequency vector control using a conventional axis deviation compensation technique.
In FIG. 3, an induction motor 40 is connected to an inverter 10 that converts direct current to alternating current of variable voltage and variable frequency by a switching operation. A load 45 is connected to the rotating shaft of the induction motor 40. A control device 2 that controls the switching of the inverter 10 by the (Pulse Width Modulation) method is connected. The input side of the induction motor 40 is provided with voltage detection means 20 for detecting the AC voltage output from the inverter 10 and current detection means 30 for detecting the AC current output from the inverter 10. On the side, speed detecting means 50 for detecting the rotational speed of the induction motor 40 is provided.

Here, the induction motor control device 2 includes a torque current command value creating means 130, a current control means 100, a rotating two-phase / three-phase coordinate converting means 110, a three-phase / rotating two-phase coordinate converting means 120, and a slip frequency calculation. Means 150, an axis deviation compensator 160, adders 71 and 72, and an integrator 140 are provided.
In the following description, the excitation axis may be expressed as γ axis or d axis, and the torque axis may be expressed as δ axis or q axis. In the following description, the value in the excitation axis direction is given a suffix of γ or d, the value in the torque axis direction is given a suffix of δ or q, and the value on the primary side is 1 or s. A suffix was added, and a secondary value was added with a suffix of 2 or r.

The torque current command value creating means 130 can create the torque current command value P0 from the excitation current command value P1 and the torque command value P2 input to the control device 2. When the excitation current command value P1 is iγ _s ^* , the torque command value P2 is T ^* , and the torque current command value P0 is iδ _s ^* , the torque current command value P0 can be obtained by the following equation (1). .
iδ _s ^* = T ^* L _r / (pM ² iγ _s ^* ) (1)
However,
M: Excitation inductance L _r : Secondary inductance p: Number of pole pairs.

The three-phase / rotation two-phase coordinate conversion means 120 converts the detected value of the three-phase current detected by the current detection means 30 based on the phase angle P14 output from the integrator 140, thereby detecting the excitation current. The excitation voltage detection value P7 and the torque voltage detection value P8 can be calculated by calculating the value P5 and the torque current detection value P6 and converting the detection value of the three-phase voltage detected by the voltage detection means 20. it can.
The current control means 100 determines each deviation between the excitation current detection value P5 and the torque current detection value P6 calculated by the three-phase / rotation two-phase coordinate conversion means 120, and the excitation current command value P1 and the torque current command value P0. Based on this, it is possible to calculate the excitation shaft voltage command value P3 and the torque shaft voltage command value P4, respectively.

The rotating two-phase / three-phase coordinate conversion means 110 converts the excitation shaft voltage command value P3 and the torque shaft voltage command value P4 into a three-phase voltage command based on the phase angle P14 output from the integrator 140, and outputs an inverter. 10 can be output.
The slip frequency calculating means 150 can calculate the slip frequency P9 of the induction motor 40 by multiplying the value obtained by dividing the torque current detection value P6 by the excitation current detection value P5 by the reciprocal of the secondary time constant.
The adder 71 can calculate the primary frequency command value P11 by adding the slip frequency P9 output from the slip frequency calculation means 150 and the rotation speed detection value P10 detected by the speed detection means 50. .
The axis deviation compensator 160 calculates the excitation axis component of the induced voltage based on the excitation current detection value P5, the torque current detection value P6, and the excitation voltage detection value P7, and controls the axis based on the secondary magnetic flux of the induction motor 40, and the control. The primary frequency compensation value P12 can be calculated based on the angle of the excitation axis in the apparatus 2.

FIG. 4 is a block diagram showing a schematic configuration of the axis deviation compensator of FIG.
In FIG. 4, the axis deviation compensator 160 is provided with an induced voltage calculation circuit 510 and a positional deviation amount calculation circuit 520.
Here, the induced voltage calculation circuit 510 receives the excitation current detection value P5, the torque current detection value P6, and the excitation voltage detection value P7, and can output the excitation axis induced voltage P41. When the excitation axis induced voltage P41 is e _2d , the excitation axis induced voltage e _2d can be obtained by the following equation (2).
e _2d = v _1d − (R ₁ + d / dtLσ) i _1d + ω ₁ Lσi _1q (2)
However,
v _1d : voltage excitation axis component ω ₁ : primary frequency i _1d : excitation axis current i _1q : torque axis current R ₁ : primary resistance Lσ: leakage inductance.

Further, the primary frequency command value P11 and the excitation axis induced voltage P41 are input to the positional deviation amount calculation circuit 520, and the primary frequency compensation value P12 can be output. If the primary frequency compensation value P12 is Δω ₁ , the primary frequency compensation value Δω ₁ can be obtained by the following equation (3).
Δω ₁ = sgn (ω ₁ ^* ) K _p {e _2d + (1 / T _I ) ∫e _2d dt} (3)
However,
ω ₁ ^* : primary frequency command value sgn (ω ₁ ^* ): sign data K _p of ω ₁ ^* : proportional gain T _I : integration time constant.

