JP6641445B2 - Power converter control method and power converter - Google Patents

Description

  The present invention relates to drive control of a power converter that drives an induction motor, and more particularly to a power converter that drives an induction motor with high accuracy during regenerative operation.

  As a control method during the regenerative operation of the induction motor, as described in JP-A-8-317698, during the regenerative operation, the frequency or voltage is corrected so that the q-axis secondary magnetic flux has a negative value, thereby changing the magnetic flux. There is a description of a technique for preventing a decrease in torque due to a torque and suppressing a torque shortage.

JP-A-8-317698

In the method described in JP-A-8-317698, robustness is ensured because the q-axis secondary magnetic flux has a negative value during regenerative operation. However, since it deviates from the ideal state of the vector control (q-axis secondary magnetic flux = 0), there is a problem that the control characteristics with respect to the speed command value deteriorate during the regenerative operation.
Therefore, an object of the present invention is to provide a control method of a power conversion device and a power conversion device capable of stably achieving high-precision speed control characteristics even during regenerative operation.

The method of the power conversion device of the present invention, the operation section, at least in the low speed range, to generate a torque by the current of the q axis is the magnetic flux and the torque shaft generated by the current of the d-axis is a magnetic flux axis component, d Calculating a d- axis voltage command value and a q- axis voltage command value so as to maintain the q-axis secondary magnetic flux estimated value calculated based on the axis voltage correction value and the speed estimated value at a predetermined value; A calculating unit for controlling the power converter based on the d- axis voltage command value and the q- axis voltage command value.
Further, the power converter of the present invention generates a torque by a magnetic flux generated by a d- axis current that is a magnetic flux axis component and a q- axis current that is a torque axis, at least in a low speed range, and a d-axis voltage correction value And a calculating unit for calculating a d- axis voltage command value and a q- axis voltage command value so as to maintain a q-axis secondary magnetic flux estimated value calculated based on the speed estimation value at a predetermined value. Controls itself based on the d- axis voltage command value and the q- axis voltage command value.

  According to the present invention, even during regenerative operation, it is possible to stably provide high-precision speed control characteristics.

FIG. 1 is a configuration diagram of a power conversion device according to an embodiment. Load operation characteristics when using the conventional technology. FIG. 2 is a configuration diagram of a frequency correction calculation unit according to the embodiment. FIG. 3 is a configuration diagram of a correction operation unit according to the embodiment. 4 shows a load operation characteristic according to the embodiment. FIG. 3 is a configuration diagram of a correction operation unit according to the embodiment. FIG. 3 is a configuration diagram of a correction operation unit according to the embodiment. FIG. 3 is a configuration diagram of a correction operation unit according to the embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 2 is a configuration diagram of a frequency correction calculation unit according to the embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment. FIG. 1 is a configuration diagram of a power converter according to an embodiment.

  Hereinafter, this embodiment will be described in detail with reference to the drawings. In addition, the same reference numerals are given to the common components in each drawing. Further, each embodiment described below is not limited to the illustrated example.

<First embodiment>
FIG. 1 illustrates a configuration diagram of a power conversion device according to an embodiment. The induction motor 1 generates a torque by a magnetic flux generated by a current of a magnetic flux axis (d-axis) component and a current of a torque axis (q-axis) component orthogonal to the magnetic flux axis. Power converter 2, the voltage command value of three-phase AC V _u ^*, V _v ^*, and outputs a voltage value proportional to V _w ^*, varies the output voltage value of the induction motor 1 and the rotation frequency value. The DC power supply 2a supplies a DC voltage to the power converter 2.

The current detector 3 outputs detection values I _uc , I _vc , and I _wc of three-phase AC currents I _u , I _v , and I _w of the induction motor 1. The current detector 3 detects two of the three phases of the induction motor 1, for example, U-phase and W-phase line currents, and detects the V-phase line currents under the AC condition (I _u + I _v + I _w = 0). ) _May be obtained as I _v = − (I _u + I _w ). The coordinate conversion unit 4 detects the d-axis and q-axis current detection values I _dc , I _dc from the detected values I _uc , I _vc , I _wc of the three-phase alternating currents I _u , I _v , I _w and the phase estimation value θ _{dc. Outputs qc} .

The speed estimation calculation unit 5 includes a d-axis current command value I _d ^* , a q-axis voltage command value V _qc ^** , a q-axis current detection value I _qc , an output frequency value ω ₁ ^**, and an electric motor of the induction motor 1. An estimated speed ω _r ^{^} of the induction motor 1 is output based on constants (R ₁ , R ₂ ′, M, L ₂ , φ _2d ^* ). The slip frequency calculator 6 calculates the slip frequency command value ω _s ^* of the induction motor 1 based on the d-axis and q-axis current command values I _d ^* and I _q ^* and the secondary time constant T ₂ of the induction motor 1. Output.

