JPS6031433Y2 - Electric motor speed control device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control device for an electric motor that drives a plurality of rotating bodies at different speeds.

For example, in the manufacturing process of continuous long objects such as paper, rubber, and plastics, a method is often adopted in which the long objects are processed into an appropriate thickness by using the tension caused by the difference in the peripheral speed of rotating bodies. ing.

In such a manufacturing process, it is necessary to control a large number of rotating bodies (for example, rollers) so that they rotate at different peripheral speeds.

FIG. 1 is an explanatory diagram showing the relationship between the position of a rotating body and its peripheral speed.

As shown in FIG. 1, the peripheral speed of the rotating body at the sending point is low, and the peripheral speed of the rotating body at the winding point is set in advance to be high.

This preset speed difference is called a standard speed difference, and this speed difference is used to apply tension to the long object and process it.

In the actual manufacturing process, once the standard speed difference is set as described above, it is necessary to make fine adjustments by changing the peripheral speed of each rotating body. It is called.

Generally, an analog control system and a digital control system are used together in a control device that controls the electric motors that respectively drive each rotating body.

Conventional digital control systems calculate the standard speed difference as a percentage of a certain virtual main speed reference, so the range of variable speed difference is narrow, and when the diameter of the rotating body decreases, the motor may overdrive. It had drawbacks such as being rotated at high speed.

FIG. 2 is a block diagram showing a conventional motor speed control device of this type that is provided for each rotating body and controls the rotating body.

Further, FIG. 4 shows an example of a conventional speed setting method, in which the curve shows the speed reference signal and the shaded area shows the variable speed difference setting range.

In Fig. 2, 1 is a main speed reference setting circuit consisting of a potentiometer, 2 is a speed difference setting circuit consisting of a potentiometer, 3 is a variable resistor, 4 is an analog-to-digital converter, 5 is a speed reference setting circuit, and 6 is a speed deviation circuit. , 7 is a digital analog converter, 8 is a rotating body diameter setting device, 9 is a sampling time setting circuit, 10 is a speed measurement circuit, 11 is a motor drive control circuit, 12 is an electric motor, 13 is a gear, 14
15 is a rotating body, 15 is a speed detector, and 16 is a pulse generator.

In addition, VMrO is the total voltage of the main speed reference setting circuit 1, ME
is the ratio of the output voltage to the total voltage of the main speed reference setting circuit 1, ■2 is the virtual main speed reference which is the output of the main speed reference setting circuit 1, SE is the ratio of the output voltage to the total voltage of the speed difference setting circuit 2, VREp is a digital speed reference signal, VpB is a speed feedback signal indicating the digital peripheral speed of the rotating body 14, and VERR is a digital speed deviation signal that is the difference between the speed reference signal ■R and the speed feedback signal VFI3. , AREF is an analog value speed reference signal consisting of the sum of the total voltage of the speed difference setting circuit 2 and the voltage of the variable resistor 3;
FB is a feedback signal consisting of an analog rotation speed Q of the rotating body 14, and AERR is an analog speed deviation signal that is the difference between the speed reference signal AREP and the speed feedback signal ApB.

In the speed control device shown in FIG. 2, only the analog control system is operated when the electric motor 12 is started, and the analog control system and the digital control system are operated in combination during normal operation.

The digital control system is used to control the electric motor 12 with high precision.

Next, the operation of the speed control device shown in FIG. 2 will be explained.

First, each rotating body 14 is set to a peripheral speed having a standard speed difference as shown in FIG. 1 with respect to the peripheral speed of its reference point.

This standard speed difference is obtained by setting the gear ratio of the gear 13 connecting the rotating body 14 and the electric motor 12 to an appropriate value.

After that, the speed reference signal ARE of all rotating bodies 14 is
By setting F to the same value, the electric motors 12 provided on each rotating body 14 are rotated at the same speed using an analog control system.

Speed reference signal ARI! F is obtained by adjusting the output of the main speed reference setting circuit 1 using the speed difference setting circuit 2 and the variable resistor 3.

At this time, the speed reference signals AREF of each electric motor 12 are made equal, but the ratio sE of the output of the speed difference setting circuit 2 to the total voltage needs to be a different value for each electric motor 12.

This is because the analog control system is configured to detect and control the rotational speed of each electric motor 12, but the digital control system is configured to detect and control the peripheral speed of each rotating body 14. This is because the speed reference signal VREF needs to have a different value for each rotating body 14 in accordance with the peripheral speed of each rotating body 14, that is, the standard speed difference.