In FIG. 3, the adder 72 adds the primary frequency command value P11 output from the adder 71 and the primary frequency compensation value P12 calculated by the axis deviation compensator 160 to thereby add the primary frequency command value. P13 can be calculated.
The integrator 140 can calculate the phase angle P14 by integrating the primary frequency command value P13 output from the adder 72.
The excitation current command value P1 and the torque command value P2 are input to the torque current command value creating unit 130, and the excitation current command value P1 is input to the current control unit 100. Then, when the excitation current command value P1 and the torque command value P2 are input to the torque current command value creating unit 130, the torque current command value creating unit 130 performs the calculation of the equation (1) to thereby obtain the torque current command value P0. And output to the current control means 100.

  The detected value of the three-phase current detected by the current detector 30 is input to the three-phase / rotating two-phase coordinate converter 120, and the detected value of the three-phase voltage detected by the voltage detector 20 is The phase angle P14 input to the three-phase / rotation two-phase coordinate conversion means 120 and calculated by the integrator 140 is input to the three-phase / rotation two-phase coordinate conversion means 120 and the rotation two-phase / three-phase coordinate conversion means 110. The Then, the three-phase / rotating two-phase coordinate conversion means 120 converts the detected value of the three-phase current into the excitation current detection value P5 and the torque current detection value P6 based on the phase angle P14 output from the integrator 140, In addition to outputting to the current control means 100, the slip frequency calculating means 150, and the axis deviation compensator 160, the detected value of the three-phase voltage is converted into the excitation voltage detection value P7 and the torque voltage detection value P8 and output to the axis deviation compensator 160. To do.

The current control unit 100 receives the excitation current detection value P5 and the torque current detection value P6 from the three-phase / rotation two-phase coordinate conversion unit 120, receives the torque current command value P0 from the torque current command value creation unit 130, and generates the excitation current. When the current command value P1 is received from the outside, the excitation shaft voltage command value P3 and the torque are determined based on the deviations between the excitation current detection value P5 and the torque current detection value P6 and the excitation current command value P1 and the torque current command value P0. The shaft voltage command value P4 is calculated and output to the rotating two-phase / three-phase coordinate conversion means 110.
Then, when the rotating two-phase / three-phase coordinate conversion means 110 receives the excitation shaft voltage command value P3 and the torque shaft voltage command value P4 from the current control means 100, based on the phase angle P14 output from the integrator 140, Excitation shaft voltage command value P3 and torque shaft voltage command value P4 are converted into a three-phase voltage command and output to inverter 10.

  Further, when the slip frequency calculation means 150 receives the excitation current detection value P5 and the torque current detection value P6 from the three-phase / rotation two-phase coordinate conversion means 120, the value obtained by dividing the torque current detection value P6 by the excitation current detection value P5. Is multiplied by the reciprocal of the secondary time constant to calculate the slip frequency P9 and output it to the adder 71. Further, the rotational speed detection value P10 detected by the speed detection means 50 is output to the adder 71. When the adder 71 receives the slip frequency P9 from the slip frequency calculating means 150 and receives the rotational speed detection value P10 from the speed detection means 50, the adder 71 adds the slip frequency P9 and the rotational speed detection value P10. The primary frequency command value P11 is calculated and output to the axis deviation compensator 160 and the adder 72.

The axis deviation compensator 160 receives the excitation current detection value P5, the torque current detection value P6, and the excitation voltage detection value P7 from the three-phase / rotation two-phase coordinate conversion means 120, and also adds the primary frequency command value P11 to the adder 71. , The primary frequency compensation value P12 is calculated by performing the calculations of equations (2) and (3), and is output to the adder 72.
When the adder 72 receives the primary frequency command value P11 from the adder 71 and receives the primary frequency compensation value P12 from the axis deviation compensator 160, the adder 72 adds the primary frequency command value P11 and the primary frequency compensation value P12. As a result, the primary frequency command value P13 is calculated and output to the integrator 140. When the integrator 140 receives the primary frequency command value P13 from the adder 72, the integrator 140 integrates the primary frequency command value P13 to calculate the phase angle P14, and the three-phase / rotation two-phase coordinate conversion means 120 and the rotation Output to the two-phase / three-phase coordinate conversion means 110.

As a result, the primary frequency can be corrected by the axis deviation compensator 160, and the direction of the excitation axis in the control device 2 and the direction of the magnetic flux axis of the induction motor 40 can be matched. Calculation can be performed accurately, and torque according to the command value can be generated.
However, in the configuration of FIG. 3, since the primary frequency compensation value Δω ₁ is obtained based on the excitation shaft induced voltage e _2d obtained using the motor parameters, when the inductance of the induction motor 40 varies depending on the operating conditions. The calculation accuracy of the primary frequency compensation value P12 deteriorates. For example, the secondary leakage inductance of the induction motor 40 varies depending on the magnitude of the secondary current. Specifically, Non-Patent Document 1 shows that, when there is a magnetic path in which magnetic saturation occurs around the rotor bar, the leakage inductance changes when the secondary current changes. Further, from the equation (2), it can be seen that the influence of the error of the leakage inductance in the calculation of the excitation axis induced voltage e _2d increases in proportion to the primary frequency ω ₁ .

