JPH03173385A - Rotating speed controller for motor - Google Patents

Abstract

PURPOSE:To reduce wow and flutter during rotating by a method wherein the title device is provided with a means, deciding a first condition, in which the stability of a control system is high, or a second condition, in which the stability of the control system is low, based on the controlling value of phase difference at every predetermined timings, and another means, changing the controlling value with respect to the phase difference by a predetermined value under the first or second condition. CONSTITUTION:A control unit 14 controls a motor 10 so that the rotating speed coincides with a commanding speed based on a speed difference and a phase difference obtained by speed difference operating process and the operating process of phase difference between a speed command and a speed difference detecting signal. When a control system is judged that it is in second condition, in which the stability of the same system is low, a proportional control range determining value is decreased to increase the affection of a correcting voltage due to the phase difference. In a first condition, in which the stability of the control system is high, the proportional control range determining value is decreased to increase the affection of the correcting voltage. The tendency of the control based on the speed difference is increased in the first condition while the tendency of the control based on the phase difference is increased in the second condition.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a motor rotation speed control device, and in particular,
The present invention relates to a motor rotation speed control device that controls the rotation speed of a motor using a PWM signal.

<Background of the Invention> Some motor rotational speed control devices are controlled by PWM (pulse width modulation) signals.

Such a rotational speed control device is employed, for example, in a DC servo motor control device for driving an optical system in a document reading device such as a copying machine.

In a servo motor control device for driving an optical system, even if the motor load fluctuates due to changes in frictional resistance as the optical system moves, the servo motor can be kept at a constant speed with good follow-up ability, and the optical system can be controlled. It must be moved at a constant speed.

Conventionally, in order to maintain a servo motor at a constant speed, proportional control has been performed in which a PWM signal is obtained using a voltage proportional to the speed difference between a target speed and an actual detected speed.

However, in conventional proportional control, the acceleration when increasing the motor speed from the actual detected speed to the target speed changes depending on the size of the target speed, and the larger the target speed, the smaller the acceleration, and the longer it takes to reach the target speed. It gets longer,
There was a drawback that followability was not good.

Let me explain more specifically.

The equation of motion when voltage V is applied to the motor is generally expressed by the following equation.

375KT dt -V-Ra (10+TBL/KT) ・”
(1) becomes.

However, Ra: amateur resistance [Ω] KT: torque constant [kga+/A] KE: induced voltage constant [V/rpa+] lo: no-load current [A] GD2: moment of inertia due to load and motor [kg
m2] Position: sliding load [kgm] n: rotational speed [rpm].

Solving this for n, if n=Np at t-0, then E dn 375KT dt RaGD2 E becomes.

From this formula, when the sampling speed is N, the voltage V
By substituting Np-N and t-0, the acceleration a during the time when .

By the way, the speed obtained by sampling the target speed No.1 is N
1 If the difference is ΔN, then the acceleration a when ΔN-K (No -N) is applied to V- by normal proportional control is given by formula (4), where ΔN is applied to V- and N-No-ΔN. It is obtained by substituting into the following equation.

a-375KTKE aGD2 - (N-ΔN)1 -375KvKE aGD2 X ((K/KE + 1) ΔN-N.

E From this formula, even if ΔN is the same value, the target speed N. It can be seen that if No is large, the acceleration a is small, and if No is small, a becomes large.

Therefore, the applicant has proposed a method in which the speed difference between the commanded speed (target speed) and the actual detected speed is determined, the phase difference between the commanded speed and the detected speed is determined, and the speed control based on the speed difference is corrected using the phase difference. We have developed a device that can control motors with good followability.

According to that device, the voltage v to be output to the servo motor in order to make the rotation speed of the servo motor follow the command speed
O is the control voltage due to the speed difference ΔN.■1, the phase difference PHD
Assuming that the control voltage due to T is 2, it is expressed by the following equation.

VO-Vl±V2 (6) Here, between the phase difference PHDT and the control voltage V2, if the predetermined maximum value of the control voltage v2 is 2 max,
There is the following relationship.

