JP3056977B2 - Induction motor vector control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vector control device for an induction motor.

[0002]

2. Description of the Related Art The voltage equation of an induction motor is given by the following equation (1) in a rectangular coordinate system (hereinafter referred to as a dq coordinate system) rotating at a frequency similar to the angular frequency (primary frequency) of the secondary flux linkage.

[0003]

(Equation 1)

(1) In equation (1), r ₁ and r ₂ are primary and secondary resistance values of the induction motor, respectively, and L ₁ and L ₂ are primary and secondary inductance values including leakage inductance, respectively. , M is a mutual inductance value between the primary winding and the secondary winding, σ is a leakage coefficient of 1−M ² / (L ₁ L ₂ ), ωs
The Hasube RiAmane the wave number, p a a d / dt becomes a differential operator, V
_1d and V _1q represent the d-axis and q components of the primary voltage, respectively, i _1d ,
i _1q represents the d-axis and q-axis components of the primary current, ie, the exciting current and the torque current, and φ _2d and φ _2q represent the d-axis and q-axis components of the secondary interlinkage magnetic flux, respectively.

[0005] The secondary flux linkage can be expressed as follows. φ _2d = Mi _1d + L ₂ i _2d φ _2q = Mi _1q q + L ₂ i _2q (2) i _2d and i _2q indicate the d-axis and q-axis components of the secondary current, respectively. Vector control means φ _2d = Mi _1d (constant), φ _2q
= 0. The way is to control the primary voltage or primary current, all RiAmane wavenumber ωs If this condition is satisfied is given by equation (3).

[0006]

(Equation 2)

[0007] ... (3) However, φ _2d = Mi _1d (constant), to <br/> base RiAmane the wave number ωs if it is not φ _2q = 0 is as shown in equation (4).

[0008]

(Equation 3)

[0009] ... (4) In other words (4) of the error component is zero and becomes as the torque current i _1q, may be controlled primary frequency - omega. In FIG. 10, the vector operation device 1 calculates the primary voltage d axis and q from the excitation current command i _1d ^* , the torque current i _1q and the primary frequency ω so that φ _2d = Mi _1d (constant) and φ _2q = 0. The axis components V _1d ^* and V _1q ^* are calculated, and are specifically given by equation (6). The coordinate converter 3 transforms the voltages V _1d ^* and V _1q ^* from the vector operation device 1 into a fixed coordinate system according to the phase angle command θ of the secondary linkage flux vector.
Inverter 2 receives voltage commands Vu ^* and V from coordinate converter 3.
It comprises a PWM inverter that controls the voltage applied to the induction motor IM by v ^* and Vw ^* , and the speed of the induction motor IM is controlled by the inverter 2. The current detector 5 detects the phase currents iu, iv, iw of the induction motor IM, and the coordinate converter 6 converts the phase currents iu, i, iw into a rotating coordinate system according to the phase angle command θ of the secondary linkage flux vector. It converts and outputs the excitation current i _1d and the torque current i _1q . The delay circuit 7 outputs a delayed torque current i _1q 'is delayed torque current i _1q. The multiplier 8 outputs an all RiAmane wavenumber .omega.s ^* by multiplying the slip constant serving proportionality constant retarding torque current i _1q '(Km). By adding the adder 9 Hasube RiAmane wavenumber .omega.s ^* to the set frequency serving rotational speed command .omega.r ^* and outputs a primary frequency omega. The integrator 10 integrates the primary frequency ω and outputs a phase angle command θ of the secondary flux linkage vector. The multiplier 1 ₁ is set an initial value consisting of primary Intakutansu L ₁ and excitation current magnetic flux command value obtained by multiplying the command phi, and outputs the magnetic flux command value phi by multiplying the primary frequency omega. Inductance identifier 11 is excited in order of the excitation current value i _1d ^* of the correction, so as to zero the difference .DELTA.i _1d of the subtracter 15 by the obtained excitation current command value i _1d ^* and the excitation current i _1d The correction value of the current command value is obtained. The obtained correction value is subtracted by the subtractor 14 from the initial value i _1d ^** of the excitation current command value.

