JPH08294299A - Induction motor control device and electrically-operated power steering device using this induction motor control device - Google Patents

Abstract

PURPOSE: To provide an induction motor control device for accurately performing torque control while eliminating necessity for a speed detector and to provide an electrically-operated power steering device which eliminates an additional mechanism such as a clutch or the like and the speed detector of an electric motor by using this induction motor control device. CONSTITUTION: A torque detector 120 for detecting the output torque of a three-phase induction motor 100 is provided, further to provide torque control means 102-116, 122 for controlling the output torque of the three-phase induction motor by changing the amplitude of a primary AC current group based on the command torque and a predetermine excitation current component and by changing the frequency of the primary AC current group based on the excitation current component, the command torque and the output of the torque detector. In an electrically-operated power steering device using an induction motor control device thus constituted, a steering force sensor for detecting the steering force and a torque converter for changing the output of this steering force sensor into the command torque are provided, thereby to give an assist steering force to a steering system by the three-phase induction motor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor control device capable of controlling the output torque of an induction motor, and an electric power steering device for generating an auxiliary steering force according to a steering force of a steering wheel using the induction motor control device. .

[0002]

2. Description of the Related Art Induction motors are inexpensive and easy to maintain due to their relatively simple structure, but they are not suitable for precise position / speed / torque control because of poor controllability. For example, if a conventional inverter control is used for torque control, the controllability is much worse than that of a DC motor, and it is difficult to obtain the desired torque, especially in the low speed range. Therefore, the application of the induction motor is limited to the case where the starting torque is not particularly required, and is not suitable for an electric power steering device or the like that requires a large starting torque.

On the other hand, a technique called vector control is being established. By using this technique, poor controllability including torque characteristics at the time of starting is improved, and controllability comparable to that of a DC motor can be obtained. Therefore, the application to speed control of induction motors is spreading. However, when vector control is applied to an induction motor, a speed sensor such as an encoder that detects the rotation speed of the induction motor is required regardless of whether speed control or torque control is performed, and as a result, when using another motor. It is disadvantageous in terms of size and cost. Therefore, in the application example to the speed control, a method of omitting the speed detector and estimating the rotation speed from the detected current value or the like is being studied.

As a method of estimating the rotation speed in vector control of an induction motor, for example, Japanese Patent Laid-Open No. 1-2142 is known.
As disclosed in Japanese Patent No. 87, there is a method of obtaining a secondary magnetic flux from a primary current and a primary voltage of an induction motor, and multiplying the secondary magnetic flux and its integral value by a constant to easily estimate the rotation speed.

Further, there is a research example in which the rotation speed is estimated by converting a three-phase induction motor into a three-phase / two-phase conversion and considering it as a two-phase induction motor. There is the following equation (Equation 1) as a basic equation representing the operation of the two-phase induction motor.

[0006]

[Equation 1]

Here, i _1d and i _1q are the d-axis current and the q-axis current flowing on the stator side, that is, the primary side, respectively,
v _1d and v _1q are the voltages thereof, and ψ _2d and ψ _2q are the axial magnetic flux and the q-axis magnetic flux on the rotor side, that is, the secondary side, respectively. Also, R
₁ , L ₁ is the resistance and inductance on the primary side, and R ₂ , L
_{2 is} the resistance and inductance on the secondary side, M is the mutual inductance, θ is the rotation angle of the motor, and p is the number of pole pairs. From the basic equation (Equation 1), the following equation (Equation 2) obtained by excluding the secondary resistance R ₂ that greatly varies with temperature change
There is known a method for estimating the rotation speed from the above method. According to this method, the rotation speed can theoretically be determined exactly without any influence of the change in the secondary resistance.

[0008]

[Equation 2]

It is also possible to estimate the rotational speed of the induction motor by applying these conventional examples for speed control and to perform torque control by vector control using this estimated speed.

