JPH0731179A - Induction motor controller - Google Patents

Abstract

PURPOSE:To provide an induction motor controller in which transient loss, as well as steady loss, can be reduced over a wide operating range. CONSTITUTION:The induction motor controller comprises a steady loss minimum flux operating section 11, a target flux operating section 12, a flux response varying section 13, and a target torque operating section 14, in addition to general vector control operating sections 15-17, wherein the torque response can be varied independently from the flux response and the transfer function at the target flux operating section 12 is varied to minimize the transient loss depending on the magnitude of flux. Transient loss is reduced by setting a minimum loss slip frequency omegase-opt for steady operation and setting a flux response for minimizing the transient loss for transient operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an induction motor used in an electric vehicle or the like, and more particularly to a high efficiency drive control technique thereof.

[0002]

2. Description of the Related Art As a conventional induction motor control method,
For example, there is one described in JP-A-2-23085. This control method, only newly provided a core-loss resistance of R _M to d-axis component of the induction motor model according to the conventional d-q axis coordinate, describes the loss of the induction motor (copper loss, iron loss), these The induction motor is driven so that the loss of is minimized in the steady state. Specifically, vector control generally used as a torque control method for an induction motor is used, and control is performed at a slip frequency derived from the condition of minimum steady loss. Since the iron loss resistance R _M changes according to the motor rotation speed, the minimum loss slip frequency can be obtained by reading the table map of the iron loss resistance R _M from the motor rotation speed and solving the minimum loss conditional expression.

[0003]

However, in such a conventional induction motor control method, the minimum loss condition is derived from the steady-state characteristics of the motor and the transient characteristics are not taken into consideration. Loss is not minimal. Then, if the slip frequency is made a function of only the motor rotation speed as in the conventional method, it is necessary to change the rotor magnetic flux stepwise when the torque command value changes stepwise. Needs to flow a large current transiently. Therefore, when the minimum loss condition is set without considering the transient characteristics as in the prior art, there is a problem that the transient loss of the motor and the current capacity of the motor drive device increase. On the contrary, if the current capacity is set not to be increased, the torque response must be delayed. In order to solve the above problem, the inventor has added a steady loss minimum magnetic flux calculation unit, a target magnetic flux calculation unit, and a target torque calculation unit to a general vector control calculation unit to obtain torque responsiveness and magnetic flux responsiveness. By adjusting the control system so that the slip frequency can be varied independently, the slip frequency can be constantly reduced to the minimum loss slip frequency ω _se-opt.
Then, an induction motor control device has been developed (unpublished) that is configured to transiently control the magnetic flux response to an optimum value according to the torque response to reduce the transient loss. In this induction motor control device, the response of the target magnetic flux calculated by the target magnetic flux calculation unit is constant regardless of the magnitude of the magnetic flux. When only the copper loss is considered as the loss of the induction motor, the loss L _c is given by the following (Formula 1).

[0004]

[Equation 1]

However, T _e : torque, ω _se : slip frequency, φ: magnetic flux K _{1 to} K ₄ : constant determined by the motor [In addition, the following (Equation 8) is described in more detail above (Equation 1)] Formula] As can be seen from the above formula (Formula 1), the transient loss of the induction motor is affected not only by dφ / dt but also by the magnetic flux φ. Therefore, since the transient loss changes depending on the magnitude of the magnetic flux φ when the magnetic flux φ changes, the transient loss can be further reduced by changing the magnitude of dφ / dt according to the magnitude of the magnetic flux φ. It becomes possible. However, in the above-mentioned prior invention by the present inventor, the response of the target magnetic flux calculated by the target magnetic flux calculation unit is constant irrespective of the magnitude of the magnetic flux. Could not be minimized.

The present invention has been made in order to solve the problems of the prior art as described above and further improve the prior invention of the present inventor, and not only the steady loss but also the transient loss over a wide operating range. An object of the present invention is to provide an induction motor control device that can be reduced.