The delay circuit 7 is composed of a subtractor 7 ₁ and a controller 7 _{2. The} subtracter 7 ₁ outputs the difference between the torque current i _1q and the delayed torque current i _1q ′ to the controller 7 ₂ to control the operation. bowl 7 ₂ outputs a delayed torque current i _1q 'as the difference becomes zero, for example, a proportional-integral control.

[0011]

In the above conventional example, the induction motor is PWM-driven by the voltage type inverter, but when the switching frequency (carrier frequency) is low, the torque current ilq is delayed. The delayed torque current i _1q ′ oscillates, thereby causing the primary frequency ω
Vibrates and the induction motor IM also vibrates. for that reason,
This oscillation can be suppressed by reducing the control gain of the delay circuit 7, but there is a problem that the speed response to the load when the load is suddenly applied becomes poor at a high carrier frequency.

In the conventional vector control, when the rotation speed of the induction motor changes from acceleration to constant speed, the bus voltage increases and the trip occurs. The present invention has been made in view of the above points, and an object of the present invention is to provide a vector control method and apparatus capable of performing stable control.

[0013]

In order to achieve the above object, according to the present invention, the induction motor is controlled by an inverter, and is obtained by multiplying a set value of a primary resistance, an exciting current and a primary frequency. The torque component is calculated from the multiplied value obtained by multiplying the exciting current by the set value of the primary resistance value and the torque current, and the multiplied value obtained by multiplying the magnetic flux command value by the primary frequency. Voltage is obtained and controlled by the primary voltage obtained from the excitation voltage and the torque voltage.
Detecting means for detecting a torque current detected from the primary current of the induction motor; a delay circuit for delaying the detected torque current; and a delay value of the torque current obtained by delaying the detected delay current, which is predetermined by the induction motor. A primary frequency is determined by adding the multiplied value determined by the multiplier and a given set frequency, a three-phase voltage is determined from the primary voltage and the primary frequency, and the three-phase voltage is calculated by PWM. A vector control device for an induction motor having a means for performing control output, wherein an adjusting means for adjusting a delay control gain of the delay circuit based on a carrier frequency for performing PWM control is provided. characterized by carrier frequency to reduce the delay control gain of the delay circuit in the low-frequency, suppressing vibration of the rotational speed of the induction motor, the delay circuit to the high frequency during late By increasing the control gain,
The load response when a load is suddenly applied can be improved.

According to the second aspect of the present invention, the induction motor is controlled by the inverter, and the excitation component voltage is obtained from the set value of the primary resistance and a value obtained by multiplying the excitation current by the primary frequency, and the primary resistance value is obtained. A torque component voltage is obtained from a multiplied value obtained by multiplying the set value and the torque current, and a multiplied value obtained by multiplying the magnetic flux command value and the primary frequency. Detection means for controlling the obtained primary voltage and detecting a torque current detected from the primary current of the induction motor; a delay circuit for delaying the detected torque current; and a torque current obtained by delaying the delay circuit. To the delay value of the induction motor .
In a vector control apparatus for an induction motor, comprising a multiplication means for multiplying a slip constant, and a means for obtaining a primary frequency by adding a multiplied value obtained by the multiplication means and a given set frequency, the rotation speed of the induction motor is increasing. Determining means for determining whether the vehicle is in constant speed, and adjusting means for adjusting the slip frequency by changing the value of an element to be multiplied by the multiplying means based on the judgment of the determining means. in rotational speed Teiren and during acceleration, by adjusting the sliding frequency, it is possible to prevent the trip which occurs to the bus voltage increases when it becomes the constant speed from the acceleration.

According to the third aspect of the present invention, the induction motor is controlled by the inverter, and the excitation component voltage is obtained from the set value of the primary resistance, the value obtained by multiplying the excitation current and the primary frequency, and the primary resistance value is calculated. A torque component voltage is obtained from a multiplied value obtained by multiplying the set value and the torque current, and a multiplied value obtained by multiplying the magnetic flux command value and the primary frequency, and is obtained from the excitation component voltage and the torque component voltage. Detecting means for detecting a torque current detected from a primary current of the induction motor, a delay circuit for delaying the detected torque current, and a torque current obtained by delaying the torque current by the delay circuit. pre-stated all in the induction motor to the delay value
Detecting means for detecting a bus voltage in a vector control apparatus for an induction motor, comprising: a multiplying means for multiplying a constant by a constant and a means for adding a multiplied value obtained by the multiplying means and a given set frequency to obtain a primary frequency. And adjusting means for adjusting the slip frequency by changing the value of the element to be multiplied by the multiplying means based on the detected bus voltage, and by adjusting the slip frequency, from acceleration to constant speed In this case, a trip caused by an increase in the bus voltage can be prevented.