(a> When the phase difference is smaller than one cycle (-1<PHDT<+1) V2-V2max -PHDT (b) When the phase difference is one cycle or more and the speed detection signal is ahead of the speed command signal (PHDT ≦-1) V2=-V2max (C) When the phase difference is one cycle or more and the speed detection signal lags behind the speed command signal (PHDT≧+1) V 2--4- V 2 ff1ax <Solved by the invention By the way, according to the control device developed by the applicant, the output voltage VO is the sum of the control voltage (1) due to the speed difference and the control voltage (2) due to the phase difference. When a speed fluctuation occurs, the rotation speed of the motor can be made to follow the command speed in a shorter time than when control is performed using only the control voltage V1 based on the speed difference.

However, on the other hand, if the ratio of the control voltage v2 based on the phase difference is large, the wow and flutter during rotation will become large and the rotation speed will be There is a problem that oscillation is likely to occur.

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotational speed control device that solves the above-mentioned problems, has good followability, and can reduce wow and flutter during motor rotation.

Means for Solving the Problem> This invention provides a speed difference control value based on the difference between the command speed and the detected speed, and a phase difference control value based on the phase difference between the speed command signal and the speed detection signal. is a motor rotation speed control device that performs feedback control of a motor, and determines whether the control system is in a relatively highly stable first state based on the output phase difference control value at each predetermined timing. or a determining means for determining whether the control system is in the second state with relatively low stability, and when the determining means determines that the control system is in the first state, the phase difference and control used to obtain the phase difference control value means for changing the relationship between the control value and the phase difference so that the control value is smaller by a predetermined value than the phase difference, and determining the phase difference control value when the control system is determined to be in the second state by the determining means. This is a motor rotational speed control device that includes means for changing the relationship between a phase difference used for this purpose and a control value so that the control value becomes larger than the phase difference by a predetermined value.

Furthermore, in the motor rotational speed control device, the determination means is configured to determine whether the control system is in 2 state is determined,
The present invention is characterized in that it is determined that the control system is in the first state based on the fact that the phase difference control value is not a predetermined maximum control value or minimum control value.

Furthermore, in the motor rotational speed control device, the determining means determines that the control system is in the first state based on the fact that the phase difference control value is within a predetermined range. , it is determined that the control system is in the second state based on the fact that the phase difference control value is not within a predetermined range.

Effects> At predetermined timings, it is determined whether the control system is in the first state or the second state based on the output phase difference control value.

When the control system is determined to be in the first state, the relationship between the phase difference and the control value used to obtain the phase difference control value is set to The control value is changed to be smaller by a predetermined value relative to the difference.

When it is determined that the control system is in the second state, in order to improve followability, the relationship between the phase difference and the control value used to obtain the phase difference control value is determined by setting the control value to the phase difference in advance. It is changed so that it becomes larger by the specified value.

The determination as to whether it is the first state or the second state may be made based on whether the output phase difference control value is not the maximum control value or the minimum control value, or the output phase difference control value The determination may be made based on whether the value is within a predetermined range.

<Embodiment> In the following, one embodiment of the present invention and 1- will be explained, taking as an example the case where it is applied to a drive control circuit of a DC servo motor for driving the optical system (illumination unit and reflection mirror) of a copying machine. do.

FIG. 1 is a block diagram showing a configuration example of a drive control circuit for a DC servo motor for driving an optical system of a copying machine. This control circuit uses PWM (pulse width ll1odula) as the voltage applied to the DC servo motor.
The circuit uses the t1on) signal.

This DC servo motor 10 is of a permanent magnet field type, and is rotationally driven by a driver section 11.
Move 7.

A rotary encoder 12 is attached to the rotating shaft of the servo motor 10.
are connected. As already known, the rotary encoder 12 outputs a rotation pulse every time the servo motor 10 rotates by a predetermined minute angle. The rotary encoder 12 of this embodiment has one servo motor 10.
By rotating, for example, 200 rotation pulses are output.