The addition unit 7 outputs an output frequency value ω ₁ ^* which is an addition value of the estimated speed value ω _r ^{^} and the slip frequency command value ω _s ^* . The frequency correction calculation unit 8 outputs a correction value Δω of the output frequency value ω ₁ ^* based on the d-axis voltage correction value ΔV _d ^* and the estimated speed value ω _r ^{^} .

The subtraction unit 9 outputs a new output frequency command value ω ₁ ^** which is a subtraction value between the output frequency value ω ₁ ^* and the correction value Δω of the output frequency value. The phase estimation calculation unit 10 integrates a new output frequency value ω ₁ ^** to output a phase estimation value _θdc .

The d-axis current command setting unit 11 outputs a d-axis current command value I _d ^* that is “positive”. In the constant torque region, the d-axis current command value _Id ^* is set or controlled to a constant value. In the constant output region, I _d ^* is set or controlled variably with respect to torque and rotation speed. Speed control calculation unit 12 outputs the current command value I _q ^* of the q-axis from the speed command value omega _r ^* and estimated speed value omega _r ^{^} deviation ^{_{(ω r * -ω r ^)}} .

Vector control calculating unit 13, the electrical constants of the induction motor _{1 (R 1, L σ,} M, L 2) and the current command value I _d ^*, based on the I _q ^* and the output frequency value omega ₁ ^**, d-axis And q-axis voltage reference values V _dc ^* and V _qc ^* . The d-axis current control calculation unit 14 outputs a d-axis voltage correction value ΔV _d ^* from a deviation (I _d ^* −I _dc ) between the d-axis current command value I _d ^* and the current detection value I _dc .

The q-axis current control calculator 15 outputs a q-axis voltage correction value ΔV _q ^* from a deviation (I _q ^* −I _qc ) between the q-axis current command value I _q ^* and the current detection value I _qc . Addition unit 16 outputs the voltage instruction value V _dc ^** is the sum of the voltage correction value [Delta] V _d ^* of the voltage reference value V _dc ^* and the d-axis of the d-axis.

The adder 17 outputs a voltage command value V _qc ^** which is an addition value of the q-axis voltage reference value V _qc ^* and the q-axis voltage correction value ΔV _q ^* . Coordinate converter 18, the voltage command value V _dc ^**, V _qc ^** and phase estimates θ voltage command values of the three-phase alternating current from the ^{_{dc V u *, V v *}} , and outputs the V _w ^*.

  First, a basic operation of the speed sensorless control method in the case where the frequency correction operation unit 8 is not used, which is a feature of the present embodiment, will be described.

The d-axis current command setting unit 11 outputs a current command value I _d ^* required to generate the d-axis secondary magnetic flux value φ _2d of the induction motor 1. Further, the speed control calculation unit 12 calculates the q-axis current command value I _q ^* by the calculation shown in (Equation 1) so that the speed estimation value ω _r ^{^} matches or approaches the speed command value ω _r ^* .

In (Equation 1), when the speed control calculation unit has a proportional control configuration (Kp _ASR ≠ 0, Ki _ASR = 0), the speed estimated value ω _r ^{^} approaches the speed command value ω _r ^* (steady deviation: ω _r ^*). −ω _r ^{^} ≠ 0), and in the case of the proportional integral control configuration (Kp _ASR ≠ 0, Ki _ASR ≠ 0), the speed estimation value ω _r ^{^} matches the speed command value ω _r ^* by the integration operation ( steady-state ^{_{error: ω r * -ω r ^ =}} 0) to follow so. Whether the speed control calculation unit has a proportional control configuration or a proportional-integral control configuration is determined by the applied system and the stability of the system.

here,
Kp _ASR : Proportional gain for speed control, Ki _ASR : Integral gain for speed control In the vector control calculation unit 13, the d-axis and q-axis current command values I _d ^* and I _q ^* and the electric constants (R ₁ , L _σ , M, L ₂ ), d-axis secondary magnetic flux command value φ _2d ^*, and output frequency value ω ₁ ^**, and voltage reference values V _dc ^* , V _qc ^* shown in ( _Equation 2) are _obtained ^. Calculate.

