JPH10191689A - Inverter apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain an induction motor from coming into an overtorque state when a rope is wound and rewound by a method wherein, while an overtorque detecting means outputs a detection signal, speed data from a speed detecting means is given to a voltage/frequency setting means as an operating frequency. SOLUTION: While an overtorque detection circuit 17 outputs a detection signal, a relay switch 18 is changed over so as to give speed data from a speed detector 23 to a voltage/frequency setting circuit 21 as an operating frequency instead of an operating frequency F from a proportional integral control circuit 16. As a result, when a torque current value detected by a torque-current detection circuit 15 exceeds a set load, the speed data from the speed detector 23 is given to the voltage/frequency setting circuit 21 as the operating frequency. However, since the speed data from the speed detector 23 does not contain slip information on an induction motor 4, the slip information is not given to the voltage/frequency setting circuit 21, and the overtorque of the induction motor 4 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inverter device for driving an induction motor for winding and rewinding a cable.

[0002]

2. Description of the Related Art For example, in a winch, a cable is laid between a reel of a reel winder and a reel of a winch, and the reel of the reel winder is rotated forward and reverse by an induction motor. The cable is wound and unwound, and the induction motor is driven by an inverter device.

In this type of conventional inverter device, a torque current detecting circuit for detecting a torque current of an induction motor is provided, and a torque command value from a torque command generator and a torque current value detected by the torque current detecting circuit are provided. And a voltage (V) / frequency for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional integration control circuit. (F) A setting circuit is provided.
A configuration is provided with a PWM control circuit that controls an inverter main circuit that drives the induction motor based on a frequency command value and a voltage command value from a / f setting circuit.

The PWM control circuit makes the voltage and frequency of the AC power supplied to the induction motor via the inverter main circuit constant at V / f based on the frequency command value and the voltage command value from the V / f setting circuit. To control the torque current value of the induction motor to become the torque command value, thereby controlling the tension of the cable.

[0005]

However, in the conventional configuration in which the torque of the induction motor is controlled by the proportional-integral control, the cable between the reel of the reel winder and the reel of the winch becomes loose at the start of operation. When the induction motor is rotated forward and the cable is wound by the reel of the reel winding machine, there is no tension in the cable, so the torque current of the induction motor is small and the rotation speed of the induction motor reaches a high speed. Would. Then, since the cable is suddenly pulled to rotate the reel of the winch, the torque current of the induction motor greatly exceeds the torque command value at that moment, causing an overtorque state, and the cable may be damaged. Or, there is a problem that the reel winder, the winch or the other machine is damaged. It is to be noted that even when the operation is not started, even when the winch suddenly stops during winding of the cable by the reel winding machine, the induction motor may be in an overtorque state.

The present invention has been made in view of the above circumstances, and an object of the present invention is to prevent an induction motor for winding and rewinding a cable from becoming overtorqued. To provide an inverter device.

[0007]

According to a first aspect of the present invention, there is provided an inverter device including an inverter main circuit for driving an induction motor for winding and rewinding a cable, and detecting a torque current of the induction motor. Detecting means for obtaining an operating frequency from the torque current value detected by the torque current detecting means by proportional integral control; and a frequency command value for the induction motor based on the operating frequency from the proportional integral control means. And a voltage / frequency setting means for outputting a voltage command value, a driving means for controlling the inverter main circuit based on the frequency command value and the voltage command value from the voltage / frequency setting means, and a speed of the induction motor. A speed detecting means for detecting is provided, and only when the torque current value detected by the torque current detecting means exceeds a set level is detected. Signal is output, and during the period when the overtorque detecting means is outputting the detection signal, the speed data from the speed detecting means is used as the operating frequency instead of the operating frequency from the proportional-integral control means. It is characterized in that a switching means for switching the voltage / frequency setting means is provided.

According to this configuration, when the torque current value detected by the torque current detecting means exceeds the set level, the speed data from the speed detecting means is used instead of the operating frequency from the proportional-integral control means. The frequency is supplied to the voltage / frequency setting means. However, since the speed data from the speed detecting means does not include slip information for the induction motor, the slip information is not supplied to the voltage / frequency setting means. Accordingly, overtorque of the induction motor can be suppressed by that much.