Further, the rotation pulses of the rotary encoder 12 include at least human-phase rotation pulses and B-phase rotation pulses, and both rotation pulses have an equal number (for example, 200 per motor rotation) and are in phase with each other. [1 is a pulse shifted by 90 degrees.

The rotation pulse output from the low-resolution encoder 12 is
The encoder signal is given to the human power section 13.

The encoder signal human input section 13 is a circuit for detecting the rotation of the servo motor 10 based on rotation pulses given from the rotary encoder 12, as will be described in detail later. The detection output of the encoder signal input section 13 is the control section 1.
given to 4.

The control unit 14 is the center that controls the entire circuit,
Speed difference calculation processing that calculates the difference between the command speed and the detected actual rotational speed of the motor; Phase difference calculation processing that calculates the phase difference between the speed command signal and the speed detection signal; and Control processing and the like are performed to control the motor 10 so that the motor rotation speed becomes equal to the command speed.

The control unit 14 includes a memory and a timer used for control operations to be described later.

The control unit 14 is also given an operation command signal and a command speed. The command speed is given to a speed command clock as a speed command signal from a control section (not shown) of the copying machine main body, or to a speed command signal manual section 15 for signal processing, and then given to the control section 14. There is. The details will be described later.

The control section 14 executes arithmetic processing based on each of these input signals, calculates PWM data, and provides it to the PWM unit 16, and also provides a driver section drive signal to the driver section 11 described above.

The PWM unit 16 is a unit for changing the pulse width (duty) of the PWM signal based on the applied PWM data. The rotational speed of the servo motor 10 is controlled by a PWM signal output from the PWM unit 16. Further, the driver unit drive signal determines the rotation direction of the servo motor 10 and performs braking.

By the way, in order to accurately rotate the servo motor 10 at a desired speed, it is necessary to accurately detect the rotation speed of the servo motor 10.

Therefore, in this drive control circuit, the configuration of the encoder signal manual section 13 is as shown in FIG. 2, and the signal reading by the control section 14 is devised so that accurate speed detection can be performed.

To explain with reference to FIG. 2, encoder signal human power section 1
3 includes an edge detection circuit 131 to which an A-phase rotation pulse (which serves as a speed detection pulse) output from the rotary encoder 12 is applied. The edge detection circuit 131 detects the rising edge of the applied rotation pulse, that is, the speed detection pulse, and derives its detection output.

The encoder signal input unit 13 also includes a free running counter 133 of, for example, 16 bits, which counts up the applied reference clock, and a capture register 134.

The capture register 134 uses the edge detection output of the edge detection circuit 131 as a capture signal, and uses the capture signal as a trigger to read and hold the count number of the free running counter 133. Note that the reference clock is a reference clock that serves as a reference for the operation timing of the entire circuit shown in FIG. 1, and if the circuit is constituted by a microcomputer, a machine clock is used.

Furthermore, if there is no such reference clock, a reference clock generation circuit may be provided.

The encoder signal human input section 13 further includes an up/down detection section 135 and an up/down counter 136. The up-down detection unit 135 determines the level of the B-phase rotation pulse when the A-phase edge detection output is given, and depending on whether the B-phase rotation pulse is at a high level or a low level, the servo motor 10 (see FIG. ) is used to determine whether the rotation is normal or reverse. The up/down counter 136 counts up or down the detection output of the edge detection circuit 131 based on the determination output of the up/down detection section 135.

Next, the operation of the circuit shown in FIG. 2 will be explained.

The contents of the capture register 134 include the capture signal,
That is, it is updated by the speed detection pulse. In addition, the up/down counter 136 has the number of edge detection signals,
In other words, the number of speed detection pulses is counted.

Therefore, if the up/down counter 136 counts n rotation pulses within a predetermined sampling time Δτ, and the number of reference pulses counted by the free running counter 133 during that period is calculated, the rotation The number N can be calculated. In other words, the rotation speed N can be calculated as follows.

