JPH03198683A - Motor controller - Google Patents

Abstract

PURPOSE:To obtain an accurate rotating speed by deciding whether the data calculated previously is erroneous or not, determining whether the data calculated this time falls within a predetermined range or not, and outputting data corresponding to the result as motor control speed data. CONSTITUTION:When data regarding the rotating speed of a motor 10 calculated previously is decided, for example, to be erroneous, data calculated this time is stored in a latest data storage area, and the data of the previous time stored in a storage means of the controller 14 is discarded. When the data of this time corresponds to the data corresponding to a center of large and small values or falls within a predetermined range to the data corresponding to the center of the large and small values, the data of this time is output as motor 10 control speed data. On the other hand, when the data of this time is out of the predetermined range to the data corresponding to the center, the data of this time is decided to be erroneous, and the data corresponding to the center is output as the motor 10 control speed data.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a motor control device.

<Background of the Invention> For example, in a DC servo motor control device for driving an optical system in a document reading device such as a copying machine, even if the motor load fluctuates due to changes in frictional resistance etc. as the optical system moves, it is difficult to follow the It is necessary to maintain the servo motor at a constant speed and move the optical system at a constant speed.

In order to keep the servo motor at a constant speed, it is necessary to accurately detect the actual rotational speed of the servo motor.

In conventional devices, the rotational speed of the servo motor is detected at predetermined timings based on the output (speed detection signal) of a speed detector such as an encoder connected to the servo motor.

However, the method of speed detection in conventional devices is
If the detected rotational speed is affected by noise or the like, there is a drawback that the motor rotational speed cannot be detected accurately.

Therefore, in order to eliminate errors caused by noise etc.
Some methods have been adopted, such as finding the average of the previously detected speed and the currently detected speed, and taking that as the current speed.

(Problem to be solved by the invention) However, in the method of calculating the average detection speed,
Since we are trying to reduce the error by averaging the detected speeds, even if an accurate rotational speed is detected, the speed will be averaged and will remain constant relative to the original speed (actual speed). This will result in a deviation of

Furthermore, if temporally large noise occurs, the noise error cannot be removed even if it is averaged, and a relatively large error remains in the speed after averaging.

For this reason, for example, if such large noise occurs in a steady state, speed unevenness will occur.

This invention was made in view of the above circumstances, and
It is an object of the present invention to provide a motor control device that can obtain an accurate speed without being affected by the fluctuation even if a speed detection signal fluctuates greatly over time due to noise or the like.

<Means for Solving the Problems> The present invention provides a calculation method for calculating data regarding the motor rotation speed at each predetermined timing in a motor control device that performs feedback control of the motor so that the motor rotation speed becomes equal to the command speed. a storage means having a plurality of storage areas capable of storing data related to the motor rotation speed for a predetermined plurality of times in chronological order; each time data related to the motor rotation speed is calculated, the previously calculated data is determined to be incorrect data; If the data calculated last time was not determined to be incorrect data, the data already stored in the storage means is shifted one by one, the oldest data is discarded, and the data calculated this time is A first storage control means stores the calculated data in the latest data storage area, and when the previously calculated data is determined to be incorrect data, the data calculated this time is stored without shifting the data already stored in the storage means. A second storage control means stores the calculated data in the latest data storage area instead of the previous data, A determination means for determining whether the data corresponds to the center of the magnitude or is within a predetermined range for the data corresponding to the center of the magnitude; the current calculated data corresponds to the data corresponding to the center of the magnitude. or when it is determined that the data is within a predetermined range with respect to the data corresponding to the center of magnitude, a means for extracting the currently calculated data as speed data to be used for motor control, and a means for extracting the currently calculated data as speed data to be used for motor control; When it is determined that the corresponding data is outside a predetermined range, the presently calculated data is determined to be incorrect data, and means is provided for extracting data corresponding to the center of the magnitude as speed data to be used for motor control. It is a motor device device characterized in that it includes.

Function> Data regarding the motor rotation speed is calculated at each predetermined timing.

Furthermore, each time data related to the motor rotation speed is calculated, it is checked whether the previously calculated data was determined to be incorrect data.

Then, if the data calculated last time is not determined to be incorrect data, the data for a predetermined number of times already stored in the storage means are shifted one by one one by one, the oldest data is discarded, and the data calculated this time is replaced instead. The calculated data is stored in the latest data storage area.

If the data calculated last time was determined to be incorrect data, the data already stored in the storage means is not shifted, and the data calculated this time is stored in the latest data storage area in place of the previous data. The previous data will be discarded.