According to a second aspect of the present invention, there is provided an inverter device comprising the same inverter main circuit as the first aspect, a torque current detecting means, a proportional integral controlling means, a voltage / frequency setting means, a driving means and a speed detecting means. Over-torque voltage command means for outputting an over-torque voltage command value lower than the voltage command value from the voltage / frequency setting means is provided, and detection is performed only during a period when the torque current value detected by the torque current detecting means exceeds a set level An over-torque detecting means for outputting a signal is provided, and during the period when the over-torque detecting means is outputting a detection signal, the speed data from the speed detecting means is used as the operating frequency instead of the operating frequency from the proportional-integral control means. The voltage / frequency setting means is switched so as to be applied to the voltage / frequency setting means. Having features overtorque voltage command value from the decree means be provided with a switching means for switching so as to provide to said drive means.

According to this configuration, when the torque current value detected by the torque current detecting means exceeds the set level, the speed data from the speed detecting means is replaced with the operating frequency instead of the operating frequency from the proportional-integral control means. As voltage / frequency setting means,
Since the overtorque voltage command value lower than the voltage command value from the frequency setting means is given to the driving means instead of the voltage command value from the voltage / frequency setting means, the overtorque of the induction motor is further suppressed. Can be.

According to a third aspect of the present invention, there is provided an inverter device comprising the same inverter main circuit, torque current detecting means, proportional-integral control means, voltage / frequency setting means and driving means as in the first aspect, and further comprising the proportional-integral control means. An initial frequency limiting means for limiting the operating frequency from the low speed to a low speed is provided, and a detection signal is provided only during a period from the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches a specified level. Is provided, and during the period when the initial over-torque detecting means is outputting the detection signal, the operating frequency from the proportional-integral control means is set to the voltage / voltage via the initial frequency limiting means.
The present invention is characterized in that a switching means for switching the frequency setting means is provided.

According to such a configuration, the operating frequency from the proportional-integral control means is changed from the initial frequency to the initial frequency only during the period from the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches the specified level. Since the operating frequency limited to the low speed by the limiting means is given to the voltage / frequency setting means, the rope is prevented from being sharply pulled in the initial stage of the operation of the induction motor.
It is possible to reliably suppress overtorque in the initial operation of the induction motor.

According to a fourth aspect of the present invention, there is provided an inverter device comprising the same inverter main circuit, torque current detecting means, proportional-integral control means, voltage / frequency setting means and driving means as in the first aspect, and further comprising the torque current detecting means. A torque current amplifying means for amplifying the detected torque current value,
Initial over-torque detecting means for outputting a detection signal only during a period from the start of operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches a specified level, is provided. A switching means for switching the torque current value detected by the torque current detecting means to the proportional-integral control means via the torque current amplifying means during the signal output period is provided.

According to such a configuration, the torque current value detected by the torque current detecting means only during a period from the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches the specified level. Since the torque current value amplified by the torque current amplifying means is given to the proportional-integral control means, the rope is prevented from being sharply pulled in the initial operation of the induction motor. It can be suppressed reliably.

According to a fifth aspect of the present invention, there is provided an inverter device comprising: an inverter main circuit for driving an induction motor for winding and rewinding the cable; and a tension detecting means for detecting a tension of the cable. A proportional / integral control means for obtaining an operating frequency from the tension value detected by the means by proportional / integral control; and a voltage / frequency for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means. Setting means; driving means for controlling the inverter main circuit based on the frequency command value and the voltage command value from the voltage / frequency setting means; speed detecting means for detecting the speed of the induction motor; An over-tension detecting means for outputting a detection signal only during a period when the tension value detected by the detecting means exceeds the set level is provided. A switching means for switching so that the speed data from the speed detecting means is given to the voltage / frequency setting means as the operating frequency instead of the operating frequency from the proportional-integral control means during the period of outputting the signal. Having.