[0007]

In order to achieve the above object, the present invention is constructed as described in the claims. That is, in addition to the same vector control calculation unit and motor drive unit as the conventional one, a steady loss minimum magnetic flux calculation unit that calculates the rotor magnetic flux that minimizes the steady loss of the induction motor at the given torque command value, and the steady state A target magnetic flux calculation unit that inputs a minimum loss magnetic flux and calculates a target magnetic flux and a first-order derivative value of the target magnetic flux based on a transfer function having a low-pass characteristic, and minimizes a transient loss according to the magnitude of the target magnetic flux. As described above, the magnetic flux response variable unit that changes the transfer function in the target magnetic flux calculation unit and the target torque calculation unit that calculates the target torque of the induction motor based on the predetermined transfer characteristic from the torque command value are provided. In addition,
The steady loss minimum magnetic flux calculation unit, the target magnetic flux calculation unit, the magnetic flux response variable unit, and the target torque calculation unit are, for example, the steady loss minimum magnetic flux calculation unit 11, the target magnetic flux calculation unit 12, and the magnetic flux response in the embodiment of FIG. 1 described later. It corresponds to the variable unit 13 and the target torque calculation unit 14, respectively. The current command value is
For example, it corresponds to the excitation current command value i _φ ′, the torque current command value i _T ′, and the current phase angle θ in the embodiment of FIG. 1 or FIG. 2 described later.

[0008]

As described above, in the present invention, the steady loss minimum magnetic flux calculation unit, the target magnetic flux calculation unit, the variable magnetic flux response unit, and the target torque calculation unit are added to the general vector control calculation unit to improve the torque response. By making the control system configuration that can vary the magnetic flux response independently, and changing the transfer function of the target magnetic flux calculation unit to minimize the transient loss according to the magnitude of the magnetic flux, The slip frequency is set to the minimum loss slip frequency ω _se-opt, and the transient loss is reduced by setting the value of the magnetic flux response so as to minimize the transient loss in the transient state. With the configuration as described above, it is possible to reduce the transient loss over a wide operating region without impairing the responsiveness, and it is possible to drive with a minimum loss similar to the conventional one in the steady state.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
1 and 2 are diagrams showing an embodiment of the present invention. FIG. 1 is a block diagram showing the details of the high-efficiency drive control calculation unit 1 in FIG. 2, and FIG. 2 is a block diagram showing the configuration of the entire system. . First, the overall configuration shown in FIG. 2 will be described. Figure 2
In FIG. 1, 1 is a high-efficiency drive control calculation unit (details will be described later), for example, a torque command value T _e ′ corresponding to an operation amount of an accelerator pedal or the like and a motor rotation speed N (rpm) detected by the rotation speed sensor 5. The excitation current command value i _φ ′, the torque current command value i _T ′, and the current phase angle θ are calculated and output. Reference numeral 2 is a coordinate conversion unit that calculates the excitation current command value i _φ ′, the torque current command value i _T ′, and the phase angle θ of the current calculated in the coordinate system that rotates at the motor power supply frequency into a three-phase alternating current. Convert to current command values _iu ', _iv ', and _iw '. A current control PWM (pulse width modulation) inverter 3 causes the three-phase alternating currents i _u , _iv , and i _w flowing in the induction motor 4 to follow the respective command values. Reference numeral 5 is a rotation speed sensor that detects the rotation speed of the induction motor 4, and 6 is a DC power supply (power supply for driving the induction motor) that is supplied to the current control PWM inverter 3.
Is.

In FIG. 1, 11 is a steady loss minimum magnetic flux calculating section, 12 is a target magnetic flux calculating section, 13 is a magnetic flux response varying section, 14 is a target torque calculating section, 15 is an exciting current calculating section, and 16 is a torque. A current calculator, 17 is a slip frequency calculator, 18 is a motor speed calculator, and 19 is an integral calculator. The exciting current calculator 15 and the torque current calculator 1
6, slip frequency calculation unit 17, motor rotation speed calculation unit 18
The integration calculation unit 19 is a unit that performs a general vector control calculation.