  On the other hand, Non-Patent Document 2 discloses a method in which the constant of the motor is normally measured by a restraint test, but the secondary inductance of the motor can be measured even during normal operation. In this method, the secondary time constant is identified, but since the secondary time constant is a value obtained by dividing the secondary inductance by the secondary resistance value, the load current changes in a short time, and the secondary time constant If a change is observed, the change in resistance is much slower than the change in inductance, so the change in secondary time constant can be considered to be due to the change in secondary inductance.

In the method of Non-Patent Document 2, the reactive power component of the following equation (4) is used.
_{F = L r / M {(} v d -σL s d / dti d) i q - (v q -σL s d / dti q) i d} ··· (4)
However,
i _d : Excitation shaft current component when the three-phase current of the induction motor 40 is three-phase two-phase converted on fixed coordinates i _q : The three-phase current of the induction motor 40 three-phase two-phase converted on fixed coordinates Torque shaft current component v _d : Excitation shaft voltage component v _q when the three-phase current of the induction motor 40 is three-phase to two-phase converted on fixed coordinates Three-phase two-phase on the fixed coordinates of the three-phase current of the induction motor 40 Torque shaft voltage component L _s when converted: The primary inductance of the induction motor 40.

This equation (4) agrees with the following equation (5) if the secondary time constant of the induction motor 40 is equal to the secondary time constant used in the slip frequency calculation in the controller 2.
F ^* = − Mω ₁ iγ _s ² (5)
In the method of Non-Patent Document 2, the second-order time constant is identified by performing PI calculation on the difference between F in Formula (4) and F ^{* in} Formula (5). By applying the algorithm proposed in Non-Patent Document 2, it is possible to stably identify the secondary time constant when there is no load and when the primary frequency ω ₁ is low.

For this reason, even when the secondary leakage inductance changes due to the change of the load current, the secondary inductance L _r can be obtained accurately from the identified secondary time constant, and the excitation inductance M must change. Thus, the secondary leakage inductance can be accurately obtained.
JP 2000-333500 A Kazuya Ogura, Yasuhiro Yamamoto, Tomoyasu Hachiro “Nonlinear Model of Secondary Leakage Inductance in Induction Motor”, 2000 Annual Conference of the Institute of Electrical Engineers of Japan, pp. 165-168 Seiichiro Wakabayashi, Toshio Kubota, Mitsunori Matsuse “Improvement of Fixed Trace Method Algorithm for Identification of Second Order Time Constants of Induction Motors—Verification by Experimental Experiments”, 2000 Annual Conference of the Institute of Electrical Engineers of Japan, No. 167

  However, in the method disclosed in Non-Patent Document 2, when the exciting current is small and the exciting inductance M does not change even if the exciting current slightly changes, the secondary leakage inductance can be accurately obtained. When the operating point is placed in a state where the current increases and the iron core is saturated, there is a problem that the calculation accuracy of the secondary leakage inductance is deteriorated.

FIG. 5 is a cross-sectional view schematically showing the internal configuration of the induction motor.
In FIG. 5, the rotor 101 is provided with an iron core 104, a rotor bar 102 is attached to the iron core 104, and a stator winding 103 is disposed around the rotor 101.
Here, in the induction motor 40 that is vector-controlled, since the rotor bar 102 through which the maximum torque current flows is disposed in the vicinity of the position through which the excitation magnetic flux passes, it is formed around the rotor bar 102 by the torque current. A portion where the leakage flux overlaps the excitation flux is generated.

  For this reason, when the torque current increases, the leakage magnetic flux formed around the rotor bar 102 increases. However, if there is a lot of exciting magnetic flux around the rotor bar 102, magnetic saturation occurs. As a result, the magnetic flux due to the excitation current is reduced, and it is suppressed that the magnetic flux is saturated and increased by the rotor bar 102. Therefore, the secondary leakage inductance of the torque shaft and the excitation inductance in the direction of the excitation shaft are large in load current. Decreases accordingly.

Therefore, the method disclosed in Non-Patent Document 2 cannot distinguish whether the change in reactive power is due to a change in excitation inductance or a change in secondary leakage inductance. It becomes impossible to ask. In addition, the inductance values of the torque shaft and the excitation shaft need to be set to different values.
Accordingly, an object of the present invention is to provide an induction motor control device capable of measuring a change in excitation inductance in the torque axis direction and a change in secondary leakage inductance when a load is applied to the induction motor. is there.