Further, when an electric motor is used as the drive means of the power steering device, the amount of fuel consumption is reduced as compared with the case where a hydraulic drive device is used, and thus the electric power steering device has recently been drawing attention. However, since the conventional electric power steering apparatus uses an electric motor such as a DC electric motor having a permanent magnet, if the wiring to the electric motor is short-circuited for some reason, dynamic braking occurs and the steering becomes very heavy, which is the worst case. In that case, steering may be impossible. In order to avoid such a possibility, it is necessary to provide a clutch between the electric motor and the steering shaft to take safety measures in case of failure, as described in, for example, Japanese Patent Laid-Open No. 4-137465.

On the other hand, when an induction motor having no permanent magnet is used, braking is not applied even if the wiring is short-circuited, so a safety mechanism such as a clutch is unnecessary. Focusing on this advantage, by applying a vector control to the induction motor by using a means for detecting or estimating the rotation speed of the electric motor,
It is possible to realize an electric power steering device that does not require a clutch.

[0012]

However, in the case of the induction motor control device described in the above-mentioned Japanese Patent Laid-Open No. 1-214287, it can be realized with a simple structure, but the rotation speed depends on the multiplication constant. Has a problem that the estimation accuracy of is poor. Also, in the second method of obtaining the rotation speed from the expression excluding the secondary resistance, the estimation accuracy is significantly deteriorated in the vicinity of the denominator of the expression (Equation 2) being 0, and the response is smoothed by using a filter or the like. It has a problem that it becomes worse.

Further, in an electric power steering apparatus using an induction motor, it is necessary to detect or estimate the speed of the electric motor, but if a speed detector is used for this purpose, it is disadvantageous in terms of cost and size. However, when the speed estimator is used, there is a drawback that the control performance is poor because the estimation accuracy is poor.

On the other hand, in the conventional electric power steering apparatus using the electric motor having the permanent magnet, an electromagnetic clutch or the like can be used to take measures against the failure of the electric motor, but when the clutch fails. It is also necessary to consider that. Further, the provision of the clutch causes disadvantages such as a complicated structure, an increase in size of the device, and an increase in cost.

Therefore, an object of the present invention is to solve the above problems of the conventional device, to provide an induction motor control device which does not need a speed detector and can control the output torque with high accuracy. And to provide a small electric power steering device using the same.

[0016]

The induction motor control device of the present invention is characterized in that a torque current component and an excitation current component of a primary alternating current group supplied to a stator of a three-phase induction motor are separately instructed, and In an induction motor control device for controlling the output torque of a three-phase induction motor by changing the amplitude and frequency of a primary alternating current group, a torque determination means for detecting or estimating the output torque of the three-phase induction motor is provided, and the three-phase induction motor is provided. The amplitude of the primary alternating current group is changed based on the command torque of the electric motor and the magnitude of the predetermined exciting current component, and the magnitude of the exciting current component, the command torque, and the output of the torque determination means are set. It further comprises torque control means for controlling the output torque of the three-phase induction motor by changing the frequency of the primary alternating current group based on the above.

Although various known torque sensors (torque detectors) can be used as the torque determining means, the torque sensor is largely limited in terms of size and cost.
If the torque is indirectly estimated by the following configuration, the torque detector can be omitted, which is preferable. That is, the torque determination means, the current determination means for detecting or estimating each of the primary AC current group,
The output of the current determination means is converted into a two-phase alternating current consisting of a predetermined d-axis primary current in the d-axis direction and a q-axis primary current in the q-axis direction having a phase difference of 90 degrees between the d-axis direction. A three-phase / two-phase current converter, a secondary magnetic flux estimator for estimating a secondary magnetic flux in the d-axis direction and the q-axis direction on the rotor side of a three-phase induction motor, and the d-axis and q-axis primary currents And a torque estimator that estimates the output torque of the three-phase induction motor from the d-axis and q-axis secondary magnetic flux. A known current sensor can be used as the current determination means.