Next, the operation will be described. First, the general operation of each arithmetic unit will be described, and subsequently, the characteristic features of this embodiment will be described in detail. In Figure 1, the steady loss minimum magnetic flux calculating unit 11 'enter the, the torque command value T _e' torque command value T _e calculating a magnetic flux phi _r 'to loss in the steady state (copper loss) at the minimum And output. Further, the target magnetic flux calculation unit 12 inputs the above-mentioned steady loss minimum magnetic flux φ _r ',
In steady state, it corresponds to the above minimum steady loss magnetic flux φ _r ', and in transient time, the target magnetic flux φ _r that makes the magnetic flux response an optimum value according to the torque response and its first derivative d / dt φ _r
And are calculated and output. Further, the magnetic flux response varying unit 13
According to the magnitude of the target magnetic flux φ _r , the transfer function in the target magnetic flux calculating unit 12, that is, the responsiveness of the magnetic flux during the transient is changed so as to minimize the transient loss. Also,
The target torque calculation unit 14 inputs the torque command value T _e ′,
The target torque T _m is calculated based on a predetermined transfer characteristic (set according to the required responsiveness, the allowable current capacity, etc.). The excitation current calculation unit 15, the torque current calculation unit 16, and the slip frequency calculation unit 17 are the units that perform general vector control calculations. First, the exciting current calculator 15 calculates and outputs an exciting current command value _iφ ′ based on the target magnetic flux φ _r and the first-order differential value d / dt φ _r given from the target magnetic flux calculator 12. . Further, the torque current calculation unit 16 inputs the target torque T _m of the target torque calculation unit 14 and the target magnetic flux φ _r of the target magnetic flux calculation unit 12 and calculates and outputs the torque current command value i _T ′. Further, the slip frequency calculation unit 17 inputs the target magnetic flux φ _r of the target magnetic flux calculation unit 12 and the torque current command value i _T ′ of the torque current calculation unit 16 and calculates and outputs the slip frequency ω _se . Further, the motor rotation speed calculation unit 17 calculates the motor rotation speed (electrical angle) ω _re by multiplying the motor rotation speed N given from the rotation speed sensor 5 of FIG. 2 by the number P of pole pairs peculiar to the induction motor. That is, ω _re = (π / 30) N × P. The sum of the motor speed ω _re and the slip frequency ω _se is the power supply frequency ω. That is, ω = ω _se + ω _re
Is. Then, the integration calculator 18 outputs a value obtained by integrating the power supply frequency ω as the phase angle θ of the current. The above-mentioned excitation current command value i _φ ′, torque current command value i _T ′, and current phase angle θ are current command values, and the coordinate conversion unit 2 of FIG.
Sent to.

Next, the details of each arithmetic unit will be described.
First, since the excitation current calculation unit 15, the torque current calculation unit 16, and the slip frequency calculation unit 17 are the units that perform general vector control calculation, a detailed description thereof will be omitted. By giving ω _se by the following formula (2), the output torque T _e of the induction motor is introduced into the form of the following formula (3).

[0013]

[Equation 2]

However, ω: power frequency, ω _re : motor speed (electrical angle), M: mutual inductance, L _r : rotor self-inductance, R _r : rotor resistance, i _T : torque current, φ _r : Rotor flux

[0015]

[Equation 3]

However, P is the number of pole pairs, and at this time, the relationship between the rotor magnetic flux φ _r and the exciting current i _φ is expressed by the following equation (4).

[0017]

[Equation 4]

However, S: Laplace operator Therefore, the calculation formula of the exciting current command value i _φ'performed by the exciting current calculating unit 15 is as shown in the following (Formula 5) to the following (Formula 5). .

[0019]

[Equation 5]

The equation for calculating the torque current command value i _T 'performed by the torque current calculator 16 is as shown in the following equation (6) from the above equation (3).

[0021]

[Equation 6]

However, T _e ': Torque command value Note that the slip frequency ω in the slip frequency calculator 17 is
The arithmetic expression of _se is as shown in the above equation (2).
The calculations performed by the motor rotation speed calculation unit 18 and the integration calculation unit 19 are as described above.

Next, the parts of the steady loss minimum magnetic flux calculating section 11, the target magnetic flux calculating section 12, the magnetic flux response varying section 13, and the target torque calculating section 14, which are features of this embodiment, will be described.
In the ordinary vector control, the rotor magnetic flux φ _r is constant (excitation current i _φ is constant) and only the torque current i _T is changed to obtain linearity and quick response of the output torque with respect to the torque current i _T. Is. However, such a constant vector control of the rotor magnetic flux φ _r supplies a constant exciting current i _φ regardless of the load, and therefore the efficiency generally deteriorates at a light load. Therefore, the copper loss is considered as the loss of the induction motor, and the condition for minimizing this is obtained. First, FIG.
The γ-δ coordinate model as shown in Fig. 6, that is, the γ-δ rotating at the power supply frequency well known as the model of the induction motor.
We will use a coordinate model. In FIG. 3, when vector control is established, it is known that the following equation (7) is established between the current component of each axis and the rotor magnetic flux φ _r . However, each current component i _γs , i _δs , i
_In γ r and i _δr , subscripts γ and δ represent axial components, r represents a rotor, and s represents a stator.