here,
T _ACR : current control delay time constant
R ₁ : Primary resistance value, L _σ : Leakage inductance value, M: Mutual inductance value
L ₂ : Secondary inductance value
The d-axis current control calculator 14 receives the d-axis current command value I _d ^* and the current detection value I _dc , and the q-axis current control calculator 15 includes a q-axis current command value I _q ^*. And the current detection value I _qc are input. Here, according to ( _{Equation 3} ), (proportional + integral) calculation is performed so that the current detection values I _dc and I _qc of the respective components follow the current command values I _d ^* and I _q ^* , and the d-axis and q The axis voltage correction values ΔV _d ^* and ΔV _q ^* are output.

here,
K _pdACR : Proportional gain for d-axis current control, K _idACR : Integral gain for d-axis current control
K _pqACR : Proportional gain for q-axis current control, K _iqACR : Integral gain for q-axis current control Further, in addition sections 16 and 17, voltage command values V _dc ^** and V _qc ^** shown in ( _Equation 4) Is calculated, and the output of the power converter 2 is controlled.

In addition, the speed estimation calculation unit 5 estimates the speed of the induction motor 1 using (Equation 5). In this speed estimation calculation, an induced voltage value of the q-axis is estimated by a disturbance observer, and ω _r ^{^} is calculated by dividing by a magnetic flux coefficient.

here,
R2 ': Primary resistance value of secondary resistance
T _obs : speed estimation delay time constant set in the disturbance observer The slip frequency calculator 6 calculates the slip frequency command value ω _s ^* of the induction motor 1 according to (Equation 6).

here,
T ₂ : Secondary time constant value Further, the adding unit 7 calculates the output frequency value ω ₁ ^* shown in (Equation 7) using the estimated speed value ω _r ^{^} and the slip frequency command value ω _s ^* .

The phase estimation calculation unit 8 estimates the phase θ _d of the magnetic flux axis of the induction motor 1 according to (Equation 8).

The criteria for controlling the phase estimates theta _dc is an estimate of the phase theta _d of the magnetic flux axis, running sensorless control operation. The above is the basic operation.

  Hereinafter, control characteristics in the case where the frequency correction calculation unit 8 which is a feature of the present embodiment is used will be described.

  FIG. 2 shows a simulation result of a load operation characteristic in the case of using Japanese Patent Application Laid-Open No. Hei 8-317698.

In a state where the speed of the induction motor 1 is controlled at 10% of the rated speed, a ramp-shaped regenerative torque τ _L is applied from point A to point B to −200%. Secondary flux phi _2q of the induction motor 1 inside the q-axis generated in the "negative", while the secondary magnetic flux phi _2d of d axis is increased by "positive", the actual speed value omega _r is the speed command value omega _r ^* lower than it can be seen that a steady rate deviation [Delta] [omega _r a later point B shown in FIG occurring.

  That is, in the regenerative operation, there is a problem that the speed control characteristics deteriorate. Here, the speed control characteristic can be improved by using the frequency correction calculation unit 8, which is a feature of the present embodiment. Hereinafter, this will be described.

  FIG. 3 shows a block diagram of the frequency correction calculation unit 8 according to the embodiment.

In the secondary magnetic flux computation portion 8a of the q-axis, d-axis voltage correction value [Delta] V _d ^* and the speed estimated value omega _r ^{^} is input, calculates q-axis secondary magnetic flux estimated value phi _2q ^{^} from equation (9) .

The q-axis secondary magnetic flux command setting unit 8b outputs a q-axis secondary magnetic flux command value φ _2q ^* .

The subtraction unit 8c outputs Δφ _2q ^{^} which is a deviation between the estimated secondary magnetic flux value φ _2q ^{^} of the q-axis and the secondary magnetic flux command value φ _2q ^* of the q-axis.

The correction calculator 8d calculates and outputs a correction value Δω of the output frequency value so as to suppress Δφ _2q ^{^} . Here, the configuration of the correction calculation unit 8d will be described.

FIG. 4 shows a case where the correction operation unit is configured by (proportional + integral). [Delta] [phi _2q ^{^} is deviation between the secondary flux command value phi _2q ^* of the secondary flux estimation value phi _2q ^{^} and q-axis of the q-axis, a proportional operation unit 8d1 with constants K _p, the constants K _i1 And the output signals thereof are input to the adder 8d3.

  That is, the correction value Δω of the output frequency value is calculated by the calculation shown in (Equation 10).