According to such a configuration, when the tension value detected by the tension detecting means exceeds the set level, the speed data from the speed detecting means is used as the operating frequency instead of the operating frequency from the proportional-integral control means. / Frequency setting means, so that the same effect as in claim 1 can be obtained.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS. First,
FIG. 3 schematically shows a reel winder and a winch which is a partner machine driven by the reel winder. That is, the reel winder 1 is provided with a reel 3 for winding and rewinding the cable 2 serving as a cable, and the reel 3 is driven by an induction motor 4 via a belt transmission mechanism 5 to rotate forward and reverse. Has become. The cable 2 is wound around the reel 7 of the winch 6 a plurality of times, and a hook (not shown) that is hooked on a load is provided at the end of the cable 2. Then, the induction motor 4 is driven by the inverter device 8.

Now, the inverter device 8 will be described with reference to FIGS. The three-phase terminal of the three-phase AC power supply 9 is connected to the AC input terminal of the three-phase full-wave rectifier circuit 10,
A smoothing capacitor 11 is connected between the DC output terminals of the three-phase full-wave rectifier circuit 10. Further, a DC output terminal of the three-phase full-wave rectifier circuit 10 is connected to an input terminal of the inverter main circuit 12. This inverter main circuit 12
Is configured by connecting an IGBT 12a, which is a semiconductor switching element, to a three-phase bridge, and has a three-phase output terminal connected to a three-phase input terminal of the induction motor 4.

Current transformers 13 and 14 serving as current detecting means are provided in two phases of a three-phase circuit connecting the three-phase output terminal of the inverter main circuit 12 and the three-phase input terminal of the induction motor 4. Each output terminal is connected to an input terminal of a torque current detection circuit 15 as a torque current detection means.
The torque current detection circuit 15 detects a torque current It from a two-phase load current of the induction motor 4 using a rotating coordinate system, and has an output terminal connected to a PI control circuit 16 serving as a proportional-integral (PI) control means. Also, it is connected to each input terminal of an over-torque detecting circuit 17 as an over-torque detecting means. The output terminal of the PI control circuit 16 is connected to a fixed contact b of a relay switch 18 composed of a changeover switch as a changeover means.

Here, as shown in FIG. 3, the PI control circuit 16 includes a torque command value Is from a torque command generator 16a comprising a variable resistor as a torque command generating means and a torque current value from a torque current detection circuit 15. Difference ΔI from the value of It
Is detected by the subtractor 16b, and the difference ΔI is calculated by the proportional calculator 16b.
The calculation is performed by c and the calculation is performed by the integration calculator 16d. The calculation result is added by the adder 16e, and the result of addition by the adder 16e is output to the operating frequency F for the induction motor 4 through the stabilization integrator 16f. It has become.

The over-torque detecting circuit 17 compares the value of the torque current It from the torque current detecting circuit 15 with a predetermined set level Ls. When the value of the torque current It is lower than the set level Ls, , Relay switch 18
The movable contact c is in contact with the fixed contact b (on) and the movable contact c is separated (off) from the fixed contact a, and when the value of the torque current It exceeds the set level Ls, the value exceeds the set level Ls. The detection signal is output only during the period, and based on this, the relay coil is energized to switch off the movable contact c and fixed contact b of the relay switch 18 and turn on the movable contact c and fixed contact a.

Further, the movable contact c of the relay switch 18
Are connected to respective input terminals of the voltage command circuit 19 and the frequency command circuit 20. The output terminals of the voltage command circuit 19 and the frequency command circuit 20 constitute a V / f setting circuit 21 as a voltage (V) / frequency (f) setting means, and each output terminal is a PWM as a driving means. Control circuit 2
2 input terminals. In this case, the voltage command circuit 19 and the frequency command circuit 20 calculate and output the voltage command value V and the frequency command value f based on the operating frequency F so as to operate the induction motor 4 at the operating frequency F.
The V / f is controlled to be constant. The PWM control circuit 22 performs PWM control on the inverter main circuit 12 so that the AC power supplied to the induction motor 4 becomes the voltage command value V and the frequency command value f.

The speed detector 23 as a speed detecting means is constituted by an encoder, a magnetic sensor and the like, and detects the rotation speed of the induction motor 4 and outputs speed data R. The output terminal of the speed detector 23 is connected to the fixed contact a of the relay switch 18.