  In order to solve the above-described problem, according to the control apparatus for an induction motor according to claim 1, the induction motor is operated based on the primary frequency determined so that the air gap magnetic flux in the torque axis direction becomes zero. Excitation inductance / secondary leakage inductance estimation means for estimating the excitation inductance in the excitation axis direction and the secondary leakage inductance in the torque axis direction based on the observed input / output values of the induction motor at the time, and the excitation inductance / secondary Excitation inductance / secondary leakage inductance storage means for storing the excitation inductance in the excitation axis direction calculated by the leakage inductance estimation means and the secondary leakage inductance in the torque axis direction is provided.

According to the control apparatus for an induction motor according to claim 2, from the excitation current command value and the torque command value, taking into account the excitation inductance in the excitation axis direction stored in the excitation inductance / secondary leakage inductance storage means. Torque current command value creating means for creating a torque current command value is provided.
According to the control device for an induction motor according to claim 3, the excitation shaft component of the induced voltage is determined by taking into account the secondary leakage inductance in the torque axis direction stored in the excitation inductance / secondary leakage inductance storage means. An axis deviation compensator is provided that calculates and calculates a primary frequency compensation value based on an angle between an axis based on the secondary magnetic flux of the induction motor and an excitation axis in the control device.

  According to the control apparatus for an induction motor according to claim 4, the excitation inductance / secondary leakage inductance estimation means is a value obtained by subtracting a voltage drop due to a primary voltage from a detected value of a voltage applied to the induction motor. The primary magnetic flux calculation means for calculating the excitation shaft primary magnetic flux and the torque shaft primary magnetic flux from the value obtained by dividing the value by the primary frequency, the torque shaft primary magnetic flux calculated by the primary magnetic flux calculation means, the torque current, and the rotational speed of the induction motor Primary frequency calculation means for calculating the primary frequency based on the relationship between the primary side and secondary side torque current when the air gap magnetic flux in the torque axis direction is zero, the values of the torque axis primary magnetic flux and the torque axis secondary magnetic flux Based on the secondary magnetic flux calculating means for calculating the secondary magnetic flux of the excitation axis, the primary magnetic flux calculated by the primary magnetic flux calculation means, and the secondary magnetic flux calculation means. The excitation axis secondary current is calculated based on the excitation axis secondary magnetic flux calculated by the means, and the excitation inductance in the excitation axis direction and the secondary leakage inductance in the torque axis direction are calculated by using the excitation axis secondary current. And an exciting inductance / secondary leakage inductance calculating means.

  As described above, according to the present invention, by observing the input / output when the induction motor is operated based on the primary frequency determined so that the air gap magnetic flux in the torque axis direction becomes zero, It is possible to measure a change in excitation inductance in the excitation axis direction and a change in secondary leakage inductance in the torque axis direction when a load is applied to the electric motor. For this reason, even when the operating point is placed in a state where the excitation current is large and the iron core is saturated, the secondary leakage inductance can be accurately calculated, and the magnetic flux calculation can be performed accurately. Therefore, torque according to the command value can be generated.

Hereinafter, an induction motor control apparatus according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a schematic configuration of a control device for an induction motor according to an embodiment of the present invention.
In FIG. 1, an induction motor 40 is connected to an inverter 10 that converts a direct current into an alternating current of variable voltage and variable frequency by a switching operation. A load 45 is connected to the rotating shaft of the induction motor 40. A control device 1 that performs switching control of the inverter 10 in a system is connected. The input side of the induction motor 40 is provided with voltage detection means 20 for detecting the AC voltage output from the inverter 10 and current detection means 30 for detecting the AC current output from the inverter 10. On the side, speed detecting means 50 for detecting the rotational speed of the induction motor 40 is provided.

Here, the induction motor control device 1 includes a torque current command value creating means 135, a current control means 100, a rotating two-phase / three-phase coordinate converting means 110, a three-phase / rotating two-phase coordinate converting means 120, a slip frequency calculation. Means 150, axis deviation compensator 165, adder 61, subtractor 62, integrator 140, excitation inductance / secondary leakage inductance estimation means 300, excitation inductance / secondary leakage inductance reference table 310, and switching means 320 are provided. Yes.
The current control means 100, the rotating two-phase / three-phase coordinate converting means 110, the three-phase / rotating two-phase coordinate converting means 120, the slip frequency calculating means 150, and the integrator 140 are the same as those in FIG.

Further, the excitation inductance / secondary leakage inductance estimation means 300 inputs / outputs the induction motor 40 when the induction motor 40 is operated based on the primary frequency determined so that the air gap magnetic flux in the torque axis direction becomes zero. Based on the observed value, it is possible to estimate the excitation inductance Mγ considering the magnetic saturation of the excitation axis and the secondary leakage inductance l _r δ in the torque axis direction. Specifically, the excitation inductance / secondary leakage inductance estimation means 300 includes an excitation current detection value P5, a torque current detection value P6, an excitation voltage detection value P7, a torque voltage detection value P8, a slip frequency P24, and a rotation speed detection value P10. Is input, and the excitation inductance Mγ in the excitation axis direction and the secondary leakage inductance l _r δ in the torque axis direction corresponding to the detected torque current value P6 are output, and the excitation inductance Mγ and the secondary leakage inductance l _r δ are estimated. Therefore, it is possible to output the primary frequency P22 necessary for this.