More preferably, the torque control means comprises a PWM inverter for supplying a primary AC current group corresponding to an input voltage command value to a three-phase induction motor, and the torque determination means comprises the three-phase voltage. The secondary magnetic flux estimator further comprises a three-phase / two-phase voltage converter for converting the command value into a two-phase AC voltage, and the output of the three-phase / two-phase current converter and the three-phase / two-phase voltage converter. It is possible to estimate the secondary magnetic flux based on the output of

The torque control means changes the amplitude and frequency of the primary alternating current group based on the command torque of the three-phase induction motor and the magnitude of the predetermined exciting current component, and the command torque and the torque. It is preferable to correct the frequency of the primary alternating current group based on the result obtained by comparing with the output of the determination means.

Next, the feature of the electric power steering device according to the present invention is that the electric power steering device is provided with a three-phase induction motor for applying an auxiliary steering force to the steering system and a steering force sensor for detecting the steering force of the steering. The apparatus is further provided with an induction motor control device as described above and a command torque generation means for converting the output of the steering force sensor into a command torque given to the induction motor control device.

Preferably, a steering angle detector for detecting the steering angle of the steering wheel may be further provided, and the command torque generating means may be configured to correct the command torque according to the output of the steering angle detector. . Further, a moving speed detector that detects the moving speed (traveling speed) of a moving body (for example, an automobile) may be provided, and the command torque may be corrected according to the output of the moving speed detector.

[0022]

According to the induction motor control device having the above characteristics, the output torque is controlled by the torque control means changing the frequency of the primary AC current group based on the measured or estimated feedback amount of the output torque. It Therefore, a speed detector and a conventional speed estimator with poor estimation accuracy are not required, and torque control with good accuracy and responsiveness becomes possible. Further, by using such an induction motor control device, the electric power steering device of the present invention does not require an additional mechanism such as a clutch or a speed detector of the electric motor, and further, for example, the winding of the electric motor is short-circuited. However, manual steering is possible without braking the electric motor.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An induction motor controller according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of an induction motor control device according to the present invention. In this figure, 100 is a three-phase induction motor, 102 is a PWM inverter, 104 is a torque current command generator, 106 is a rotary / stationary coordinate converter, 108 is a two-phase / three-phase converter, 110 is a slip frequency calculator, 112 is an adder, 114 is an integrator,
Reference numeral 116 is a current controller, 118a, 118b and 118c are current detectors, 120 is a torque detector as torque determining means, and 122 is a torque comparator. In the configuration shown in FIG. 1, the part excluding the three-phase induction motor 100 and the torque detector 120 corresponds to the torque control means.

The operation of the induction motor controller configured as described above is as follows. First, the operation of the torque current command generator 104 will be described. Generally, most induction motors are three-phase induction motors, but they can be considered as two-phase induction motors by performing three-phase / two-phase conversion. Therefore, the output torque τ of the three-phase induction motor is calculated by the following equation (Equation 3) using the two-phase induction motor model as in the conventional example.
Can be written as

[0026]

(Equation 3)

Here, i _1d and i _1q are respectively the d-axis current and the q-axis current on the primary side flowing to the stator side, and i _2d and i _1d
2q is the secondary side d-axis current flowing on the rotor side and q
It is the axis current. L ₂ is the inductance on the secondary side,
M is mutual inductance, and p is the number of pole pairs. further,
I _1d and I _1q are excitation current and torque current (both are DC values), and the relationship between i _1d and i _1q and I _1d and I _1q is expressed by the following equation (Equation 4). Note that θ ₀ is the electrical phase angle.

[0028]

[Equation 4]

As can be seen from the equation (Equation 3) expressing the output torque τ, the torque current command generator 104 calculates the command torque τ.
^A torque current command value I obtained from the following equation (Equation 5) using ^* and a predetermined constant exciting current command value I _1d ^*
Output _1q ^* .