Next, the operation of the present embodiment will be described with reference to the timing chart of FIG. When the induction motor 4 is rotating forward, the reel 3 of the reel winder 1
Is rotated in the direction of arrow A by the belt transmission mechanism 5 (clockwise rotation)
Then, the cable 2 is wound up. Therefore, the induction motor 4 enters a power running operation state. Then, the torque current detection circuit 15 detects the torque current It of the induction motor 4,
The PI control circuit 16 calculates the torque command value Is and the torque current I
The V / f setting circuit 21 calculates the voltage command value V and the frequency command value f based on the operating frequency F based on the difference ΔI from the operating frequency F (see FIG. 4A).
It is given to the WM control circuit 22. Thereby, the PWM control circuit 22 performs PWM control of the inverter main circuit 12 so that the AC power supplied to the induction motor 4 becomes the voltage command value V and the frequency command value f, thereby reducing the torque current It of the induction motor 4. The control is performed so that the value matches the torque command value Is (see FIG. 4B), so that the tension of the cable 2 is kept constant. At this time, the over-torque detection circuit 17
As a result, the portion between the movable contact c and the fixed contact b of the relay switch 18 is turned on (see FIG. 4C).

Here, when the inverter device 8 appropriately controls the torque current It of the induction motor 4 by PI control, the operating frequency F for the induction motor 4 is expressed by the following equation. Operating frequency F = speed of induction motor 4 + slip amount of induction motor 4 (1)

In the power running operation state of the induction motor 4, for example, when the winch 6 which is the partner machine is suddenly decelerated or stopped, the tension of the cable 2 increases and the torque current It of the induction motor 4 is increased. Rapidly increases (see FIG. 4B). Then, the torque current detection circuit 15
When the torque current It detected exceeds the set level Ls (time T1 in FIG. 4), the overtorque detection circuit 17 outputs a detection signal, and based on the output of the detection signal, the relay switch 1
8 between the movable contact c and the fixed contact a. As a result, the V / f setting circuit 21 is supplied with the speed data R from the speed detector 23 as a new operating frequency F ′ instead of the operating frequency F from the PI control circuit 16.

Here, the operating frequency F 'given from the speed detector 23 to the V / f setting circuit 21 instead of the operating frequency F from the PI control circuit 16 is expressed by the following equation. Operating frequency F '= speed of induction motor 4...... (2)

Therefore, the V / f setting circuit 21 calculates the voltage command value V and the frequency command value f on the basis of the operating frequency F '. In this case, the V / f setting circuit 21 is evident from the equations (1) and (2). As such, the operating frequency F ′ includes the operating frequency F
Unlike this, since the slip information of the induction motor 4 called “slip amount of the induction motor 4” is not included, the frequency command value f becomes substantially equal to the operation frequency F ′. Therefore, when the voltage command value V and the frequency command value f based on the operating frequency F ′ are given to the PWM control circuit 22 to drive the inverter main circuit 12, the torque current It of the induction motor 4 is reduced by the amount of the slip information. Decrease.

Thereafter, when the torque current It of the induction motor 4 falls below the set level Ls (at time T in FIG. 4).
2) Since the over-torque detection circuit 17 stops outputting the detection signal, the movable contact c-fixed contact b of the relay switch 18
The operation frequency F is again supplied to the V / f setting circuit 21 from the PI control circuit 16.

When the cable 2 is rewound, the induction motor 4 is rotated in the reverse direction, and the reel 3 of the reel winding machine 1 is rotated (rotated to the left) in the direction opposite to the arrow A direction. And
At this time, since a tensile force acts on the reel 3 of the reel winder 1 from the load via the cable 2, the induction motor 4 enters a regenerative operation state, and the inverter device 8 does not perform PI control.

As described above, according to the present embodiment, the operating frequency F from the PI control circuit 16 is changed to the V / f setting circuit 21 during the normal power running operation of the induction motor 4 (when winding the cable 2). When the torque current It of the induction motor 4 detected by the torque current detection circuit 15 exceeds the set level Ls, the over torque detection circuit 17 switches the relay switch 18 to replace the operation frequency F with the speed detector. The speed data R of the induction motor 4 detected by the motor 23 is converted to the operating frequency F '.
To the V / f setting circuit 21. Therefore, during a period in which the torque current It of the induction motor 4 exceeds the set level Ls, the inverter main circuit 12 is driven based on the operating frequency F ′ that does not include slip information, and accordingly, the torque current It is correspondingly increased. Is reduced, the induction motor 4 is suppressed from being in an overtorque state, and the cable 2 is damaged or the reel winding machine 1
It is possible to prevent the winch 6 or the like as the partner machine from being damaged.

