JP2685631B2 - Induction motor controller and operating method thereof - Google Patents

Description

The present invention relates to a control device for an induction motor used in general industrial machines, machine tools and the like.

[Prior Art] A servo control device conventionally used in a machine tool or the like requires stable speed control from extremely low speed to high speed rotation for rotation speed control and positioning control. Also, a servo controller that feeds back the speed value and performs vector control has been used. However, recently, due to the workability of aluminum materials, higher speed rotation has been required.

In this case, in the servo controller that controls the induction motor by feedback control, the output current detection sampling time is the same from low speed to high speed, so the detected value within one cycle of the output current becomes discrete as the speed increases. Therefore, the upper limit frequency for feedback control is limited, and even if an attempt is made to increase the rotation speed beyond this, control is impossible.

In the ultra-high-speed rotation range where the servo control device cannot be applied as described above, an inverter device that operates by open loop control by setting the ratio of the terminal voltage V of the induction motor and the drive frequency F to a predetermined ratio has been used conventionally. ) Was applied, but with an inverter, low speed control and high precision positioning were not possible.

In the servo control device, if an abnormality occurs in the feedback detector during operation, for example, if an abnormality occurs in the rotation detector, the actual speed or rotational position cannot be detected correctly and the induction motor will run out or burn out. Therefore, the base drive signal of the power transistor of the inverter circuit section was cut off to stop the free run. As described above, conventionally, when an abnormality occurs in the feedback detector during operation, it has not been considered to continue the operation.

Furthermore, when configuring a material processing line using a large number of these induction motors and control devices, if a feedback detector malfunctions in any of these, free-run stop processing was performed. In the control of the film winding line, it has been unavoidable that the material is out of order and the product is defective. For these, there was no way to continue operation, and there was no way to deal with it by anticipating defective products.

[Problem to be Solved by the Invention] An object of the present invention is to provide an induction motor control device capable of continuing the operation in a wider area by switching the operation mode of the control device according to the control state. More specifically, there are the following points.

1) To provide an induction motor control device that can obtain servo performance with excellent responsiveness at low speed and can continue operation even at ultra-high speed.

2) To provide an induction motor control device that can continue operation without stopping operation even if the feedback detector becomes abnormal.

3) If a large number of induction motor controllers are used in the material processing line and the feedback detector malfunctions in any of them, the operation mode of other controllers is not switched and the line is not stopped. To provide an induction motor control system that can continue operation.

[Means for Solving the Problems] In order to solve the above-mentioned technology, two control calculation units, that is, a feedback control calculation unit and a V / F control calculation unit, are provided, and the switching command signal is detected by detecting the operating state of the induction motor control device. The feedback control and V / F are performed by the operation status detector that outputs
A switching control means for controlling switching of control is provided.

[Operation] The control state of the induction motor and its control device is monitored by the operation state detection unit, and the switching command signal is output according to the operation state, so that the switching control unit is stable according to the operation state. The operation mode (feedback control or V / F control) that can be operated is automatically switched.

[Embodiment] FIG. 7 is a block diagram showing an embodiment of the present invention. 101 is a power converter that outputs an arbitrary variable frequency, 4 is an induction motor connected to the output of the power converter,
Reference numeral 5 is a current detector that detects the current of the induction motor 4, 6 is a rotation rotation detector that detects the rotation of the induction motor 4, 7 is a rotation speed command unit that commands the rotation speed of the induction motor 4, and 8 is the induction motor 4 V / F control calculation unit for open loop control
Is a feedback for feedback controlling the induction motor 4 by inputting the value of the speed command unit 7 which commands the rotation speed of the induction motor 4, the feedback signal detected by the current detector 5 and the feedback signal detected by the rotation detector 6. The control calculation unit 33 is an operation state detection unit that detects the operation state of the induction motor control device (states such as the number of revolutions of the induction motor 4, the current, and the output frequency of the power converter), and 102 is a feedback control calculation unit 9 and V / Switching control means for inputting the signal of the F control calculation unit 8 and switching the signal of the feedback control calculation unit and the signal of the V / F control calculation unit based on the output of the operating state detection unit 33 and outputting to the digital 101 Is.