FIG. 5 shows a simulation result of the load operation characteristics according to the present embodiment (the load conditions used in FIG. 2 are set). Comparing the results of the load characteristics disclosed in FIG. 2 and FIG. 5, it can be seen that in the case of the control using the frequency correction calculation unit 8 which is a feature of the present embodiment, two axes of the d-axis and the q-axis inside the induction motor in the figure are used. The accuracy of both the secondary magnetic flux values φ _2d and φ _2q is remarkably improved, and the steady speed deviation Δω _r = 0 of the actual speed value ω _r of the induction motor (speed command value ω _r ^* = actual speed value ω _r ). The effect of the frequency correction calculator 8 of the present embodiment is clear.

That is, by calculating the secondary magnetic flux value φ _2q of the q axis from the voltage correction value ΔV _d ^{* of} the d axis and correcting the output frequency value ω ₁ ^* , a feedback loop related to the generation of φ _2q is added. This is a feature of the present embodiment, and a more accurate speed control can be realized as compared with FIG.

Further, in the above embodiment, in the correction calculation unit 8d in the frequency correction calculation unit 8, the calculation configuration is (proportional + integral). However, as shown in FIG. Further, it may be configured to integrate. 8d1, 8d2, 8d3 in the figure are the same as those in FIG. In the configuration of FIG. 6, it is added to the addition unit 8d5 and the integration unit 8d4 having a constant of K _i2. The output signal of the integration operation unit 8d4 is added to the output signal of the addition unit 8d3 which is the output of FIG.

  That is, the correction value Δω of the output frequency value is calculated by (Equation 11).

With such a configuration, the action of bringing the q-axis secondary magnetic flux estimated value φ _2q ^{^} closer to the q-axis secondary magnetic flux command value φ _2q ^* is increased. That is, the stability of the feedback loop relating to the suppression of the secondary magnetic flux value φ _{2q on} the q-axis can be improved, and stable operation with little torque fluctuation can be realized.

Further, in the correction calculation unit 8d in the frequency correction calculation unit 8, the gains (K _p , K _i1 , K _i2 ) of the proportional calculation and the integration calculation are set to fixed values. It may be changed according to the value ω _r ^{^} .

8d ′ in FIGS. 7 and 8 correspond to 8d in FIGS. 4 and 6, respectively. In FIG. 7, Δφ _2q ^{^,} which is the deviation between the q-axis secondary magnetic flux estimated value φ _2q ^{^} and the q-axis secondary magnetic flux command value φ _2q ^* , changes according to the magnitude of the speed estimated value ω _r ^{^.} is inputted to the integration unit 8d'2 with proportional operation unit 8d'1 and K _I'1 with K _p 'to be, they are added by the adding unit 8D'3, the correction value Δω of the output frequency value .

8d'1, 8d'2, 8d'3 in FIG. 8 are the same as those in FIG. In the configuration of FIG. 8, an integral operation unit 8d′4 having an _Ki′2 that changes according to the magnitude of the estimated speed value ω _r ^{^} and an addition unit 8d′5 are added. The output signal of the integration operation unit 8d'4 is added to the output signal of the addition unit 8d'3 which is the output of FIG.

7 and 8, by changing K _{p ′} , K _i′1 and K _i′2 substantially in proportion to the speed estimation value ω _r ^{^} , the secondary magnetic flux estimation value φ of the q-axis _The action of bringing _2q ^{^} closer to the q-axis secondary magnetic flux command value φ _2q ^* changes according to the speed. In other words, the stability of the feedback loop relating to the generation of the secondary magnetic flux value φ _2q of the q-axis can be improved from the low speed range to the high speed range of the induction motor, and operation with less torque fluctuation can be realized. .

  Further, as a switching element constituting the power converter 2 of the present embodiment, even a Si (silicon) semiconductor element, a wide band gap semiconductor element such as SiC (silicon carbide) or GaN (gallium nitride) is used. There may be.

<Second embodiment>
FIG. 9 is a configuration diagram of the power converter according to the embodiment. In the first embodiment, the q-axis secondary magnetic flux command value inside the frequency correction calculation unit 8 is set to a fixed value. However, the present embodiment is a method of changing the q-axis secondary magnetic flux command value. In the figure, 1 to 7, 9 to 18, and 2a are the same as those in FIG.

The frequency correction calculator 8 ′ outputs a correction value Δω of the output frequency value ω ₁ ^* based on the d-axis voltage correction value ΔV _d ^* , the speed estimation value ω _r ^{^,} and the q-axis current command value I _q ^*. I do.

  FIG. 10 shows the configuration of the frequency correction operation unit 8 '. 8a, 8c and 8d are the same as the frequency correction calculation unit 8 in the first embodiment.