FIG. 5 shows a second embodiment of the present invention.
The same reference numerals are given to the same parts as in the embodiment of
The different parts will be described. An over-torque voltage command circuit 24 serving as an over-torque voltage command means outputs an over-torque voltage command value Vo lower than the voltage command value V output from the voltage command circuit 19 based on the operating frequency F from the PI control circuit 16. The output terminal is connected to a fixed contact a of a switching switch type relay switch 25 serving as a switching means.

The relay switch 25 is a relay switch 1
8 is turned on and off in conjunction with the relay switch 8. When the movable contact c and the fixed contact b of the relay switch 18 are on, the movable contact c and the fixed contact b of the relay switch 25 are turned on.
When the range between the movable contact c and the fixed contact a of the relay switch 18 is on, the range between the movable contact c and the fixed contact a of the relay switch 25 is turned on. In the relay switch 25, the fixed contact b is connected to the voltage command circuit 19
And the movable contact c is connected to the PWM control circuit 2
2 input terminals.

When the torque current It detected by the torque current detection circuit 15 is lower than the set level Ls,
Each movable contact c-fixed contact b of the relay switches 18 and 25
Since the interval is ON, the operating frequency F from the PI control circuit 16 is given to the V / f setting circuit 21. When the torque current It detected by the torque current detection circuit 15 exceeds the set level Ls, since the movable contact c and the fixed contact a of the relay switches 18 and 25 are turned on during the period of the excess, the PI control is performed. Operating frequency F from circuit 16
Is given to the V / f setting circuit 21 as the operating frequency F 'instead of the speed data R from the speed detector 23,
Instead of the voltage command value V from the voltage command circuit 19, the over-torque voltage command value Vo from the over-torque voltage command circuit 24 is PW
M control circuit 22.

Therefore, according to the second embodiment, the voltage level of the AC power supplied from the inverter main circuit 12 to the induction motor 4 is further lower than that of the first embodiment.
The torque current It of the induction motor 4 is further reduced, so that the induction motor 4 can be further suppressed from being in an overtorque state.

FIG. 6 shows a third embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and different parts will be described below. An initial over-torque detecting circuit 26 serving as an initial over-torque detecting means replaces the over-torque detecting circuit 17, and an input terminal thereof is connected to an output terminal of the torque current detecting circuit 15. The initial overtorque detection circuit 26 detects the detection signal only during a period from the start of the operation of the induction motor 4 until the value of the torque current It detected by the torque current detection circuit 15 first reaches a specified level (preset). The relay coil (not shown) is energized while the detection signal is being output. The relay switch 27 of a changeover switch type as a switching means always keeps the contact between the movable contact c and the fixed contact b turned on, and is movable while the relay coil of the initial over-torque detection circuit 26 is energized as described above. The connection between the contact c and the fixed contact a is turned on.

In the relay switch 27, the movable contact c is connected to the output terminal of the PI control circuit 16, and the fixed contact b is connected to each input terminal of the voltage command circuit 19 and the frequency command circuit 20. The contact a is connected to an initial frequency limit circuit 28 as an initial frequency limit means.
Is connected to the input terminal of When the operating frequency F is provided from the PI control circuit 16 as described later, the initial frequency limit circuit 28 compares the operating frequency F with a preset limit operating frequency, and determines that the operating frequency F has reached the limit operating frequency. When the frequency is lower than the frequency, the operating frequency F is output as it is, and when the operating frequency F exceeds the limit operating frequency, the limit operating frequency is output instead of the operating frequency F. The output terminal of the initial frequency limit circuit 28 is connected to the input terminals of the voltage command circuit 19 and the frequency command circuit 20.