[0024]

[Equation 7]

On the other hand, the copper loss L _c of the induction motor is as shown in the following (Formula 8) from FIG. 3 and the above (Formula 7).

[0026]

[Equation 8]

However, R _s : Stator resistance, K ₁ , K ₂ : constants determined by the motor In the above formula (Equation 8), the differential term dφ _r / dt of φ _r is 0 when the steady state is considered. The slip frequency ω _se-opt that minimizes the copper loss L _c can be calculated by the following equation (9) from the condition of dL _c / dω _se = 0.

[0028]

[Equation 9]

Therefore, the slip frequency ω _se is given by ( _Equation 9)
If the value of the formula is maintained, it is possible to drive the copper loss to the minimum.
Specifically, in order to keep the slip frequency at the minimum loss slip frequency ω _se-opt from the above equation (2), the torque current i
It is understood that the relationship between _T and the magnetic flux φ _r may be set as shown in the following (Equation 10).

[0030]

[Equation 10]

Next, by substituting the equation (10) into the equation (3) and erasing i _T , the relationship between the torque command value T _e 'and the magnetic flux φ _r is shown by the following equation (11). Like

[0032]

[Equation 11]

Therefore, when the torque command value T _e 'is input, the steady-state minimum magnetic flux φ _r ' is derived by the equation (11), and the torque current command value i _T 'is calculated by the equation (10), the exciting current. The command value i _φ 'is the equation (5) and the slip frequency ω _se is the equation (2)
By calculating each with the equation, it is possible to constantly drive the copper loss to the minimum. At this time, the slip frequency ω _se
Corresponds to the minimum loss slip frequency ω _se-opt , and the output torque T _e follows the torque command value T _e ′. However, when the torque command value T _e 'changes stepwise, the steady loss minimum magnetic flux φ _r ' also becomes stepwise according to the equation (11). Then, as shown in the equation (5),
Since the calculation of the excitation current command value i _φ 'includes dφ _r / dt, if a stepwise torque command value change occurs,
The exciting current command value _iφ 'becomes a transiently large value, and therefore the transient loss increases. The above phenomenon can be understood from the equation (8), where L _c is a function of dφ _r / dt. Further, in the present embodiment, only copper loss is considered as the loss, but the same problem occurs when copper loss and iron loss are taken into consideration as described in the above-mentioned conventional example (JP-A-2-23085). Occurs. Therefore, in consideration of transient loss, it is not a good idea from the viewpoint of efficiency to keep the slip frequency at the loss minimum slip frequency ω _se-opt . Further, when the upper limit value of the current is determined from the current capacity of the semiconductor switching element used for the current control PWM inverter 3 of FIG. 2, the torque response must be delayed during the transient when the current becomes large. Therefore, in the present embodiment, the target torque calculation unit 14 and the steady loss minimum magnetic flux calculation unit 11 that determine the torque response are determined.
And the target magnetic flux calculation unit 12 are added to the general vector control calculation units 15, 16 and 17 so that the torque response and the magnetic flux response can be independently varied, so that the slip frequency can be steadily increased. Is a loss minimum slip frequency ω _se-opt, and transiently controls the magnetic flux response to an optimum value according to the torque response to reduce the transient loss. By providing the variable transmission characteristic of the magnetic flux response in the target magnetic flux calculation unit 12 according to the magnitude of the target magnetic flux φ _r , the transient loss can be kept low in a wider operating range of the induction motor. is there.

First, the contents of calculation of the steady loss minimum magnetic flux calculation unit 11 are the equations (11), and the rotor magnetic flux which minimizes the loss steadily, that is, the steady loss minimum magnetic flux φ _r 'is calculated. In addition, the target magnetic flux calculation unit 12 that calculates the target magnetic flux φ _r
Is a filter having a steady gain of 1, and in the present embodiment, is a first-order low-pass filter as shown in the following (Equation 12).

[0035]

[Equation 12]

However, τ _{φ is} the time constant of the target magnetic flux, S is the Laplace operator, and the transfer characteristics in the target magnetic flux calculating section 12 will be described later. In addition, the target torque calculation unit 14 that calculates the target torque T _m is defined by the following (Equation 13) in this embodiment.
The transfer characteristic is as shown in the equation. This transfer characteristic is appropriately set according to the required responsiveness and current capacity.