The excitation inductance / secondary leakage inductance reference table 310 receives the torque current detection value P6 as an input, the excitation inductance Mγ in the excitation axis direction calculated by the excitation inductance / secondary leakage inductance estimation means 300, and the secondary in the torque axis direction. The leakage inductance l _r δ can be stored in correspondence with the detected torque current value P6.
When estimating the exciting inductance Mγ and the secondary leakage inductance l _r δ, the switching unit 320 selects the primary frequency P22 necessary for estimating the exciting inductance Mγ and the secondary leakage inductance l _r δ as an output, During normal operation of the induction motor 40, the primary frequency command value P21 obtained by compensating the slip frequency P9 output from the slip frequency calculating means 150 with the primary frequency compensation value P20 calculated by the axis deviation compensator 165 is selected as an output. can do.

The torque current command value creating unit 135 considers the excitation inductance Mγ in the excitation axis direction stored in the excitation inductance / secondary leakage inductance reference table 310, and determines the torque current command value from the excitation current command value P1 and the torque command value P2. P00 can be created. The torque current command value creating means 135 is arranged so that the excitation inductance Mγ in the excitation axis direction instead of the nominal excitation inductance M in the expression (1), and the excitation inductance direction in the excitation axis direction instead of the secondary inductance L _{r in} the expression (1). By using the value L _r γ = Mγ + l _r obtained by adding the excitation inductance Mγ and the nominal secondary leakage inductance l _r , the torque current command value P00 = iδ _s ^* can be obtained by the following equation (6). it can.
iδ _s ^* = T ^* L _r γ / (pMγ ² iγ _s ^* ) (6)

The shaft misalignment compensator 165 calculates the excitation shaft component of the induced voltage by considering the secondary leakage inductance l _r δ in the torque axis direction stored in the excitation inductance / secondary leakage inductance reference table 310, and the induction motor 40 The primary frequency compensation value P20 can be calculated based on the angle between the axis based on the secondary magnetic flux and the angle of the excitation axis in the control device 1. The axis deviation compensator 165 can use the following equation (7) instead of the equation (2) when _{obtaining the} excitation axis induced voltage e _2d .
e _2d = v _1d − (R ₁ + d / dtLσ) i _1d + ω ₁ Lσ ₂ i _1q (7)
However, in the last term of equation (7), Lσ ₂ = (1−M ² / (L _r σL _s )) L _s , L _r σ = M + l _r δ, and the leakage flux of the torque axis magnetic flux is calculated. In addition, the secondary leakage inductance l _r δ of the torque shaft can be used.

The adder 61 can calculate the primary frequency command value P21 by adding the slip frequency P9 output from the slip frequency calculating means 150 and the primary frequency compensation value P20 calculated by the axis deviation compensator 165. it can.
The subtractor 62 can calculate the slip frequency P24 by subtracting the rotational speed detection value P10 from the primary frequency P22 output from the exciting inductance / secondary leakage inductance estimating means 300.

In the embodiment of FIG. 1, the method of providing the voltage detection means 20 for detecting the AC voltage output from the inverter 10 has been described. However, the output voltage of the inverter 10 is determined from the voltage command value applied to the inverter 10. If accurate calculation is possible, voltage estimation means for estimating the output voltage of the inverter 10 from the voltage command value may be provided instead of the voltage detection means 20.
When the excitation inductance Mγ and the secondary leakage inductance l _r δ are estimated, the switching unit 320 selects the primary frequency P22 output from the excitation inductance / secondary leakage inductance estimation unit 300 as an output.

  When the induction motor 40 is operated with the load 45 applied and is in a steady state, the excitation current detection value P5 and the torque current detection value P6 calculated by the three-phase / rotation two-phase coordinate conversion means 120 are assumed. The excitation voltage detection value P7 and the torque voltage detection value P8 are input to the excitation inductance / secondary leakage inductance estimation means 300, and the rotational speed detection value P10 detected by the speed detection means 50 is the excitation inductance / secondary leakage. Input to the inductance estimation means 300.

  Then, the excitation inductance / secondary leakage inductance estimating means 300 determines the primary frequency P22 so that the air gap magnetic flux in the torque axis direction becomes zero. Then, the primary frequency P22 determined by the excitation inductance / secondary leakage inductance estimation means 300 is output to the integrator 140 via the switching means 320, and the primary frequency P22 is integrated by the integrator 140. After the phase angle P23 is calculated, it is output to the rotating two-phase / three-phase coordinate converting means 110 and the three-phase / rotating two-phase coordinate converting means 120.