The initial over-torque detection circuit 26
From the start of operation of the induction motor 4, the torque current detection circuit 15
The movable contact c− of the relay switch 27 only during a period until the value of the torque current It detected by
Since the area between the fixed contacts a is turned on, the operating frequency F from the PI control circuit 16 is given to the initial frequency limit circuit 28. The initial frequency limit circuit 28 compares the operating frequency F with the limit operating frequency, When F is equal to or lower than the limit operation frequency, the operation frequency F is output as it is, and when the operation frequency F exceeds the limit operation frequency, the limit operation frequency is output instead of the operation frequency F, and the V / f setting circuit 21 is output. To give to.

Therefore, according to the third embodiment, when the cable 2 between the reel winder 1 and the winch 6 is loose at the start of the operation of the induction motor 4, the induction motor 4
The rotation speed of the induction motor 4 is suppressed (limited) to a low speed, and unlike the related art, the induction motor 4 does not become a high speed, and the cable 2 pulls the reel 7 of the winch 6 rapidly, so that the induction motor 4 An over-torque state can be reliably prevented.

FIG. 7 shows a fourth embodiment of the present invention. The same parts as those in the first and third embodiments are denoted by the same reference numerals, and different parts will be described below. In the relay switch 27, the movable contact a is connected to the output terminal of the torque current detection circuit 15, and the fixed contact b is the (-) input terminal of the subtractor 16b in the PI control circuit 16 (the input terminal of the PI control circuit 16). The fixed terminal a is connected to an input terminal of a torque current amplifier circuit 29 as a torque current amplifier. In this case, the torque current amplification circuit 2
Reference numeral 9 is configured to amplify the torque current It from the torque current detection circuit 15 given as described later by several times and output an amplified torque current It '. The output terminal of the torque current amplifying circuit 29 is connected to the PI control circuit 16
Is connected to the input terminal of

Thus, the initial overtorque detection circuit 26
From the start of operation of the induction motor 4, the torque current detection circuit 15
The movable contact c− of the relay switch 27 only during a period until the value of the torque current It detected by
Since the portion between the fixed contacts a is turned on, the torque current detection circuit 1
5 is supplied to the torque current amplifying circuit 29, and the torque current amplifying circuit 29 amplifies the torque current It several times and provides the amplified torque current It 'to the input terminal of the PI control circuit 16 as an amplified torque current It'. Become.

Therefore, according to the fourth embodiment, when the cable 2 between the reel winder 1 and the winch 6 is loose at the start of the operation of the induction motor 4, the induction motor 4
Is amplified more than the actual value and is given to the PI control circuit 16, so that the PI control circuit 16
Operating frequency F that suppresses
The rotation speed of the induction motor 4 is suppressed to a low speed, and unlike the related art, the induction motor 4 does not become high speed, and the cable 2 pulls the reel 7 of the winch 6 rapidly, so that the induction motor 4 The torque state can be reliably prevented.

FIG. 8 shows a fifth embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals, and different parts will be described below. A tension detecting circuit 30 serving as a tension detecting means is used in place of the torque current detecting circuit 15, and is provided for the cable 2 between the reel 3 of the reel winder 1 and the reel 7 of the winch 6 (refer to FIG. 3). Tension T
The output terminal is connected to the input terminal of the PI control circuit 16. The input terminal of the over-tension detecting circuit 31 serving as the over-tension detecting means is connected to the output terminal of the tension detecting circuit 30.
When the value of the tension Tn detected by 0 exceeds the set level, a detection signal is output during the period in which the tension Tn exceeds the set level, and the movable contact c and the fixed contact a of the relay switch 18 are turned on based on the detection signal. .

Thus, the tension of the cable 2 is proportional to the torque of the induction motor 4, and the torque of the induction motor 4 is proportional to (torque current × field current) of the induction motor 4. In this case, the field current of the induction motor 4 is constant by the V / f constant control by the V / f setting circuit 21. Therefore, even if the tension detecting circuit 30 and the over-tension detecting circuit 31 are used instead of the torque current detecting circuit 15 and the over-torque detecting circuit 17, the same effects as those of the first embodiment can be obtained.