[0030]

(Equation 5)

Further, the slip frequency calculator 110 uses the exciting current command value I _1d ^* and the torque current command value I _1q ^* to determine the slip angular velocity ω _s from the following equation (Equation 6).

[0032]

(Equation 6)

Next, the torque comparator 122 compares the output torque τ detected by the torque detector 120 with the command torque τ ^*, and, for example, the corrected angular velocity ω as a comparison result obtained according to the following equation (Equation 7). Output _f . In addition, K _I , K
Each _p is a feedback gain.

[0034]

(Equation 7)

Then, the corrected angular velocity ω _f and the slip angular velocity ω
_s is added by the adder 112, and the result is the integrator 11
An electrical phase angle θ ₀ can be obtained by integrating at 4. Using the obtained electrical phase angle θ ₀ and the excitation current command value I _1d ^* and the torque current command value I _1q ^* , the rotary / stationary coordinate converter 106 has a two-phase phase difference of 90 degrees. The primary alternating current command values i _1d ^* and i _1q ^* are calculated according to the following equation (Equation 8).

[0036]

(Equation 8)

Thereafter, these two-phase alternating current command values i_1d
^*, I_1q ^*Is calculated by the two-phase / three-phase converter 108 as
According to 9), the three-phase primary alternating current command value i_1a ^*,
i_1b ^*, I_1c ^*Is converted to.

[0038]

[Equation 9]

That is, the three-phase alternating current command values i _1a ^* , i _1b ^* ,
The amplitude A of i _1c ^* can be obtained from the command torque τ ^* and the exciting current command value I _1d ^* as shown in the following formula (Equation 10), and the frequency is determined by the electrical phase angle θ _0. As shown in the equations (Equation 6) and the equation (Equation 7), the output torque τ
And the command torque τ ^* and the exciting current command value I _1d ^* .

[0040]

[Equation 10]

Further, the current controller 1 is arranged so that the actual primary alternating currents follow the corresponding primary alternating current command values.
16 performs current feedback control. For example, the current controller 116 includes the current detectors 118a, 118b, 1
18c output i _1z (z = a, b, c) is used to obtain a voltage command value v _1z (z = a, b,
c) is output to the PWM inverter 102.

[0042]

[Equation 11]

Then, the PWM inverter 102 controls the current.
Voltage command value v from controller 116_1zOf the pulse width corresponding to
The output voltage is supplied to the induction motor 100. The following formula
As shown in (Equation 12), the induction motor 100 is supplied with
Three-phase primary alternating current i_1a, I _1b, I_1cAdd
And the relationship of zero is established, whichever of the three phases
Or current detection only for two phases, and
May be calculated from the detected two-phase current values

[0044]

(Equation 12)

As described above, the primary AC current supplied to the induction motor can be controlled so as to match the desired command value. By performing such torque feedback control and current feedback control, it becomes possible to generate a desired torque in the induction motor without using the rotation speed detector of the induction motor.

In this embodiment, when the torque detector 120 is removed, that is, when the output torque information is not used, the torque comparator 122 is also unnecessary and only the electrical phase angle θ ₀ slip angular velocity ω _s is obtained. It is the integrated value. Even in this case, the rotation speed of the induction motor is almost zero.
Therefore, it is possible to control the output torque so as to match the desired command torque. However, when the rotation speed of the induction motor is not 0, the output torque decreases as the rotation speed increases, and the output torque becomes 0 when the slip angular speed ω _s is divided by the pole pair number p. Therefore, in this embodiment, the output torque is monitored, and the torque is controlled even when the induction motor is rotating by correcting the output torque with the correction angular velocity ω _f shown in, for example, the equation (7). However, in this embodiment, the torque feedback control is performed based on the equation (Equation 7) and the current feedback control is performed based on the equation (Equation 11), but other known control methods may be used.

