JP2001103777A - Electric motor control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric motor control device that suppresses the occurrence of an excessive offset between a speed reference and a speed signal in fluctuation of a load. SOLUTION: This control device is provided with a current-control loop with a current-limiting circuit as a minor loop against a speed-control loop to control the speed of an electric motor 2. When receiving a current-limiting signal generated by a current-limiting circuit 11 as the load of the electric motor 2 increases while an electric motor speed reference signal rises in the speed controlling loop, and a signal for detecting the state that the speed of the electric motor 2 given from a reset signal generating part 30 is unable to follow the electric motor speed reference signal, this device holds and outputs the electric motor speed reference signal at the time when the current-limiting signal is generated as the replacement of the original reference signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for controlling the speed of an electric motor by providing a current control loop with a current limiting circuit as a minor loop with respect to a speed control loop. The present invention relates to a control device suitable for application to a driving motor system.

[0002]

2. Description of the Related Art FIG. 7 shows an example of this type of steel strip rolling equipment, in which a material to be rolled 40 is conveyed by a group of conveying rolls 41 from an upstream side, rolled by rolling rolls 42, and conveyed to a downstream side. It is transported by the roll group 43. The rolling roll 42 is driven by an electric motor 45 whose speed is controlled by a control device 44. The transport rolls 41 and 43 include control devices 46 and 47, respectively.
Are driven by electric motors 48 and 49 whose speeds are controlled by.

[0003] Rolling roll 4 in such a steel strip rolling plant
As a control device of the electric motor 45 for driving the motor 2 as shown in FIG.
As shown in (1), there is a control device with a current control minor loop.

[0004] In FIG. 8, a motor 2 corresponds to a motor 45 for driving the rolling roll 42 in FIG. The speed SP_F of the electric motor 2 is detected by the speed detector 3.

The speed controller 7 compares the speed reference SP_R provided from the acceleration / deceleration rate circuit 6 with the detected speed SP_F, and outputs a torque reference ASPR_OUT. The torque limiter 8 having received the torque reference ASPR_OUT performs a limit process and outputs a final torque reference T_R.

The current reference section 9 receives the torque reference T_R, divides it by the magnetic flux, and obtains the torque current reference Iq_R
And a magnetic flux reference corresponding to the speed reference, and further outputs a magnetic flux current reference Id_R corresponding to the magnetic flux.

The current control unit 11 has a torque current reference Iq_
R and the torque current Iq detected via the current detector 10
_F, and the voltage reference Eq_R or the magnetic flux current reference Id_R is compared with the magnetic flux current Id_F detected via the current detector 10 to output the voltage reference Ed_R.

The voltage reference section 12 receives voltage references Eq_R and Ed_R, which are the results of current control, and θ, which is information on magnetic flux position, to obtain a three-phase voltage reference. This 3
The phase voltage reference is input to the PWM control unit 13 and outputs a gate pulse signal to the power converter 1 based on the voltage reference of each phase.

[0009]

The operation of the above-described conventional control device will be described with reference to an example of a steel strip rolling facility shown in FIG.
First, when the speed reference SP_R is given and the leading end of the material to be rolled 40 enters the rolling roll 42, the load on the electric motor 45 (2) increases. At this time, if the torque reference signal T_R is limited by the torque limiter 8 and the state where the speed of the electric motor 45 (2) cannot follow the speed reference SP_R continues, an excessive offset occurs between the speed reference SP_R and the speed signal SP_F. Will remain.

Here, when the tail end of the material to be rolled 40 comes off from the rolling roll 42, that is, when the trailing end is in a butt-removed state, the electric motor 4
The load of 5 (2) decreases rapidly. Then, the torque that has been output up to that time acts as acceleration torque, and the speed of the electric motor 45 (2) increases, and eventually the speed signal SP_F
Exceeds the speed reference SP_P, but the motor speed further increases due to a delay in the reset operation of the speed controller 7, and the motor terminal voltage also increases, so that overspeed protection or overvoltage protection may be activated. Such an operation directly stops the operation of the rolling equipment, and requires time and labor for setting the material to be rolled for the re-operation, and causes a decrease in the operation efficiency.