With such a configuration, the operation state detection unit 33 that monitors the operation state of the induction motor control device 4 can detect the feedback control calculation unit 9 and the V / F control calculation unit from the output frequency range, the feedback control signal abnormality signal, and the like. 8 is judged, and a switching command signal is output to the switching control means 102.
The switching control means 102 can switch the operation mode by a signal from the operation state detection unit 33. In this way, since the operation mode (feedback control or V / F control) can be automatically switched according to the operation state, the operation can be stably continued.

In order to set the data so that the output of the power converter is continuous at the time of switching, the signals of the V / F control calculation unit 8 and the feedback control calculation unit 9 are exchanged through the switching control unit 102.

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The main circuit for supplying electric power to the induction motor 4 includes a converter section 2 for exchanging a three-phase AC power supply for direct current, and an inverter section 3 for converting the DC output of the converter section 2 into AC of variable frequency and supplying electric power to the induction motor. Composed. The converter unit 2 includes six rectifying elements D for full-wave rectifying three-phase alternating current,
Current limiting resistor RS that limits the current when the three-phase AC power is turned on and RS
Capacitor C and electromagnetic contactor connected through
It consists of 84 and. The electromagnetic contactor 84 is a smoothing capacitor C
After the power is turned on, after charging up through the current limiting resistor RS, the operation delay time of the contacts is used to short-circuit the current limiting resistor, and power is supplied through 84 contacts during normal operation. The inverter unit 3 includes six switching elements Q
And a flywheel diode DF, and converts the DC output of the converter unit 2 into AC of variable frequency. The current of the induction motor 4 is fed back to the control circuit by the current detector 5.

First, the operation of the feedback control calculation unit when the rotation detector 6 is normal and the induction motor 4 is low speed will be described.

The soft switches SW1 and SW2 in the block diagram are in the OFF state (as in the state shown in FIG. 1). The rotation speed of the induction motor 4 is detected by the rotation detector 6, and the current is detected by the current detector 5 and sent to the feedback control calculation unit 9. The feedback control calculation unit 8 calculates the speed and the current based on the command value of the speed setter 7, the speed detection value and the current detection value, and determines the magnitude of the output voltage V ₁ of the induction motor 4 and the output angular frequency ω. ₁ for outputting 1
The rotation angle Δθ per sampling is output. These ω ₁ and Δθ are input to the three-phase PWM generation / calculation section 10 and signals for controlling the on / off states of the six switching elements Q are output. This on / off state signal is amplified by the switching element drive circuit 11 and sent to the inverter unit 3. The switching element Q is turned on / off by this signal, and the DC output of the converter unit 2 is converted into an AC having a variable frequency.

Next, when the speed change range is large and high-speed operation at a rotational speed of tens of thousands rpm is required, the primary output frequency of the induction motor becomes high, and thus current control becomes difficult with feedback control. Therefore, the speed-torque characteristic (N
Feedback control is performed at low speeds as shown in the control region on the −T curve), and open loop control is performed by switching to V / F control at high speeds above the rotational speed N ₀ . However, only the rotation speed and the current detection are continuously detected by the feedback control calculation unit 9.

The switching operation from low speed to high speed is the same procedure as the detector abnormality of FIG. In Fig. 2, the alarm process is activated by the occurrence of an abnormality in the rotation detector. In this case, however, feedback control operation is performed below a certain rotation speed, and V / F control operation is performed above a predetermined rotation speed. It suffices to start it by the output of the operation state detection unit 33 that controls switching to.

On the contrary, the switching operation from high speed to low speed is as follows. FIG. 1 The data of the output voltage magnitude | V ₂ | of the V / F control calculation unit 8 and the rotation angle Δθ per sampling of the output primary angular frequency ω ₁ are transferred to the feedback control calculation unit 9 from the soft switch SW2, Soft switches after calculating the initial values for switching to feedback control from the rotational speed and current value that were continuously detected even during V / F control operation, and setting each value to the corresponding calculation unit shown in Fig. 5. Switch SW1 to the feedback control side. In addition, FIG. 4 shows a hysteresis characteristic for the rotation speed N ₀ for switching between the feedback control and the V / F control (when the rotation speed rises, the switch is turned on at the rotation speed N ₀₁ ,
In this case, the switching is switched off at the rotation speed N ₀₂ when the rotation speed decreases). In this way, the switching chattering at N ₀ does not occur, so that the control state can be smoothly switched.