Here, )iSS clock frequency is f [Hz], and when the servo motor 10 rotates once, the low-return encoder 1
The number of A-phase rotation pulses output from 2 is C[apr], and the capture register 13 at the current sample timing.
CPT the contents of 1. , Capture register 13 at the previous sample timing
Let the contents of 1 be CPT, .

By the way, in equation (6), since the reference clock frequency f and the number of rotational pulses C are constants, N--1Δ...(8
) A CPT, -CPTn-1X However, A knee! -X60X: CPTll -CPT,.

becomes.

FIG. 3 shows that the control unit 14 samples the contents of the capture register 134 and the up/down counter 136 at a sampling time Δ.
It is a flowchart showing the control operation for calculating the rotation speed N by reading every t.

Note that the sampling time Δt is set to an appropriate time that satisfies Δt≧CPT, −CPTfl−1 (9).

Next, explanation will be given with reference to FIGS. 2 and 3.

Each time the internal timer reaches a certain sampling time Δt (step S1), the control unit 14 resets the timer (step S2), and reads the contents of the capture register 134 and the up/down counter 136 (step S3).
).

Then, after subtracting the count number CPTn-1 of the previously read capture register 134 stored in the memory from the read count number CPT of the capture register 134, the reference clock number X within one sample time Δ is obtained. CPT, is stored in memory (step S4)
.

Also, from the read count number UDC, of the up-down counter 136, the count number UDC, -+ of the up-down counter 136 read last time stored in the memory.
After subtracting the number of rotation pulses within one sample time Δ, UDC is stored in the memory (step S5).

Then, based on the above equation (6), the servo motor 1
0 rotation speed N is determined (step S6).

Next, the speed command signal input section 15 will be explained in detail.

FIG. 4 is a block diagram showing a specific example of the configuration of the speed command signal input section 15. As shown in FIG. In the speed command signal input section 15,
It includes an edge detection circuit 151 for detecting, for example, a rising edge of the speed command clock, a free running counter 152, a capture register 153, and an up counter 154.

The free running counter 152 is, for example, a 16-bit counter that counts up the applied basic clock. This free running counter 152
may be used in common with the free running counter 133 of the encoder signal input section 13 described above.

The capture register 153 uses the edge detection output of the edge detection circuit 151 as a capture signal, and uses the capture signal as a trigger to read and hold the count number of the free running counter 152.

The up counter 154 is for counting up the output pulses of the edge detection circuit 151.

The operation of this circuit is as follows.

A speed command clock outputted from a control side microcomputer on the apparatus main body side, for example, a copying machine main body, is applied to an edge detection circuit 151, and a rising edge is detected. Since the output of the edge detection circuit 151 is given to the free running counter 152 as a capture signal, the contents of the capture register 153 are updated in response to the rising edge of the speed command clock. Therefore,
Capture register 15 based on a certain edge detection signal
3, read the contents of the capture register 153 based on the next edge detection signal, and find the difference between them, thereby making it possible to measure the count number of the free running counter 152 in one cycle of the speed command clock. In other words, it is possible to obtain rotation speed data (command speed data) that is 1 Rin.

Note that in this embodiment, each time the contents of the capture register 153 are updated, the difference between the count number after the update and the count number before the update is calculated. , the same reading method as the count number reading of the capture register 153 in the encoder signal input section 13 is used.

That is, the control unit 14 reads the contents of the capture register 153 and the contents of the up counter 154 at every predetermined sampling time Δt, calculates the difference between the count number read this time and the count number read last time in the capture register 153, and calculates the difference between the count number read this time and the count number read last time in the capture register 153. A more accurate reference clock number within one cycle of the speed command clock is obtained by dividing by the difference between the count number read this time and the count number read last time in the up counter.

Then, the speed difference ΔN between the command speed and the detected rotation speed N of the motor 10 is determined.

FIG. 5 shows a procedure for calculating the phase difference between the speed command clock and the speed detection signal by the control unit 14.

First, the edge detection circuit 13 of the encoder signal input section 13
1, when the rising edge of the speed detection pulse is detected (step 511), the count value of the free running counter 133 is read and the value is stored as the phase comparison value PDTn (step 512). Since the free running counter 133 starts counting the reference clock from the start of motor control, the value of the phase comparison value PDT is a value corresponding to the time from the start of motor control to the current pulse rise detection point. Become.