An object of the present invention is to provide a motor control device which suppresses the occurrence of an excessive offset between a speed reference and a speed signal due to a load change.

[0012]

According to another aspect of the present invention, a current control loop with a current limiting circuit is provided as a minor loop with respect to a speed control loop to reduce the speed of the motor. In the controlling device, the first motor speed reference signal in the speed control loop increases while the load of the motor increases while the current limiting circuit generates a current limiting signal, and the speed of the motor is controlled by the first motor speed reference signal. A switching means for switching from the first motor speed reference signal to the second motor speed reference signal when a signal for detecting a state that cannot follow the motor speed reference signal is input.

According to the first aspect of the present invention,
While the first motor speed reference signal is rising, when a load on the motor increases and a current limit occurs, a state where the motor speed cannot follow the first motor speed reference signal is detected.
By switching to the larger second motor speed reference signal instead of the first motor speed reference signal, the speed control loop can be prevented from having an excessive offset with respect to the speed reference, Even when the load suddenly decreases, it is possible to prevent the motor speed and the motor terminal voltage from increasing due to the reset of the speed control circuit.

According to another aspect of the present invention, the above object is achieved.
The invention according to the present invention provides a current control loop with a current limiting circuit as a minor loop with respect to the speed control loop, and in a device for controlling the speed of the motor, wherein the motor speed reference signal in the speed control loop increases the motor load reference signal. When a current limit signal generated from the current limit circuit by increasing and a signal for detecting a state where the speed of the motor cannot follow the motor speed reference signal are input,
Switching means for holding and outputting the motor speed reference signal when the current limit signal is generated, instead of the motor speed reference signal, is provided.

According to the second aspect of the present invention,
While the initial motor speed reference signal is rising, when the load on the motor increases and a current limit occurs, a state in which the motor speed cannot follow the motor speed reference signal is detected, and instead of the initial motor speed reference signal, By switching to the motor speed reference signal that holds the motor speed reference signal, the speed control loop can be prevented from having an excessive offset with respect to the speed reference, even when the load of the motor is rapidly reduced. It is possible to prevent the motor speed and the motor terminal voltage from increasing due to the reset of the speed control circuit.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a motor control device according to the present invention will be described below with reference to FIGS.

The control device according to the first embodiment is different from the conventional control device shown in FIG. 8 in that a hold circuit 14 composed of an RS flip-flop and a motor speed as switching means for switching the motor speed reference signal are provided. Signal generation section 30 for generating a signal (reset signal) for detecting the continuation of a state in which the state cannot follow the initial motor speed reference signal
And an acceleration / deceleration rate circuit 6 'different from that of FIG.
Is provided. The acceleration / deceleration rate circuit 6 'outputs a second speed reference SP_REF2 which holds the rise of the first speed reference SP_REF1 in response to the acceleration holding signal CHG from the hold circuit 14.

The hold circuit 14 includes a torque limit signal C / L output from the torque limiter 8 when the torque reference signal T_R is limited by the torque limiter 8;
Also, a reset signal generated from the reset signal generator 30 is input. Hold circuit 14 receiving both signals
Outputs an acceleration holding signal CHG to the acceleration / deceleration rate circuit 6, and the acceleration / deceleration rate circuit 6 outputs the first speed reference SP_R
Second speed reference SP_RE holding the rise of EF1
Output F2.