Ratio S of the output of the speed difference setting circuit 2.

By setting V to a different value for each rotating body 14, the speed reference signal VREP for each rotating body 14 can be set to a different value as described above.

The variable resistor 3 is adjusted to equalize the speed reference signals A of the rotating bodies 14 when the value of the output ratio SE of the speed difference setting circuit 2 is different for each rotating body 14.

The operation of the digital control system of the speed control device shown in FIG. 2 will be explained below.

Output V of main speed setting device 1 obtained by dividing voltage VMTOF
yr6p X ME is converted into a digital virtual main speed reference signal vM by the analog-to-digital converter 4 and supplied to the speed reference setting circuit 5.

The speed reference setting circuit 5 generates speed reference signals Rf, . . . p for the digital control system according to the following equation.

VREF = VM (1stir)
---(t) 0<a<1 0≦SE≦1 Here, a is a constant indicating the maximum speed difference setting value.

As is clear from equation (1), in the digital control system of the conventional speed control device, the speed reference signal Vya of each rotating body 14 is calculated from the virtual main speed reference (8).

I was getting .

Therefore, the ratio SE of the output of the speed difference setting circuit 2 is calculated by the formula (1
) is set so that the speed reference signal (R) of each rotating body calculated from the equation (2) is set to a value corresponding to the standard speed difference determined by the gear 13.

On the other hand, the speed measuring circuit 10 detects the actual peripheral speed Q of the rotating body 14 and outputs a speed feedback signal VFB.

The speed deviation circuit 6 calculates the difference between the speed reference signal VREF and the speed feedback signal VPB and outputs a speed deviation signal VERvt.

Speed deviation signal ■ of speed deviation circuit 6.

RR is converted into an analog signal by the digital-to-analog converter 7, and then added to the speed deviation signal AERR and applied to the motor drive control circuit 11.

However, in order to control the speed of the electric motor 12 with high precision, for example, if the speed deviation signal A8RR of the analog control system is IV, the speed deviation signal ① of the digital control system.

RR is 0. It is reduced to IV level. Speed deviation signal VERR
Since is an intermittent signal, the speed deviation signal Ao.

If the ratio is too large, smooth rotation of the electric motor 12 will be hindered.

As mentioned above, each rotating body 14 is controlled by adding a standard speed difference to its peripheral speed, but in the process of processing a long object, once the standard speed difference is set, the speed is further adjusted. There is a need to.

In FIG. 2, the speed of the rotating body 14 is adjusted by changing the output ratio SE of the speed difference setting circuit 2.

When the value of the ratio SE changes, the speed reference signal AR and the speed reference signal VREF change, so the speed of the rotating body 14 also changes.

The pulse generator 16 generates a fixed number of pulses per rotation of the electric motor 12.

The rotating body diameter setting device 8 outputs the diameter D (set value) of the rotating body 14 to the sampling time setting circuit 9.

The sampling time setting circuit 9 sets a sampling time ΔT calculated by the following equation.

ΔT=Ki...(2) Here, D
is the diameter of the rotating body 14, R is the gear ratio, and K is the proportionality constant.

On the other hand, since the number of rotations N of the electric motor 12 is proportional to the number of pulses per unit time, the speed measuring circuit 10 calculates the number of pulses generated by the pulse generator 16 within the sampling time ΔT. A speed feedback signal VpB related to the peripheral speed Q of is obtained, and the speed deviation circuit 6
supply to.

Note that the peripheral speed Q of the rotating body 14 is determined by the following equation.

fDN...(3) Q=R Here, N is the number of revolutions of the electric motor 12 per unit time.

As is clear from equations (2) and (3), the rotating body 14
The peripheral speed Q of is proportional to the product NΔT of the sampling time ΔT and the rotation speed N of the electric motor 12.

By the way, when the diameter of the rotating body 14 is reduced in friction, the speed reference signal VREF of the digital control system does not change, but the speed feedback signal Vpa decreases, so the speed deviation signal VERR increases by the amount of decrease in the speed feedback signal VPB.

If this happens, the electric motor 12 will be rotated at a considerably higher speed than the rated speed, which will shorten its lifespan, which is undesirable.

In addition, in order to change the gear ratio of the gear 13 for each rotary body 14 and add a standard speed difference to the peripheral speed, when calculating the digital speed reference signal V□2 from equation (1) using the virtual main speed reference vM. , it was necessary to set the output ratio S5 of the speed difference setting device 2 to a different value for each rotating body 14.