Next, the phase reference value PPI. is calculated and stored according to the following equation (step 813).

PPI, -PPI+, 1) + SPD - (10) Here, PP L--11: Previously stored phase reference value SPD
: Reference clock number S for one cycle of speed command clock
PD (SPD is a fixed value).

However, since the initial value of P P I o-u is zero, the corresponding phase reference value PP1. The value of is SPD.

Thereafter, the phase difference PHDT is calculated using the following equation and stored (step 514).

SPD Then, the above processing is repeated. That is, each time the rising edge of the speed detection signal is detected (step 5ll),
Reading the count value of the free running counter 133 and the phase comparison value PDT.

(step 512), phase reference value PPI.

(step 813) and the phase difference P
The HDT calculation (step 514) is repeated.

After the start of motor control, when the second rise of the speed detection pulse is detected in step S11, step 8
The value of the phase reference value PP1 calculated in step 13 becomes 2SPD, and becomes 3SPD when the third rising edge of the speed detection pulse is detected. That is, the phase reference value PPI calculated in step 313. The value is the product of SPD and the total number of speed detection pulses output from the start of motor control to the current rise of the speed detection pulse.

Since SPD is a fixed value depending on the period of the speed command clock, the phase reference value PPI calculated in step 313
The value of , is a value corresponding to the time from the start of motor control to the time of the rise of the speed command clock corresponding to the speed detection pulse whose rise was detected this time.

Then, a value (phase comparison value PD
T, ) and the value (phase reference value PPI,) corresponding to the time from the start of motor control to the time of the rise of the speed command clock corresponding to the speed detection pulse whose rise was detected this time is calculated as the speed command clock. Value according to the period of (SPD)
The phase difference PHDT is obtained by dividing by . Therefore, even if the phase difference between the speed command clock and the speed detection pulse is equal to or more than one cycle of the speed command clock, the phase difference PHDT can be accurately detected.

Next, a method for calculating PWM data output from the control unit 14 will be explained.

The voltage VO to be output to the servo motor 10 in order to make the rotational speed of the servo motor 10 follow the command speed is calculated by the following formula, %, where vl is the control voltage due to the speed difference ΔN, and V2 is the control voltage due to the phase difference PHDT. (12) The control voltage (2) by the phase difference PHDT is obtained as follows.

(a) When the absolute value of the phase difference I PHDT l is smaller than the proportional control range determination value W determined in the phase difference/correction voltage relationship determination process described later: (l PHDT l <
W) V2-a ・PHDT - (13) However, α is the predetermined maximum value of ■2 V2m
When ax (constant) is assumed, it is expressed by the following equation.

a-V2max/W-(1
4) (b) When the absolute value of the phase difference I PHDT I is greater than or equal to the proportional control range determination value W and the speed detection pulse is ahead of the speed command clock: (PHDT≦-W) V2-1α...・(15)(c
) If the absolute value of the phase difference l PHDT l is greater than or equal to the proportional control range determination value W and the speed detection pulse lags behind the speed command clock (PHDT≧+W) V2-+α (16) Therefore, the proportional If the control range determination value W is 1, for example, a-
V2max, the phase difference PHDT and the control voltage V2
The relationship with is shown in FIG. 6A.

Further, when the proportional control range determination value W is 2, for example, a
-V2max/2, and the relationship between the phase difference PHDT and the control voltage V2 is as shown in FIG. 6B.

In other words, the absolute phase difference is 1til! In the range where IPHDTI is less than or equal to the proportional control range determination value W, the smaller the proportional control range determination value W, the larger the control voltage V2 for the phase difference PHDT becomes. The control voltage V2 for the PHDT becomes smaller.

In other words, the smaller the proportional control range determination value W is, the smaller the proportional control range determination value W is, the more the proportional control range determination value W is
Conversely, the larger the proportional control range determination value W is, the smaller the influence of the control voltage (2) due to the phase difference PHDT with respect to the control voltage (20) becomes.