Here, the reset signal generating unit 30 is replaced with the one shown in FIG.
This will be described in detail. After the torque limit 8 is released, the reset signal generator 30 detects a signal -C / L_T that is turned on after a timer from the timer circuit 18 and the presence or absence of a load on the electric motor 2 input from outside the control device. A load-off signal -LR1 of the load relay signal LR1, a load-off signal -LR2 output from the internal load relay circuit 17 operating according to the level of the torque reference T_R,
The speed reference lowering signal DEC detected by the acceleration / deceleration rate circuit 6 that the first speed reference SP_REF1 has dropped is compared with the speed reference SP_R and the speed signal SP_F of the electric motor 2, and the deviation is smaller than a set value. Offset detector 19 for detecting that the speed suppression of the electric motor 2 is completed by the
And the output OS_CMP is input to the OR circuit 20, and its output is used as a reset signal of the hold circuit 14. Here, reference numerals 31, 32 and 33 are inversion circuits.

FIGS. 1 and 2 show the operation of the control device of this embodiment.
First, as shown in FIG. 3, after the rising first speed reference SP_REF1 is input to the acceleration / deceleration rate circuit 6, the speed control unit 7 outputs the speed signal SP_F. As a result, a torque reference ASPR_OUT is output, a limit process is performed by the torque limiter 8, and a final torque reference T_R is output.

Here, the load on the electric motor 2 increases due to the tip of the material to be rolled 40 shown in FIG.
Then, the torque reference signal T_R is limited by the torque limiter 8 and the torque limiter 8
/ L is output. The hold circuit 14 having received the torque limit signal C / L outputs an acceleration holding signal CHG to the acceleration / deceleration rate circuit 6 ', and the acceleration / deceleration rate circuit 6', as shown in FIG. The second speed reference SP_REF2 holding the rise of the reference SP_REF1 is output.

As a result, the torque reference signal T_R is limited, and the speed of the motor 2 is reduced to the first speed reference SP_RE.
Even if the vehicle cannot follow F1, the second speed reference SP_R
The speed controller 7 does not have an excessive offset with respect to EF2. In FIG. 3, the acceleration / deceleration rate circuit 6 '
Outputs the second speed reference SP_REF2 holding the rise of the first speed reference SP_REF1, so that the torque current value becomes equal to or less than the current limit.

Further, when the control device of the present embodiment is applied to the rolling equipment shown in FIG. 7, even if the load on the electric motor 2 suddenly decreases due to the loss of the material to be rolled 40, the speed reference is used. On the other hand, since the speed control loop does not have an excessive offset, the increase in the motor speed and the motor terminal voltage is suppressed, the operation stop of the rolling equipment is prevented, and the operation efficiency does not decrease.

Further, the control device of the present embodiment has a configuration in which the hold circuit 14 and the reset signal generation unit 30 are substantially provided in the conventional control device, so that the modification of the existing control device is minimized. , And the operating efficiency of the rolling equipment can be improved in a cost-effective manner.

Next, a control device according to a second embodiment of the present invention will be described with reference to FIG.

In FIG. 4, the same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. The control device according to the second embodiment is different from the conventional control device shown in FIG. 8 as switching means for switching the motor speed reference signal.
A hold circuit 14 comprising an RS flip-flop; a reset signal generator 30 for generating a signal (reset signal) for detecting a continuation of a state where the motor speed cannot follow the initial motor speed reference signal; In response to the reference switching signal CHG, the speed reference SP_R
And a speed reference switching circuit 15 for switching to a second speed reference SP_REF2 of a level at which an assumed load can be driven, which is set in advance in the apparatus.

The operation of this embodiment will be described. In FIG. 4, after the first speed reference SP_REF1 is input to the acceleration / deceleration rate circuit 6, the speed control unit 7 controls the speed signal S_REF1.
Compared with P_F, a torque reference ASPR_OUT is output, a limit process is performed by the torque limiter 8, and a final torque reference T_R is output.

When the load on the motor 2 increases and the torque reference signal T_R is limited by the torque limiter 8, the torque limiter 8 outputs a torque limit signal C / L, and the hold circuit 14 sends the speed reference switching circuit 15 The reference switching signal CHG is output. The speed reference switching circuit 15 switches the speed reference SP_R to a second speed reference SP_REF2 which is set in advance in the apparatus and has a level at which an assumed load can be driven, based on the speed reference switching signal CHG.