When adjusting the peripheral speed Q of the rotating body 14, the ratio SE value once set as described above is changed again.

Therefore, the adjustment range of the output ratio S of the speed difference setter 2 is narrowly limited, and in some cases, a situation may arise in which a sufficient variable speed difference cannot be obtained.

In other words, when rotating each rotating body 14 with a standard speed difference, the value of the ratio S of each rotating body 14 is, for example, 0.2.
~0.8.

However, in the case of the rotating body 14 where the ratio 85 is set to 0.2, the adjustment range of the value of the ratio S is only 0.2 degrees below, so it is inevitable that the peripheral speed Q of the rotating body 14 will be lower. This means that the variable adjustment range is narrowly limited.

As explained above, in conventional speed control devices, when the diameter of the rotating body decreases in friction, the speed feedback signal decreases in the digital control system, but the speed reference signal does not change, which has the disadvantage of causing overspeed operation of the motor. there were.

Furthermore, in conventional speed control devices, when setting the standard speed difference or adjusting the peripheral speed of the rotating body, the output ratio of the speed difference setting circuit was changed, so the adjustment range of the peripheral speed was narrow and limited. There was a drawback that could not be helped.

Normally, when machining continuous long objects, if the variable adjustment range of the peripheral speed of the rotating body that applies tension to the long objects is narrow, there is a risk that machining will not be possible. It was hoped that it would appear.

This idea was made in view of the above problems, and it is necessary to
Based on the speed reference signal of each main rotating body (hereinafter referred to as the main rotating body), the speed reference signal of the other subordinate rotating bodies (hereinafter referred to as the slave rotating body) is calculated and further adjusted. It is an object of the present invention to provide a speed control device that solves the above problems.

Hereinafter, a speed control device for an electric motor according to this invention will be explained based on the drawings.

FIG. 3 is a block diagram showing one embodiment of the speed control device for an electric motor according to the present invention for controlling one slave rotary body.

FIG. 5 shows an embodiment of the speed setting method according to this invention.

In FIG. 3, the same reference numerals as in FIG. 2 indicate the same parts.

Further, 17 is a standard speed difference setting circuit for setting a standard speed difference, and 18 is a variable speed difference setting circuit for adjusting the output of the standard speed difference setting circuit 17.

The sampling time ΔT is inputted to the standard speed difference setting circuit 17 from the sampling time setting circuit 9 .

The output V MToPX ME of the main speed reference setting circuit 1 is
It is converted into a signal VN by an analog-to-digital converter 4 as a speed reference signal for the main rotating body.

A sampling time ΔTN is also input to the standard speed difference setting circuit 17 from a control device similarly provided corresponding to the main rotating body (not shown), and the standard speed difference ■ is determined according to the following formula. Calculated and output as a set value.

△T VN x,,T,,"Vs"'(4)
As is clear from equations (2) and (3), the peripheral speed Q of the rotating body 14 is proportional to the product of the sampling time Δd and the rotational speed N of the electric motor 12.

Therefore, the ratio of sampling times ΔT/ΔTN in equation (4)
has the same value as the ratio of the peripheral speed Q of the main rotating body and the secondary rotating body 14.

The standard speed difference Vs becomes a speed reference signal VREF of the digital control system when rotating the rotating body 14.

In order to cope with the need to adjust the standard speed difference and the peripheral speed Q, the variable speed difference setting circuit 18
The standard speed difference Vs of the standard speed difference setting circuit 17 is adjusted according to the following equation to set the speed reference signal (R) of the digital control system.

VREF = VS (t b 1 SE)
...+5+0<b<1 0≦SE≦1 Here, b is a constant indicating the maximum speed difference setting value.

However, if no adjustment is required, set (1-b+SE) to “1”.
Make it ゛.

Further, adjustment of the speed reference signal VREF is obtained by changing the ratio SR, thereby widening its variable adjustment range.

In operation, assuming that the rotating body 14 is located between the reference point and the winding point shown in FIG. .

According to the input signal consisting of the sum of the signal based on
Drive 2.

Electric motor 12 is mechanically coupled to rotating body 14 via gear 13 to rotate it.

The rotational speed Q of the rotating body 14 is detected by a speed measuring circuit 10 connected to a speed detector 15 and a pulse generator 16, respectively.

The speed detector 15 converts the rotational speed Q into a feedback signal AFB.

The difference between the feedback signal ApB and the speed reference signal AREP output from the speed difference setting circuit 2 is calculated, and the difference is calculated between the feedback signal ApB and the speed deviation signal AE.
It becomes RR.