Then, the excitation inductance / secondary leakage inductance estimation means 300 detects the excitation current detection value P5 when the induction motor 40 is operated based on the primary frequency P22 determined so that the air gap magnetic flux in the torque axis direction becomes zero. By using the torque current detection value P6, the excitation voltage detection value P7, and the torque voltage detection value P8, the excitation inductance Mγ in the excitation axis direction and the secondary leakage inductance l _r δ in the torque axis direction are estimated, and these excitation inductances Mγ. And the secondary leakage inductance l _r δ are stored in the excitation inductance / secondary leakage inductance reference table 310.

And when performing the normal driving | operation of the induction motor 40, the switching means 320 selects the primary frequency command value P21 output from the adder 61 as an output. The excitation current command value P1 and the torque command value P2 are input to the torque current command value creating unit 135, and the excitation current command value P1 is input to the current control unit 100. Further, the torque current detection value P6 calculated by the three-phase / rotation two-phase coordinate conversion means 120 is input to the excitation inductance / secondary leakage inductance reference table 310, and the excitation inductance / secondary leakage inductance reference table 310 stores the torque. The excitation inductance Mγ corresponding to the detected current value P6 is input to the torque current command value creating means 135, and the secondary leakage inductance l _r δ corresponding to the detected torque current value P6 is input to the axis deviation compensator 165.

When the excitation current command value P1, the torque command value P2, and the excitation inductance Mγ are input to the torque current command value creation unit 135, the torque current command value creation unit 135 performs torque calculation by performing the calculation of equation (6). A current command value P00 is created and output to the current control means 100.
Further, the three-phase / rotational two-phase coordinate conversion means 120 converts the detected value of the three-phase current into the excitation current detection value P5 and the torque current detection value P6 based on the phase angle P23 output from the integrator 140, In addition to outputting to the current control means 100, the slip frequency calculating means 150, and the axis deviation compensator 165, the detected value of the three-phase voltage is converted into the excitation voltage detection value P7 and the torque voltage detection value P8, and output to the axis deviation compensator 165. To do.

  The current control means 100 receives the excitation current detection value P5 and the torque current detection value P6 from the three-phase / rotation two-phase coordinate conversion means 120, receives the torque current command value P00 from the torque current command value creation means 135, When the current command value P1 is received from the outside, the excitation shaft voltage command value P3 and the torque are determined based on the deviations between the excitation current detection value P5 and the torque current detection value P6 and the excitation current command value P1 and the torque current command value P00. The shaft voltage command value P4 is calculated and output to the rotating two-phase / three-phase coordinate conversion means 110.

When the rotating two-phase / three-phase coordinate conversion means 110 receives the excitation shaft voltage command value P3 and the torque shaft voltage command value P4 from the current control means 100, the rotation two-phase / three-phase coordinate conversion means 110, based on the phase angle P23 output from the integrator 140, Excitation shaft voltage command value P3 and torque shaft voltage command value P4 are converted into a three-phase voltage command and output to inverter 10.
Further, when the slip frequency calculation means 150 receives the excitation current detection value P5 and the torque current detection value P6 from the three-phase / rotation two-phase coordinate conversion means 120, the value obtained by dividing the torque current detection value P6 by the excitation current detection value P5. Is multiplied by the reciprocal of the secondary time constant to calculate the slip frequency P9 and output it to the adder 61.

Further, the axis deviation compensator 165 receives the secondary leakage inductance l _r δ from the excitation inductance / secondary leakage inductance reference table 310 and outputs the excitation current detection value P5, the torque current detection value P6, and the excitation voltage detection value P7. When received from the phase / rotation two-phase coordinate conversion means 120, the primary frequency compensation value P <b> 20 is calculated by performing the calculations of the equations (7) and (3), and is output to the adder 61.

  When the adder 61 receives the slip frequency P9 from the slip frequency calculating means 150 and receives the primary frequency compensation value P20 from the axis deviation compensator 165, the adder 61 adds the slip frequency P9 and the primary frequency compensation value P20. The primary frequency command value P21 is calculated and output to the integrator 140 via the switching means 320. When the integrator 140 receives the primary frequency command value P21 from the adder 61, the integrator 140 integrates the primary frequency command value P21 to calculate the phase angle P23, and the three-phase / rotation two-phase coordinate conversion means 120 and the rotation Output to the two-phase / three-phase coordinate conversion means 110.

Thereby, when the load is applied to the induction motor 40 by observing the input / output when the induction motor 40 is operated based on the primary frequency determined so that the air gap magnetic flux in the torque axis direction becomes zero. It is possible to measure the change in the excitation inductance Mγ in the excitation axis direction and the change in the secondary leakage inductance l _r δ in the torque axis direction. For this reason, even when the operating point is placed in a state where the excitation current increases and the iron core is saturated, the secondary leakage inductance can be accurately calculated, and the magnetic flux calculation can be performed accurately. Therefore, torque according to the command value can be generated.