As a result, similarly to the first embodiment, the torque reference signal T_R is limited and the speed of the electric motor 2 is reduced to the first speed.
The speed controller 7 does not have an excessive offset with respect to the second speed reference SP_REF2 even when the speed controller 7 cannot follow the speed reference SP_REF1.

Therefore, when the control device of the present embodiment is applied to the rolling equipment shown in FIG. 7 similarly to the first embodiment, the load on the electric motor 2 suddenly decreases even if the material to be rolled 40 becomes loose. However, since the speed control loop does not have an excessive offset with respect to the speed reference, the increase in the motor speed and the motor terminal voltage is suppressed, the operation stop of the rolling equipment is prevented, and the operation efficiency does not decrease. .

Next, a control device according to a third embodiment of the present invention will be described with reference to FIG.

In FIG. 5, the same parts as those in FIGS. 1 and 4 are denoted by the same reference numerals, and description thereof will be omitted. The control device according to the third embodiment is different from the control device according to the second embodiment in the manner in which the second speed reference SP_REF2 is provided. That is, in the present embodiment, the electric motor 2 when the speed reference switching signal CHG is turned on by the speed signal memory circuit 21 is set.
Is stored and a second speed reference SP_REF2 is generated based on the stored value.

The operation of this embodiment will be described. In FIG. 5, after the first speed reference SP_REF1 is input to the acceleration / deceleration rate circuit 6, the speed control unit 7 controls the speed signal S_REF1.
Compared with P_F, a torque reference ASPR_OUT is output, a limit process is performed by the torque limiter 8, and a final torque reference T_R is output.

When the load on the motor 2 increases and the torque reference signal T_R is limited by the torque limiter 8, the torque limiter 8 outputs a torque limit signal C / L, and the hold circuit 14 sends the speed reference switching circuit 15 The reference switching signal CHG is output. Speed signal memory circuit 2
1 stores the speed signal SP_F of the electric motor 2 when the speed reference switching signal CHG is turned on, and stores the second speed reference S
Outputs P_REF2. Speed reference switching circuit 15
Is the speed reference SP by the speed reference switching signal CHG.
_R is switched to a second speed reference SP_REF2.

As a result, the torque reference signal T_R is limited, and the speed of the motor 2 is reduced to the first speed reference SP_REF.
1, the second speed reference SP_RE
The speed controller 7 does not have an excessive offset with respect to F2.

When the control device of this embodiment is applied to the rolling equipment shown in FIG. 7 as in the first and second embodiments,
Even if the load on the motor 2 suddenly decreases due to the bottom of the material to be rolled 40, the speed control loop does not have an excessive offset with respect to the speed reference, so that the motor speed and the motor terminal voltage are not changed. The rise is suppressed, the operation stop of the rolling equipment is prevented, and the operation efficiency does not decrease.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

In FIG. 6, the same parts as those in FIGS. 1, 4 and 5 are denoted by the same reference numerals, and description thereof will be omitted. The control device according to the fourth embodiment includes a second speed reference SP_RE.
The application form of F2 is different from the control devices of the second and third embodiments. That is, in the present embodiment, the second speed reference SP_REF2 that is switched and output from the speed reference switching circuit 15 is generated in the speed reference calculation circuit 16 by the speed reference switching signal CHG. Switch.

The speed reference calculation circuit 16 outputs a second speed reference obtained by adding a preset bias amount SP_BIAS to the speed signal SP_F of the electric motor 2 in accordance with the polarity of the speed signal SP_F.

The operation of the present embodiment will be described. In FIG. 6, after the first speed reference SP_REF1 is input to the acceleration / deceleration rate circuit 6, the speed control unit 7 controls the speed signal S_REF1.
Compared with P_F, a torque reference ASPR_OUT is output, a limit process is performed by the torque limiter 8, and a final torque reference T_R is output.

When the load on the motor 2 increases and the torque reference signal T_R is limited by the torque limiter 8, the torque limiter 8 outputs a torque limit signal C / L.