Next, the configuration of the second embodiment of the induction motor control device according to the present invention will be described with reference to the block diagram of FIG. In the above-mentioned first embodiment, the rotation speed detector of the induction motor is not necessary, but since a torque detector for detecting the output torque of the induction motor is required, it is advantageous in terms of cost and size. I can't say. Therefore, in the second embodiment, the torque detector is also unnecessary as described below.

In FIG. 2, the three-phase induction motor 100, P
WM inverter 102, torque current command generator 104,
Rotation / stationary coordinate converter 106, two-phase / three-phase converter 10
8, slip frequency calculator 110, adder 112, integrator 114, current controller 116, current detector 118a, 11
8b, 118c and the torque comparator 122 are the same as those in the first embodiment shown in FIG. As newly added elements, 200 is a three-phase / two-phase current converter that converts a three-phase alternating current into a two-phase alternating current, and 202 is a three-phase / two-phase that converts a three-phase alternating current voltage into a two-phase alternating current voltage. It is a voltage converter, 204 is a secondary magnetic flux estimator, and 206 is a torque estimator.

Regarding the operations of the PWM inverter 102, the torque current command generator 104, the rotary / stationary coordinate converter 106, the two-phase / three-phase converter 108, the slip frequency calculator 110, the current controller 116, and the torque comparator 122. This is the same as the case of the first embodiment. Here, the operation of estimating the output torque of the induction motor from the measured current value and the like by the three-phase / two-phase converters 200 and 202, the secondary magnetic flux estimator 204, and the torque estimator 206 will be described.

First, the three-phase / two-phase current converter 200 converts the three-phase alternating currents i _1a , i _1b , i _1c detected by the current detectors 118a, 118b, 118c into a two-phase alternating current according to the following equation (Equation 13). The currents i _1d and i _1q are converted.

[0051]

(Equation 13)

Similarly, the three-phase / two-phase voltage converter 202 is
The three-phase voltage command value v _1z (z = a, b, c) is calculated by the following equation (Equation 1)
According to 4), it is converted into two-phase AC voltages v _1d and v _1q .

[0053]

[Equation 14]

From the two-phase AC current and the two-phase AC voltage obtained by the converters 200 and 202, the secondary magnetic flux estimator 204 calculates the secondary magnetic flux according to the following two equations (15) and (16). Estimate ψ _2d and ψ _2q .

[0055]

(Equation 15)

[0056]

[Equation 16]

Next, the operation of the torque estimator 206 will be described. The output torque of the induction motor is expressed as shown in the equation (Equation 3). When this equation is transformed into the form using the secondary magnetic fluxes ψ _2d and ψ _2q , the following equation (Equation 17) is obtained.

[0058]

[Equation 17]

Therefore, the torque estimator 206 uses the above equation (Equation 1)
The output torque τ can be estimated according to 7). Using this estimated output torque τ, the torque comparator 122
Outputs a corrected angular velocity ω _f for controlling the output torque to be the command torque. In this way, the control for obtaining the desired torque is performed as in the first embodiment.

In the first and second embodiments, the two-phase / three-phase converter 108 generates a three-phase primary alternating current command value,
The current controller 116 compares these command values with the detected values to obtain the three-phase voltage command values to be output to the PWM inverter 102. However, instead of this structure, the following structure may be used. it can. That is, the three-phase primary alternating current detected by the current detector is converted into a two-phase primary alternating current by the three-phase / two-phase converter, and the two-phase primary alternating current detection value and the two-phase / three-phase converter 108 are entered. The two-phase voltage command value obtained by comparing the previous two-phase primary alternating current command value may be converted into a three-phase voltage command value by the two-phase / three-phase converter.

Further, here, the voltage command value is output instead of the actual voltage, but this has the advantage that a voltage detector for detecting the voltage is not required. However, when the power supply voltage fluctuates, it is necessary to measure and correct the power supply voltage.

