JP3266790B2 - Induction motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector control device for an induction motor, and more particularly to an induction motor in which iron loss cannot be ignored, and good vector control performance even when driving an induction motor having a large temperature change during operation. And an induction motor control device capable of maximum efficiency operation,
The present invention relates to a control device for an induction motor that eliminates saturation of output voltage and prevents deterioration of torque control characteristics.

[0002]

2. Description of the Related Art As is well known, a vector control system for an induction motor separates a primary current of the induction motor into an excitation current component and a torque current component, and can freely control a generated torque and a secondary magnetic flux. It is a method. Here, assuming that the exciting current component is Io and the torque current component is It, the generated torque Tm of the induction motor is expressed by the following equation.

[0003]

(Equation 1) Here, Pm is the number of pole pairs, and M is the primary and secondary mutual inductance of the induction motor.

The primary frequency ω of the induction motor is given by the following equation.

[0005]

(Equation 2) Here, ωr is the rotation frequency of the induction motor, and ωs is the slip frequency given by the following equation.

[0006]

[Equation 3]

As can be seen from the above equation (1), there are countless combinations of Io and It for obtaining a certain value of generated torque. By adjusting the combination of Io and It, the induction motor can be operated with high efficiency. As a first related art related to this, a document [Paper Paper No. 574] is known. According to this method, the operation can be performed with the efficiency of the induction motor maximized by controlling each of Io and It according to the torque command so as to satisfy the following equation.

[0008]

(Equation 4)

At this time, from equation (3), it can be seen that ωs has a constant value as in the following equation.

[0010]

(Equation 5)

FIG. 23 shows a conventional example of a control device for an induction motor that performs the maximum efficiency operation of the induction motor based on the first prior art. This control device is disclosed in JP-A-5-38181. In this figure, reference numeral 1 denotes an induction motor, and primary currents Ius, Ivs, and Iws for each phase supplied from the PWM inverter 10 to the induction motor 1 are detected by a current detector 4. The actual rotation speed of the induction motor 1, that is, the rotation frequency ωr, is detected by the speed detector 7 and input to the subtractor 121.

The subtractor 121 outputs the rotation frequency ωr and the speed command ωr * output from a speed command generator (not shown).
Is obtained and input to the amplifier 122. Amplifier 12
2 outputs the deviation result as a torque current component command It *. The multiplier 123 multiplies the torque current component command It * by the excitation current component command Io * obtained by an operation described later, and outputs a signal T proportional to the torque to the function generator 124.

When the function generator 124 receives the signal T, the function generator 124 calculates an excitation current component command Io * and outputs it via a compensation circuit 125. The exciting current component command Io * is obtained by a multiplier 123 and a divider 126 to which the torque current component command It * is input.
And to the vector calculator 129.

The divider 126 outputs a torque current component command It.
* And the exciting current component command Io * are divided, and the result of the division is input to the coefficient unit 127 for calculating the slip frequency ωs. The adder 128 calculates the slip frequency ωs and the rotation frequency ωr
And the primary frequency ω of the induction motor 1 is calculated and input to the vector calculator 129. Further, the vector calculator 129 outputs the primary current commands Ius *, Ivs *, and the like for each phase to be supplied to the induction motor 1 from the input torque current component command It *, excitation current component command Io *, and primary frequency ω. Iws * is calculated and output.

Differences between these primary current commands and the primary currents Ius, Ivs and Iws detected by the current detector 4 are obtained by subtracters 130, 131 and 132, respectively, and these deviations are calculated by amplifiers 133 and 134. And 135, and outputs to the PWM inverter 10 as primary voltage commands Vus *, Vvs *, and Vws * for each phase of the induction motor 1.

The operation of the conventional device will be described. First,
The difference between the speed command ωr * output from the speed command generator (not shown) and the rotation frequency ωr output from the speed detector 7 is obtained by the subtractor 121,
2 is input. Then, the torque current component command It * is output from the amplifier 122.

Next, the multiplier 123 multiplies the torque current component command It * by an excitation current component command Io * obtained by a calculation described later, and outputs a signal T proportional to the torque. Here, from equation (1), the signal T
Is represented by the following equation.

[0018]

(Equation 6)

When the signal T is input to the function generator 124, an exciting current component command Io * is obtained according to the following equation.

[0020]

(Equation 7)

Here, K is a constant, and is given by the following equation from equation (1).

[0022]

(Equation 8)

The compensation circuit 125 is provided for the purpose of correcting the secondary magnetic flux of the induction motor 1 because it has a first-order lag response characteristic to the exciting current component. The excitation current component command Io * is output.

Next, when the torque current component command It * and the excitation current component command Io * are input to the divider 126, It *
/ Io * is determined. Then, when the output of the divider 126 is input to the coefficient unit 127 whose coefficient value is equal to Rr / M, the slip frequency ωs is output by the calculation of the equation (3). Subsequently, the slip frequency ωs and the speed detector 7
Is added by the adder 128 to the rotation frequency ωr output from the first frequency ωr.
Is required.

Further, the torque current component command It *,
When the excitation current component command Io * and the primary frequency ω are input to the vector calculator 129, the primary current commands Ius *, Ivs *, and Iws * for each phase to be supplied to the induction motor 1 are output. Subsequently, these primary current commands and the primary currents Ius, Ivs, and I
ws are subtracted by subtractors 130, 131 and 1 respectively.
32. These deviations are calculated by the amplifier 13
3, 134 and 135, the primary voltage commands Vus *, Vvs * and Vws * for each phase of the induction motor 1 are output, respectively.

With the PWM inverter 10, the primary voltages Vus, Vvs and Vws of the induction motor 1 are respectively
Control is performed so as to follow these primary voltage commands. As a result, the primary currents Ius, Ivs and I of the induction motor 1
ws follows each command. Eventually, the exciting current component and the torque current component of the induction motor 1 also follow the respective commands.

In the conventional vector control method for an induction motor, when the output voltage is saturated due to the limitation of the DC voltage on the power supply side, the output waveform of the inverter is disturbed, causing vibration and deterioration of torque control performance. As a second related art related to this, a vector control device disclosed in Japanese Utility Model Laid-Open No. 6-21394 is known. In the vector control device according to the prior art, a limit value of an outputable primary voltage obtained from a DC voltage on a power supply side is compared with a primary voltage command, and a correction component of a magnetic flux command is obtained by a proportional integral (PI) calculation. When voltage saturation occurs, the magnetic flux command is corrected by the above-described magnetic flux command correction component, thereby eliminating voltage saturation.

FIG. 24 shows a vector control device according to this prior art. In the drawing, the same reference numerals as those in FIG. 23 indicate the same or corresponding parts. In FIG. 24, 141 is a three-phase power supply,
Reference numeral 142 denotes a converter for converting three-phase alternating current from the three-phase power supply 141 into direct current. Reference numeral 143 denotes a direct-current voltage detection unit that detects the direct-current voltage converted by the converter 142 and outputs it as an output signal Vdc. Inputs the detected three-phase currents Ius, Ivs and Iws, and outputs the d-axis component Ids of the primary current on the orthogonal rotation coordinate axis (referred to as dq axis).
And a coordinate transformation unit (A) for outputting a q-axis component Iqs, 14
8 is a primary current q-axis component command I used for the torque current command.
As qs *, an ASR amplifier (speed command ωr * and speed ω
A switching unit 144 for selecting either the output of the amplifier r of deviation of r) or an externally set torque command, the switch 144 converts the DC voltage Vdc and a primary voltage command Vs *, which is an output of a coordinate conversion unit (B) described later. A field weakening calculating unit that inputs and outputs an excitation command correction component ΔIds at the time of voltage saturation. 145 is a limiter processing unit that inputs a field command set value and performs limiter processing. 146 is an excitation command that has performed limiter processing. Is subtracted from the excitation command correction component ΔIds to be used for the excitation current command.
A subtractor 150 for inputting a d-axis component command Ids * of the primary current; 150, a subtractor for inputting the q-axis component command Iqs * of the primary current and the q-axis component Iqs to obtain the deviation; 151, d for the primary current
Subtractors 152 and 153 that input the axis component command Ids * and the d-axis component Ids and obtain the deviation thereof, amplify the deviation obtained by the subtractors 150 and 151, respectively, and amplify the q-axis correction components ΔVqs and d of the primary voltage. An ACR amplifier (amplifier) 147 for outputting the axis correction component ΔVds is a d-axis component command Ids * and a q-axis component command Iqs * of the primary current and a speed detector 7.
An induction machine model that inputs the rotation frequency ωr, which is the output of the above, performs a vector calculation simulating the induction machine 1 and outputs the d-axis component Vds and the q-axis component Vqs of the primary voltage, and 154 is 1
An adder for adding the q-axis component Vqs of the secondary voltage and the q-axis correction component ΔVqs to form a q-axis component command Vqs * of the primary voltage;
155 is a d-axis component Vds of primary voltage and a d-axis correction component ΔV
The adder 156 adds the ds to the primary voltage d-axis component command Vds *, and the adder 156 includes the primary voltage q-axis component command Vqs * and d.
A coordinate conversion unit (B) for inputting the axis component command Vds * and converting it into polar coordinates to output a primary voltage command Vs * and a phase ψ;
Numeral 57 inputs the primary voltage command Vs * and the phase １, and the primary voltage commands Vus *, Vvs * and Vw for each phase of the induction motor 1.
158 is a PWM operation unit that obtains s * and performs a PWM operation.
This is a base circuit that receives an output of the WM operation unit 157 and generates a switching signal of each phase in the PWM inverter.

FIG. 25 is a block diagram showing a detailed configuration of the field weakening calculating section 144 described above. Field weakening calculation unit 1
Reference numeral 44 denotes a limit output calculator 161 that receives the DC voltage Vdc, calculates and outputs a limit Vsmax of the primary voltage that can be output by the PWM inverter 10, and a primary voltage command Vs *.
To obtain the first order delay component Vs * F, and Vs * F <
In the case of Vsmax, the saturation voltage command Vs * '= Vsm
ax, when Vs * F ≧ Vsmax, a saturation voltage command generator 162 that outputs Vs * ′ as a saturation voltage command Vs * ′ = Vs * F, and a limit Vsmax of the primary voltage that can be output. It comprises a subtractor 163 for obtaining a deviation of the saturation voltage command Vs * ', and a PI operation unit 164 for amplifying the deviation and outputting an excitation command correction component ΔIds.

The operation of the conventional device will be described. First, the switching unit 148 selects whether to operate the induction motor 1 by a speed control system or a torque control system. When switching to the ASR amplifier 122 side, the speed control system is selected, and when switching to the externally set torque command side, the torque control system is selected. When the speed control system is selected, the difference between the speed command ωr * and the rotation frequency ωr output from the speed detector 7 is obtained by the subtractor 121, and the output of the ASR amplifier 122 that receives this difference is used as the torque current command. Q-axis component command I of primary current to be used
qs *. When the torque control system is selected, the externally set torque command becomes the q-axis component command Iqs * of the primary current used for the torque current command.

The excitation command set value that has passed through the limiter processing unit 145 is subtracted by a subtractor 146 from a PI calculation unit 1 described later.
Excitation command correction component ΔIds at the time of voltage saturation output by 64
And a d-axis component command Ids * of the primary current used for the excitation current command is output.

When the primary currents Ius, Ivs, and Iws detected by the current detector 4 are input to the coordinate converter (A) 149, the d-axis component Ids and the q-axis component Iq of the primary current are input.
s is output.

Next, the difference between the q-axis component command Iqs * of the primary current and the q-axis component Iqs is obtained by the subtractor 150. When this deviation is input to the ACR amplifier 152, a q-axis correction component ΔVqs of the primary voltage is output. Further, the difference between the d-axis component command Ids * of the primary current and the d-axis component Ids is obtained by the subtractor 151. When this deviation is input to the ACR amplifier 153, the d-axis correction component ΔVd of the primary voltage
s is output.

Further, the primary current d is added to the induction machine model 147.
When the axis component command Ids *, the q-axis component command Iqs * and the rotation frequency ωr are input, the d-axis component Vds and the q-axis component Vqs of the primary voltage are obtained based on the voltage / current equation of the induction motor.
Is required. Subsequently, the adder 154 adds the q-axis component Vqs of the primary voltage and the q-axis correction component ΔVqs, and outputs a q-axis component command Vqs * of the primary voltage. The adder 155 adds the d-axis component Vds of the primary voltage and the d-axis correction component ΔVds, and outputs a d-axis component command Vds * of the primary voltage.