According to a fourth aspect of the present invention, in the second and third aspects of the present invention, the means for adjusting a slip frequency includes
An adjusting means for adjusting a slip constant to be multiplied by a delay value of the luc current is provided. In the invention of claim 5,
The invention according to claims 2 and 3 is characterized in that, as means for adjusting the slip frequency, adjusting means for adjusting a delay control gain of a delay circuit for delaying a torque current is provided.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the vector control system of the present invention is basically the same as that of the above-mentioned conventional example, but here, first consider a voltage source inverter based on FIG. When performing vector control with this voltage source inverter, in a steady state (differential term is zero), φ _2d = Mi _1d (constant) and φ _2q = 0 are substituted into the above equation (1), and (5) It can be realized by applying the voltage given by the equation.

[0018]

(Equation 4)

[0019] ... (5) However, in a transient state, appears error term due to the differential term, all RiAmane the wave number ωs is as shown in equation (6).

[0020]

(Equation 5)

(6) This is obtained by substituting equation (5) into equation (7) obtained by transforming equation (1) into a state equation and solving for ωs.

[0022]

(Equation 6)

.. (7) l₁, L_Two= Primary and secondary leakage inductance r_Two’= R_Two(M / L_Two)^Two l_Two’= L_TwoM / L_Two Next, the operation performed by the vector operation device 1 will be described.
You. The vector operation device 1 generates an exciting current command i_1d ^*And primary
Anti-r₁Multiplied by the set value of the excitation current command i _1d ^*Or
Excitation current i_1dCorrection value Δi obtained by subtracting_1dThe current control
Vessel 1_TwoAnd the value obtained through
Coefficient σ and primary inductance L₁Multiplied value σL₁And primary
Multiplier 1 with frequency ω_ThreeCan be subtracted from
And the excitation component voltage V_1d ^*Ask for. Vector operation equipment
First, the primary inductance L ₁And the excitation current command
The excitation command value φ is obtained by multiplication. Next, the torque current value i
_1qAnd the primary resistance r₁And the magnetic flux command
Multiplier 1 with value φ and primary frequency ω₁And the product multiplied by
To calculate the torque voltage V_1q ^*Ask for. Coordinate change
The converter 3 calculates the three-phase output voltages of the inverter 2.
Then, an operation as shown in equation (8) is performed, and the primary voltage V₁Seeking
And the primary voltage V₁And the calculation from the primary frequency ω
Then, three-phase output voltages are obtained.

[0024]

(Equation 7)

(8) Next, an embodiment of the present invention will be described with reference to FIGS. Since the configuration shown in FIG. 1 is the same circuit as FIG. 10, the configuration will be briefly described here. First, the vector operation device 1 determines the d-axis and q-axis components V _{1d of the} primary voltage from the excitation current command i _1d ^* , the torque current i _1q and the primary frequency ω so that φ _2d = Mi _1d (constant) and φ _2q = 0. ^* , V _1q ^* . The coordinate converter 3 converts the voltages V _1d ^* and V _1q ^* from the vector operation device 1 into the phase angle command θ of the secondary flux linkage vector.
Is converted into a fixed coordinate system according to the following formula. The inverter 2 is composed of a PWM inverter that controls the voltage applied to the induction motor IM by the voltages Vu ^* , Vv ^* , Vw ^* from the coordinate converter 3, and the induction motor IM is an inverter. 2 is speed controlled. The current detector 5 detects the phase currents iu, iv, iw of the induction motor IM. The coordinate converter 6 converts the phase currents iu, iv, iw into a rotational coordinate system according to the phase angle command θ of the secondary flux linkage vector, and converts the excitation current i
_1d , the torque current i _1q is output. The delay circuit 7 outputs a delayed torque current i _1q 'is delayed torque current i _1q.
The multiplier 8 calculates the delay torque current i _1q ′ and the slip constant (Km).
Multiplied by the output of the all RiAmane wavenumber ωs in. By adding the rotational speed .omega.r ^* and outputs a primary frequency ω to the adder 9 lotus <br/> base RiAmane wavenumber .omega.s. The integrator 10 integrates the primary frequency ω and outputs a phase angle command θ of the secondary flux linkage vector. The multiplier ₁₁ has an initial value set as a magnetic flux command value φ obtained by multiplying the primary inductance L ₁ and the exciting current command i _1d ^* , and outputs the magnetic flux command value φ by multiplying the primary frequency ω. .