FIG. 2 is a block diagram showing a schematic configuration of the exciting inductance / secondary leakage inductance estimating means of FIG.
In FIG. 2, the exciting inductance / secondary leakage inductance estimating means 300 is provided with a primary magnetic flux calculating means 400, a primary frequency calculating means 410, a secondary magnetic flux calculating means 420, and an exciting inductance / secondary leakage inductance calculating means 430. Yes.
In the following description, since the excitation current does not change, it is assumed that the primary leakage inductance l _s and the secondary leakage inductance l _r γ in the excitation axis direction do not change much from the nominal values. In addition, the induction motor 40 is operated with a load 45 applied and is in a steady state.

Here, the primary magnetic flux calculation means 400 uses the primary frequency obtained by subtracting the voltage drop due to the primary resistance from the excitation voltage detection value P7 and torque voltage detection value P8 output from the three-phase / rotation two-phase coordinate conversion means 120. it is possible to calculate the excitation axis primary flux Ramudaganma _s and torque shaft primary flux Ramudaderuta _s from a value obtained by dividing. Specifically, the primary magnetic flux calculation means 400, by performing the calculation of the following equation (8), it is possible to calculate the excitation axis primary flux Ramudaganma _s and torque shaft primary flux λδ _{s.
λγ s = (vδ s -R s} iδ s) / ω 1, λδ s = - (vγ s -R s iγ s) / ω 1 ··· (8)
However,
vγ _s : excitation voltage detection value v δ _s : torque voltage detection value i γ _s : excitation shaft primary current i δ _s : torque shaft primary current R _s : primary resistance.

Primary frequency calculating means 410 calculates the deviation (λδ _s -l _{s iδ s)} from the primary magnetic flux calculation means 400 torque axis primary flux Ramudaderuta _s and a torque-axis primary current i? _S calculated in the deviation (λδ _s - The primary frequency ω ₁ can be calculated by adding the value obtained by PI calculation of l _s iδ _s ) to the rotation speed value. Specifically, the primary frequency calculation means 410 can calculate the primary frequency ω ₁ by performing the calculation of the following equation (9).
_{ω 1 = K p (λδ s} -l s iδ s) + K i ∫ (λδ s -l s iδ s) + ω re ··· (9)
However,
l _s : primary leakage inductance K _p : proportional gain K _i : integral gain ω _re : rotational speed

Thus, by controlling the primary frequency ω _1, the torque shaft primary flux Ramudaderuta _s converges to l _s i? _S, the air gap flux Ramudaderuta _m of torque shaft converges to zero. At this time, the magnitude of the torque axis primary current i? _S and torque shaft secondary current i? _R will be equal, satisfy the relationship of iδ _s = -iδ _r. Further, the torque shaft secondary magnetic flux λδ _r becomes equal to l _r δiδ _s .
Secondary flux calculation means 420, the relationship of the torque axis of the air gap flux Ramudaderuta _m torque axis primary current i? _S and torque shaft secondary current i? _R when the zero torque axis primary flux Ramudaderuta _s and torque shaft secondary based on the value of the magnetic flux λδ _r, it can be calculated excitation axis secondary flux Ramudaganma _r from the value divided by the slip frequency value obtained by multiplying the secondary resistance and the torque current.

Here, the excitation shaft primary magnetic flux λγ _s and the excitation shaft secondary magnetic flux λγ _r can be _expressed by the following equations (10) and (11), respectively.
_{λγ s = Mγiγ r + L s} iγ s = Mγiγ m + l s iγ s ··· (10)
_{λγ r = Mγiγ s + L r} γiγ r = Mγiγ m + l r γiγ r ··· (11)
However,
iγ _m = iγ _s + iγ _r
iγ _s : exciting shaft primary current i γ _r : exciting shaft secondary current l _r γ: secondary leakage inductance of the exciting shaft.
The values of the excitation shaft primary magnetic flux λγ _s and the excitation shaft secondary magnetic flux λγ _r include the excitation inductance Mγ that changes as the torque current increases, but the excitation shaft primary magnetic flux λγ _s and the excitation shaft secondary magnetic flux λγ. _{Since r} can be calculated observably, the excitation inductance Mγ can be calculated.

Exciting inductance and secondary leakage inductance computing means 430, based on the primary magnetic flux calculation means 400 excitation axis primary flux calculated in Ramudaganma _s and the secondary magnetic flux calculation means exciting axis two calculated at 420 rotor flux Ramudaganma _r By calculating the excitation shaft secondary current iγ _r and using the excitation shaft secondary current, the excitation inductance Mγ in the excitation axis direction and the secondary leakage inductance l _r δ in the torque axis direction can be calculated. Specifically, the excitation inductance / secondary leakage inductance calculation means 430 performs the calculation of the following equation (12) using the equations (10) and (11), thereby obtaining the excitation shaft secondary current iγ _r. Further, the excitation inductance Mγ can be calculated.
_{iγ r = (λγ r - (} λγ s -l s iγ s)) / l r γ, Mγ = (λγ s -l s iγ s) / iγ m
(12)

Further, by using the excitation shaft secondary current iγ _r , the secondary leakage inductance l _r δ in the torque axis direction can be calculated by the following equation (13).
l _r δ = −R _r iγ _r / ω _se iδ _s (13)
Then, in accordance with the operation range of the induction motor 40, an operation is performed in which torque currents having different magnitudes are passed, and the excitation inductance Mγ and the secondary leakage inductance l _r for each torque current are calculated by the equations (12) and (13). After obtaining δ, it can be stored in the excitation inductance / secondary leakage inductance reference table 310.