When the q-axis component command Vqs * and the d-axis component command Vds * of these primary voltages are input to the coordinate conversion section (B) 156, the primary voltage command Vs * is converted by the following equation. And the phase 出力 are output.

[0036]

(Equation 9)

The primary voltage command Vs * and the phase ψ are expressed by PW
When input to the M calculation unit 157, the primary voltage command V
us *, Vvs *, and Vws * are obtained, and a PWM operation is performed. The base circuit 158 generates a switching signal of each phase of U, V, and W based on the PWM operation result,
The WM inverter 10 is driven. Therefore, the induction motor 1
Are controlled so as to follow these primary voltage commands, respectively. As a result, the primary currents Ius, Ivs and Iw of the induction motor 1 are controlled.
s follows each command. Eventually, the exciting current component and the torque current component of the induction motor 1 also follow the respective commands.

Here, the DC voltage Vdc output from the DC voltage detection unit 143 and the primary voltage command Vs * output from the coordinate conversion unit (B) 156 are input to the field weakening calculation unit 144. Inside the field weakening calculation unit 144, the limit output calculation unit 161 calculates the limit Vsmax of the primary voltage that can be output from the DC voltage Vdc based on the following equation, and outputs the calculated limit Vsmax.

[0039]

(Equation 10)

Further, the saturation voltage command generator 162 obtains a primary delay component Vs * F of the primary voltage command Vs *, and outputs a saturation voltage command Vs * 'according to the following equation.

[0041]

(Equation 11)

If Vs * F <Vsmax, it indicates that no voltage saturation has occurred, and Vs * F ≧ Vsmax
The case of indicates that voltage saturation has occurred. Subtractor 1
At 63, the output limit voltage Vsmax and the saturation voltage command Vs
* 'Deviation is determined. When voltage saturation has not occurred, the deviation is zero (0), and when voltage saturation has occurred, the deviation depends on the degree of saturation. This deviation is input to the PI calculation unit 164, and the above-described excitation command correction component ΔIds is obtained as an output. That is, the presence / absence of voltage saturation is detected by the saturation voltage command generation unit 162, and if voltage saturation has occurred, the excitation command correction component ΔIds is adjusted according to the degree of the voltage saturation, and the primary This suppresses the d-axis component command Ids * of the current. Suppressing the d-axis component command Ids * of the primary current suppresses the primary voltage command, thereby eliminating voltage saturation.

[0043]

In the first conventional control device, the exciting current component and the torque current component are controlled in accordance with the equations (4) and (5) in order to perform high-efficiency vector control. . Incidentally, these equations are relational equations obtained by ignoring iron loss of the induction motor. Therefore, when the exciting current component and the torque current component are controlled according to the equations (4) and (5), the copper loss of the induction motor, that is, the loss generated by the primary resistance and the secondary resistance can be minimized, but the iron loss Is not minimal. Here, the iron loss of the induction motor is proportional to the 1.6th power of the primary frequency.
Reference [Symposium S.I. 10
-6]. Therefore, for example, in a high-speed rotation induction motor used for driving an electric railway or an electric vehicle, iron loss cannot be ignored with respect to copper loss.

As a result, the conventional control device cannot operate at maximum efficiency when driving these induction motors. In particular, in the case of an electric vehicle, since the energy source is a battery, realizing maximum efficiency operation of the driving induction motor is an important issue in order to reduce the size and weight of the battery.

In addition, the size of the induction motor used in such applications is reduced and the overload 2 exceeds the rating.
It is often operated with an output that reaches 00% or more,
Fluctuations in the motor constant due to changes in the motor temperature during operation are large, and this causes a problem of deterioration in torque control performance.

The second conventional control device detects the occurrence of voltage saturation, corrects and reduces the magnetic flux command according to the degree of voltage saturation, suppresses the primary voltage command, and reduces the voltage saturation state. It will be resolved. However, since the magnetic flux command is operated immediately upon occurrence of voltage saturation, there is a problem that when operating as a torque control system, the output torque is insufficient against the command torque immediately upon occurrence of voltage saturation.

Therefore, a first object of the present invention is to solve the above-mentioned problems of the first prior art, and to drive an induction motor in which iron loss cannot be ignored, and also to reduce the temperature change during operation. Even if the motor constant fluctuates, maximum efficiency operation is possible, and high-precision, high-speed response vector control can be realized. In addition, such maximum high-efficiency control can be realized with a non-high-speed control operation capability. Accordingly, it is an object of the present invention to provide a control device for an induction motor, which saves computation. A second object of the present invention is to solve the problem of the second prior art, and to eliminate the output torque against the command torque as much as possible and eliminate the voltage saturation even when the voltage saturation occurs. An object of the present invention is to provide a control device for such an induction motor.

[0048]

According to a first aspect of the present invention, there is provided a control apparatus for an induction motor, comprising: an induction motor; and a speed (rotation frequency) detecting a rotation frequency of the induction motor. And a calculation result of a predetermined function using the constant of the induction motor including a constant related to the iron loss as a coefficient value as data, and inputting a variable relating to the predetermined function to input a torque current command and an exciting current. A current ratio storage arithmetic circuit for outputting a ratio of command amplitudes (referred to as a current ratio);
The torque command of the induction motor and the current ratio are input, and the excitation current command is rotated at a primary frequency.
current component command calculating means for outputting the primary current as a d-axis component command on the primary current and outputting the torque current command of the induction motor as a primary current q-axis component command;
A current detector for detecting a primary current of the induction motor;
An integrator that integrates a next frequency to output a phase, an output of the current detector and the phase, and a current component calculation unit that calculates a d-axis component and a q-axis component of the primary current;
A slip frequency for inputting at least one of the d-axis component command and the d-axis component of the primary current and at least one of the q-axis component command and the q-axis component of the primary current and calculating a slip frequency of the induction motor. Calculating means, an adder for adding the slip frequency output from the slip frequency calculating means and the output of the rotation frequency detector to form the primary frequency, a d-axis component and a q-axis of the primary current each component is a current component control circuit for controlling the primary current of said induction motor so as to follow the d-axis component command and a q-axis component command of the primary current, the primary current on the orthogonal rotation coordinate axes
Enter the d-axis component and the rotation frequency, and
Correlation between magnetizing current and rotation frequency and exciting inductance
An output that determines and outputs the excitation inductance from the data
Means for calculating the current component command.
The stage is adapted to store the torque command of the induction motor and the current ratio memory.
Current ratio output by the arithmetic circuit and the above inductance correction means
Input the exciting inductance output by the
Excitation current command that outputs as the primary current d-axis component command
The arithmetic circuit and the maximum value of the primary current d-axis component command
A limiting circuit flux is limited to the value of the limit of saturation, the induced
The component proportional to the motor torque command is output from the above limit circuit.
Q-axis component of primary current as torque current command, divided by force
Is composed of a command and eggplant divider, the value of the product of the output of the current component command calculation means is proportional to the torque command, and the ratio of the amplitudes using the constants of the induction motor comprising a constant related to the iron loss A primary current command that is equal to a predetermined function value is output.

An induction motor control device according to a second aspect of the present invention, which relates to the first object, relates to an induction motor, a speed (rotation frequency) detector for detecting a rotation frequency of the induction motor, and an iron loss. A calculation result of a predetermined function using the constant of the induction motor including the constant obtained as a coefficient value as a coefficient value is stored as data, and a variable related to the predetermined function is input and the ratio of the amplitude of the torque current command and the excitation current command (current Called ratio)
And a current ratio storage / calculation circuit for outputting the torque command of the induction motor and the current ratio, and the excitation current command on the orthogonal rotation coordinate axis (referred to as dq axis) rotating at a primary frequency.
Current component command calculating means for outputting the d-axis component command of the secondary current and outputting the torque current command of the induction motor as the q-axis component command of the primary current; and current detection for detecting the primary current of the induction motor And an integrator for integrating the primary frequency to output a phase, and a current component for inputting the output of the current detector and the phase to calculate the d-axis component and the q-axis component of the primary current Calculating means for inputting at least one of a d-axis component command and a d-axis component of the primary current and at least one of a q-axis component command and a q-axis component of the primary current, and calculating a slip frequency of the induction motor; The slip frequency calculating means for calculating, the slip frequency (referred to as the pre-correction slip frequency) output from the slip frequency calculating means and the rotation frequency are input, and the induction motor includes a constant related to iron loss. Approximate from the ratio of the slip frequency obtained from the predetermined function calculation result with the coefficient value as the coefficient and the slip frequency obtained from the predetermined function calculation result with the constant of the induction motor not related to iron loss as the coefficient value. The slip frequency iron loss component correction means for interpolating the pre-correction slip frequency and outputting the corrected slip frequency by using the predetermined linear function obtained in the above-described manner, and the slip frequency iron loss component correction means output from the slip frequency iron loss component correction means. An adder for adding the corrected slip frequency and the output of the rotation frequency detector to form the primary frequency,
A current component control circuit for controlling the primary current of the induction motor such that the d-axis component and the q-axis component of the primary current follow the d-axis component command and the q-axis component command of the primary current, respectively ; The d-axis component of the primary current on the orthogonal rotation coordinate axis and
And the rotation frequency.
From the correspondence data between rotation frequency and excitation inductance
Inductor that calculates and outputs the excitation inductance
And a scan compensation means, the current component command calculation means, on
The torque command of the induction motor and the current ratio storage arithmetic circuit are
The output current ratio and the output
Input the excitation current, and set the excitation current command to the primary
Excitation current command calculation circuit that outputs as d-axis component command of current
And the magnetic flux saturates the maximum value of the primary axis d-axis component command.
A limiting circuit that limits the value of the induction motor to
Divide the component proportional to the torque command by the output of the above limiting circuit
And a q-axis component command of the primary current which is a torque current command.
Is constituted by a to divider, the value of the product of the output of the current component command calculation means is proportional to the torque command, and the ratio of the amplitude of the predetermined using constants of the induction motor comprising a constant related to the iron loss A primary current command that is equal to the function value is output.

According to the third aspect of the present invention, there is provided a control device for an induction motor according to the first aspect.
In the above, further comprising a motor temperature detector for detecting the temperature of the stator winding of the induction motor, the predetermined function having a constant value of the induction motor including a constant related to iron loss as a coefficient value is at least a function of the temperature of the motor By setting at least one of the variables related to the predetermined function input to the current ratio storage operation circuit to the temperature of the motor, the operation can be performed with high efficiency in response to the temperature change of the induction motor. Is to be maintained.

[0051]

[0052] The first control unit for an induction motor according to the invention of claim 4 associated with the purpose of the induction motor, the induction
Speed (rotation frequency) detection for detecting the rotation frequency of conductive motive
Of the induction motor, including the
Calculation result of a predetermined function that uses numbers as coefficient values as data
Memorize and input variables related to the above-mentioned predetermined function.
The ratio of the amplitude of the current command to the excitation current command (called the current ratio
A current ratio storage operation circuit for outputting a department), the induction motor
Input the torque command and the above current ratio, and set the excitation current command to primary
On the orthogonal rotation coordinate axis (called the dq axis) rotating at the frequency
As the primary current d-axis component command, and
Set the torque current command of the motor as the q-axis component command of the primary current.
A current component command calculation means for outputting Te, of the induction motor
A current detector that detects the primary current, and integrates the primary frequency
And an integrator that outputs the phase of the current detector.
And the d-axis component of the primary current and the q-axis
Current component calculating means for calculating the component , and d of the primary current
At least one of the axis component command and the d-axis component,
The current q-axis component command and at least one of the q-axis components
Input and calculate the slip frequency of the induction motor.
Output from the slip frequency calculating means and the slip frequency calculating means.
The output of the slip frequency and the rotation frequency detector
A primary frequency and makes the adder above by adding the force, the 1
The d-axis component and the q-axis component of the
Up to follow the d-axis component command and q-axis component command of the flow
A current component control circuit for controlling a primary current of the induction motor;
Comprising a, the current ratio data stored in the current ratio storage operation circuit becomes a linear function relating to at least the rotational frequency, the product of the output of the current component command calculation means
Is proportional to the torque command, and the amplitude ratio is related to iron loss.
A predetermined function using the constant of the induction motor including the constant
A primary current command that is equal to a numerical value is output .