The delay circuit 7 is composed of a subtractor 7 ₁ and a controller 7 _{2. The} subtracter 7 ₁ outputs the difference between the torque current i _1q and the delayed torque current i _1q ′ to the controller 7 ₂ , 7 ₂ and outputs a delayed torque current i _1q 'as the difference becomes zero. As shown in FIG. 2, when the PWM drive carrier frequency is low, the delay torque current i _1q ^* vibrates as shown in FIG. 2A, and the rotational speed becomes uneven, so that the induction motor IM vibrates. Therefore, the inverter 2, the carrier frequency is determined several, so as to adjust the control constants to determine the controller 7 ₂ as fast as the response of the delay circuit 7 accordingly. For example, as shown in FIG. 3, when more than a certain frequency carrier frequency of less than a value preset are shown in figure a fast is delay control gain response of the controller 7 ₂
Adjust the delay constant so as to gradually lower it. FIG. 2
(B) shows the delay torque current i _1q ′ when the carrier frequency is high.

Next, another embodiment of the present invention will be described with reference to FIGS.
It will be described based on. The configuration of the present embodiment is shown in FIG.
The setting frequency given to the induction motor IM in the circuit of FIG.
ωr ^*A determination unit 12 for determining whether the vehicle is accelerating or not,
The bus voltage for driving the inverter 2 is detected, and the bus voltage is
A judgment unit 13 for judging which level is added
is there.

As shown in FIG. 5A, the set frequency ω
When r ^* changes from accelerating to constant speed, the bus voltage jumps and exceeds the trip level TL as shown in FIG.
The inverter 2 trips and stops to protect a drive circuit such as a transistor. Therefore it is determined whether the acceleration in either constant speed in decision 12, thereby to the sliding constants used in the multiplier 8 illustrated in FIG. 6 (c), during acceleration during constant speed
Set the slip constant to a value smaller than the set value (Km) of the slip constant, and when the speed becomes constant, set the slip constant to the slip constant set value (Km).
And gradually use it for calculations. FIG.
(A) shows a state when the set frequency ωr ^* changes from accelerating to constant speed. FIG. 6B shows the relationship between the bus voltage and the trip level TL.

As shown in FIG. 7C, the delay control gain may be changed instead of the slip constant. FIG. 7A shows a state where the set frequency ωr ^* changes from accelerating to constant speed. FIG. 7B shows the relationship between the bus voltage and the trip level TL. Before the bus voltage reaches the trip level TL as shown in FIG. 8 (b), a determination unit 13 is provided for determining whether the bus voltage exceeds the constant adjustment level TL '. And
As a result of the determination, the slip constant of the multiplier 8 is changed to the value shown in FIG.
The slip constant setpoint value smaller than (Km) as shown in, the slip constant setting value is smaller as (Km), to use it in the calculation. FIG. 8A shows the set frequency ω.
This shows the state when r ^* changes from accelerating to constant speed.

As shown in FIG. 9B, a determination unit 13 is provided for determining whether the bus voltage exceeds a constant adjustment level TL 'set before reaching the trip level TL, as in the case of FIG. It is determined whether the bus voltage is higher or lower. Based on the determination result, the delay control gain of the delay circuit 7 is set as shown in FIG. 9C when the bus voltage is higher than the constant adjustment level TL '. To a value less than
Conversely, when the value is small, it may be used as a set value for the calculation. FIG. 9A shows a state where the set frequency ωr ^* changes from during acceleration to constant speed.