A detailed block diagram of FIG. 1 is shown in FIG. The detailed operation of the feedback control calculation unit 9 will be described with reference to FIG.

 Output N of rotation detector 6_fbIs input to the speed calculator 12 to rotate
Number feedback signal N_fAnd calculate this N_fAnd speed setter
The difference from the output of 7 is calculated by the subtraction unit 17 and the proportional calculation unit 1
3. Send to the integral calculator 14. These signals are added by the adder 15.
Calculated and limited by limiter 16, torque command
Torque current command signal Iq^*Is obtained. On the other hand, the rotation speed
Feedback signal N_fMagnetic flux setting in which the relationship between
The excitation magnetic flux command signal Φ is output from the unit 20 and the excitation current setting
Coefficient k in constant part₁Multiply by the magnetic flux current command signal Id^*Is obtained
You. In addition, the actual current I of the U-phase and the W-phase that flows through the induction motor 4_U, I_W
Is detected by the current detector 5, and 28 sample and hold circuits are used.
After holding each, alternate with switch 31
It is converted into a digital value by the A / D converter 29. More
Is the output Δθ of the rotation angle calculation unit 27_1aAmount of alternating current depending on signal
From the DC amount to the DC amount in the 3-phase / 2-phase conversion calculation unit 30
Feedback I df and torque current feedback I
It is output separately in qf. These I df and I qf are subtracted by the subtraction unit 17.
Each of the above command current Iq , Id^*And it
Difference is output. Torque current of these signals
The difference is calculated by the proportional calculation unit 22 and the integral calculation unit 23.
After being calculated by the adder unit 15 and the limiter unit 16, the induced voltage
The induced voltage is added by the calculation unit 32 and the q-axis voltage command Vq^*Get
It is sent to the vector calculation unit 26. Also, the exciting current difference is proportional
The calculation unit 24 and the integral calculation unit 25 perform proportional-plus-integral calculation, and the addition unit 15
D-axis excitation voltage command Vd by the mitter 16^*And output
To the operation unit 26.

In the vector calculation unit 26, from Vd ^* and Vq ^* Is calculated and output to soft switch SW1, and Id ^* , I
Rotation angle calculator 2 by calculating the current phase θ as shown below from q ^*
Output θ to 7.

On the other hand, the torque current signal Iq ^* is calculated by the slip angle frequency calculation unit 18
To output the slip angular frequency ωs, and the rotational angular frequency output calculation unit 19 outputs the rotational angular frequency ωr from the speed feedback Nf. ωs and ωr output the primary angular frequency ω ₁ by the addition unit 15, and the induced voltage calculation unit 32 already described.
Is sent to the rotation angle calculation unit 27, and the rotation angle calculation unit 27 outputs the rotation angle per sampling.

Reference numeral 8 in FIG. 5 shows the details of the V / F control calculation unit 8 in FIG.

The speed command signal is supplied to the rotation angle calculation unit 8-1 and the voltage calculation unit 8-
The voltage calculation unit 8-2 outputs the voltage | V _1b | of the induction motor 4, and the rotation angle calculation unit outputs Δθ _1b . A control state detection unit 33 constantly monitors whether it is low speed, high speed, or whether the detector is abnormal, and outputs a signal for switching the soft switches SW1 and SW2 according to the state.

 Next, the operation when switching will be described.

(1) From feedback control in the low speed range to V / in the high speed range
The operation when switching to the F control is almost the same as when switching to the abnormal detector described later (Fig. 2). In this case, the switching timing may be a detection signal of a predetermined frequency instead of the detector abnormality signal. In this way, the output voltage, frequency, and phase can be matched before and after switching, so switching can be performed without impact.

(2) The switching from the V / F control in the high speed range to the feedback loop in the low speed range will be described below in the order of (a) to (e).

(A) The slip angular frequency is determined by ωs = ω ₁ −ωr from the primary angular frequency ω ₁ and the actual rotational angular frequency ωr in the final sampling of V / F control.