[0053] The first control unit for an induction motor according to the invention of claim 5 in relation to the purpose of the induction motor, the induction
Speed (rotation frequency) detection for detecting the rotation frequency of conductive motive
Of the induction motor, including the
Calculation result of a predetermined function that uses numbers as coefficient values as data
Memorize and input variables related to the above-mentioned predetermined function.
The ratio of the amplitude of the current command to the excitation current command (called the current ratio
A current ratio storage operation circuit for outputting a department), the induction motor
Input the torque command and the above current ratio, and set the excitation current command to primary
On the orthogonal rotation coordinate axis (called the dq axis) rotating at the frequency
As the primary current d-axis component command, and
Set the torque current command of the motor as the q-axis component command of the primary current.
A current component command calculation means for outputting Te, of the induction motor
A current detector that detects the primary current, and integrates the primary frequency
And an integrator that outputs the phase of the current detector.
And the d-axis component of the primary current and the q-axis
Current component calculating means for calculating the component , and d of the primary current
At least one of the axis component command and the d-axis component,
The current q-axis component command and at least one of the q-axis components
Input and calculate the slip frequency of the induction motor.
Output from the slip frequency calculating means and the slip frequency calculating means.
The output of the slip frequency and the rotation frequency detector
A primary frequency and makes the adder above by adding the force, the 1
The d-axis component and the q-axis component of the
Up to follow the d-axis component command and q-axis component command of the flow
A current component control circuit for controlling a primary current of the induction motor;
Comprising a, the current ratio data stored in the current ratio storage operation circuit becomes a linear function relating to at least said primary frequency, the product of the output of the current component command calculation means
Is proportional to the torque command, and the amplitude ratio is related to iron loss.
A predetermined function using the constant of the induction motor including the constant
A primary current command that is equal to a numerical value is output .

[0054] The first control unit for an induction motor according to the invention of claim 6 in relation to the purpose of the induction motor, the induction
Speed (rotation frequency) detection for detecting the rotation frequency of conductive motive
Of the induction motor, including the
Calculation result of a predetermined function that uses numbers as coefficient values as data
Memorize and input variables related to the above-mentioned predetermined function.
The ratio of the amplitude of the current command to the excitation current command (called the current ratio
A current ratio storage operation circuit for outputting a department), the induction motor
Input the torque command and the above current ratio, and set the excitation current command to primary
On the orthogonal rotation coordinate axis (called the dq axis) rotating at the frequency
Output as a d-axis component command of the primary current of
Set the torque current command of the motor as the q-axis component command of the primary current.
A current component command calculation means for outputting Te, of the induction motor
A current detector that detects the primary current, and integrates the primary frequency
And an integrator that outputs the phase of the current detector.
And the d-axis component of the primary current and the q-axis
Current component calculating means for calculating the component , and d of the primary current
At least one of the axis component command and the d-axis component,
The current q-axis component command and at least one of the q-axis components
Input and calculate the slip frequency of the induction motor.
Output from the slip frequency calculating means and the slip frequency calculating means.
The applied slip frequency (referred to as the pre-correction slip frequency)
) And the above rotation frequency, and enter a constant related to iron loss.
A predetermined function that uses the constant of the induction motor including the coefficient as a coefficient value
The slip frequency obtained from the calculation results and the
Predetermined function operation using the constant of the induction motor as a coefficient value
It can be obtained by approximating the slip frequency ratio obtained from the result.
By using a predetermined linear function, the slip frequency before correction is calculated as follows.
A slip frequency iron that outputs slip frequency after interpolation and correction
Loss component correction means, and the slip frequency iron loss component correction means
The corrected slip frequency and the rotation frequency output from
Addition of the output of the number detector and the above primary frequency
And the d-axis component and the q-axis component of the primary current are respectively
It is, add to the d-axis component directive and the q-axis component command of the primary current
Current for controlling the primary current of the induction motor to follow
And a component control circuit, the predetermined linear function of the slip frequency iron loss component correction means ne as a function of the primary frequency
Ri, the value of the product of the output of the current component command calculation means torque
Includes constants proportional to the command and whose amplitude ratio is related to iron loss.
Equal to a predetermined function value using the constant of the induction motor
Thus, a primary current command is output .

According to a seventh aspect of the present invention, there is provided a control apparatus for an induction motor, wherein a voltage type inverter is used to rotate a torque current and an exciting current at a primary frequency. In a device for controlling an induction motor by a vector control method in which the primary current is divided into a q-axis component and a d-axis component separately and controlled, A voltage detector, and a torque current command 1 for the induction motor.
A q-axis component command of the secondary current (referred to as a pre-correction primary current q-axis component command) and a d-axis component command of the primary current which is an excitation current command (referred to as a pre-correction primary current d-axis component command) are input. A current ratio calculating means (A) for outputting a ratio of the amplitude (referred to as a current ratio FA), a maximum output voltage calculating circuit for inputting the power supply side DC voltage and calculating a maximum output primary voltage value; , The primary voltage command on the three-phase coordinate axis or the dq axis and the outputtable maximum primary voltage value are input, the presence or absence of voltage saturation is detected, and the degree of voltage saturation is determined by a first saturation component. A voltage saturation detecting means, which is expressed and output as follows, and a rotation frequency of the induction motor and other variables are input, and a q-axis component of the primary current which minimizes a primary voltage required to output a torque according to a torque command. Ratio of amplitude of command and d-axis component command (referred to as current ratio FB) A current ratio calculating means (B) for calculating and outputting the result of the calculation or the result of the calculation into map data, and the first saturation component, the current ratio FA and the current ratio FB, and 1 after correction according to
The amplitude ratio (called current ratio FC) between the q-axis component command of the secondary current (referred to as the corrected primary current q-axis component command) and the d-axis component command (referred to as the corrected primary current d-axis component command). A current ratio adjusting means for outputting, a torque command for the induction motor and the current ratio FC, and a corrected current for outputting the corrected primary current q-axis component command and the corrected primary current d-axis component command. And a component command calculating means.

In the control device for an induction motor according to the invention of claim 8 relating to the second object, in claim 7 , the voltage saturation is maintained even if the current ratio adjusting means adjusts the current ratio FC. When this occurs, this is detected and a second saturation component corresponding to the degree of saturation is also output. The second saturation component and the torque command are input to correct the torque command. This is further provided with a torque command correction means.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Before proceeding to a detailed description of the operation of the embodiment of the present invention, first, a vector control method of an induction motor in consideration of iron loss, which is a basis of the first invention, will be described.

First, the voltage / current equation of the induction motor on the dq coordinate axis rotating at the primary frequency is given by the following equation.

[0059]

(Equation 12) However, Rs, Rr and Rm are each one of the induction motors.
These are the secondary resistance, the secondary resistance, and the iron loss resistance. Ls, Lr and M are the primary self-inductance of the induction motor, respectively.
Secondary self-inductance and mutual inductance. In addition, Vds and Vqs are respectively the primary voltage d.
The axis component and the q-axis component. Ids and Iqs are the d-axis component and the q-axis component of the primary current, respectively, and Idr and Iqr are the d-axis component and the q-axis component of the secondary current, respectively.

Ω and ωs are the primary frequency and slip frequency of the induction motor, respectively, and P is the differential operator (= d / dt). In the above equation, the iron loss resistance Rm
Is zero, it matches the voltage / current equation on the dq coordinate axis of the induction motor when iron loss is ignored.

Next, the d-axis component Φdr and the q-axis component Φqr of the secondary magnetic flux of the induction motor in consideration of iron loss are given by the following equations.

[0062]

(Equation 13)

Further, the generated torque Tm is given by the following equation.

[0064]

[Equation 14]

The equation (20) holds regardless of the presence or absence of iron loss. From the equations (18) and (19), the presence of the iron loss resistance Rm affects the d-axis component Φdr of the secondary magnetic flux by the q-axis components Iqs and Iqr of the primary current and the secondary current,
Conversely, it can be seen that the q-axis component Φqr of the secondary magnetic flux is affected by the d-axis components Ids and Idr of the primary current and the secondary current. As a result, it can be seen from Expression (20) that the generated torque Tm is also affected by iron loss.

Next, the equations (18) and (19) are converted to the equations (16),
When Ids and Iqs are eliminated by substituting into equation (17), the following equation is obtained.

[0067]

(Equation 15)

The equations (18) and (19) are modified to obtain I
When dr and Iqr are determined, the following equation is obtained.

[0069]

(Equation 16)

Next, when the condition that Φqr = 0 is obtained,
From equation (22), it can be seen that the slip frequency ωs may be given by the following equation.

[0071]

[Equation 17]

Here, since it is difficult to directly detect Iqr, substituting equation (24) into equation (26) and eliminating Iqr yields the following equation.

[0073]

(Equation 18)

Further, if Idr is eliminated by substituting equation (23) into equation (21) and Φqr = 0, the following equation is obtained.

[0075]

[Equation 19]

Therefore, if the induction motor is controlled at the slip frequency ωs that satisfies the expression (27), Φqr is set to zero as in the steady state even in the transient state where the secondary magnetic flux changes with time. That is, the direction of the secondary magnetic flux vector can be made to coincide with the d-axis. Here, the d-axis component Φdr of the secondary magnetic flux is 1 by the calculation of Expression (28).
It can be obtained from the d-axis component Ids and the q-axis component Iqs of the secondary current.

The d-axis component Ids and the q-axis component I of the primary current
If qs is detected, the slip frequency ωs can be obtained by the calculation of Expression (27). Note that, in Expressions (27) and (28), the value of k is a function of the primary frequency ω as is apparent from Expression (25). Further, as is well known, the value of the core loss resistance Rm also changes according to the primary frequency ω.

Therefore, when performing the calculations of the equations (27) and (28), the primary frequency ω is necessary. However, as shown in the equation (2), ω is the rotational frequency ωr of the induction motor and the slip frequency. and ωs.

Next, since Φqr = 0 always holds,
From equation (20), it can be seen that the following equation holds not only in a steady state but also in a transient state.

[0080]

(Equation 20)

Using this equation, the d-axis component command Φdr * of the secondary magnetic flux and the q-axis component command Iqr * of the secondary current are obtained according to the torque command input from the outside, and the secondary D-axis component Φdr of magnetic flux and q-axis component I of secondary current
If qr is controlled to follow these command values, the torque generated by the induction motor can be controlled as a result of the command values.

However, since the d-axis component Φdr of the secondary magnetic flux of the induction motor and the q-axis component Iqr of the secondary current cannot be directly controlled, the d-axis component command Φdr * of the secondary magnetic flux and the q-axis A d-axis component command Ids * and a q-axis component command Iqs * of the primary current are obtained from the component command Iqr *, and a d-axis component Ids and a q-axis component Iq of the primary current of the induction motor are obtained.
s is controlled so as to follow each command value. Therefore, first, the following equations are obtained by modifying equations (18) and (19) to obtain Ids and Iqs.

[0083]

(Equation 21)

Substituting equation (21) into the above equation to eliminate Idr,

[0085]

(Equation 22) Then, the following equation is obtained.

[0086]

(Equation 23)

Therefore, the d-axis component command Id of the primary current is calculated from the d-axis component command Φdr * of the secondary magnetic flux and the q-axis component command Iqr * of the secondary current by the calculations of the equations (34) and (35).
s * and q-axis component command Iqs * can be obtained.
In both formulas, the value of k and the value of Rm change depending on the value of the primary frequency ω, so that the value of ω is required in the calculation.

In the equation (36), (Lr−M)
Is equal to the value of the secondary leakage inductance of the induction motor, the value of the time constant Tr3 is much smaller than the value of Tr2. Therefore, in the calculation of the equation (35), Tr3
Even if = 0, there is almost no difference in control.

As described above, the d-axis component command Ids * and the q-axis component command Iqs * of the primary current are obtained, so that the d-axis component Ids and the q-axis component Iqs of the primary current of the induction motor are calculated from these. What is necessary is just to control so that each may follow a command value.

Here, as is known, the d-axis component Ids and the q-axis component Iqs of the primary current are divided into the primary currents Ius, Iv
It is determined from s and Iws and the primary frequency ω by the following equation.

[0091]

(Equation 24)

Next,

(Equation 25) By using the relationship to eliminate Iws from equations (37) and (38), the following equation is obtained.

[0093]

(Equation 26)

Therefore, the control may be performed so that the d-axis component Ids and the q-axis component Iqs of the primary current obtained by the calculation of the above equation follow the respective command values.

The above is the vector control method of the induction motor in consideration of the iron loss, which is the basis of the first invention. The d-axis component Φdr of the secondary magnetic flux and the q-axis component Iq of the secondary current of the induction motor are described.
By operating r, good torque control performance can be realized even when iron loss cannot be ignored.