[0031]

According to a first aspect of the present invention, an induction motor is controlled by an inverter, and an excitation component voltage is obtained from a set value of a primary resistance, a value obtained by multiplying an exciting current and a primary frequency, and a primary resistance is obtained. A torque divided voltage is determined from a multiplied value obtained by multiplying the set value of the value and the torque current, and a multiplied value obtained by multiplying the magnetic flux command value and the primary frequency. Detecting means for controlling a torque voltage detected from the primary current of the induction motor, a delay circuit for delaying the detected torque current, and a torque obtained by delaying by the delay circuit. Multiplying means for multiplying the delay value of the current by a constant predetermined by the induction motor; adding the multiplied value obtained by the multiplying means and a given set frequency to obtain a primary frequency; More, in the vector control apparatus for an induction motor and means for outputting the PWM control the three-phase voltage seeking three-phase voltage, the delay control gain of the delay circuit based on the carrier frequency that is performing PWM control
It is provided with the adjusting means for adjusting, by the carrier frequency to reduce the delay control gain of the delay circuit in the low-frequency, suppressing vibration of the rotational speed of the induction motor, by increasing the delay control gain of the delay circuit to the high frequency at ,
There is an effect that a load response when a load is suddenly applied can be improved.

According to a second aspect of the present invention, an induction motor is controlled by an inverter, and an excitation component voltage is obtained from a set value of a primary resistance and a value obtained by multiplying an excitation current by a primary frequency. A torque component voltage is obtained from a multiplied value obtained by multiplying the set value and the torque current, and a multiplied value obtained by multiplying the magnetic flux command value and the primary frequency. Detection means for controlling the obtained primary voltage and detecting a torque current detected from the primary current of the induction motor; a delay circuit for delaying the detected torque current; and a torque current obtained by delaying the delay circuit. pre-stated all in the induction motor to the delay value of
In a vector control device for an induction motor including a multiplication means for multiplying the constant by a constant and a means for obtaining a primary frequency by adding the multiplied value obtained by the multiplication means and a given set frequency, the rotation speed of the induction motor is increasing. Or a constant-speed determining means, and based on the determination of the determining means, adjusting means for adjusting the slip frequency by changing the value of the element to be multiplied by the multiplying means, so that the rotational speed of the induction motor is reduced. By adjusting the slip frequency during acceleration and during a fixed cycle, it is possible to prevent a trip caused by an increase in the bus voltage when the speed changes from acceleration to constant speed.

According to a third aspect of the present invention, an induction motor is controlled by an inverter, and an excitation component voltage is obtained from a set value of a primary resistance, a value obtained by multiplying an exciting current by a primary frequency, and a primary resistance value is obtained. A torque component voltage is obtained from a multiplied value obtained by multiplying the set value and the torque current, and a multiplied value obtained by multiplying the magnetic flux command value and the primary frequency, and is obtained from the excitation component voltage and the torque component voltage. Detecting means for detecting a torque current detected from a primary current of the induction motor, a delay circuit for delaying the detected torque current, and a torque current obtained by delaying the torque current by the delay circuit. pre-stated all in the induction motor to the delay value
Detecting means for detecting a bus voltage in a vector control apparatus for an induction motor, comprising: a multiplying means for multiplying a constant by a constant and a means for adding a multiplied value obtained by the multiplying means and a given set frequency to obtain a primary frequency. And the adjusting means for adjusting the slip frequency by changing the value of the element to be multiplied by the multiplying means based on the detected bus voltage. This has the effect of preventing trips caused by an increase in the bus voltage of the semiconductor device.

[0034] The invention according to claim 4, characterized in that in the invention of claim 2, as a means for adjusting the slip frequency, the torr
Since the adjusting means for adjusting the slip constant to be multiplied by the delay value of the braking current is provided, the same effect as in claims 2 and 3 can be obtained by adjusting the slip constant. A fifth aspect of the present invention, regulation in the invention of claim 2, as a means for adjusting the slip frequency, is provided with the adjusting means for adjusting the delay control gain of the delay circuit for delaying the torque current, the delay control gain By doing so, the same effects as those of the second and third aspects are obtained.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a carrier frequency and a delay torque current according to the first embodiment.

FIG. 3 is an explanatory diagram showing a relationship between a carrier frequency and a control constant according to the first embodiment.

FIG. 4 is an overall configuration diagram of another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a relationship between a bus voltage and a frequency according to the first embodiment;

FIG. 6 is an operation explanatory view of the above.