Next, check whether the current data corresponds to the data corresponding to the center of the size among the multiple data stored in the storage means (these data include the current data), or It is determined whether or not the data corresponding to the center is within a predetermined range.

When it is determined that the current data corresponds to the data corresponding to the center of magnitude or is within a predetermined range with respect to the data corresponding to the center of magnitude, the current data is the current data to be used for motor control. Extracted as speed data.

On the other hand, when it is determined that the current data is outside the predetermined range with respect to the data corresponding to the center of magnitude, the current data is determined to be incorrect data, and the data corresponding to the center of magnitude is determined to be outside the predetermined range. It is extracted as the current speed data to be used.

<Embodiment> An embodiment of the present invention will be described below, taking as an example a case where the present invention is applied to a control circuit of a DC servo motor for driving an optical system (illumination unit and reflection mirror) of a copying machine.

FIG. 1 is a block diagram showing an example of the configuration of a control circuit for a DC servo motor for driving an optical system of a copying machine. This control circuit uses PWM (pulse width modulation) as the voltage applied to the DC servo motor.
n) signals are used.

This DC servo motor 0 is of a permanent magnet field type, and is rotationally driven by a driver section 11.
Move 7.

Rotary encoder 12 is installed on the rotation axis of servo motor 0.
are connected. As already known, the rotary encoder 12 outputs a speed detection pulse every time the servo motor 0 rotates by a predetermined minute angle. The rotary encoder 12 of this embodiment outputs A-phase and B-phase speed detection pulses (speed detection signals) that have the same period and are 90 degrees out of phase with each other, and the servo motor 0
When the motor rotates once, each phase, for example, 200 speed detection pulses are output.

The speed detection pulse outputted from the 0-Tari encoder 12 is given to the encoder signal input section 13. The encoder signal input section 13 is a circuit for detecting the rotational speed of the servo motor 10 based on the speed detection pulse given from the rotary encoder 12, as will be described in detail later. The output of the encoder signal input section 13 is given to the control section 14.

The control unit 14 includes a CPU, an RO that stores programs, etc.
M, is equipped with RAM etc. to store necessary data,
Calculation process of difference between command speed and detected speed, calculation process of phase difference between speed detection signal and speed command signal, servo motor 10
Performs processing such as calculation of PWM data for controlling.

The control section 14 is given an operation command signal and a speed command signal (speed command clock) from a control section (not shown) of the main body of the copying machine.

The control section 14 executes arithmetic processing based on each input signal, calculates PWM data, and provides it to the PWM unit 16, and also provides a driver section drive signal to the driver section 110 described above.

The PWM unit 16 receives PW from the control unit 14.
PWM of pulse width (output duty) according to M data
This is a unit for generating signals. The servo motor 1 is activated by the PWM signal output from the PWM unit 16.
0 rotation speed is controlled. Further, the driver unit drive signal determines the rotation direction of the servo motor 10 and performs braking.

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

Therefore, in this control circuit, the encoder signal input section]3
The configuration 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 input section 1
3 is a rise detection circuit 13 that detects the rise of the A-phase speed detection pulse sent from the rotary encoder 12;
1. For example, use a 16-bit free running counter [33] and rise detection circuit] 31 to count up the reference tally as a capture signal, and use the capture signal as a trigger to read and hold the count number of the free running counter 133. A capture register] 34 is provided.

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 when the circuit is composed of a microcomputer, a machine clock is used. Also, if there is no such reference clock,
A reference clock generation circuit may also be provided.

The encoder signal input section 13 further includes an up/down detection section 135 and an up/down counter 136. The up/down detection section 135 includes a rise detection circuit 1
When the rising detection output of the A-phase speed detection pulse is given from 31, the level of the B-phase rotation pulse is determined, and depending on whether the B-phase rotation pulse is high level or low level, the servo motor 10 (Fig. 1) This is to determine whether 2 is rotating in the forward direction or in the reverse direction. Up/down counter 136
is based on the discrimination output of the up-down detection section 135,
The detection output of the rising edge detection circuit 131 is counted up or down.

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 every time the rising edge of the A-phase speed detection pulse is detected. In addition, up/down counter 13
6 counts the number of times the rising edge of the speed detection pulse is detected, in other words, the number of speed detection pulses.

Therefore, within a predetermined sampling time Δτ, if the up/down counter 136 counts n rotation pulses, and during that time the free running counter 133 measures the number of reference pulses, the number of rotations will be calculated based on that. It is possible to calculate N.