Next, from equation (30), it can be seen that there are countless combinations of Φdr and Iqr for obtaining a certain value of generated torque. Therefore, how to select the values of Φdr and Iqr to achieve the maximum efficiency operation of the induction motor will be described. First, the differential terms in the equations (14) to (17) are ignored. Then, the following equation is obtained from the condition of Φqr = 0 and the equation (21).

[0097]

[Equation 27]

The following equations are obtained by ignoring the differential term in equations (14) and (15) and further substituting equation (43).

[0099]

[Equation 28]

In the equations (31) and (32), Φ
If qr = 0 and Idr = 0, the following equation is obtained.

[0101]

(Equation 29)

Now, the active power P input to the induction motor
in is given by the following equation as is known.

[0103]

[Equation 30]

Therefore, the equations (44) to (47) are changed to (48)
Substituting into the equation gives:

[0105]

[Equation 31]

Next, the mechanical output Pout of the induction motor
Is given by the following equation as is known.

[0107]

(Equation 32)

Here, ωrm is the mechanical rotation frequency of the induction motor, and has the following relationship with the electrical rotation frequency ωr.

[0109]

[Equation 33]

When ωs is eliminated by substituting equation (26) into equation (51), the following equation is obtained.

[0111]

(Equation 34)

Therefore, the equations (30) and (52) are replaced by (5)
When Tm and ωrm are eliminated by substituting into equation (0), the following equation is obtained.

[0113]

(Equation 35)

Then, from the equations (49) and (53), the loss Ploss generated in the induction motor is given by the following equation.

[0115]

[Equation 36]

Under the condition that the generated torque is constant, (5
Φ such that the loss Ploss represented by the expression 4) is minimized.
It can be seen that maximum efficiency operation can be realized by obtaining a combination of dr and Iqr. Then, next, the loss Plos
A combination of Φdr and Iqr that minimizes s is obtained. First, the condition that the generated torque is constant is expressed by the following equation from the relationship of the equation (30).

[0117]

(37)

Therefore, when Φdr is eliminated by substituting equation (55) into equation (54), the following equation is obtained.

[0119]

[Equation 38]

From equation (56), it can be seen that the loss Ploss is minimized when the condition that the value obtained by differentiating the right side of equation (56) with Iqr ² is zero is satisfied. Therefore, from this condition and equation (55), the relationship between Φdr and Iqr when the loss Ploss is minimized is given by the following equation.

[0121]

[Equation 39]

That is, the ratio of the amplitudes of Φdr and Iqr is (5
Maximum efficiency operation can be realized by controlling Φdr and Iqr according to the torque command so as to satisfy the expression (7). still,
The expression (57) is derived by ignoring the differential term in the expressions (14) to (17). However, the expressions (14) to (17) express the voltage / current equations of the induction motor on the rotating coordinate axis as described above. Represents.

Therefore, when the induction motor is accelerated / decelerated with a constant torque, the differential terms in equations (14) to (17) become zero, so that maximum efficiency operation can be realized by equation (57).

As described above, as a procedure for realizing the maximum efficiency operation, the d-axis component command Φdr * of the secondary magnetic flux and the q-axis component command Iqr * of the secondary current satisfying the equation (57) according to the torque command. Then, control may be performed so that the d-axis component Φdr of the secondary magnetic flux and the q-axis component Iqr of the secondary current follow the respective commands. However, as described above, Φdr, Iq
Since r cannot be directly controlled, d-axis component command Ids * and q-axis component command Iq of the primary current are obtained from Φdr * and Iqr *.
s * is determined, and the d-axis component Ids and the q-axis component I of the primary current
qs is controlled so as to follow each command value.

That is, Φdr * and Iqr * corresponding to the torque command Tm * and the primary frequency ω are obtained by using the equations (30) and (57), and are obtained by using the equations (34) and (35). Φdr * and Iqr * are converted into Ids * and Iqs *, and control is performed so that Ids and Iqs follow their respective command values.

However, based on the above procedure, the d-axis component command Ids * and the q-axis component command Iqs * of the primary current are
The computation process is complicated until is obtained, and a high computation capability is required to realize it. Therefore, this calculation process is simplified, and the calculation of Ids * and Iqs * is reduced.

First, the absolute value of the ratio between the amplitudes of Iqs * and Ids * is expressed by the following equation from equations (34) and (35).

[0128]

(Equation 40)

When the absolute value | ω | of the primary frequency is determined, (5)
Equation (7) is determined, and therefore equation (58) is determined. Therefore, | Iqs * / Ids * | corresponding to | ω |
Can be obtained in advance and converted into map data.

The generated torque Tm is expressed by the following equation using the d-axis component Ids and the q-axis component Iqs of the primary current.

[0131]

(Equation 41)

Here, Tm = Tm *, Ids = Ids *, Iqs = Iq using the fact that the signs of Tm * and Iqs * match, and | Iqs * / Ids * | and equation (59).
Substituting s * gives the following equation:

[0133]

(Equation 42)

As described above, regarding the generation of the primary current command, | Iqs * / Iqs * | that satisfies the maximum efficiency condition (57) is calculated from the map data using the primary frequency ω. * Tokara (60), (61)
By using the formula to obtain Ids * and Iqs *, computation can be saved.

Next, the slip frequency ωs is calculated from equation (27) using the d-axis component Φdr of the secondary magnetic flux, the d-axis component Ids of the primary current, and the q-axis component Iqs. Φ
dr is obtained by equation (28) using Ids and Iqs. However, the slip frequency calculation process when these iron losses are taken into consideration is complicated and requires a high calculation capability. Therefore, for the purpose of effectively utilizing the limited computing power, the computations of the equations (27) and (28) are simplified, and the computation of ωs is reduced.

First, when iron loss is not considered, Φdr is given by the following equation by setting k = 0 in equation (28).

[0137]

[Equation 43]

Accordingly, the slip frequency ωs ′ when iron loss is not taken into account (expressed as ωs ′ to distinguish it from the above-mentioned slip frequency taking into account iron loss) is k = 0 in equation (27).
Using the equation (62), the following equation can be used.

[0139]

[Equation 44]

Here, when the ratio between the slip frequency ωs in which iron loss is taken into consideration and the slip frequency ωs ′ in which iron loss is not taken into account is obtained, as shown in FIG. Takes the form of the following function: Therefore, the ratio between ωs and ωs ′ is approximated to a linear function as in the following equation.

[0141]

[Equation 45]

Here, N and O are constants determined by the constants and operating conditions of the induction motor. Using the equation (64), the slip frequency ωs considering the iron loss is calculated by the following equation from the slip frequency ωs ′ not considering the iron loss and the rotation frequency ωr.

[0143]

[Equation 46]

As described above, by using the equations (63) to (65), it is possible to reduce the calculation required for calculating the slip frequency ωs.

The conditional expression for the maximum efficiency control represented by the expression (57) includes the primary resistance Rs and the secondary resistance Rr. As is known, the values of Rs and Rr depend on the temperature.
For example, when the stator winding is made of copper, the relationship between the temperature and the value of the primary resistance Rs is as follows.

[0146]

[Equation 47]

Further, Rr is similarly represented by a function of temperature. Therefore, Rs and Rs are changed by the temperature change of the motor.
The r value fluctuates, and the value on the right side of equation (57) changes. As a result, the right side of equation (58) also changes, so that the d-axis component command Ids * and the q-axis component command Iqs * of the primary current for performing the maximum efficiency control can be said to be variables dependent on the temperature of the electric motor.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Embodiment 1 FIG. FIG. 1 is a block diagram showing a configuration of an induction motor control device according to Embodiment 1 of the present invention. still,
In the figure, the same reference numerals as those in FIG. 23 indicate the same or corresponding parts.
In FIG. 1, reference numeral 2a denotes a q-axis component of a primary current on an orthogonal rotating coordinate axis (referred to as a dq axis) rotating at a primary frequency which is a torque current command based on a rotation frequency ωr input from a speed detector 7. This is a current ratio storage / arithmetic circuit that outputs an amplitude ratio (referred to as a current ratio) between a command Iqs * and a d-axis component command Ids * of a primary current as an excitation current command. 3a is a torque command Tm * of the induction motor 1 and a current ratio storage arithmetic circuit 2a.
A current component command calculating means for outputting a d-axis component command Ids * and a q-axis component command Iqs * of the primary current based on the current ratio input from. 12 is the output I of the current detector 4
This is a current component calculating unit that inputs us, Ivs, and a phase θ obtained by integrating a primary frequency ω described later, and calculates a d-axis component Ids and a q-axis component Iqs of the primary current. Reference numeral 8 denotes a slip frequency calculation circuit that receives the d-axis component Ids and the q-axis component Iqs of the primary current and calculates a slip frequency ωs ′ when the iron loss of the induction motor 1 is not considered, and 9 denotes a slip frequency calculation circuit. 8 is an adder that adds the slip frequency ωs ′ when the iron loss is not taken into consideration and the rotational frequency ωr output from the speed detector 7 to form a primary frequency ω, and 11 integrates the primary frequency ω. The integrator 5 outputs the phase θ to the current component calculation means 12 and a voltage command calculation circuit 6 described later. The integrator 5 includes a d-axis component Ids and a q-axis component I
qs controls the primary current of the induction motor 1 so as to follow the d-axis component command Ids * and the q-axis component command Iqs *, respectively, to obtain the d-axis component command Vds * and the q-axis component command Vqs * of the primary voltage. The output current component control circuit 6 outputs a primary voltage command V based on Vds * and Vqs * output from the current component control circuit 5 and the phase θ output from the integrator 11.
us * (U phase), Vvs * (V phase), Vws * (W phase)
Are output to the PWM inverter 10.

FIG. 2 is a block diagram showing a detailed configuration of the current ratio storage operation circuit 2a. As shown in the figure, the current ratio storage operation circuit 2a receives the rotation frequency ωr, and calculates the absolute value | ωr |
And the q-axis component command Iqs * and the d-axis component command Ids * of the primary current based on the stored map data.
And a map data section 24a that outputs the ratio of the amplitudes of the current (current ratio | Iqs * / Ids * |).

FIG. 3 is a block diagram showing a detailed configuration of the current component command calculating means 3a. As shown in the figure, the current component command calculating means 3a includes a coefficient unit 31 for multiplying a torque command Tm * by a predetermined coefficient and outputting the result, an absolute value circuit 32 for obtaining an absolute value of the output of the coefficient unit 31, Using the output of the absolute value circuit 32 as a numerator, the current ratio storage operation circuit 2a
The current ratio | Iqs * / Ids * |, which is the output of, as a denominator, and divides to obtain Ids * ² ;
Calculates the square root of ds * ² and obtains d-axis component command I of primary current.
ds *, a square root operation circuit 34, and a torque command T
a code discriminator 35 which outputs 1 when m * is input and Tm *> 0, -1 when Tm * <0, and 0 when Tm * = 0, and its sign discriminator 35 multiplied by the current ratio | Iqs * / Ids * |
Is multiplied by Ids *, which is the output of the square root operation circuit 34, and the output of the multiplier 36 to obtain the q-axis component command I of the primary current.
and a multiplier 37 for outputting qs *.

FIG. 4 is a block diagram showing a detailed configuration of the slip frequency calculation circuit 8. As shown in FIG. As shown in this figure, the slip frequency calculation circuit 8 includes a coefficient unit 41 for multiplying a q-axis component Iqs of the primary current by a predetermined coefficient, and a d-axis component Iqs of the primary current.
a first-order delay circuit 42 which inputs ds, sets a time constant to Tr, and outputs a first-order delay component, a coefficient unit 43 which multiplies the output of the first-order delay circuit 42 by a predetermined coefficient and outputs the result, and a coefficient unit 41 And a divider 44 that divides the output of the coefficient unit 43 as a denominator using the output of the coefficient unit 43 as a numerator and outputs the slip frequency ωs ′ without considering the iron loss.

Next, the operation of the first embodiment will be described. The current ratio storage arithmetic circuit 2a receives the rotation frequency ωr, and receives the ratio of the amplitude of the primary current q-axis component command Iqs * and the d-axis component command Ids * that satisfies the condition (57) of the maximum efficiency control (current ratio | Iqs * / Ids * |) is output.
The inside of the current ratio storage arithmetic circuit 2a has the configuration shown in FIG. 2, and the absolute value circuit 23 calculates the absolute value | ωr of the rotation frequency ωr.
Is obtained, and a corresponding current ratio is extracted based on the map data of the current ratio (Expression (58)) satisfying Expression (57) stored in advance in the map data section 24a.