[0037]

[Equation 13]

However, τ _T : Time constant of target torque FIG. 4 shows the torque command value T _e 'in the control system shown in FIG.
FIG. 9 is a characteristic diagram showing a peak value of the loss of the induction motor with respect to the time constant τ _φ of the target magnetic flux and a calculated value of loss energy within a certain time when an input that changes stepwise as is added. It can be seen from FIG. 4 that each loss has a minimum value and that each loss has a minimum value when the time constant τ _φ is a certain value. Therefore, in the control system shown in FIG. 2, when the torque response is given by the formula (12), the time constant τ _{φ of} the target magnetic flux that minimizes the transient loss obtained from FIG.
If the magnetic flux response is determined by using, it becomes possible to drive the motor with less loss both in the transient state and in the steady state. That is,
Basically, the value of the time constant τ _φ that minimizes the loss in FIG. 4 may be used in the equation (11). However, since the time constant τ _φ that minimizes the loss also changes depending on the magnitude of the target magnetic flux φ _r , it is necessary to consider that point. Hereinafter, that point will be described. As can be seen from the equation (8), there is a term φ _r · (dφ _r / dt) in the equation expressing the loss L _c , so the loss L _c is the target magnetic flux when the target magnetic flux φ _r changes. Affected by the size of φ _r . Therefore, in the case where the target magnetic flux phi _r rises from zero, the target magnetic flux phi _r is a stand up from one value would transition losses are different. Therefore, if the transfer characteristic in the target magnetic flux calculation unit 12 is made variable according to the magnitude of the target magnetic flux φ _r , the transient loss can be suppressed low in a wider operating range of the motor.

In FIG. 5, the transfer characteristic in the target magnetic flux calculating section 12 is given by the above equation (12), and the target torque calculating section 14 is calculated.
FIG. 4 is a characteristic diagram showing the relationship between the transient torque peak and the time constant τ _φ of the target magnetic flux with respect to the step torque response (response when the torque changes stepwise) when the transfer characteristic in Equation (13) is given. is there. In FIG. 5, L _c0 is the target magnetic flux φ _r before the torque command value changes stepwise.
Characteristics of loss L _c but in the case of 0, L _c1 indicates the characteristics of the losses L _c when the target magnetic flux phi _r before the torque command value changes stepwise non-zero. As can be seen from FIG. 5, the time constant τ of the target magnetic flux that minimizes the transient loss is determined by the magnitude of the target magnetic flux φ _r before the torque command value changes stepwise (dφ _r / dt = 0 in this state). The value of _φ is changing. Therefore, _if the relationship between the time constant τ _φ that minimizes the transient loss and the size of the target magnetic flux φ _r is table-mapped and the time constant τ _φ is changed according to the target magnetic flux φ _r , Motor transient losses can be reduced over a wider operating range.

FIG. 6 and FIG. 7 are characteristic diagrams showing the results of speed control simulation. FIG. 6 shows the case where the conventional method of keeping the slip frequency at the loss minimum slip frequency ω _se-opt in both transient and steady state is used. , FIG. 7 shows the characteristics when the value (fixed value) of the time constant τ _φ that minimizes the loss in FIG. 4 is used. In addition, FIG. 8 shows the case of using the value (fixed value) of the time constant τ _φ that minimizes the loss shown in FIG. 7 and the case of the present embodiment (the time depending on φ _r to minimize the loss. It is a characteristic view which shows the speed control simulation result with what changes the constant (tau) ( _phi ). In FIG. 8, the solid line shows the characteristic of FIG.
The broken line shows the characteristics of this embodiment. The torque responsiveness was the same for both. 6 and 7, the characteristics (responsiveness) of the torque T and the rotation speed N are the same, but the characteristics of the copper loss L _c are clearly reduced in FIG. 7 during the transition. In addition, in the steady state, the slip frequency drive minimizes the copper loss as in the conventional case. Therefore, the characteristic of FIG. 7 can reduce the loss during the transition while maintaining the same response characteristic. Also, FIG.
In the case where the target magnetic flux φ _r rises from 0 (the torque command value T _e 'rises from 0) at t = 0, both have the same level of loss, but the target magnetic flux φ _r has a certain value ( In the torque transient state after φ _r ≠ 0), the loss is suppressed lower in this embodiment.