8e is a driving mode judging unit of the power running / regeneration, if the current command value I _q ^* and the estimated speed value omega _r ^{^} is the same sign of the q-axis, it is determined that power running operation to "0", and I _q ^* If ω _r ^{^} has a different sign, it is determined that regenerative operation is being performed, and “1” is output. 8b 'is a q-axis secondary magnetic flux command setting unit. In 8b', when the output of 8e is "0": φ _2q ^* is zero, and when the output of 8e is "1": φ _2q ^* is zero. Alternatively, a value having the same polarity as the q-axis current command value I _q ^* is set. That is, during regenerative operation, by setting or controlling φ _2q ^* to a constant value having the same sign as I _q ^* , speed control with high accuracy and high robustness can be realized.

Here, at the time of regenerative operation, phi _2q ^* a was a constant value of the same sign as I _q ^{*, φ} _2q ^* size may constitute a setting error [Delta] R ₁ and power converter of the primary resistance of the induction motor 1 This is related to the error voltage value when performing the dead time compensation of the switching element.

If the set value and the actual value match, φ _2q ^* = 0 is sufficient, but in consideration of the setting error in advance, for example, φ _2q ^* Then, more stable operation can be realized. The above value of φ _2q ^* is an example, and is not limited to this value.

<Third embodiment>
FIG. 11 is a configuration diagram of the power converter according to the embodiment. In the first embodiment, the output frequency value ω ₁ ^* is corrected from the output value of the frequency correction calculation unit 8, but in the present embodiment, the speed estimation value ω _r ^{^} is corrected. In the figure, 1 to 8, 10 to 18 and 2a are the same as those in FIG.

Subtraction unit 9 'outputs a new estimated speed omega _r ^{^^} minus the frequency offset Δω from the calculated estimated speed omega _r ^{^.} The speed control calculator 12 calculates the q-axis current command value I _q ^* such that the speed estimated value ω _r ^{^^} matches or approaches the speed command value ω _r ^* .

  That is, by correcting the estimated speed value instead of the output frequency value, high-precision speed control can be realized similarly to the first embodiment, and the same effect can be obtained.

<Fourth embodiment>
FIG. 12 is a configuration diagram of the power converter according to the embodiment. In the first to third embodiments, one secondary magnetic flux command value φ _2q ^* of the q-axis set in the correction operation unit 8d of the frequency correction operation unit 8 is set, but in the present embodiment, the q-axis Set two secondary magnetic flux command values. In the figure, 1 to 7, 9 to 18, and 2a are the same as those in FIG.

_Step 19 sets two secondary magnetic flux command setting values ( _φ2q1 ^* , _φ2q2 ^* ) of the q-axis. For example, the first q-axis secondary magnetic flux command set value φ _2q1 ^* is zero, and the second q-axis secondary magnetic flux command set value φ _2q2 ^* has the same polarity as the q-axis current command value I _q ^*. Set a value less than or equal to the secondary magnetic flux command φ _2d ^{* of} the d-axis.

In the frequency calculation unit 8 '', first, the actual operation is performed by setting the q-axis secondary magnetic flux command value to the first q-axis secondary magnetic flux command value ( _φ2q1 ^* ). If an overcurrent trip occurs, the q-axis secondary magnetic flux command value is automatically changed to the second q-axis secondary magnetic flux command value (φ _2q2 ^* ) at the next calculation timing. With such a configuration, an optimal q-axis secondary magnetic flux command value can be set.

  Further, in the present embodiment, as the secondary magnetic flux command value of the q-axis, a method of controlling using two set values that are the first set value and the second set value has been described, but three or more set values The control may be performed by using. In this way, by providing several q-axis secondary magnetic flux command values, stable and highly accurate speed control can be realized in any load torque state (torque magnitude and inclination).

<Fifth embodiment>
FIG. 13 is a configuration diagram of the power converter according to the embodiment. In the present embodiment, the present embodiment is applied to an induction motor driving system. In the figure, components 1 to 18 and 2a are the same as those in FIG.

  The induction motor 1 as a component of FIG. In the power converter 20, 1 to 18 and 2a in FIG. 1 are implemented as software and hardware.

The secondary magnetic flux command value of the q-axis (φ _2q ^* , φ _2q1 ^* , φ 2 q ₁ ^* , and the digital operator 20 b of the power conversion device 20, the personal computer 21, the tablet 22,
The value of φ _2q2 ^* ) may be set.

  If this embodiment is applied to an induction motor drive system, highly accurate speed control characteristics can be realized.

  In this embodiment, the first embodiment is disclosed, but the second to fourth embodiments may be used.