FIG. 7 is another operation explanatory view of the above embodiment.

FIG. 8 is another operation explanatory view of the above embodiment.

FIG. 9 is a diagram illustrating still another operation of the above.

FIG. 10 is an overall configuration diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vector arithmetic unit 2 Inverter 3 Coordinate converter 6 Coordinate converter 7 Delay circuit 8 Multiplier 9 Adder 10 Integrator IM Induction motor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-39183 (JP, A) JP-A-4-145892 (JP, A) JP-A-2-254997 (JP, A) JP-A 63-39 11093 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H02P 21/00 H02P 5/408-5/412 H02P 7/628-7/632

Claims (5)

(57) [Claims] An induction motor is controlled by an inverter, an excitation partial voltage is obtained from a set value of a primary resistance and a value obtained by multiplying an excitation current and a primary frequency, and a set value of a primary resistance value and a torque are obtained. A multiplication value obtained by multiplying the current and a multiplication value obtained by multiplying the magnetic flux command value and the primary frequency are used to obtain a torque component voltage, and a primary voltage obtained from the excitation component voltage and the torque component voltage is used. Detecting means for controlling and detecting a torque current detected from a primary current of the induction motor; a delay circuit for delaying the detected torque current; and a delay circuit for inducing a delay value of the torque current obtained by the delay circuit. Multiplying means for multiplying a predetermined constant by an electric motor, and a multiplication value obtained by the multiplying means and a given set frequency are added to obtain a primary frequency, and a three-phase voltage is obtained from the primary voltage and the primary frequency. It based the Umate the three-phase voltage in the vector control device of an induction motor and means for outputting the PWM control, the carrier frequency that is performing PWM control
And an adjustment means for adjusting a delay control gain of the delay circuit. An induction motor is controlled by an inverter, and an excitation component voltage is obtained from a set value of a primary resistance and a value obtained by multiplying an exciting current and a primary frequency. The set value of the primary resistance value and torque A multiplication value obtained by multiplying the current and a multiplication value obtained by multiplying the magnetic flux command value and the primary frequency are used to obtain a torque component voltage, and a primary voltage obtained from the excitation component voltage and the torque component voltage is used. Detecting means for controlling and detecting a torque current detected from a primary current of the induction motor; a delay circuit for delaying the detected torque current; and a delay circuit for inducing a delay value of the torque current obtained by the delay circuit. and multiplying means for multiplying the previously stated slip constant by the electric motor, vector of the induction motor provided with a means for obtaining a primary frequency by adding the setting frequency given a multiplication value obtained by this multiplication means In the control unit, a determination unit configured rotational speed of the induction motor is determined whether during or accelerating a constant speed, based on the determination of the determining means, the value of the element to be multiplied by the multiplying means
Vector controller for induction motor characterized by comprising an adjustment means for adjusting the slip frequency by changing the. 3. An induction motor is controlled by an inverter, an excitation voltage is obtained from a set value of a primary resistance, a value obtained by multiplying an exciting current and a primary frequency, and a set value of a primary resistance value and a torque current are obtained. And the multiplication value obtained by multiplying the magnetic flux command value and the primary frequency to obtain a torque component voltage, and control by the primary voltage obtained from the excitation component voltage and the torque component voltage. Detection means for detecting a torque current detected from a primary current of the induction motor, and a delay circuit for delaying the detected torque current,
Multiplying means for multiplying a delay value of the torque current obtained by delaying the delay circuit by a slip constant predetermined by the induction motor, and adding the multiplied value obtained by the multiplying means and a given set frequency to obtain a primary frequency; A vector control device for an induction motor, comprising: a detecting means for detecting a bus voltage; and a multiplier for detecting a bus voltage based on the detected bus voltage.
An adjusting means for adjusting a slip frequency by changing a value of an element to be multiplied in a stage . 4. A method for adjusting a slip frequency, comprising :
4. The vector control device for an induction motor according to claim 2, further comprising adjusting means for adjusting a slip constant multiplied by a delay value of the torque current . As means for adjusting the 5. slip frequency, Torr
4. The vector control device for an induction motor according to claim 2, further comprising an adjusting means for adjusting a delay control gain of the delay circuit for delaying the starting current .