The present invention is not limited to the embodiment described above and shown in the drawings, and the following modifications and extensions are possible. In the first to fifth embodiments, the relay switches 18, 25, 27 are shown as the switching means, but analog switches may be used instead. 1 to 4
In the first embodiment shown in (1), means for reducing the speed data R of the speed detector 23 may be provided. In the second embodiment shown in FIG. 5, the over-torque voltage command value Vo of the over-torque voltage command circuit 24 is
5 may be varied in accordance with the level of the torque current It detected by the control circuit 5. In the fourth embodiment shown in FIG. 7, the torque command generator 16a in the PI control circuit 16
May be reduced by the initial over-torque detection circuit 26. In addition, as a cord,
Instead of the cable 2, a rope, a wire, a chain, or the like may be used.

[0046]

Since the present invention is as described above,
The following effects can be obtained. According to the inverter device of the first aspect, when the torque current value of the induction motor detected by the torque current detection means exceeds a set level, the induction motor from the speed detection means instead of the operation frequency from the proportional-integral control means. Is supplied to the voltage / frequency setting means as the operating frequency. Since the speed data from the speed detection means does not include slip information for the induction motor, the voltage / frequency setting means Slip information is not given,
Accordingly, overtorque of the induction motor can be suppressed, and accordingly, damage to the cable, the mating machine, and the like can be prevented.

According to the inverter device of the second aspect,
When the torque current value detected by the torque current detecting means exceeds the set level, the speed data from the speed detecting means is supplied to the voltage / frequency setting means as the operating frequency instead of the operating frequency from the proportional-integral control means. At the same time, an overtorque voltage command value lower than the voltage command value from the voltage / frequency setting means is given to the driving means instead of the voltage command value from the voltage / frequency setting means. Can be further suppressed.

According to the inverter device of the third aspect,
An operating frequency in which the operating frequency from the proportional-integral control means is limited to a low speed by the initial frequency limiting means only during a period from the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches a specified level. Is applied to the voltage / frequency setting means, so that in the initial operation of the induction motor, even if the cable is loosened, it is prevented from being pulled sharply, and therefore, the excessive torque in the initial operation of the induction motor is reliably suppressed. be able to.

According to the inverter device of the fourth aspect,
The torque current value detected by the torque current detecting means is amplified by the torque current amplifying means only during a period from the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches a specified level. Since it is provided to the integral control means, in the initial stage of operation of the induction motor, even if the cable is loose, it is prevented from being pulled sharply, and therefore, the same effect as in claim 3 can be obtained.

According to the inverter device of the fifth aspect,
When the tension value of the cable detected by the tension detecting means exceeds a set level, speed data from the speed detecting means is supplied to the voltage / frequency setting means as the operating frequency instead of the operating frequency from the proportional-integral control means. Therefore, the same effect as the first aspect can be obtained.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a proportional-integral control circuit.

FIG. 3 is a diagram showing a schematic configuration of a reel winder and a winch.

FIG. 4 is a timing chart for explaining the operation.

FIG. 5 is a view corresponding to FIG. 1 showing a second embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 1, showing a third embodiment of the present invention.

FIG. 7 is a view corresponding to FIG. 2, showing a fourth embodiment of the present invention;

FIG. 8 is a view corresponding to FIG. 1, showing a fifth embodiment of the present invention.

[Explanation of symbols]

In the drawing, 1 is a reel winding machine, 2 is a cable (cord), 4
Is an induction motor, 6 is a winch (other machine), 8 is an inverter device, 12 is an inverter main circuit, 13 and 14 are current transformers, 15 is a torque current detection circuit (torque current detection means), and 16 is a proportional integral control circuit. (Proportional integral control means),
17 is an overtorque detection circuit (overtorque detection means), 18 is a relay switch (switching means), 21 is a voltage / frequency setting circuit (voltage / frequency setting means), 22 is a PWM control circuit (driving means), and 23 is a speed. Detector (speed detection means), 2
4 is an overtorque voltage command circuit (overtorque voltage command means),
25 is a relay switch (switching means), 26 is an initial overtorque detection circuit (initial overtorque detection means), 27 is a relay switch (switching means), 28 is an initial frequency limit circuit (initial frequency limit means), and 29 is a torque current. Amplifying circuit (torque current amplifying means), 30 is a tension detecting circuit (tension detecting means), 31 is an over tension detecting circuit (over tension detecting means)
Is shown.