In the first to fifth embodiments so _far , voltage correction values ΔV _d ^* and ΔV _q ^* are created from the current command values I _d ^* and I _q ^* and the current detection values I _dc and I _qc. The calculation shown in ( _Equation 2) was performed in which the voltage correction value and the voltage reference value of the vector control were added, but the vector control calculation was performed based on the current detection values I _dc and I _qc for the current command values I _d ^* and I _q ^*. using intermediate current command value I _d ^** shown in equation (12), to create the I _q ^**, and the current command value, using an output frequency value omega ₁ ^** and electrical constants of the induction motor 1 , A vector control method for calculating the voltage command values V _dc ^*** and V _qc ^*** according to ( _Equation 13),

Where K _pdACR1 : proportional gain of d-axis current control,
K _idACR1 : d-axis current control integral gain,
K _pqACR1 : Proportional gain for q-axis current control,
K _iqACR1 : q-axis current control integration gain,
T _d : Electric time constant of d axis (L _d / R), T _q : Electric time constant of q axis (L _q / R)

Current command value I _d ^*, I _q ^* on the current detection value I _dc, the I _qc, the voltage correction value of the proportional calculation component of d-axis used in the vector control calculating [Delta] V _{d_p} ^*, voltage correction integral calculation component of d-axis the value [Delta] V _{d_i} ^*, voltage correction value of the proportional calculation component in q-axis _ΔV q_p ^*, is calculated by the voltage correction value of the integral calculation component in the q-axis [Delta] V _{q_i} ^* (number 14)

Using these voltage correction values, the output frequency value ω ₁ ^**, and the electric constants of the induction motor 1, a vector for calculating the voltage command values V _dc ^**** and V _qc ^**** according to ( _Equation 15) Control method,

Further, by using the electric parameters of the current command value I _d ^* and q-axis current detection value primary delay signal I I _{qc Qctd} and speed command value omega _r ^* and the induction motor 1 the d-axis, shown in equation (16) The present invention can also be applied to a control method for calculating the output frequency command value ω ₁ ^*** and the voltage command values V _dc ^***** and V _qc ^***** shown in ( _Equation 17).

  In the first to sixth embodiments described above, the speed estimation calculation unit 5 calculates the speed estimation value according to (Equation 5), but in the q-axis current control, the current control and the speed estimation are used together. A method may be used.

As shown in ( ^Equation 18), the speed estimation value ω _r ^{^^^} is calculated.

here,
K _pqACR2 : Proportional gain for current control, K _iqACR2 : Integral gain for current control Further, in the first to fifth embodiments described above, the speed estimation calculation unit 5 calculates a speed estimation value according to ( _Equation 5). However, as disclosed in FIG. 14, a method may be used in which the speed detection encoder 26 is attached to the induction motor 1 and the speed detection value is calculated from the encoder signal.

In this case, a speed detection encoder is attached to the induction motor 1 and a speed detection calculation unit 5 ′ is provided instead of the speed estimation calculation unit 5 disclosed in the first to fifth embodiments, so that the induction motor 1 It is possible to accurately detect the actual speed value (speed detection value) ω _rd .
<Sixth embodiment>
FIG. 15 is a configuration diagram of the power converter according to the embodiment. The same effect can be obtained by using 8 ′ or 8 ″ as an alternative to the component 8 in FIG. 15 and 9 ′ as an alternative to the component 9 in FIG. The difference is that the output frequency ω _1r ^* is given as the command value instead of the speed command value ω _r ^* .
The slip frequency command value ω _s ^* is subtracted from the output frequency command value ω _1r ^* by the subtraction unit 24, and the speed command value ω _r ^* is output.

As disclosed in FIG. 14, by providing a speed detection calculation unit 5 'instead of the speed estimation calculation unit 5, a method of calculating a speed detection value ω _rd as an alternative to the speed estimation value ω _r ^{^} of the induction motor 1 is also possible. good.
<Seventh embodiment>
FIG. 16 is a configuration diagram of the power converter according to the embodiment. The same effect can be obtained by using 8 ′ or 8 ″ as an alternative to the component 8 in FIG. 16 and 9 ′ as an alternative to the component 9 in FIG. The difference gives a speed command value omega _r ^* instead output frequency omega _1r ^* as a command value, subtracts the output frequency value omega ₁ ^* subtraction unit 25 from the output frequency command value omega _1r ^*, the speed control calculation section of the This is the input signal. As disclosed in FIG. 14, by providing the speed detection calculating unit 5 'instead of the speed estimating calculation unit 5, also in a manner of calculating the speed detection value omega _r as a speed estimate omega _r ^{^} alternative induction motor 1 good.