(B) The proportional-integral calculation output of the speed control system, that is, the torque current command Iq ^* is obtained from Iq ^* ∝ωs.

This is the case where the induction motor has a constant torque, but the same can be considered for the constant torque, although the calculation formula is different.

(C) Next, the proportional calculation unit 13 and the integral calculation unit 14 of the speed control system
The initial value of is set as follows, depending on whether the speed control system is saturated or in an unsaturated operating state.

a) When the speed control system is saturated (when the change in the number of revolutions is rapid) The set value of the proportional calculation unit 13 = Iq ^* The set value of the integral calculation unit = 0 b) When the speed control system is unsaturated (When the change in the number of revolutions is gradual) The setting value of the proportional calculating unit 13 = 0 The setting value of the integrating calculating unit 14 = Iq ^* and the initial value are set and feedback control is performed.

As described above, the initial values of the proportional calculation unit 13 and the integral calculation unit 14 differ depending on the operating state, but since the proportional unit is dominant in the transient state, the integral unit is set to zero, and conversely, in the steady state, Since the steady-state deviation is corrected by the integrating part, the proportional part is set to zero.

Next, the initial setting of the proportional calculation unit 22 and the integral calculation unit 23 of the current control system will be described.

(D) The output current phase θ is calculated from the output current detection value (feedback value) at the final sampling in V / F control operation. Is obtained as

(E) The power factor angle ψ of the output is obtained from the phase of the output voltage (command value V ₁ ) and the phase of the output current detected in (d) above.

(F) The value of the primary voltage V ₁ is decomposed into the d-axis voltage V _1d ^* and the q-axis voltage V _1q ^* from the sum of the current phase θ and the power factor angle ψ (θ + ψ).

V _1d ^* = V ₁ cos (θ + ψ) V _1q ^* = V ₁ sin (θ + ψ) These V _1d ^* and V _1q ^* are set in the proportional calculation unit 22 and the integral calculation unit 23 according to the current state as follows.

a) When the current control system is saturated (when the current change is abrupt) Set value of q-axis proportional calculation unit 22 = V _1q ^* = Set value of integral calculation unit 23 = 0 d-axis proportional calculation unit 24 Setting value = V _1d ^* 〃 setting value of integral calculation unit 25 = 0 b) When the current control system is unsaturated (when the current change is gradual) Setting value of q-axis proportional calculation unit 22 = 0 〃 integral calculation Set value of part 23 = V _1q ^* Set value of proportional calculation part 24 of d axis = 0 = Set value of integral calculation part 25 = V _1d ^* Set initial value and switch from V / F control to feedback control. However, since the current phase is continuously performed from the V / F control, problems such as impact do not occur. In addition,
The initial values of proportionality and integration differ from the current state for the same reason as in the case of proportionality integration of the speed control system.

According to this embodiment, it is possible to switch from feedback control to V / F control and vice versa.Therefore, when the shift range is large, for example, at high speed V / F control up to a high speed of tens of thousands rpm, There is an effect that it is possible to continuously operate even in a wide gear shift range such as 1: 100000 such as the orientation control 0.5 rpm used for positioning such as tool exchange of a low speed machine tool. If this servo controller is used, V / F controlled inverter operation can also be performed without a speed detection cable. If precision is required, feedback control is used, and if it is not required, V / F control is used.

Next, the operation when the rotation detector 6 that detects the speed of the induction motor 4 fails or the wiring to the feedback calculation unit 9 is opened or shorted will be described.

A rotation detector attached to a place that outputs power like an induction motor, for example, a detector that outputs an AB phase with a 90 ° phase difference is composed of electronic parts and is attached to a place with a bad atmosphere. Vibration and heat from the machine may be applied, resulting in failure. At this time, the rotation of the induction motor 4 becomes unknown. When the normal wiring is open or short-circuited, no signal is sent, and the feedback control calculation unit 9 detects that the rotation speed is zero. Therefore, when a certain constant speed setting is given, the feedback control works so as to obtain the maximum torque in an attempt to keep the rotation of the induction motor 4 constant. For this reason, the maximum current may flow through the induction motor 4 and the burnout may occur. In order to prevent this, after the control state detection unit 33 detects an abnormality, the switching element Q is turned off to turn off the induction motor 4
Free run, but problems may occur depending on the load. For example, if one motor runs abnormally during winding control of paper, film, etc., the material may run out due to the relationship with the front and rear flow lines, and the material may become a defective product that cannot be used later. is there.