Claims (5)

[Claims] 1. An inverter main circuit for driving an induction motor for winding and rewinding a cable, torque current detection means for detecting a torque current of the induction motor, and a torque current detected by the torque current detection means. Proportional / integral control means for obtaining an operating frequency from the value by proportional / integral control; voltage / frequency setting means for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means; Drive means for controlling the inverter main circuit based on a frequency command value and a voltage command value from a frequency setting means; speed detecting means for detecting the speed of the induction motor; and a torque current value detected by the torque current detecting means. Over-torque detecting means for outputting a detection signal only during a period when the signal exceeds the set level; Period during which a force,
A switching means for switching so as to give speed data from the speed detecting means as an operating frequency to the voltage / frequency setting means instead of the operating frequency from the proportional-integral control means. 2. An inverter main circuit for driving an induction motor for winding and rewinding a cable, torque current detection means for detecting a torque current of the induction motor, and a torque current detected by the torque current detection means. Proportional / integral control means for obtaining an operating frequency from the value by proportional / integral control; voltage / frequency setting means for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means; Drive means for controlling the inverter main circuit based on a frequency command value and a voltage command value from a frequency / frequency setting means; speed detection means for detecting a speed of the induction motor; and a voltage command value from the voltage / frequency setting means. Over-torque voltage command means for outputting a lower over-torque voltage command value, and a torque current value detected by the torque current detecting means. And over-torque detection means only outputs a detection signal periods exceeds a set level, the period during which the over-torque detection means is outputting a detection signal,
While switching so as to give the speed / speed data from the speed detecting means as the operating frequency to the voltage / frequency setting means instead of the operating frequency from the proportional integral control means,
A switching means for switching so as to supply an over-torque voltage command value from the over-torque voltage command means to the drive means instead of the voltage command value from the voltage / frequency setting means. 3. An inverter main circuit for driving an induction motor for winding and rewinding the cable, torque current detection means for detecting a torque current of the induction motor, and a torque current detected by the torque current detection means. Proportional / integral control means for obtaining an operating frequency from the value by proportional / integral control; voltage / frequency setting means for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means; A drive unit for controlling the inverter main circuit based on a frequency command value and a voltage command value from a / frequency setting unit; an initial frequency limit unit for limiting an operation frequency from the proportional-integral control unit to a low speed; From the start of the operation of the induction motor to the time when the torque current value detected by the torque current detecting means first reaches a specified level. Initial over-torque detecting means for outputting a detection signal only during the period of; and, during the period when the initial over-torque detecting means detection signal is being output, the operating frequency from the proportional-integral control means via the initial frequency limiting means. Switching means for switching to give to the frequency setting means. 4. An inverter main circuit for driving an induction motor for winding and rewinding the cable, torque current detection means for detecting a torque current of the induction motor, and a torque current detected by the torque current detection means. Proportional / integral control means for obtaining an operating frequency from the value by proportional / integral control; voltage / frequency setting means for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means; Drive means for controlling the inverter main circuit based on a frequency command value and a voltage command value from a / frequency setting means; a torque current amplifying means for amplifying a torque current value detected by the torque current detecting means; This is the period from the start of operation of the motor until the torque current value detected by the torque current detecting means first reaches a specified level. An initial over-torque detecting means for outputting a detection signal, and a torque current value detected by the torque current detecting means during the period when the initial over-torque detecting means outputs the detection signal. A switching means for switching so as to give to the integration control means. 5. An inverter main circuit for driving an induction motor for winding and rewinding a cable, tension detecting means for detecting the tension of the cable, and a proportional integral from a tension value detected by the tension detecting means. Proportional / integral control means for obtaining an operating frequency by control; voltage / frequency setting means for outputting a frequency command value and a voltage command value of the induction motor based on the operating frequency from the proportional / integral control means; A drive unit that controls the inverter main circuit based on a frequency command value and a voltage command value from a speed controller, a speed detector that detects a speed of the induction motor, and a tension value detected by the tension detector exceeds a set level. Over-tension detecting means for outputting a detection signal only during a period of time during which the over-tension detecting means outputs a detection signal. Inverter formed by and a switching means for switching so giving to the voltage / frequency setting means the speed data as the operation frequency from the speed detecting means instead of the frequency.