Next, the torque command Tm * and the current ratio | Iqs
* / Ids * | to the current component command calculating means 3a,
The d-axis component command Ids * and the q-axis component command Iqs * of the primary current are output using the relations of equations (60) and (61).

The specific operation of the current component command calculation means 3a will be described below with reference to FIG. Torque command Tm *
Is input to the absolute value circuit 32 through the coefficient unit 31. When the obtained absolute value is input to the divider 33 using the numerator and the current ratio | Iqs * / Ids * | as the denominator, Ids * ² is obtained. When the Ids * ² is input to the square root operation circuit 34, the Ids * represented by the equation (60) is output. When the torque command Tm * is input to the code discriminator 35,
1 if Tm *> 0, -1 if Tm * <0,
When Tm * = 0, 0 is output. Sign discriminator 35
And the current ratio | Iqs * / Ids * |
Further, when the output of the multiplier 36 and the output Ids * of the square root operation circuit 34 are multiplied by the multiplier 37, Iqs * represented by the equation (61) is obtained.

Next, 1 is detected by the current detector 4.
Next current Ius (U phase), Ivs (V phase) and integrator 11
Is input to the current component calculating means 12, the equations (41) and (42) are calculated, and the d-axis component Ids and the q-axis component Iqs of the primary current are output.

Subsequently, when the d-axis component Ids and the q-axis component Iqs of the primary current output from the current component calculating means 12 are input to the slip frequency calculating circuit 8, the formula (63) is calculated and the iron loss is considered. A slip frequency ωs ′ that is not to be output is output. Specifically, as shown in FIG. 4, a product obtained by multiplying the q-axis component Iqs of the primary current by the coefficient of the coefficient unit 41 is obtained by passing the d-axis component Ids of the primary current through the primary delay circuit 42. When a product obtained by multiplying the obtained output by the coefficient of the coefficient unit 43 is input to the divider 44 as a denominator, the operation of Expression (63) is performed and ω
s' is output.

Next, the rotation frequency ωr output from the speed detector 7 and the rotation frequency ωr output from the slip frequency
The primary frequency ω is obtained by adding s ′ by the adder 9. Further, when the primary frequency ω is integrated by the integrator 11, (3
The phase θ is obtained as shown by the equation 9).

Subsequently, the d-axis component command Ids * and the q-axis component command Iqs * of the primary current output from the current component command calculating means 3a, and the d-axis component of the primary current output from the current component calculating means 12 Ids, the q-axis component Iqs, and the primary frequency ω are input to the current component control circuit 5, and Ids is set to Id
The deviation between Ids * and Ids is amplified to follow s * (P
I control), a primary voltage d-axis component command Vds * is output. Similarly, when the difference between Iqs * and Iqs is amplified (PI control) so that Iqs follows Iqs *, q-axis component command Vqs * of the primary voltage is output.

Next, the voltage command calculation circuit 6 outputs the d-axis component command Vds of the primary voltage output from the current component control circuit 5.
* And q-axis component command Vqs *, and the following (6
7), (68) and (69), the primary voltage command Vu
s * (U phase), Vvs * (V phase), Vws * (W phase) are output. Here, equations (37), (38), and (40) hold in the same manner for voltage, and therefore, in these equations, Ius, Ivs, Iws, Ids, and Iqs are respectively represented by Vus *, Vvs *, Vws *, and Vds. *, Vqs *, and then solving for Vus *, Vvs *, Vws *, the following equation is obtained.

[Equation 48]

Subsequently, by the PWM inverter 10,
The primary voltage of each phase applied to the induction motor 1 is dq
The control is performed so as to follow the primary voltage command output from the current component control circuit 5 on the axis. As a result, the d-axis component Ids and the q-axis component Iqs of the primary current of the induction motor 1 follow the respective commands, and the maximum efficiency condition (5
The induction motor 1 can be operated based on the equation (7).

Embodiment 2 FIG. 5 is a block diagram showing a configuration of an induction motor control device according to Embodiment 2 as an embodiment related to the first invention. Note that in FIG.
The same reference numerals indicate the same or corresponding parts. In FIG. 5, in the second embodiment, the slip frequency (slip frequency before correction) ωs ′ not considering the iron loss output from the frequency calculation circuit 8 is changed to the slip frequency (slip frequency after correction) ωs considering the iron loss. Embodiment 1 of FIG. 1 except that a slip frequency iron loss component correcting means 13 for correcting
Is the same as

FIG. 6 shows the slip frequency iron loss component correcting means 13.
FIG. 3 is a block diagram showing a detailed configuration of the embodiment. As shown in the figure, the slip frequency iron loss component correction means 13 receives an absolute value circuit 51 for inputting the rotation frequency ωr to obtain an absolute value | ωr | and a rotation of the induction motor 1 by inputting | ωr | A linear function calculator 52 that outputs a calculation result of a predetermined linear function with respect to the frequency ωr as a slip frequency ratio J, and a slip frequency ratio J output from the linear function calculator 52 and an output from the slip frequency calculator 8 And a multiplier 53 that multiplies the slip frequency ωs ′ that does not consider the iron loss and outputs the slip frequency ωs that takes the iron loss into account.

A specific operation of the slip frequency iron loss component correcting means 13 will be described with reference to FIG. Rotation frequency ωr
Is input to the absolute value circuit 51 to obtain | ωr |
r | is input to the linear function calculator 52. Then, (6
4) Slip frequency ωs ′ not considering iron loss and slip frequency ω considering iron loss, approximated by a linear function represented by equation (4)
A ratio (slip frequency ratio) J to s is output. When the output J of the linear function calculator 52 and the slip frequency ωs ′ not considering the iron loss output from the slip frequency calculation circuit 8 are multiplied by the multiplier 53, the iron loss is considered based on the equation (65). The obtained slip frequency ωs is obtained. The slip frequency ratio J approximated by a linear function is expressed as shown in FIG.

Next, the rotation frequency ωr output from the speed detector 7 and the slip frequency ωs considering the iron loss output from the slip frequency iron loss component correcting means 13 are added by the adder 9 to obtain 1 The next frequency ω is obtained.

Embodiment 3 FIG. 8 is a block diagram showing a configuration of an induction motor control device according to Embodiment 3 as an embodiment related to the first invention, in which the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In this embodiment, as shown in FIG. 8, an electric motor temperature detector 14 for detecting the temperature of the stator winding of the induction motor 1 is provided, and the output of the electric motor temperature detector 14 is supplied to the current ratio storage operation circuit 2b. This is input and reflected in the calculation of the current ratio.

That is, as described above, for example, when the stator winding is made of copper, the value of the primary resistance Rs fluctuates according to the equation (66) due to a change in the motor temperature. Therefore, (5
Since the value on the right side of equation (7) changes with temperature, (5)
The right side of equation 8) also changes. Thus, the ratio of the amplitude of the primary current q-axis component command Iqs * and the d-axis component command Ids * for realizing the maximum efficiency control (current ratio | Iqs * / Ids *)
|) Is a function of the motor temperature.

Therefore, the current ratio | Iqs * / Ids * stored in the map data section 24b of the current ratio storage operation circuit 2b.
| Data is taken into account the variation due to temperature, (57),
It is assumed that the results calculated according to the equations (58) and (66) are converted into map data. FIG. 9 shows a current ratio storage operation circuit 2b.
FIG. 3 is a block diagram showing a detailed configuration of the embodiment. That is, the current ratio storage arithmetic circuit 2b determines the rotation frequency ωr and the motor temperature detector 1
4 and the motor temperature, and outputs a current ratio | Iqs * / Ids * | according to the state of each input.

Embodiment 4 FIG. 10 is a block diagram showing a configuration of an induction motor control device according to Embodiment 4 as an embodiment related to the first invention, in which the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In FIG. 10, the fourth embodiment includes an inductance correction unit 15 that inputs the d-axis component Ids of the primary current and the rotation frequency ωr, and outputs an excitation inductance M ′ according to the state of each input. The output of the inductance correction means 15 is input to the current component command calculation means 3b and reflected in the calculation. That is, the current component command calculation means 3b outputs the torque command Tm * of the induction motor 1, the current ratio output from the current ratio storage calculation circuit 2a, and the excitation inductance M 'output from the inductance correction means 15.
To output a primary current d-axis component command Ids * and a q-axis component command Iqs *.

FIG. 11 is a block diagram showing a detailed configuration of the inductance correcting means 15. As shown in this figure, the inductance correction means 15 receives the rotation frequency ωr and obtains the absolute value | ωr |
And a map data unit 62 that receives | ωr | and the d-axis component Ids of the primary current and outputs the excitation inductance M ′ based on the map data.

FIG. 12 is a block diagram showing a detailed configuration of the current component command calculating means 3b. The current component command calculation means 3b receives the torque command Tm *, the current ratio | Iqs * / Ids * | output from the current ratio storage calculation circuit 2a, and the excitation inductance M 'output from the inductance correction means 15, and Current d-axis component commands Ids * and (Tm *
An excitation current command calculation circuit 70 that calculates and outputs (Lr) / (Pm · M′2); and a limiting circuit that inputs Ids *, limits the maximum value to the limit value at which magnetic flux is saturated, and outputs the limit value. 71 and (Tm * · Lr) / (Pm · M′2) as numerators, and Ids * output from the limiting circuit 71 as a denominator, which is divided by dividing by the q-axis component command Iqs * of the primary current. And a divider 72. Further, the excitation current command calculation circuit 70 includes a coefficient unit 73 that multiplies the torque command Tm * by a predetermined coefficient and outputs the result.
A multiplier 74 which squares the output of the excitation inductance M ′, which is the output of the multiplier 74, and an output of the coefficient unit 73 are used as a numerator, and an output of the multiplier 74 is input as a denominator and divided (Tm * · L
r) / (Pm · M′2), an absolute value circuit 76 for obtaining the absolute value of the output of the divider 75, and a current ratio storage arithmetic circuit using the output of the absolute value circuit 76 as a numerator. The current ratio | Iqs * / Ids * | output from 2a is input as a denominator and divided to obtain Ids * ² by a divider 77.
And the square root of Ids * ² to calculate the d-axis component command Ids
And a square root operation circuit 78 for outputting *.

Next, the operation of the fourth embodiment will be described. When the rotation frequency ωr and the d-axis component Ids of the primary current are input to the inductance correction means 15, the absolute value circuit 61 calculates the absolute value | ωr | of the rotation frequency inside the inductance correction means 15, and this | ωr Excitation inductance M ′ associated with | and Ids is output from map data unit 62. This is the output of the inductance correction means 15. Next, the torque command Tm
*, Excitation inductance M ′, and current ratio | Iqs * /
When Ids * | is input to the current component command calculating means 3b,
Inside the numerator, the torque command Tm * multiplied by the coefficient of the coefficient unit 73 is used as the numerator, and the exciting inductance M ′ is multiplied by the multiplier 7.
(Tm * · Lr) / (Pm · M ′ ² ) is obtained by the divider 75 using the squared value of 4 as the denominator. Further, | (Tm * · Lr) / (Pm ·) obtained by passing (Tm * · Lr) / (Pm · M ′ ² ) through the absolute value circuit 76
M ′ ² ) | is a numerator and the current ratio | Iqs * / Ids * |
Is used as the denominator, Ids * ² is obtained by the divider 77, and Ids * is obtained by the square root operation circuit 78. The above calculation process is based on equation (60). Next, Ids
* Is limited by the limiting circuit 71 to the maximum value at which the magnetic flux is saturated. Further, (Tm * · Lr) / (Pm ·
Ids * passed through the limiting circuit 78 with M ′ ² ) as the numerator
Is divided by the divider 72 as a denominator, Iqs * is obtained by the operation based on the expression (59).

Embodiment 5 FIG. In the first to fourth embodiments, the map data unit 24 of the current ratio storage operation circuit 2a
a, or the map data of the current ratio stored in the map data section 24b of the current ratio storage operation circuit 2b may be data obtained by linearly approximating at least the rotation frequency ωr. FIG. 13 shows an example of the relationship of the current ratio | Iqs * / Ids * | to | ωr | in this case.

Embodiment 6 FIG. In the current ratio storage operation circuit 2a or 2b of the fifth embodiment, the primary frequency ω output from the adder 9 may be used instead of inputting the rotation frequency ωr output from the speed detector 7.

Embodiment 7 In the slip frequency iron loss component correcting means 13 of the second embodiment, the primary frequency ω output from the adder 9 may be used instead of inputting the rotation frequency ωr output from the speed detector 7.