In the present invention, as shown in FIG. 2, after detecting the rotation detector abnormality occurrence at the sampling t _n time, the signal given to the induction motor 4 is calculated by the feedback control calculation unit 9 and the value at the final sampling t _n-1 is calculated. It is switched to the V / F control operation unit 8 by outputting it as an initial setting value to the V / F control operation unit 8 through the soft switch SW2 in FIG. 1 and turning on the soft switch SW1 after transferring the internal operation data. Output voltage V ₁
Since Δθ and Δθ are switched by the same value, there is no particular abnormal impact. After this, continue operation as it is,
Alternatively, switching to emergency operation, slowly lowering the value of the speed setter 7 to lower the entire line, stopping without running out of material, etc., and then taking measures against the abnormal point and restarting the operation by the feedback control calculation unit 9 again. Is also possible. If the line does not need to be stopped, the operation can be continued.

This operation will be described in more detail below in (1) to (3).

(1) Final sampling at feedback control t _n-1
From the relationship between the output frequency ω ₁ ′ and the speed command N ′ at Ask for.

(2) Output frequency ω after switching to V / F control
₁ gives a primary angular frequency with ω ₁ = k ₁ · N ₁ ^* for an arbitrary speed command N ₁ ^* .

(3) Next, the primary voltage V ₁ of the induction motor is proportional to the output voltage V ₁ ′ at the final sampling during feedback control and the speed command N ′. Ask for.

Next, the primary voltage is calculated with V ₁ = k ₂ · N ₁ ^* for any speed command N ₁ ^* . The current phase at the time of switching is naturally controlled in accordance with the phase at the time of the feedback control loop, so that there is no fear of torque shock.

According to this embodiment, V / F control operation without using a detector can be automatically switched and continuous operation can be performed, so that there is an excellent effect that the safety and reliability of the system are improved.

If the controller and the induction motor are installed separately, and either one is on the trolley, the induction motor supplies power with a pantograph or brush, but the rotation detector output signal is a weak wire, so contact failure with the brush configuration Occurs, the disconnection is frequently detected, and it becomes a free run. Even in such a case, since it is switched to V / F control, not only can it be continued as it is, but if the connection state returns to normal, it is possible to return to feedback control again, so there is an excellent effect that such operation is possible. is there.

In this embodiment, the case where the rotation detector is abnormal is described. However, the same can be considered for the abnormality of the current detector and the torque detector abnormality when the torque feedback control is performed. It is not limited to.

Next, FIG. 6 shows an example of the line control of the multi-unit operation to which the present invention is applied.

Fig. 6 is a film magnetic coating or processing line.
34 is a feeding machine, 35 is a winding machine, and 36 is a pinch roller.

The overall line speed is set by the line speed setter 43, and the soft start circuit 41 gives an acceleration / deceleration command by a ramp function. The speed command is input to the control device 39-2 and drives the induction motor 4-2. The speed of the induction motor 4-2 is fed back by the rotation detector 6-2 and the pinch roller
36 determines line speed. Next, the winder 35 detects the signal of the dancer roll by the detector 38 such as celsin, and the feedback control is performed by the subtraction unit 17 so that the induction motor 4-3 is slow when the dancer roll rises and fast when the dancer roll falls. I do. In the winder 35, the peripheral speed increases due to the thickening of the winding, so that the dancer roll rises and, as a result, the induction motor 4-3 is controlled to slow down. In the delivery 34, the tension is detected by the tension detector 37, the difference between the tension amplifier 40 and the tension setter 42 is calculated by the calculator 17, and the difference is sent to the controller 39-1. The induction motor 4-1 is driven as back tension control. Here, the rotation detector of the induction motor 4-2 fails and the control device 39-
When 2 is switched to V / F control, the broken line V shown in Fig. 6
The signal output during / F control is input to the V / F external switching signal of the control device 39-3 to forcibly switch the induction motor 4-3 to V / F control. If the broken line is not connected, only the control device of 39-2 is used for switching, and the difference in response between them appears as the upper and lower sides of the dancer roll, and the winder 35 follows the induction motor 4-2 having a slow response. The induction motor 4-3 is controlled.