In this embodiment, the magnetic flux response is calculated by
Although the equation (2) and the torque response are given by the equation (13), they are not necessarily limited to this transfer characteristic. For example, a secondary vibration system [G (S) = ω _n ² /
S ² + 2ζω _n S + ω _n ² ], and similarly, the magnetic flux response may be given by a secondary vibration system. However, in order to obtain the first-order derivative value of the target magnetic flux without performing the differential operation,
It is necessary that the relative order between the numerator and the denominator be 1 or more. When the magnetic flux response is given by the secondary vibration system, the relationship between the damping ratio ζ and the natural frequency ω _n shown in Fig. 4 is obtained, and the magnetic flux is calculated using ζ and ω _n that minimize the transient loss. Good.

[0042]

As described above, according to the present invention, the means for calculating the steady loss minimum magnetic flux that minimizes the steady loss from the torque command value and the target torque of the induction motor from the torque command value are calculated. In the wider operating region, the means and the means for making the torque of the induction motor follow the target torque from the steady-state minimum magnetic flux and varying the transfer characteristic so that the transient loss is minimized are provided. It is possible to reduce the transient loss of the induction motor,
If the current capacity is the same, the torque responsiveness can be increased. Further, there is an effect that the motor drive control that minimizes the loss becomes possible in the steady state as in the conventional method.

[Brief description of drawings]

FIG. 1 is a block diagram showing details of a high-efficiency drive control calculation unit 1 in FIG.

FIG. 2 is a block diagram showing the overall configuration of a system according to an embodiment of the present invention.

FIG. 3 is a diagram showing a γ-δ coordinate model of an induction motor.

FIG. 4 shows the peak value of the loss of the induction motor with respect to the time constant τ _φ of the target magnetic flux when a stepwise input is added as the torque command value T _e ′, and the calculated value of the energy loss in a certain time. FIG.

FIG. 5 is a characteristic diagram showing a relationship between a time constant τ _φ of a target magnetic flux and a transient loss peak with respect to a response when the torque changes stepwise.

FIG. 6 is a characteristic diagram showing a speed control simulation result in a conventional example.

FIG. 7 is a characteristic diagram showing a speed control simulation result when a value of a time constant τ _φ that minimizes loss is used.

FIG. 8 shows a case where a value (fixed value) of the time constant τ _φ that minimizes the loss is used and this embodiment (where the time constant τ _φ is changed according to φ _r so that the loss is minimized). The characteristic view which shows a speed control simulation result.

[Explanation of symbols]

1: High-efficiency drive control calculation unit 4: Induction motor 2: Coordinate conversion unit 5: Rotation speed sensor 3: Current control PWM inverter 6: DC power supply 11: Steady loss minimum magnetic flux calculation unit 16: Torque current calculation unit 12: Target magnetic flux Calculation unit 17: Slip frequency calculation unit 13: Magnetic flux response variable unit 18: Motor rotation speed calculation unit 14: Target torque calculation unit 19: Integral calculation unit 15: Excitation current calculation unit _Te ': Torque command value _Tm : Target torque φ _r ': Minimum steady loss magnetic flux φ _r : Target magnetic flux N: Motor rotation speed (rpm) ω: Power supply frequency ω _se : Slip frequency ω _re : Motor rotation speed (electrical angle) i _φ ': Excitation current command value i _T ': Torque current command value θ: Current phase angle τ _φ : Time constant of target magnetic flux _iu ', _iv ', _iw ': Three-phase AC current command values _iu , _iv , _iw : Three-phase AC Electric current

Claims (1)

[Claims] 1. An induction motor control device for calculating an electric current instruction value according to a torque instruction value and a rotation speed of an induction motor and driving the induction motor with a polyphase alternating current corresponding to the electric current instruction value. The minimum steady-state magnetic flux calculation unit that calculates the rotor magnetic flux that minimizes the steady-state loss of the induction motor at the specified torque command value, and the above steady-state minimum magnetic flux are input, and the target magnetic flux and target based on the transfer function having the low-pass characteristic are input. A target magnetic flux calculation unit that calculates a first-order differential value of the magnetic flux; a magnetic flux response variable unit that changes the transfer function in the target magnetic flux calculation unit so as to minimize the transient loss according to the magnitude of the target magnetic flux; A target torque calculation unit that calculates a target torque of the induction motor from the torque command value based on a predetermined transfer characteristic, and the target magnetic flux based on the circuit constant of the induction motor. A vector control calculation unit that calculates the current command value according to the first-order differential value of the target magnetic flux, the target torque, and the rotation speed of the induction motor, and causes the current flowing in the induction motor to follow the current command value. An induction motor control device comprising: a motor drive unit; and controlling the output torque of the induction motor to a value corresponding to the target torque.