On the other hand, the speed measuring circuit 10 outputs pulses supplied from the pulse generator 16 and proportional to the rotational speed Q to the speed feedback signal VPB.
and input it to the speed deviation circuit 6.

The speed deviation circuit 6 generates a speed deviation signal ■ from the difference between the speed reference signal VREF output from the variable speed difference setting circuit 18 and the speed feedback signal ■FB.

RR is detected and supplied to a digital-to-analog converter 7 to convert it into a digital signal.

This digital signal is supplied as an input signal to the motor drive circuit 11 together with the speed deviation signal AERR as described above.

Therefore, the rotating body 14 is feedback-controlled by an analog control system including a speed detector 15 and a digital control system including a pulse generator 16, a speed measurement circuit 10, a speed deviation circuit 6, and a digital-to-analog converter 7. It is driven so that the deviation signals AERR and VERR are minimized.

In such an operation, the speed reference signal VREty sets the set value ■N according to equation (4), that is, based on the sampling time ΔTN set for the main rotating body at the reference point shown in FIG. This is a setting signal obtained by correcting by the standard speed setting circuit 17 and further correcting by the variable speed difference setting circuit 18 based on formula (5), that is, the arbitrarily adjusted ratio S5 and the maximum speed difference setting value S.

Therefore, when the sampling time ΔTN is changed, the speed reference signal V REP is changed, so that the rotational speed Q of the rotating body 14 can be controlled so as not to become excessive in response to the reduction in friction.

When rotating each rotating body 14 by multiplying the standard speed difference Vs by the peripheral speed Q of each control device, first, set b=0.5 for the variable speed difference setting circuit 18, and 5E=0 for the variable speed difference setting circuit 18.
Set to 5.

Thereafter, the peripheral speed Q of the rotating body 14 is determined by a ratio S for each control device.

Set the value in the range 0 to 1.

This allows the speed reference signals of all rotating bodies 14 to be adjusted by ±50
It can be changed within a range of %.

Since the speed control device for an electric motor according to this invention is configured as described above, it has the following superior effects compared to conventional speed control devices.

(a) Even if the diameter of the rotating body is reduced in friction, the motor will not be operated at overspeed.

(b) The setting range of the peripheral speed of the rotating body can be widened.

This idea controls the speed of multiple rotating bodies driven by electric motors and can be used to control paper, rubber, plastic, etc.

In the process of manufacturing continuous long objects, manufacturing efficiency can be significantly improved.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the installation point and peripheral speed of a rotating body used in the process of continuously manufacturing long objects; Fig. 2 is a block diagram showing an example of a conventional electric motor control device; 3
Figure 4 is a block diagram showing an example of a motor control device according to this invention, Figure 4 is a graph showing an example of a conventional speed setting method, and Figure 5 is a graph showing an example of a speed setting method according to this invention. be. 1 is a main speed reference setting circuit, 6 is a speed deviation circuit, 12 is an electric motor, 14 is a rotating body, 17 is a standard speed difference setting circuit, 18
is a variable speed difference setting circuit. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] Speed control of an electric motor that is controlled to reduce a speed deviation between a detected speed detected from a rotating body and a preset reference speed, and the reference speed is set in relation to the rotational speed of another rotating body. In the apparatus, a main speed standard setting circuit that sets a speed standard for an electric motor that drives a main rotating body installed at a reference point among the rotating bodies, and a main rotating body that provides a speed difference with respect to the speed of the main rotating body. A speed difference setting circuit for the secondary rotating bodies other than the main rotating body, calculates a ratio between the peripheral speed of the main rotating body and the peripheral speed of the secondary rotating body, and digitally calculates the product of this ratio and the speed reference signal of the main rotating body. a standard speed difference setting circuit, a variable speed difference setting circuit that digitally variably adjusts the output of the standard speed difference setting circuit from the ratio of the output of the speed difference setting circuit, a speed detector that detects the rotational speed of the electric motor;
A pulse generator for detecting the peripheral speed of the rotating body; a rotating body diameter setting device for setting the diameter of the rotating body; a sampling time setting circuit for digitally measuring the peripheral speed; a speed measuring circuit for calculating the peripheral speed of the rotating body; a speed deviation circuit that digitally calculates the deviation between the outputs of the speed setting circuit and the speed detection circuit; a speed deviation circuit that digitally calculates the deviation between the outputs of the variable speed difference setting circuit and the speed measurement circuit; A speed control device for an electric motor, characterized in that the electric motor is driven by a signal added to the electric motor.