As an application example, the response of the induction motor driven by another normal control unit should be matched with the V / F control response of the control unit that has switched to V / F control due to an abnormality in the detector. You can also This is because the normal controller is V /
The response of the feedback control is changed by receiving the F control in-progress signal so that the rotations of the plurality of induction motors are matched as a whole. In this case, the normal control device does not switch to V / F control. This way V
It is possible to make subtle adjustments that cannot be done with / F control operation.

[Advantages of the Invention (Invention)] According to the present invention, 1) it is possible to provide a control device for an induction motor which has a wide speed range and which can obtain a servo performance with a low response at a low speed and can be operated even at a super high speed.

2) Even if the rotation detector becomes abnormal, the operation can be continued without stopping the operation.

3) If a large number of induction motor control devices are used in the material processing line, even if any of them have an abnormal rotation detector, all control devices are switched to the same mode without stopping the line. Can continue to operate.

And so on.

[Brief description of the drawings]

FIG. 1 is an overall block diagram showing an embodiment of the present invention.
Fig. 3 is a software processing diagram when the detector is abnormal in Fig. 1, 3
FIG. 4 is a diagram showing a control state switching region in a shift range,
The figure shows the hysteresis characteristic of the switching timing.
FIG. 7 is a detailed view of the control circuit of FIG. 1, FIG. 6 is a view showing an embodiment of the present invention, and FIG. 7 is a view showing an embodiment of the present invention. Explanation of symbols 1 ... Three-phase AC power supply, 2 ... Converter section, 3 ... Inverter section, 4 ... Induction motor, 5 ... Current detector, 6 ...
... Rotation detector, 7 ... Speed setter, 8 ... V / F control calculation unit, 9 ... Feedback control calculation unit, 10 ... PWM generation calculation unit, 11 ... Switching element drive circuit, 12 ... Speed Calculation unit, 13 ... Speed control unit Proportional calculation unit, 14 ... Speed control unit Integral calculation unit, 15 ... Addition calculation unit, 16 ... Limiter, 17
…… Subtraction calculator, 18 …… Slip angular frequency calculator, 19 ……
Rotational angular frequency calculation unit, 20 ... Flux setting unit, 21 ... Excitation current setting unit, 22 ... Current control q-axis proportional calculation unit, 23 ... Current control q-axis integral calculation unit, 24 ... Current control d-axis Proportional operation part,
25 …… Current control d-axis integral calculation unit, 26 …… Vector calculation unit, 27 …… Rotation angle calculation unit, 28 …… Sample hold circuit, 29 …… A / D converter, 30 …… 3-phase / 2-phase conversion Calculation unit, 31 ... Changeover switch, 32 ... Induction voltage calculation unit, 33
...... Driving state detector, 34 …… Sending machine, 35 …… Winding machine, 36 …… Pinch roller, 37 …… Tension detector,
38 ... Angle detector, 39 ... Control device, 40 ... Tension amplifier, 41 ... Soft start circuit, 42 ... Tension setting device, 43 ... Line speed setting device, D ... Rectifying element, 84
...... Electromagnetic contactor, 101 ・ ・ ・ Power converter, 102 ・ ・ ・ Switch control means, RS ・ ・ ・ Current limiting resistance, C ・ ・ ・ Smoothing capacitor, Q ・ ・ ・
… Switching element, DF… Flywheel diode,
SW1 …… Soft switch, SW2 …… Soft switch

Claims (5)