The hold circuit 14 outputs a speed reference switching signal CHG to the speed reference switching circuit 15.

The speed reference calculation circuit 16 outputs a second speed reference obtained by adding a preset bias amount SP_BIAS to the speed signal SP_F of the electric motor 2 in accordance with the polarity of the speed signal SP_F.

The speed reference switching circuit 15 switches the speed reference SP_R to the second speed reference SP_REF2 according to the speed reference switching signal CHG.

Thus, the torque reference signal T_R is limited, and the speed of the electric motor 2 is reduced to the first speed reference SP_REF.
1, the second speed reference SP_RE
The speed controller 7 does not have an excessive offset with respect to F2.

When the control device of this embodiment is applied to the rolling equipment shown in FIG. 7 as in the first to third embodiments,
Even if the load on the motor 2 suddenly decreases due to the bottom of the material to be rolled 40, the speed control loop does not have an excessive offset with respect to the speed reference, so that the motor speed and the motor terminal voltage are not changed. The rise is suppressed, the operation stop of the rolling equipment is prevented, and the operation efficiency does not decrease.

[0047]

As described above, according to the present invention, even when the current reference is limited by the current limiting circuit and the speed of the motor cannot follow the speed reference, the speed control loop has an excessive offset with respect to the speed reference. By eliminating
It is possible to provide a motor control device in which the motor speed and the motor terminal voltage are prevented from increasing due to the reset of the speed control circuit when the load of the motor suddenly decreases.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electric motor control device according to a first embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of a reset signal generation unit in FIG. 1;

FIG. 3 is a waveform chart showing the operation of the embodiment.

FIG. 4 is a configuration diagram of a motor control device according to a second embodiment of the present invention.

FIG. 5 is a configuration diagram of a motor control device according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram of a motor control device according to a fourth embodiment of the present invention.

FIG. 7 is a configuration diagram of a steel strip rolling facility.

FIG. 8 is a configuration diagram of a conventional motor control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power converter 2 ... Electric motor 3 ... Speed detector 5 ... Speed signal calculator 6 ... Rate circuit 7 ... Speed control circuit 8 ... Torque limiter 9 ... Current reference circuit 10 ... Current detection circuit 11 ... Current control circuit 12 ... Voltage Reference circuit 13 ... PWM circuit 14 ... Hold circuit 15 ... Speed reference switching circuit 16 ... Speed reference calculation circuit 17 ... Internal load relay 18 ... Timer circuit 19 ... Offset detector 20 ... Logical OR circuit 21 ... Memory circuit 30 ... Reset signal generation Department

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tadamitsu Yoshikawa 1 Toshiba-cho, Fuchu-shi, Tokyo F-term in the Fuchu Plant, Toshiba Corporation 5H550 AA03 BB08 DD01 EE03 FF03 GG03 GG05 GG08 JJ06 JJ17 JJ18 LL01 LL22 LL32 LL48 LL48 MM03 MM05

Claims (2)

[Claims] 1. An apparatus for controlling a speed of a motor, wherein a current control loop with a current limiting circuit is provided as a minor loop with respect to a speed control loop, wherein the motor is controlled while a first motor speed reference signal in the speed control loop is rising. When a current limit signal generated from the current limit circuit due to an increase in the load of the motor and a signal for detecting a state where the speed of the motor cannot follow the first motor speed reference signal are input, the first A control device for a motor, comprising switching means for switching from a motor speed reference signal to a second motor speed reference signal. 2. An apparatus for controlling a speed of a motor, wherein a current control loop with a current limiting circuit is provided as a minor loop with respect to a speed control loop, wherein the motor speed reference signal in the speed control loop is increased while the load of the motor is reduced. When a current limit signal generated from the current limit circuit by increasing and a signal for detecting a state in which the speed of the motor cannot follow the motor speed reference signal are input, instead of the motor speed reference signal, A control device for a motor, comprising switching means for holding and outputting the motor speed reference signal when a current limit signal is generated.