  As described above, as a characteristic configuration in the embodiment, a step of outputting an estimated speed or a detected speed of the induction motor, a step of outputting a slip frequency command value of the induction motor, and a correction voltage value of current control A frequency correction value calculation step of calculating a frequency correction value so that the secondary magnetic flux estimated value calculated from or approaches the secondary magnetic flux command value, the speed estimated value or the speed detected value, and the frequency command value, A control step of controlling an output frequency value of the power converter based on the frequency correction value (configuration 1).

  Further, in the control method of the power conversion device according to Configuration 1, in the frequency correction value calculation step, the secondary magnetic flux estimated value of the q axis calculated from the correction voltage value of the d-axis current control is a secondary magnetic flux of the q axis. This is a control method for a power conversion device characterized by calculating a frequency correction value so as to match or approach a magnetic flux command value (Configuration 2).

  The control method for a power conversion device according to Configuration 2, wherein a current detection value of a d-axis (magnetic flux component) and a q-axis (torque component) of the induction motor, an output frequency value of the power conversion device, Current control for controlling the d-axis and q-axis current detection values according to the electric constants of the induction motor, the voltage reference value based on the d-axis and q-axis current command values, and the d-axis and q-axis current command values. Correction voltage value, d-axis and q-axis voltage command values calculated from the voltage reference value and the correction voltage value of the current control, a phase estimation value obtained by integrating the output frequency value of the power converter, and the d A power converter comprising a switching element controlled in accordance with a three-phase AC voltage command value calculated from the axis command values and the q-axis voltage command values, and a three-phase AC voltage command value. This is a method for controlling the conversion device (Configuration 3).

  Further, in the control method of the power conversion device according to any one of Configurations 1 to 3, in the control step, one of the slip frequency command value and the speed estimation value is corrected by the frequency correction value. This is a control method of the power conversion device characterized by being executed (Configuration 4).

  Also, in the control method of the power converter according to any one of Configurations 1 to 4, the secondary magnetic flux estimated value of the q-axis is calculated so as to match or approach the secondary magnetic flux command value of the q-axis. The frequency correction value is a control method of the power conversion device characterized by comprising a proportional operation value and an integral operation value (Configuration 5).

  Also, in the control method of the power converter according to any one of Configurations 1 to 4, the secondary magnetic flux estimated value of the q-axis is calculated so as to match or approach the secondary magnetic flux command value of the q-axis. The frequency correction value is a control method of the power conversion device, characterized in that the frequency correction value is configured by further performing an integral operation on an output value constituted by a proportional operation and an integral operation (Configuration 6).

  7. The control method for a power conversion device according to configuration 5 or 6, wherein the control step includes a proportional operation and an integral operation based on a speed estimation value, a speed detection value, or a speed command value of the induction motor. This is a control method for the power conversion device, characterized by automatically correcting the control gain obtained (Configuration 7).

  Further, in the control method of the power converter according to any one of Configurations 1 to 4, the secondary magnetic flux command value of the q-axis is zero in the powering mode, and zero in the regenerative mode. Alternatively, there is provided a control method for a power conversion device characterized by setting or controlling the same polarity as a torque command value or a q-axis current command value (Configuration 8).

  Further, in the control method of the power conversion device according to the configuration 7 or 8, the control gain or the secondary magnetic flux command value of the q-axis is a micro-controller mounted in the power conversion device including the power converter. This is a control method for a power conversion device, wherein the value is set in a computer internal memory or the like and a digital operator, a personal computer, a tablet, or a smartphone device is connected, and the value can be freely set and changed (configuration 9). .

  Also, in the control method of the power conversion device according to Configuration 9, the q-axis secondary magnetic flux command value can be set to at least two or more, and the operation cannot be performed correctly with the first set value. In this case, the control method for the power conversion device is characterized in that the second and subsequent settings are automatically set (configuration 10).

  A speed detection calculation unit that outputs a speed estimation value or a speed detection value of the induction motor; a slip frequency calculation unit that outputs a slip frequency command value of the induction motor; and a secondary magnetic flux calculated from a correction voltage value of current control. A frequency correction calculation unit that calculates a frequency correction value such that the estimated value matches or approaches the secondary magnetic flux command value, the speed estimated value or the speed detection value, the frequency command value, and the frequency correction value. And a control unit that controls an output frequency value of the power conversion device based on the power conversion device (Configuration 11).

  Further, in the power conversion device according to Configuration 11, the frequency correction calculation unit may calculate the secondary magnetic flux estimated value of the q-axis calculated from the correction voltage value of the d-axis current control to the secondary magnetic flux command value of the q-axis. This is a control method for a power conversion device, wherein a frequency correction value is calculated so as to match or approach (configuration 12).