Next, before describing the embodiment of the second invention, a vector control method for generating a predetermined torque with a minimum primary voltage, which is a basis of the second invention, will be described.
The voltage of the induction motor on the dq axes rotating at the primary frequency
When a steady state is considered without assuming iron loss, the current equation is expressed by the following equation from equations (14) to (17) as is known.

[0176]

[Equation 49] Here, Rs and Rr are the primary resistance and the secondary resistance of the induction motor, respectively. Ls, Lr, and M are a primary self inductance, a secondary self inductance, and a mutual inductance of the induction motor, respectively. Vds and Vqs are the d-axis component and the q-axis component of the primary voltage, respectively. Ids and Iqs are the d-axis component and the q-axis component of the primary current, respectively, and Idr and Iqr are respectively 2
These are the d-axis component and the q-axis component of the secondary current. ω and ωs ′ are the primary frequency of the induction motor and the slip frequency without assuming iron loss, respectively.

Here, if the Φqr of the d-axis component Φdr and the q-axis component Φqr of the secondary magnetic flux is set to zero in order to make the direction of the secondary magnetic flux vector coincide with the d-axis, the slip frequency in the known vector control is obtained. ωs ′ is expressed by Expression (63), and the generated torque Tm is expressed by Expression (59).
The d-axis component Φdr of the next magnetic flux and the voltage / current equation are expressed by the following equations, respectively.

[0178]

[Equation 50]

From equations (75) and (76), the primary voltage Vs
Becomes as follows.

[0180]

(Equation 51)

Here, the case where the generated torque Tm = TA and the primary voltage Vs = VsA will be considered. From equation (59), Ids
Iqs can be expressed as the following equation.

[0182]

(Equation 52)

The equation (78) is substituted into the equation (77), and the following equation is applied.

[0184]

(Equation 53)

Here, the ellipse expressed by the equation (79) and (7)
8) When the curve represented by the equation is in contact at one point, the combination of the d-axis component Ids and the q-axis component Iqs of the primary current at the contact generates a torque TA, and the primary voltage is V
This is the only combination that is sA. This pattern is shown in FIG.
Shown in Other than this, Ids and Iq satisfying the expression (78)
In the combination of s, a value larger than VsA is required as the primary voltage to generate the torque TA. In other words, by using a combination of Ids and Iqs when the ellipse represented by the equation (79) and the curve represented by the equation (78) meet at one point, a required torque is generated at the minimum primary voltage, or The maximum torque can be generated at a predetermined primary voltage.

The contact point between the ellipse shown by the equation (79) and the curve shown by the equation (78) is obtained as follows.
From Expression (78), Iqs is expressed by using Ids as follows.

[0187]

(Equation 54)

By substituting equation (80) into equation (79) and rearranging both sides by Ids ² , the following equation is obtained.

[0189]

[Equation 55]

Here, the condition where the expressions (79) and (78) meet at one point is as follows:

[0191]

[Equation 56] Than,

[0192]

[Equation 57]

Therefore, it is expressed by the following equation.

[0194]

[Equation 58]

At this time, Ids is

[0196]

[Equation 59] Therefore, the combination of Ids and Iqs is expressed by the following equation when expressed by the ratio of the amplitudes of Iqs and Ids.

[0197]

[Equation 60]

From the above, 1 is obtained based on the equation (86).
By controlling the d-axis component Ids and the q-axis component Iqs of the secondary current, a required torque can be generated at a minimum primary voltage, or a maximum torque can be generated at a predetermined primary voltage. Hereinafter, the control method using this method will be referred to as a minimum primary voltage control method.

Embodiment 8 FIG. FIG. 16 is a block diagram showing a configuration of an induction motor control device according to Embodiment 8 as an embodiment related to the second invention, in which the same reference numerals as those in FIG. 1 denote the same or corresponding parts. In FIG. 16, the induction motor control device according to the embodiment differs from the component 5-12 of the embodiment 1 in FIG. 1 in that the following components are used instead of the current component command calculation means 3a and the current ratio storage calculation circuit 2a. It has components. In other words, the induction motor control device includes a DC power supply 25 that supplies an AC converted signal or a DC voltage, a DC voltage detection unit 16 that detects a voltage value of the DC voltage supplied by the DC power supply 25, and a DC voltage detection unit. A maximum output voltage calculation circuit 17 that calculates and outputs a maximum value Vsmax of a primary voltage that can be output based on the DC voltage value input from the unit 16;
Whether voltage saturation has occurred based on the maximum primary voltage value Vsmax that can be output and the d-axis component command Vds * and the q-axis component command Vqs * of the primary voltage input from the current component control circuit 5 And a voltage saturation detecting means 18 for outputting the degree of voltage saturation as a first saturation amount component Vovr1, and a rotation frequency ω output from the speed detector 7.
A current that outputs a ratio (current ratio) FB = | IqsB * / IdsB * | of the amplitude of the q-axis component command IqsB * and the d-axis component command IdsB * of the primary current at the time of minimum primary voltage control based on r. A ratio calculation means (B) 19, a q-axis component command Iqs * of a primary current which is a torque current command output by a current command generator of a conventional device (not shown) (referred to as a pre-correction primary current q-axis component command), and A primary current d-axis component command Ids * (referred to as an uncorrected primary current d-axis component command), which is an exciting current command, is input, and the amplitude ratio (current ratio) FA = | Iqs * /
A current ratio calculating means (A) 20 for outputting Ids * | and a first saturation component Vov output from the voltage saturation detecting means 18
r1 and the current ratio FB output by the current ratio calculating means (B) and the current ratio FA output by the current ratio calculating means (A) are input, and q of the corrected primary current is determined according to the magnitude of Vovr1.
The axis component command Iqs * '(referred to as the corrected primary current q-axis component command) and the d-axis component command Ids *' (the corrected primary current d
Ratio (current ratio) FC = | Iq
current ratio adjusting means 21a for outputting s * '/ Ids *' |
Based on the torque command Tm * of the induction motor 1 and the current ratio FC input from the current ratio adjusting means 21a.
And a corrected current component command calculating means 30a for outputting the secondary current d-axis component command Ids * 'and the corrected primary current q-axis component command Iqs *'.

FIG. 17 is a block diagram showing a detailed configuration of the current ratio calculating means (A) 20. As shown in this figure,
The current ratio calculating means (A) 20 is a primary current q-axis component command I before correction output from a current command generator of a conventional device (not shown).
qs * is a numerator, primary current before correction d-axis component command Ids
It is composed of a divider 81 for dividing by inputting * as a denominator, and an absolute value circuit 82 for calculating and outputting an absolute value FA = | Iqs * / Ids * | of the output of the divider 81.

FIG. 18 is a block diagram showing a detailed configuration of the voltage saturation detecting means 18. As shown in FIG. As shown in this figure, the voltage saturation detecting means 18 has a d-axis component Vds * of the primary voltage command.
Multiplier 91 for calculating the square Vds * ² of the primary voltage command and multiplier 9 for calculating the square Vqs * ² of the q-axis component Vqs * of the primary voltage command
2, an adder 93 for adding and outputting Vds * ² and Vqs * ² , a square root operation circuit 94 for obtaining a square root of the output of the adder 93, and a maximum primary voltage value Vsmax that can be output.
A subtractor 95 for comparing and comparing the output of the square root operation circuit 94 with the output of the square root operation circuit 94 to obtain the deviation, and a limiting circuit 96 for limiting the minimum value of the output of the subtracter 95 to zero.

FIG. 19 is a block diagram showing a detailed configuration of the current ratio adjusting means 21a. As shown in the figure, a current ratio adjusting unit 21a includes a coefficient unit 101 that multiplies a first saturation amount component Vovr1 output from the voltage saturation detecting unit 18 by a predetermined coefficient K1 and outputs the result. A limiting circuit 102 for limiting the maximum value of the output by 1.0, a current ratio FA output from the current ratio calculating means (A), and a current ratio FB output from the current ratio calculating means (B) are input. A subtractor 103 for calculating the deviation, an output of the limiting circuit 102 and the subtractor 10
3 is multiplied by the output of the multiplier 104, and the output of the multiplier 104 is subtracted from the current ratio FA.
And a subtractor 105 that outputs

Next, the operation of the eighth embodiment will be described. When the uncorrected primary current q-axis component command Iqs * and the uncorrected primary current d-axis component command Ids * output from the current command generator of the conventional device (not shown) are input to the current ratio calculating means (A) 20, The current ratio FA = | Iqs * / Ids * | is output through the divider 81 and the absolute value circuit 82. When the rotation frequency ωr output from the speed detector 7 is input to the current ratio calculating means (B) 19, the q-axis component command Iq of the primary current in the minimum primary voltage control based on the equation (86)
An amplitude ratio (current ratio) FB = | IqsB * / IdsB * | between the sB * and the d-axis component command IdsB * is calculated and output from a calculation or a map of the calculation result.

Subsequently, the DC voltage detection unit 16
5 is detected, and the maximum output voltage operation circuit 17 is detected.
Output to In the maximum output voltage calculation circuit 17, (12)
The maximum primary voltage value Vsmax that can be output is calculated and output based on the equation.

Next, the maximum primary voltage value Vsmax that can be output to the voltage saturation detecting means 18 and the primary voltage d-axis component command V
When ds * and the q-axis component command Vqs * are input, the presence / absence of voltage saturation is detected, and the degree of voltage saturation is set to the first level.
Is output as the saturation amount component Vovr1. Hereinafter, FIG.
The specific operation of the voltage saturation detecting means 18 will be described with reference to FIG.

The primary voltage d-axis component command Vds * and the q-axis component command Vqs * are squared by multipliers 91 and 92, respectively, and are added by an adder 93 to Vds * ² + Vqs * ^2.
Is calculated. Subsequently, (1)
The primary voltage command Vs * is output by the calculation based on the equation (0). Next, the maximum output primary voltage values Vsmax and Vs
* Is matched by the subtractor 95, and the deviation is input to the limiting circuit 96. The limiting circuit 96 limits the minimum value of the deviation to 0, and outputs the result as the first saturation amount component Vovr1. When Vs * <Vsmax, voltage saturation has not occurred and the deviation is negative, so that Vovr1 = 0 is output. When Vs * ≧ Vsmax, voltage saturation has occurred and the deviation is positive, so that an amount proportional to the deviation is output as Vovr1.

Next, when the first saturation amount component Vovr1 and the current ratio FB and the current ratio FA are input to the current ratio adjusting means 21a, if voltage saturation occurs, Vovr1
, The current ratio FA of the primary current command before correction is shifted so as to approach the current ratio FB in the minimum primary voltage control, and the correction operation is performed, and the corrected current ratio FC is output. Hereinafter, a specific operation of the current ratio adjusting unit 21a will be described with reference to FIG.

The current ratio FA and the current ratio FB are subtracted by the subtractor 103.
And the deviation (FA-FB) is obtained. Further, after the first saturation amount component Vovr1 is multiplied by K1 by the coefficient unit 101, the maximum value is limited to 1.0 by the limiting circuit 102, and is multiplied by (FA-FB) by the multiplier 104. As a result, the adjustment amount ΔF when shifting the current ratio from FA to FB = (FA−FB) · K1 · Vovr1
Is calculated. The adjustment amount ΔF is subtracted from the current ratio FA by the subtracter 105, and the corrected current ratio FC (= FA−Δ
F) is output. Here, the limit value 1.0 in the limiting circuit 102 is a numerical value caused by controlling the current ratio FC to shift to FB, and finally controlling the shift to FB when FC = FB. And is obtained as follows. If FC = FB, the following equation is obtained.

[0209]

[Equation 61]

The above equations are arranged as follows for the current ratio FA and the current ratio FB.

[0211]

(Equation 62)

Therefore, when FA ≠ FB, FC and FB match when 1−K1 · Vovr1 = 0, ie,

[0213]

[Equation 63] Is the case. Therefore, by limiting the maximum value of K1 · Vovr1 to 1.0, the FC shift is stopped when FC = FB. Note that when FA = FB, ΔF = 0 from FA−FB = 0.

Next, when the torque command Tm * and the current ratio FC are input to the corrected current component command calculating means 30a, (6)
0), the corrected primary current d-axis component command Ids * 'and the corrected primary current q-axis component command Iqs using the relations of equations (61).
* 'Is output. The configuration and operation of the corrected current component command calculation means 30a are the same as those of the current component command calculation means 3a in the first embodiment.