Further, here, the torque is estimated by the equation (Equation 1)
Although the secondary magnetic flux is used based on 7), as an alternative method, it is possible to estimate the secondary currents i _2d and i _2q and calculate the torque from the following equation (Equation 18). .

[0063]

(Equation 18)

Alternatively, the primary magnetic fluxes ψ _1d and ψ _1q are estimated,
The torque may be calculated from the following equation (Equation 19).

[0065]

[Formula 19]

Next, an embodiment of an electric power steering apparatus using an induction motor control device capable of torque control without the speed detector as described above will be described with reference to FIG. The electric power steering device shown in the block diagram of FIG. 3 uses an induction motor controlled by an induction motor control device that does not require a speed detector, thereby adding an emergency clutch or speed detector. A desired auxiliary steering force can be applied to the steering system without requiring a device.

In FIG. 3, 100 is a three-phase induction motor,
300 is an induction motor control device, 302 is a steering wheel, 304 is a steering shaft, 306 is a steering gear, 308 is a wheel, 310 is a steering force sensor, 312
Is a speed reducer and 314 is a torque converter as command torque generating means.

In such a structure, when the steering wheel 302 attached to the steering shaft 304 is rotated, the wheels 308 are steered via the steering gear 306. In the electric power steering apparatus of this embodiment, the reduction gear 312 is attached to the steering shaft 304.
The three-phase induction motor 100 is connected through the three-phase induction motor 100, and an auxiliary steering force is applied by the three-phase induction motor 100. That is, the output of the steering force sensor 310 attached to the steering shaft 304 is converted into a command torque by the torque converter 314, and this command torque is given to the electromotive motor control device 300. This conductive motive control device 300
For this, the one described in the first embodiment or the second embodiment is used. In this way, the three-phase induction motor 100 is controlled so as to give the auxiliary steering force of the desired torque.

Since the induction motor does not use a permanent magnet, even if the wiring to the motor is short-circuited for some reason,
The induction motor is not braked and is completely free. Therefore, in this case, the electric power steering apparatus according to the present embodiment is only a normal steering apparatus that cannot obtain the auxiliary steering force. Therefore, a clutch as a safety mechanism, that is, a clutch for disconnecting the connection between the electric motor and the steering shaft, which is necessary in the device using the DC electric motor having the permanent magnet, is unnecessary.

As described above, the induction motor is used as the drive means for generating the auxiliary steering force of the electric power steering apparatus, and in order to control the induction motor, the induction motor control described in the first embodiment or the second embodiment is performed. By using the device, a safety mechanism such as a clutch, which is unnecessary for the original function, can be omitted, and a speed detector of the induction motor is also unnecessary. Therefore, a power steering device having a small and simple structure can be provided. Can be realized.

Here, the torque converter 314 determines the command torque given to the electromotive motor controller 300 based on the output of the steering sensor 310. For example, the faster the traveling speed of the vehicle, the smaller the auxiliary steering force. Alternatively, the command torque may be corrected according to the vehicle speed or the steering angle such that the command torque is changed according to the steering angle of the steering to improve the steering feeling.

[0072]

As described above, according to the present invention, there is provided torque determining means for detecting or estimating the output torque of the three-phase induction motor, and the primary alternating current is based on the command torque and the magnitude of the predetermined exciting current component. Change the amplitude of the current group, and
Since the frequency control unit controls the output torque of the three-phase induction motor by changing the frequency of the primary AC current group based on the magnitude of the exciting current component, the command torque, and the output of the torque detector, the speed detection is performed. Is unnecessary,
Moreover, it is possible to realize an induction motor control device that can control the output torque with high accuracy.

Further, the electric power steering system of the present invention comprises a three-phase induction motor for giving an auxiliary steering force to the steering system and a steering force sensor for detecting the steering force of the steering. Since a command torque generating means for converting the output of the steering force sensor into a command torque is provided, an additional mechanism such as a clutch and a speed detector are unnecessary, so that the structure can be made small with a simple structure, and It has excellent advantages such as good control performance and manual steering even in the event of a failure.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an induction motor control device according to the present invention.