Alternatively, if the operating range of the induction motor 40 is unknown, the torque control of the induction motor 40 can be performed using the primary frequency output from the excitation inductance / secondary leakage inductance estimation means 300, and therefore this primary frequency is used. While operating the induction motor 40, the excitation inductance Mγ and the secondary leakage inductance l _r δ for each torque current are obtained by the calculations of the equations (12) and (13), and the excitation inductance / secondary leakage inductance reference table 310 is obtained. You may make it store in.
When the excitation inductance Mγ and the secondary leakage inductance l _r δ for each torque current are stored in the excitation inductance / secondary leakage inductance reference table 310, the primary output from the adder 61 by switching the switching means 320. The frequency command value P21 can be input to the integrator 140 to perform normal operation of the induction motor 40.

It is a block diagram which shows schematic structure of the control apparatus of the induction motor which concerns on one Embodiment of this invention. It is a block diagram which shows schematic structure of the excitation inductance and secondary leakage inductance estimation means of FIG. It is a block diagram which shows schematic structure of the control apparatus of the conventional induction motor. FIG. 4 is a block diagram illustrating a schematic configuration of the axis deviation compensator of FIG. 3. It is sectional drawing which shows the internal structure of an induction motor typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Control apparatus of induction motor 10 Inverter 20 Voltage detection means 30 Current detection means 40 Induction motor 45 Load 50 Speed detection means 61 Adder 62 Subtractor 100 Current control means 110 Rotating two-phase / three-phase coordinate conversion means 120 Three-phase / Rotation Two-phase coordinate conversion means 135 Torque current command value creation means 140 Integrator 150 Slip frequency calculation means 165 Axis offset compensator 300 Excitation inductance / secondary leakage inductance estimation means 310 Excitation inductance / secondary leakage inductance reference table 320 Switching means 400 Primary 400 Magnetic flux calculation means 410 Primary frequency calculation means 420 Secondary magnetic flux calculation means 430 Excitation inductance / secondary leakage inductance calculation means

Claims (4)

Excitation inductance and torque in the excitation axis direction based on the observed values of input and output of the induction motor when the induction motor is operated based on the primary frequency determined so that the air gap magnetic flux in the torque axis direction becomes zero Exciting inductance / secondary leakage inductance estimating means for estimating the axial secondary leakage inductance,
An excitation inductance / secondary leakage inductance storage means for storing the excitation inductance in the excitation axis direction calculated by the excitation inductance / secondary leakage inductance estimation means and the secondary leakage inductance in the torque axis direction is provided. Induction motor controller.   Torque current command value creation means for creating a torque current command value from the excitation current command value and the torque command value while taking into account the excitation inductance in the excitation axis direction stored in the excitation inductance / secondary leakage inductance storage means. The control apparatus for an induction motor according to claim 1.   Axis deviation for calculating the primary frequency compensation value based on the value calculated for the excitation axis component of the induced voltage by considering the secondary leakage inductance in the torque axis direction stored in the excitation inductance / secondary leakage inductance storage means 3. The induction motor control apparatus according to claim 1, further comprising a compensator. The exciting inductance / secondary leakage inductance estimating means is:
Primary magnetic flux calculation means for calculating the excitation axis primary magnetic flux and the torque axis primary magnetic flux from the value obtained by subtracting the voltage drop due to the primary voltage from the detected value of the voltage applied to the induction motor and dividing by the primary frequency;
Primary frequency calculation means for calculating a primary frequency based on the torque shaft primary magnetic flux calculated by the primary magnetic flux calculation means, torque current and the rotation speed of the induction motor;
Secondary that calculates the excitation shaft secondary magnetic flux based on the relationship between the torque current on the primary side and the secondary side when the air gap magnetic flux in the torque axis direction is zero, the value of the torque shaft primary magnetic flux and the torque shaft secondary magnetic flux Magnetic flux calculation means;
An excitation axis secondary current is calculated based on the excitation axis primary flux calculated by the primary flux calculation means and the excitation axis secondary flux calculated by the secondary flux calculation means, and the excitation axis secondary current is calculated. 4. An excitation inductance / secondary leakage inductance calculation means for calculating an excitation inductance in the excitation axis direction and a secondary leakage inductance in the torque axis direction by using the excitation inductance and the secondary leakage inductance calculation means. Induction motor controller.

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