Subsequently, based on a known vector control method, the d-axis component Ids and the q-axis component Iqs of the primary current are converted into the corrected primary current d-axis component command Ids * 'and the corrected primary current q-axis component. Control is performed so as to follow the command Iqs * '.

According to the above procedure, the presence or absence of the occurrence of voltage saturation is detected, and the d-axis component command and the q-axis component command of the primary current are changed according to the degree of saturation to the d-axis component command of the primary current in the minimum primary voltage control. And by approaching the q-axis component command, it is possible to obtain an output torque according to the command torque while eliminating the voltage saturation state. This pattern is shown in FIG. The primary voltage d-axis component command Vds * is detected by the voltage saturation detecting means 18.
Instead of calculating the primary voltage command Vs * from the q-axis component command Vqs * and each phase component command Vus * (U
Phase), Vvs * (V phase), Vws * (W phase) to Vs *
May be calculated. Also, Vs * matched inside the voltage saturation detecting means 18 and the maximum primary voltage value V that can be output
smax may be a Vs * ² and Vsmax ^2.

[Embodiment 9] FIG. 20 is a block diagram showing a configuration of an induction motor control device according to a ninth embodiment as an embodiment related to the second invention.
The same reference numerals indicate the same or corresponding parts. 20, the ninth embodiment is the same as the eighth embodiment of FIG. 16 except that a current ratio adjusting unit 21b and a torque command correcting unit 22 are provided. The current ratio adjusting unit 21b outputs the first saturation amount component Vov output from the voltage saturation detecting unit 18.
r1, the current ratio FB output by the current ratio calculation means (B) and the current ratio FA output by the current ratio calculation means (A) are input and V
q-axis component command Iqs * 'of the primary current after correction according to the magnitude of ovr1 (referred to as a corrected primary current q-axis component command)
And the amplitude ratio (current ratio) FC = | Iqs * 'of the d-axis component command Ids *' (referred to as the corrected primary current d-axis component command)
/ Ids * '| and the second saturation component Vovr2 representing the degree of voltage saturation when voltage saturation still occurs even after using the corrected primary current command. The torque command correcting means 22 includes a torque command Tm * and a current ratio adjusting means 2.
1b, the second saturation amount component Vovr2 is input, the torque command is corrected according to the magnitude of Vovr2, and the corrected torque command Tm * 'is output.

FIG. 21 is a block diagram showing a detailed configuration of the current ratio adjusting means 21b. As shown in this figure, the current ratio adjusting means 21b sets 0 when the output of the coefficient unit 101 is 1.0 or less with respect to the current ratio adjusting means 21a shown in FIG. Has a configuration in which a saturation amount calculation circuit 106 that outputs an amount exceeding 1.0 as the second saturation amount component Vovr2 is added.

FIG. 22 is a block diagram showing a detailed configuration of the torque command correcting means 22. As shown in this figure, the torque command correcting means 22 receives the torque command Tm * and outputs 1 if Tm *> 0, -1 if Tm * <0,
Code discriminator 111 that outputs 0 when Tm * = 0
And a coefficient unit 112 for multiplying the second saturation amount component Vovr2 output from the current ratio adjusting means 21b by a predetermined coefficient K2 and outputting the result, and multiplying the output of the code discriminator 111 and the output of the coefficient unit 112 to obtain a torque It is composed of a multiplier 113 for providing a command correction amount ΔTm *, and a subtractor 114 for subtracting the correction amount ΔTm * from the torque command Tm * and outputting a corrected torque command Tm * ′.

Next, the operation of the ninth embodiment will be described. First, when the first saturation amount component Vovr1 and the current ratio FB and the current ratio FA are input to the current ratio adjusting means 21b, if the voltage saturation has occurred, the value of 1 before correction according to the magnitude of Vovr1 is obtained. Correction calculation is performed by shifting the current ratio FA of the next current command so as to approach the current ratio FB in the minimum primary voltage control, and the corrected current ratio FC is output. If voltage saturation occurs even when the corrected primary current command is used, the degree of voltage saturation is determined by the second saturation amount component Vo.
Output as vr2. Vovr2 is specifically generated as follows. When the output K1 · Vovr1 of the coefficient unit 101 in FIG. 21 is input to the saturation operation circuit 106, if K1 · Vovr1 ≦ 1.0, Vovr2 is obtained.
= 0.0, Vov if K1 · Vovr1> 1.0
r2 = K1.Vovr1-1.0 is output.
Vovr2 is a component that indicates the degree of voltage saturation when voltage saturation occurs even when the current ratio FC is adjusted to match the current ratio FB during the minimum primary voltage control.

Subsequently, when the torque command Tm * and the second saturation amount component Vovr2 are input to the torque command correction means 22, a corrected torque command Tm * 'corrected according to the magnitude of Vovr2 is output. You. Hereinafter, a specific operation of the torque command correction unit 22 will be described.

The second saturation amount component Vovr2 is calculated by the coefficient unit 11
2 is multiplied by a predetermined coefficient K2, and the torque command Tm
The output of the code discriminator 111 for discriminating the sign of * and the multiplier 1
13, the correction amount ΔT of the torque command is obtained.
m * is generated. Next, the torque command T is calculated by the subtractor 114.
The correction amount ΔTm * of the torque command is subtracted from m *, and the corrected torque command Tm * ′ is output.

Next, when the corrected torque command Tm * 'and current ratio FC are input to the corrected current component command calculating means 3a, the corrected primary current d-axis component command Ids *' and the corrected 1
The next current q-axis component command Iqs * 'is output. Subsequently, based on a known vector control method, the d-axis component Ids and the q-axis component Iqs of the primary current are respectively converted into a corrected primary current d-axis component command Ids * 'and a corrected primary current q-axis component command. It is controlled to follow Iqs * '.

According to the above-described procedure, in the eighth embodiment, when voltage saturation occurs, the d-axis component and the q-axis component of the primary current command are replaced with the d-axis component and the q-axis component of the primary current command in the minimum primary voltage control. If voltage saturation still occurs even when the axial component is matched, the occurrence of voltage saturation can be prevented by reducing the torque command.

It is needless to say that the configurations described in the embodiments relating to the first invention and the second invention can be used in combination with each other. Further, the hardware configured in the above embodiment may be realized by software processing using a microcomputer. In addition, in the first to seventh embodiments,
The first embodiment is the same as any one of the fourth to sixth embodiments.
Embodiment 2 is applied in combination with Embodiment 4 or Embodiment 4.
Is applied in combination with 7.

[0226]

As described above, according to the first aspect, by operating the primary current of the induction motor based on the condition for minimizing the loss including the iron loss, the iron loss cannot be ignored. Even when the induction motor is driven, a control device capable of operating the induction motor with high efficiency can be obtained. Further, the iron loss should be taken into account also in the slip frequency, the primary current should be manipulated in consideration of the temperature fluctuation by detecting the stator winding temperature of the electric motor, and the fluctuation in the excitation inductance such as magnetic flux saturation should be taken into consideration. By manipulating the secondary current, a control device for an induction motor that prevents a decrease in torque control performance can be obtained. Further, according to the second aspect, even if voltage saturation occurs during the operation of the induction motor, the primary current of the induction motor is operated as the first step to ensure the output torque as instructed. If the induction motor is operated to eliminate the voltage saturation and the voltage saturation is not eliminated even in the first stage, the induction motor can be operated to eliminate the voltage saturation by reducing the torque command as the second stage. . Therefore, the output voltage and the output current are not distorted by the occurrence of the voltage saturation, and it is possible to prevent the vibration of the induction motor and the decrease in the torque control accuracy due to the output voltage and the output current.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an entire first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a current ratio storage operation circuit according to the first embodiment of the present invention;

FIG. 3 is a block diagram illustrating a configuration of a current component command calculation unit according to the first embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a slip frequency calculation circuit according to Embodiment 1 of the present invention;

FIG. 5 is a block diagram showing an entire embodiment 2 of the present invention.

FIG. 6 is a block diagram showing a configuration of a slip frequency iron loss component correcting means according to Embodiment 2 of the present invention.

FIG. 7 is an explanatory diagram of an operation principle according to the second embodiment of the present invention.

FIG. 8 is a block diagram showing the entirety of a third embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a current ratio storage arithmetic circuit according to Embodiment 3 of the present invention.

FIG. 10 is a block diagram showing the entirety of a fourth embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of an inductance correction unit according to a fourth embodiment of the present invention.

FIG. 12 is a block diagram showing a configuration of a current component command calculating means according to Embodiment 4 of the present invention.

FIG. 13 is an explanatory diagram of an operation principle according to the fifth embodiment of the present invention.

FIG. 14 is an explanatory diagram of an operation principle according to the eighth embodiment of the present invention.

FIG. 15 is an explanatory diagram of an operation principle according to the eighth embodiment of the present invention.

FIG. 16 is a block diagram showing an entire embodiment 8 of the present invention.

FIG. 17 is a block diagram showing a configuration of a current ratio calculating means (A) according to Embodiment 8 of the present invention.

FIG. 18 is a block diagram illustrating a configuration of a voltage saturation detecting unit according to an eighth embodiment of the present invention.

FIG. 19 is a block diagram showing a configuration of a current ratio adjusting unit according to Embodiment 8 of the present invention.

FIG. 20 is a block diagram showing an entire ninth embodiment of the present invention.

FIG. 21 is a block diagram showing a configuration of a current ratio adjusting unit according to Embodiment 9 of the present invention.

FIG. 22 is a block diagram showing a configuration of a torque command correction unit according to Embodiment 9 of the present invention.

FIG. 23 is a block diagram showing an entire control device for an induction motor based on a first conventional technique.

FIG. 24 is a block diagram showing an entire control device for an induction motor based on a second conventional technique.

FIG. 25 is a block diagram showing a configuration of a field weakening calculation unit of a control device for an induction motor based on a second conventional technique.

[Explanation of symbols]

1 Induction motor, 2a, 2b Current ratio storage arithmetic circuit, 3
a, 3b current component command calculating means, 4 current detector, 5
Current component control circuit, 6 voltage command calculation circuit, 7 speed (rotation frequency) detector, 8 slip frequency calculation circuit,
9, 93, 128, 154, 155 Adder, 10 P
WM inverter, 11 integrator, 12 current component calculation means, 13 slip frequency iron loss component correction means, 14 motor temperature detector, 15 inductance correction means, 16,
143 DC voltage detecting section, 17 maximum output voltage calculating circuit, 18 voltage saturation detecting means, 19 current ratio calculating means (B), 20 current ratio calculating means (A), 21a, 21b
Current ratio adjusting means, 22 torque command correcting means, 23,
32, 51, 61, 76, 82 absolute value circuit, 24a,
24b, 62 Map data part, 25 DC power supply, 3
1, 41, 43, 73, 101, 112, 127 coefficient unit, 33, 44, 72, 75, 77, 81, 126 divider, 34, 78, 94 square root operation circuit, 35, 111
Code discriminators, 36, 37, 53, 74, 91, 92,
104, 113, 123 multiplier, 42 first-order delay circuit, 52 first-order function calculator, 70 excitation current command calculation circuit, 71, 96, 102 limiting circuit, 95, 103, 1
05,114,121,130-132,146,15
0, 151, 163 subtractor, 106 saturation amount operation circuit, 122, 133 to 135 amplifier, 124 function generator, 125 compensation circuit, 129 vector operation circuit, 1
41 three-phase power supply, 142 converter, 144 field weakening operation unit, 145 limiter processing unit, 147 induction machine model, 148 switching unit, 149 coordinate conversion unit (A), 1
52, 153 ACR amplifier, 156 coordinate conversion unit (B), 157 PWM operation unit, 158 base circuit,
161 limit output calculation unit, 162 saturation voltage command generation unit, 164 PI calculation unit.