FIG. 2 is a block diagram showing a second embodiment of the induction motor control device.

FIG. 3 is a block diagram showing an embodiment of an electric power steering device according to the present invention.

[Explanation of symbols]

 100 Three-Phase Induction Motor 102 PWM Inverter 104 Torque Current Command Generator 106 Rotation / Stationary Coordinate Converter 108 Two-Phase / Three-Phase Converter 110 Slip Frequency Calculator 112 Adder 114 Integrator 116 Current Controller 118a, 118b, 118c Current Detector 120 Torque determination means (torque detector) 122 Torque comparator 200 Three-phase / two-phase current converter 202 Three-phase / two-phase voltage converter 204 Secondary magnetic flux estimator 206 Torque estimator 300 Induction motor controller 302 Steering Wheel 304 Steering shaft 306 Steering gear 308 Wheel 310 Steering force sensor 312 Decelerator 314 Command torque generation means (torque converter)

Claims (7)

[Claims] 1. A three-phase induction motor is provided with a command for a torque current component and an excitation current component of a primary alternating current group supplied to the stator of the three-phase induction motor separately, and the amplitude and frequency of the primary alternating current group are changed. In an induction motor control device for controlling the output torque of an induction motor, a torque determination means for detecting or estimating the output torque of the three-phase induction motor is provided, and the command torque of the three-phase induction motor and the magnitude of the predetermined excitation current component By changing the amplitude of the primary AC current group, and by changing the frequency of the primary AC current group based on the magnitude of the exciting current component, the command torque and the output of the torque determination means, An induction motor control device further comprising torque control means for controlling output torque of a three-phase induction motor. 2. The current determining means for detecting or estimating each of the primary alternating current groups by the torque determining means, and the d-axis primary current in the predetermined d-axis direction and the d for the output of the current determining means. A three-phase / two-phase current converter for converting into a two-phase alternating current consisting of a q-axis primary current in the q-axis direction having a phase difference of 90 degrees from the axial direction, and the d on the rotor side of the three-phase induction motor. A secondary magnetic flux estimator for estimating secondary magnetic flux in the axial direction and the q-axis direction, the d-axis and q-axis primary currents, and the d-axis and q
The induction motor controller according to claim 1, further comprising a torque estimator that estimates an output torque of the three-phase induction motor from the shaft secondary magnetic flux. 3. The torque control means includes a PWM inverter that supplies a primary AC current group corresponding to an input voltage command value to a three-phase induction motor, and the torque determination means includes the three-phase voltage command value. Further comprising a three-phase / two-phase voltage converter for converting the
3. The secondary magnetic flux estimator estimates the secondary magnetic flux based on the output of the three-phase / two-phase current converter and the output of the three-phase / two-phase voltage converter. Induction motor controller. 4. The torque control means changes the amplitude and frequency of the primary alternating current group based on the command torque of the three-phase induction motor and the magnitude of a predetermined exciting current component, and the command torque and the The frequency of the primary alternating current group is corrected based on a result obtained by comparing the output of the torque determination means.
The induction motor controller described. 5. An electric power steering apparatus comprising: a three-phase induction motor that applies an auxiliary steering force to a steering system; and a steering force sensor that detects the steering force of the steering. Induction motor controller,
An electric power steering apparatus further comprising: a command torque generating means for converting an output of the steering force sensor into a command torque given to the induction motor control device. 6. A steering angle detector for detecting a steering angle of a steering, further comprising: said command torque generating means correcting said command torque according to an output of said steering angle detector. The electric power steering device described. 7. A moving speed detector for detecting a moving speed of a moving body is further provided, and the command torque generating means corrects the command torque according to an output of the moving speed detector. 5. The electric power steering device according to item 5.