In other words, the rotation speed N [rpm] of the servo motor 10 is the frequency of the reference clock f [Hz], and the number of A-phase rotation pulses output from the rotary encoder 12 when the servo 3 motor] 0 rotates once is C. [ppr]
, CPT the contents of the current capture register 131, .
CP T n of the contents of [previous capture register] 31
If it is set to -1, it can be calculated as follows (1).

Here, in equation (1), since the reference clock frequency f and the number of rotational pulses C are constants, N = n A = agony (2)
cp'rll-cp'T,, X However, A: LX60 X: CPT, CPTo-+.

FIG. 3 shows the motor rotational speed detection processing procedure by the control section 14, and FIG. 4 shows two types of memories M1 and M2 used in this processing.

In FIG. 4, the memory M1 is for storing rotational speed data for five times in order from the newest to the oldest rotational speed data storage area. 5 storage areas E1
~E5.

In other words, El is the current rotational speed data N. However, E2 contains the previous rotation speed data N. -1) is the rotation speed data N, two times before E3. -2, is the rotation speed data N, three times before E4. -9, is the rotation speed data N, 4 times before E5. −
4) are respectively stored.

Memory M2 contains five rotational speed data N stored in memory M1. -N(n-4+) for sorting, that is, arranging in order of size, five storage areas El
1 to E15. Five rotation speed data N0 to N stored in the memory M1. -4) is sorted and stored in memory M2, for example, area E11
The largest of the five rotational speed data N, ...NLn-4) is in area E12, the third largest is in area E135, and the fourth largest is in area E14. , the smallest one is stored in area Ell. Therefore, the area E13 stores rotation speed data corresponding to the center of the five rotation speed data stored in the memory M1.

Returning to FIG. 3, the motor rotation speed detection process is performed every sample time Δt.

The sampling time Δt is set to an appropriate time that satisfies the following equation: Δt≧X=CPTfi CPTll−+ (3).

Next, explanation will be given with reference to FIGS. 1 to 4.

In the control unit 14, an internal timer keeps a constant sampling time Δt.
Each time the timer reaches (step S1), the timer is reset (step S2), and the contents of the capture register 134 and up/down counter 136 are read (step S3).

Then, from the count number CPT of the capture register 134 read this time, the count number CPT of the capture register 134 read last time that has been stored,
, -+, the number of reference clocks X within 16 sample times Δ is determined, and then CPT is stored (step S4).

In addition, from the count number UDCfi of the up-down counter 136 read this time, the count number U of the up-down counter 136 that has already been read last time is calculated.
After the number n of rotational pulses within one sample time Δ is determined by subtracting D Cn-1, UDC is stored (step S5).

After that, the rotation speed N of the servo motor (current rotation speed data N) is calculated based on the above-mentioned formula (2).
Step S6).

When the rotation speed data Nn is calculated, it is checked whether the previous rotation speed data N+n-++ was determined to be incorrect data. This confirmation is performed when flag F is set (F=
1) is checked (step S7).

As will become clear later, the flag F is the previous rotation speed data N. -1) is determined to be incorrect data, it is set to the set state (F=1), and the previous rotation speed data N. −
1) is not determined to be incorrect data, it is set to a reset state (F-0).

In the case of F=O, that is, the previous rotation speed data N
. -1) If the data is not determined to be incorrect, the five rotational speed data N already stored in the memory M1.

-N +n-41 is shifted (step S8). As a result, the rotation speed data up to that point is N. is N(,,-1+
As a result, rotation speed data N (II-11 is N
,. -2, and rotation speed data N in area E3. -2
, is placed in area E4 as NLn-31, and rotation speed data N
I-3, is N. -4, is stored in area E5,
The oldest data is the rotation speed data NLfi-4
, will no longer be remembered.

The rotation speed data N, which was calculated this time, is stored in the memory M.
1 area E1 (step S9).

On the other hand, in step S7, in the case of F-1, that is, the previous rotation speed data N. -1, is determined to be incorrect data, the process continues at step s9 without shifting the five rotational speed data N n -N (n -4)7 8 already stored in the memory M1. Move on to
Rotation speed data N calculated this time. is stored in area E1 of memory M1 (step S9).

As a result, the current rotation speed data Nn is the previous rotation speed data N. Instead, it will be stored in area E1.

Note that data N is stored in areas E2 to E5. −
1) to Nun-111 are retained as they are.

That is, the previously calculated erroneous data is removed from the memory M1, and the currently calculated rotational speed data N, . . . is stored in the memory M1 instead.