FIG. 7 shows a phase difference/control voltage relationship determination processing procedure by the control unit 14 to determine the proportional control range determination value W1, that is, the relationship between the control voltage and the phase difference, according to the state of the control system. There is.

This process is performed every time the phase difference PHDT is calculated in the phase difference detection process, that is, every time Δt. The initial value of the proportional control range determination value W is set in advance to, for example, "1".

When the phase difference PHDT is calculated, the absolute λ・I value l of the phase difference
It is determined whether PHDT I is smaller than the proportional control range determination value W (step 521).

If the absolute value I PHDT l of the phase difference is smaller than the proportional control range determination value W, it is determined that the control system is in the first state with relatively high stability. Then, the current proportional control range determination value W is set to a predetermined upper limit value Wmax,
For example, it is determined whether it is equal to [7] (step 522).

If the proportional control range determination value W is not equal to the upper limit value Wmax, the proportional control range determination value W is updated to a value incremented by +1 (
Step 23), the current process ends. If the proportional control range determination value W is equal to the upper limit value WIIlax, the current process ends without updating the proportional control range determination value W.

If it is determined in step S21 that the absolute value IPHDTI of the phase difference is larger than the proportional control range determination value W, it is determined that the control system is in the second state with relatively low stability. Then, it is determined whether the current proportional control range determination value W is equal to a predetermined lower limit value Wm1n%, for example, "1" (step 524).

If the proportional control range determination value W is not equal to the lower limit value W min , the proportional control range determination value W is updated to a value minus 1 (step 25), and the current process ends. If the proportional control range determination value W is equal to the lower limit W min , the current process ends without updating the proportional control range determination value W.

Such processing is performed every time the phase difference PHDT is calculated in the phase difference detection processing, and each time, the above-mentioned (13)
Control voltage V2 is calculated based on equation (16), control voltage VO is calculated based on V2 and Vl, and servo motor 10 is controlled by control voltage vO.

Therefore, when the control system is in the first state with relatively high stability, the proportional control range determination value W is increased, and the influence of the correction voltage V2 due to the phase difference PHDT is reduced. Conversely, when the control system is in the second state with relatively low stability, the proportional control range determination value W is made small, and the phase difference PH
The influence of the correction voltage v2 due to DT is increased. As a result, when the control system is in the first state, there is a strong tendency for control to be based on the speed difference, and when the control system is in the second state, there is a strong tendency for control to be based on the phase difference.

Therefore, in the second state where the motor load fluctuation is large, the motor rotation speed can be made to follow the command speed in a relatively short time using phase difference control.

Furthermore, in a stable state, wow and flutter during motor rotation can be reduced.

In the phase difference/control voltage relationship determination process, in order to determine whether the control system is in the first state or the second state, the absolute value I PHDT of the phase difference is determined in step S21.
Although it is determined whether l is smaller than the proportional control range determination value W, it may be determined whether the absolute value I PHDT l of the phase difference is smaller than an arbitrary value, for example, 1. .

The control voltage V1 due to the speed difference ΔN is calculated using the following formula (17) Ra: amateur resistance [Ω = torque constant [kgm] KE + induced voltage constant [V/rpm ■ o: no-load current [ A] GD2: Moment of inertia due to load and motor [kgα2
TBL: Sliding load [kg11].

FIG. 8 is a block diagram showing a specific example of the configuration of the PWM unit 16, and FIG. 9 is a timing chart for explaining the operation of the PWM unit 16.

The PWM2 unit 16 includes a set signal generation section 161,
PWM data register 162 and down counter 163
and an RS flip-flop 164.

The set signal generator 161 generates a set signal at regular intervals. This set signal generating section 161
is set to 1 by a ring counter, for example, and a set signal is generated every time a certain number of reference clocks are counted.