  13. The power converter according to configuration 12, wherein a current detection value of a d-axis (magnetic flux component) and a q-axis (torque component) of the induction motor, an output frequency value of the power converter, and the induction motor A voltage reference value based on the electrical constants of the d-axis and q-axis current command values, and a correction voltage for current control for controlling the d-axis and q-axis current detection values according to the d-axis and q-axis current command values. Values, the d-axis and q-axis voltage command values calculated from the voltage reference value and the correction voltage value of the current control, a phase estimation value obtained by integrating the output frequency value of the power converter, and the d-axis and q A power converter comprising a power converter composed of a switching element controlled according to a three-phase AC voltage command value calculated from a shaft voltage command value and a three-phase AC voltage command value. (Configuration 13).

1 ... induction motor, 2 ... power converter, 2a ... DC power supply, 3 ... current detector, 4 ... coordinate converter,
5: speed estimation operation unit, 6: slip frequency operation unit, 7: addition unit, 8, 8 ', 8 "... frequency correction operation unit, 9, 24 ... subtraction unit, 10 ... phase estimation operation unit, 11 ... d Axis current command setting section, 12: Speed control calculation section, 13: Vector control calculation section, 14: d-axis current control calculation section, 15: q-axis current control calculation section, 16, 17, 25: addition section, 18: coordinates conversion unit, 20 ... power conversion device, 20a ... contents of the power converter, 22 ... personal computer, 23 ... tablet, 24 ... subtracting unit, 25 ... subtracting unit, 26 ... speed detecting encoder, I _d ^* ... d-axis Current command value, I _q ^* ... q-axis current command value, ω _r ... speed of induction motor 1, ω _r ^{^} ... speed estimated value, ω _r ^{^ ^} ... new speed estimated value, ω _rd ... speed detected value, ω _s … Slip of induction motor 1, ω _s ^* … Slip frequency command value, ω _1r ^* … Output frequency command value, ω _1r … Output frequency value, ω ₁ ^* … Output frequency value of induction motor 1, ω ₁ ^** … New Out Frequency value, the correction amount of [Delta] [omega ... output frequency values, theta _dc ... phase estimates, omega _r ^* ... speed command value, the reference value of the voltage command V _dc ^* ... d-axis, V _qc ^* ... q-axis voltage command Reference value, _Vdc ^** , _Vdc ^*** , _Vdc ^**** , _Vdc ^***** ... d-axis voltage command value, _Vqc ^** , _Vqc ^*** , _Vqc ^{* ***} , V _qc ^***** … Voltage command value of q axis

Claims (6)

The calculation unit generates a torque by a magnetic flux generated by a d- axis current that is a magnetic flux axis component and a q- axis current that is a torque axis, at least in a low speed range, and based on a d-axis voltage correction value and a speed estimation value. Calculating the d- axis voltage command value and the q- axis voltage command value so as to maintain the estimated q-axis secondary magnetic flux value at a predetermined value;
Controlling the power conversion device based on the d- axis voltage command value and the q- axis voltage command value,
A control method for a power conversion device comprising:   Outputting the speed estimation value based on a d-axis current command value, a q-axis voltage command value, a q-axis current detection value, an output frequency value, and an electric constant of a power converter,
  The control method for a power conversion device according to claim 1, further comprising:   The calculating unit calculates a d-axis voltage command value and a q-axis voltage command value so as to maintain the q-axis secondary magnetic flux estimated value at a predetermined value. Using values,
  The control method for a power converter according to claim 1 or 2, wherein:   The arithmetic unit further performs an integral operation on the output value configured by the proportional operation and the integral operation to maintain the secondary magnetic flux estimated value of the q-axis at a predetermined value.
  The method for controlling a power conversion device according to claim 3, wherein:   The method according to claim 3, wherein the calculation unit changes a control gain of the proportional calculation and a control gain of the integration calculation in proportion to the estimated speed value. At least in a low-speed region, a torque is generated by a magnetic flux generated by a d- axis current that is a magnetic flux axis component and a q- axis current that is a torque axis, and q is calculated based on a d-axis voltage correction value and a speed estimation value. An arithmetic unit that calculates a d- axis voltage command value and a q- axis voltage command value so as to maintain the secondary magnetic flux estimated value of the axis at a predetermined value,
The computing unit controls itself based on the d- axis voltage command value and the q- axis voltage command value,
A power converter characterized by the above-mentioned.

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