Continuation of the front page (56) References JP-A-6-284772 (JP, A) JP-A-64-81679 (JP, A) JP-A-9-233898 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00 JICST file (JOIS)

Claims (8)

(57) [Claims] An induction motor, a speed (rotation frequency) detector for detecting a rotation frequency of the induction motor, and a calculation of a predetermined function using a constant of the induction motor including a constant related to iron loss as a coefficient value. A current ratio storage operation circuit for storing a result as data, inputting a variable relating to the predetermined function, and outputting a ratio (referred to as a current ratio) of an amplitude of a torque current command and an exciting current command, and a torque of the induction motor; Command and the above-described current ratio, and the exciting current command is rotated at the primary frequency by the orthogonal rotation coordinate axis (d−
current component command calculating means for outputting the primary current as a d-axis component command of the above primary current, and outputting the torque current command of the induction motor as a q-axis component command of the primary current; A current detector for detecting a primary current, an integrator for integrating a primary frequency to output a phase, and an output of the current detector and the phase,
Current component calculating means for calculating a d-axis component and a q-axis component of a secondary current; at least one of a d-axis component command and a d-axis component of the primary current; a q-axis component command and a q-axis component of the primary current And a slip frequency calculating means for calculating a slip frequency of the induction motor; adding the slip frequency output from the slip frequency calculating means to an output of the rotational frequency detector to calculate the slip frequency;
An adder forming a primary frequency; and a primary current of the induction motor so that a d-axis component and a q-axis component of the primary current follow a d-axis component command and a q-axis component command of the primary current, respectively. A current component control circuit for controlling , a d-axis component of a primary current on the orthogonal rotation coordinate axis, and a rotation circumference;
Enter the wave number, and find the excitation current and rotation frequency
From the correspondence data between the number and the exciting inductance,
Inductance correction means for obtaining and outputting conductance
With the door, the current component command calculation means, the torque command and the current ratio stored arithmetic circuit of the induction motor
Output current ratio and the above inductance correction means output
The magnetizing inductance to enter, the primary excitation current directive
Excitation current command calculation cycle output as d-axis component command of current
And the magnetic flux saturates the maximum value of the d-axis component command of the primary current.
A limiting circuit that limits the value of the limit , and a component proportional to the torque command of the induction motor is limited
Divide by the output of the circuit to obtain the primary current
a divider for forming a q-axis component command, wherein the value of the product of the output of the current component command calculation means is proportional to the torque command, and the ratio of the amplitude includes a constant related to iron loss, including the constant of the induction motor. A control device for an induction motor, which outputs a primary current command that is equal to a predetermined function value using the following. 2. An induction motor, a speed (rotation frequency) detector for detecting a rotation frequency of the induction motor, and calculation of a predetermined function using a constant of the induction motor including a constant related to iron loss as a coefficient value. A current ratio storage operation circuit for storing a result as data, inputting a variable relating to the predetermined function, and outputting a ratio (referred to as a current ratio) of an amplitude of a torque current command and an exciting current command, and a torque of the induction motor; Command and the above-described current ratio, and the exciting current command is rotated at the primary frequency by the orthogonal rotation coordinate axis (d−
a current component command calculating means for outputting as a d-axis component command of the primary current above, and outputting a torque current command of the induction motor as a q-axis component command of the primary current; A current detector for detecting a primary current, an integrator for integrating a primary frequency to output a phase, and an output of the current detector and the phase,
Current component calculating means for calculating a d-axis component and a q-axis component of a secondary current; at least one of a d-axis component command and a d-axis component of the primary current; a q-axis component command and a q-axis component of the primary current And a slip frequency calculating means for calculating a slip frequency of the induction motor; inputting the slip frequency (referred to as a pre-correction slip frequency) output from the slip frequency calculating means and the rotation frequency; A slip frequency obtained from a predetermined function operation result having a coefficient value of the constant of the induction motor including a constant related to iron loss, and a predetermined coefficient having a constant of the induction motor not related to iron loss as a coefficient value. A slip which outputs the corrected slip frequency by interpolating the above-mentioned corrected slip frequency by using a predetermined linear function obtained by approximating the slip frequency ratio obtained from the function operation result. A wave number iron loss component correcting means, an adder for adding the corrected slip frequency output from the slip frequency iron loss component correcting means and an output of the rotation frequency detector to form the primary frequency, and each d-axis component and the q-axis component of the following current, and a current component control circuit for controlling the primary current of said induction motor so as to follow the d-axis component command and a q-axis component command of the primary current, the orthogonal D-axis component of primary current on rotating coordinate axis and rotating circumference
Enter the wave number, and find the excitation current and rotation frequency
From the correspondence data between the number and the exciting inductance,
Inductance correction means for obtaining and outputting conductance
With the door, the current component command calculation means, the torque command and the current ratio stored arithmetic circuit of the induction motor
Output current ratio and the above inductance correction means output
Input the excitation inductance, and set the excitation current command to primary
Excitation current command calculation cycle output as d-axis component command of current
And the magnetic flux saturates the maximum value of the d-axis component command of the primary current.
A limiting circuit that limits the value of the limit , and a component proportional to the torque command of the induction motor is limited
Divide by the output of the circuit to obtain the primary current
a divider for forming a q-axis component command, wherein the value of the product of the output of the current component command calculating means is proportional to the torque command, and the ratio of the amplitude includes a constant related to iron loss, including a constant of the induction motor. A control device for an induction motor, which outputs a primary current command that is equal to a predetermined function value using the following. 3. The control device for an induction motor according to claim 1, further comprising: a motor temperature detector for detecting a temperature of a stator winding of the induction motor, wherein the constant related to the iron loss. A predetermined function that uses a constant of the induction motor as a coefficient value is a function of at least the motor temperature, and at least one of the inputs of the current ratio storage operation circuit is the motor temperature. Control device. 4. An induction motor and a speed (rotation frequency) for detecting a rotation frequency of the induction motor.
Number) Coefficient of detector and constant of induction motor including constant related to iron loss
Store the calculation result of a predetermined function as a value as data
Input the variables related to the above predetermined function
Outputs the ratio of the amplitude of the command and the excitation current command (called the current ratio)
And a current ratio storage operation circuit to input the torque command of the induction motor and the current ratio to excite
An orthogonal rotation coordinate axis (d-
output as the d-axis component command of the primary current
And the torque current command of the induction motor is
current component command calculating means for outputting as a q-axis component command, a current detector for detecting a primary current of the induction motor , an integrator for integrating a primary frequency to output a phase, and an output of the current detector And the phase, and
Current component calculation for calculating d-axis component and q-axis component of next current
Means and at least the d-axis component command and the d-axis component of the primary current.
One is the command of the q-axis component of the primary current and the
At least one, and enter the slip frequency of the induction motor.
Frequency calculating means for calculating the number, and the slip frequency output from the slip frequency calculating means.
The sum of the wave number and the output of the rotation frequency detector is added to the 1
The adder forming the next frequency and the d-axis component and the q-axis component of the primary current are respectively
It follows the d-axis component command and q-axis component command of the primary current.
Current component control for controlling the primary current of the induction motor
And the current ratio stored in the current ratio storage operation circuit.
The data is at least a linear function of the rotation frequency
And the value of the product of the outputs of the current component command calculation means is the torque command.
And the amplitude ratio includes a constant related to iron loss.
It becomes equal properly with a predetermined function value using the constants of the serial induction motor
A control device for an induction motor, which outputs such a primary current command . 5. An induction motor and a speed (rotation frequency) for detecting a rotation frequency of the induction motor.
Number) Coefficient of detector and constant of induction motor including constant related to iron loss
Store the calculation result of a predetermined function as a value as data
Input the variables related to the above predetermined function
Outputs the ratio of the amplitude of the command and the excitation current command (called the current ratio)
And a current ratio storage operation circuit to input the torque command of the induction motor and the current ratio to excite
An orthogonal rotation coordinate axis (d-
output as the d-axis component command of the primary current
And the torque current command of the induction motor is
current component command calculating means for outputting as a q-axis component command, a current detector for detecting a primary current of the induction motor , an integrator for integrating a primary frequency to output a phase, and an output of the current detector And the phase, and
Current component calculation for calculating d-axis component and q-axis component of next current
Means and at least the d-axis component command and the d-axis component of the primary current.
One is the command of the q-axis component of the primary current and the
At least one, and enter the slip frequency of the induction motor.
Frequency calculating means for calculating the number, and the slip frequency output from the slip frequency calculating means.
The sum of the wave number and the output of the rotation frequency detector is added to the 1
The adder forming the next frequency and the d-axis component and the q-axis component of the primary current are respectively
It follows the d-axis component command and q-axis component command of the primary current.
Current component control for controlling the primary current of the induction motor
And the current ratio stored in the current ratio storage operation circuit.
The data is at least a linear function of the primary frequency
And the value of the product of the outputs of the current component command calculation means is the torque command.
And the amplitude ratio includes a constant related to iron loss.
It becomes equal to a predetermined function value using the constant of the induction motor
A control device for an induction motor, which outputs such a primary current command . 6. An induction motor and a speed (rotation frequency) for detecting a rotation frequency of the induction motor.
Number) Coefficient of detector and constant of induction motor including constant related to iron loss
Store the calculation result of a predetermined function as a value as data
Input the variables related to the above predetermined function
Outputs the ratio of the amplitude of the command and the excitation current command (called the current ratio)
And a current ratio storage operation circuit to input the torque command of the induction motor and the current ratio to excite
An orthogonal rotation coordinate axis (d-
output as the d-axis component command of the primary current
And the torque current command of the induction motor is
current component command calculating means for outputting as a q-axis component command, a current detector for detecting a primary current of the induction motor , an integrator for integrating a primary frequency to output a phase, and an output of the current detector And the phase, and
Current component calculation for calculating d-axis component and q-axis component of next current
Means and at least the d-axis component command and the d-axis component of the primary current.
One is the command of the q-axis component of the primary current and the
At least one, and enter the slip frequency of the induction motor.
Frequency calculating means for calculating the number, and the slip frequency output from the slip frequency calculating means.
The wave number (called the pre-correction slip frequency) and the rotation frequency
Of the induction motor including the constants related to iron loss.
A function obtained from the result of a predetermined function operation using a constant as a coefficient value
The slip frequency and the constant of the induction motor not related to iron loss
Slip obtained from the result of a given function operation with
A predetermined linear function obtained by approximation from the frequency ratio
The slip frequency before correction by interpolating the slip frequency before correction.
And slip frequency iron loss component correction means for outputting a wave number, the output from the slip frequency iron loss component correction means
The corrected slip frequency and the output of the rotation frequency detector are
The adder that adds the primary frequency to form the primary frequency, and the d-axis component and the q-axis component of the primary current are respectively
It follows the d-axis component command and q-axis component command of the primary current.
Current component control for controlling the primary current of the induction motor
A predetermined primary function of the slip frequency iron loss component correcting means.
The number is a function of the primary frequency, and the product value of the output of the current component command calculating means is the torque command.
And the amplitude ratio includes a constant related to iron loss.
It becomes equal to a predetermined function value using the constant of the induction motor
A control device for an induction motor, which outputs such a primary current command . 7. A method for controlling a torque current using a voltage type inverter.
And an orthogonal rotating coordinate axis that rotates the exciting current at the primary frequency
Q-axis component and d-axis component of the primary current
Vector control system that separates and controls each
An apparatus for controlling an induction motor, a direct current to detect the power supply side DC voltage of the voltage-type inverter
A voltage detector, and a q-axis of a primary current as a torque current command for the induction motor.
Component command (referred to as primary current q-axis component command before correction) and excitation
D-axis component command of primary current, which is a magnetic current command (primary primary
(Referred to as current d-axis component command), and the amplitude ratio (current
Current ratio calculating means (A) for outputting a current ratio (referred to as a current ratio FA), and the maximum primary voltage which can be outputted by inputting the power source side DC voltage.
A maximum output voltage calculation circuit for calculating a value, a primary voltage command on a three-phase coordinate axis or a dq axis, and
Input the maximum primary voltage that can be output and
The presence / absence is detected and the degree of voltage saturation is used as the first saturation amount component.
Input the voltage saturation detection means to output and output the rotation frequency of the induction motor and other variables.
Primary voltage required to output torque as instructed by Luc
Q-axis component command and d-axis component finger of the primary current to minimize
Of the command amplitude (called the current ratio FB)
Calculate and output the result of calculation from map data
Current ratio calculating means (B), the first saturation component, the current ratio FA and the current ratio FB
And q of the primary current after correction according to the degree of saturation.
Axis component command (referred to as corrected primary current q-axis component command) and
of the d-axis component command (referred to as the corrected primary current d-axis component command)
A current ratio adjuster that outputs the amplitude ratio (called the current ratio FC)
Input and stage, the torque command and the current ratio FC of the induction motor
Then, the corrected primary current q-axis component command and the corrected primary current
A current d-axis component command that outputs a current d-axis component command
Control for an induction motor, characterized in that it comprises a stage, a. 8. The control device for an induction motor according to claim 7, wherein
Even if the current ratio adjusting means adjusts the current ratio FC,
Detects when pressure saturation occurs, and adjusts the degree of saturation.
The second saturation amount component is also output in accordance with the second saturation amount component and the torque command.
A control device for an induction motor , further comprising torque command correction means for correcting a command .