The PWM data register 162 is for holding PWM data given from the control unit 14. The PWM data given from the control unit 14 is the L data mentioned above. m
Vachita V O-V 1 + V 2 te. This P
The WM data is the PW output from the PWM unit 16.
Used to determine the duty of the M output signal.

The down counter 163 receives a PWM basic clock (in this embodiment, the PWM basic clock is a reference clock used in the encoder signal input section 13 and the speed command signal input section 15). It counts down and outputs a reset signal when the set number is counted.

The operation of the PWM unit 16 is as follows.

When the set signal is output from the set signal generating section 161, the contents of the PWM data register 162, that is, the control section 1
The PWM data given from 4 is sent to the down counter 16.
3, and the flip-flop 164 is also set by the set signal. Therefore, the output of the flip-flop 164, that is, the PWM signal becomes high level.

Next, the down counter 163 counts down based on the PWM reference clock, and when the set count value reaches "0", a heliset signal is given to the flip-flop 164. Therefore, the output of flip-flop 164 is inverted to low level.

As a result, the duty is determined by the value held in the PWM data register 162, that is, the voltage data vO, and a PWM signal is derived from the PWM unit 16.

The present invention is applicable not only to the optical system ifi control of a copying machine as described above, but also to a motor for controlling a reading device of a facsimile machine and other general motor control circuits.

Further, the present invention can be applied to the case where the applied voltage is calculated using other than PWM signals.

<Effects of the Invention> Since the present invention is configured as described above, it is possible to realize rotational speed control of a motor with good followability and less wow and flutter during motor rotation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of a drive control circuit for an optical system drive DC servo motor to which an embodiment of the present invention is applied. FIG. 2 is a circuit block diagram showing the electrical configuration of a rotational speed detection device for a DC servo motor for driving an optical system according to an embodiment of the present invention. FIG. 3 is a flowchart showing the rotational speed detection processing procedure in the embodiment of the present invention. FIG. 4 is a block diagram showing a specific example of the configuration of the speed command signal input section. FIG. 5 is a flowchart showing the phase difference detection processing procedure in the embodiment of the present invention. FIGS. 6A and 6B are graphs showing the relationship between the phase difference PHDT and the control voltage v1 based on the phase difference. FIG. 7 is a flowchart showing a phase difference/control voltage relationship determination processing procedure in an embodiment of the present invention. FIG. 8 is a block diagram showing a specific electrical configuration of the PWM unit. FIG. 9 is a timing chart showing the operation of the PWM unit. In the figure, 10...DC servo motor, 11...
Driver section, 12... Rotary encoder, 13...
・Encoder signal human power section, 14...control section, 15...
・Speed command signal input section, 16... PWM unit is shown.

Claims (1)

[Claims] 1. Speed based on the difference between command speed and detected speed Degree difference control value, speed command signal and speed detection The phase difference control value based on the phase difference with the signal and is the controlled variable, and the motor is fed back. A rotation speed control device for a motor that controls There it is, is output at each predetermined timing. Based on the phase difference control value, the control system In contrast, the first state with high stability is the or a second state with relatively low stability. determination means for determining whether The determining means determines whether the control system is in the first state. When it is determined, obtain the phase difference control value. The relationship between the phase difference and control value used for The control value is predetermined for the phase difference. means to change the value so that it is smaller by the value In addition, the control system is determined by the determination means. When the second state is determined, phase difference control The phase difference and control used to find the value The relationship between the control value and the control value relative to the phase difference. is changed so that it becomes larger by a predetermined value. means to change; A motor rotation speed control device equipped with. 2. Rotational speed of the motor according to claim 1 In the control device, The determination means is based on the output phase difference control. The control value is a predetermined maximum control value or The control system is based on the minimum control value. is in the second state, and the phase difference The control value is a predetermined maximum control value or is not the minimum control value. Determine whether the system is in the first state. It is characterized by the following. 3. Rotational speed of the motor according to claim 1 In the control device, The determination means uses a phase difference control value determined in advance. based on the value being within the range Determine that the system is in the first state, and The phase difference control value must be within the predetermined range. Based on the fact that the control system is in the second state, Characterized by determining something It is.