(57) [Claims] 1. A power conversion device for converting to an arbitrary variable frequency, an induction motor connected to an output of the power conversion device for rotation control, a rotation detector for detecting rotation of the induction motor, and a rotation command. In an induction motor control device including a control circuit that controls the induction motor by varying the output frequency of the power converter according to the control circuit, the control circuit inputs the rotation command and the output signal of the rotation detector and feeds it back. A feedback control calculation unit that generates a control signal, a V / F control calculation unit that inputs the rotation command and generates an open loop control signal, and outputs a switching command signal by detecting the operating state of the induction motor control device The operation state detection unit, and the power change by switching the signals of the feedback control calculation unit and the V / F control calculation unit based on the output of the operation state detection unit. Induction motor control apparatus characterized by comprising a switching control means for outputting to the device. 2. A power conversion device for converting to an arbitrary variable frequency, an induction motor connected to an output of the power conversion device for rotation control, a rotation detector for detecting rotation of the induction motor, and a rotation command. In an induction motor control device including a control circuit that controls the induction motor by varying the output frequency of the power converter according to the control circuit, the control circuit inputs the rotation command and the output signal of the rotation detector and feeds it back. A feedback control calculation unit that generates a control signal, a V / F control calculation unit that inputs the rotation command and generates an open-loop control signal, and a signal that corresponds to the output frequency of the power conversion device is input and predetermined. The predetermined switching reference frequency, and outputs a switching command signal by comparing the magnitude with the predetermined switching reference frequency, and the feedback controller according to the output of the driving state detection unit. Control operation of the output and the V / F control induction motor control apparatus characterized by comprising a switching control means for outputting the arithmetic unit switches the output to the power converter. 3. A power conversion device for converting to an arbitrary variable frequency, an induction motor connected to an output of the power conversion device for rotation control, a rotation detector for detecting rotation of the induction motor, and a rotation command. In an induction motor control device including a control circuit that controls the induction motor by varying the output frequency of the power converter according to the control circuit, the control circuit inputs the rotation command and the output signal of the rotation detector and feeds it back. A feedback control calculation unit that generates a control signal, a V / F control calculation unit that inputs the rotation command and generates an open loop control signal, and an operation that detects an abnormality of the rotation detector and outputs a switching command signal The state detection unit, the output of the feedback control calculation, the output of the V / F control calculation unit and the output of the operation state detection unit are input, and the difference of the operation state detection unit is input. When the detection signal received induction motor control apparatus characterized by comprising a switching control means for outputting the output of the V / F control calculation unit to the power converter. 4. A power conversion device for converting to an arbitrary variable frequency, an induction motor connected to an output of the power conversion device for rotation control, a rotation detector for detecting rotation of the induction motor, and the rotation command. And a feedback control calculation unit for inputting the output signal of the rotation detector to generate a feedback control signal, a V / F control calculation unit for inputting the rotation command and generating an open loop control signal, and a V / F control V / F external switching signal receiver that can command operation from the outside, and the V / F
Input the external switching signal and the signal from the rotation detector to detect V / F when the rotation detector is abnormal or when the V / F external switching signal is received.
A driving condition detection unit that outputs a switching command signal for switching to control, the output of the feedback control calculation, the output of the V / F control calculation unit, and the output of the driving condition detection unit are input and a switching command of the driving condition detection unit A switching control unit that outputs the output of the V / F control calculation unit to the power converter according to a signal, and a V / F that outputs a V / F control-in-progress signal during abnormal V / F control operation of the rotation detector. A plurality of induction motor control devices having a control-in-progress signal output unit are provided, and at least one control device of the plurality of control devices
A control system for an induction motor, wherein the V / F control signal output unit is connected to a V / F external switching signal reception unit of at least one other control device of the plurality of control devices. 5. A power converter for converting to an arbitrary variable frequency, an induction motor connected to an output of the power converter for rotation control, a rotation detector for detecting rotation of the induction motor, and the rotation. A feedback control calculation unit that inputs a command and an output signal of the rotation detector to generate a feedback control signal, a V / F control calculation unit that inputs the rotor to generate an open loop control signal, and the induction motor A driving state detection unit that detects the driving state of the control device and outputs a switching command signal, and switches the signals of the feedback control calculation unit and the V / F control calculation unit based on the output of the driving state detection unit A step of recognizing an output change of the operating state detection unit when operating an induction motor control device having a switching control means for outputting to the power conversion device; Voltage, frequency, the step of initially setting the data for continuous phase to the feedback control arithmetic unit or the V / F control arithmetic unit of the switching destination, and the calculation result of the control arithmetic unit of the switching destination after the initial setting is completed. A method of operating an induction motor control device, comprising the step of starting output to a power conversion device.