By performing this processing, there are the following advantages. In other words, if the calculated data is erroneous data that differs significantly from the actual motor rotation speed due to the influence of noise, etc., if this erroneous data is sequentially shifted in the memory M1, the reliable data existing in the memory M1 will be This results in a substantial reduction in the number of data to be used, and the reliability of the data decreases. More specifically, when sorting the five data stored in the memory M1 as described later, the false 9 data always comes at the end (because the false data is extremely large or small), so in the end , the reliability of the data decreases because the central data is extracted from the data after removing erroneous data. In particular, if incorrect data is calculated continuously, the incorrect data may be taken out as the current rotational speed data to be used for motor control, and in such a case, severe drive unevenness will occur.

According to the above-described control, if erroneous data is calculated, the erroneous data is replaced with the currently calculated rotational speed data Nゎ, so the above-mentioned problem does not occur. Therefore, according to the control according to this embodiment, the reliability of the central data Nm, which will be described later, becomes high, and even if incorrect rotational speed data is calculated continuously, the incorrect rotational speed data becomes the central data Nm. .

It is possible to prevent it from being closed and confirmed.

Next, the five rotational speed data N, ... ~N (II-41) stored in the memory M1 are sorted and stored in the memory M2 (step 510). 0 to 5 rotation speed data N.-N (.-4) are stored in order of increasing size.In this case, area E13 stores the five rotation speed data N.-N(.-4) in the center of the size among the five rotation speed data N0 to NIn-4). Corresponding rotation speed data (central data N□) is stored.

The center data N□ stored in the area E13 of the memory M2 is the rotation speed data corresponding to the center of the magnitude of the five rotation speed data for the current time and the past four times.

Therefore, if this rotational speed data Nff1 is used for control as the current rotational speed N, even if the speed detection signal fluctuates due to noise or the like and incorrect rotational speed data N, . The rotation speed data NIl can be removed.

However, this method alone can prevent false detections due to sudden fluctuations due to noise, etc. However, if the motor rotation speed is changing in one direction over a long period of time (for example, if the rotation speed is increasing) ) etc., there are the following problems.

For example, if the motor rotational speed is 1 as shown in FIG. 10, the commanded speed N. If it is rising towards the current time t. Then, the memory M1 stores data from time 1n to time j Ln-
41 rotation speed data N, ~NLn-4+ for five times are stored.

Then, among these data, data N corresponds to the center of the size. -2, is the latest data N. Since the value is always smaller than N, the actual motor rotation speed is almost the command speed N. Even if the current rotational speed reaches the commanded speed N. It is determined that the motor rotation speed is lower, and the motor rotation speed is controlled to further increase.

As a result, the motor rotation speed is the command speed N. It becomes bigger. Then, the speed is controlled to decrease, but in this case as well, the actual motor rotational speed is approximately the commanded speed N. Even if the current rotation speed reaches the command speed N
. It is determined that the motor rotation speed is higher than that, and the motor rotation speed is controlled to further decrease.

Therefore, the motor rotation speed is the command speed N, as shown in FIG. This results in undulations (hunting) centered around .

2. Therefore, in this embodiment, in order to prevent such a hunting phenomenon, the following steps 811 to 313 are controlled.

It is determined whether the current rotational speed data Nn stored in area E1 of memory M1 is within a certain range with respect to central data N□ stored in area E13 of memory M2 (step 511).

In other words, the latest rotation speed data N. It is determined whether or not is within the range shown by the following formula.

Nm (1-p)≦N,≦N, (1+q)...(4) However, p and q are values determined in consideration of the following characteristics of the motor when changing the motor rotation speed. be.

If the latest rotation speed data N0 is not within the range shown by equation (4) (No in step S11), it is determined that the current rotation speed data N, is not accurate due to the influence of noise etc. The central data N, determined and stored in area E13 of memory M2, is taken out as the current motor rotation speed N, stored in a buffer, for example, and used for control.

Also, flag F is set (F=1) (step 5
12). Therefore, even if the speed detection signal suddenly fluctuates greatly due to noise or the like, it is not used as the rotational speed N for control, so that erroneous control operations due to noise or the like can be prevented.

Also, the latest rotation speed data N. is within the range shown by formula (4) (YES in step S11)
, latest rotation speed data N. is determined not to have been affected by noise etc., and the latest rotation speed data N stored in area E1 of memory M1 is taken out as the current motor rotation speed N, stored in a buffer, for example, and controlled. used for. Further, flag F is reset (F-0) (step 813). Therefore, as shown in FIG. 10, even when the motor rotational speed changes in one direction over a long period of time, accurate speed data can be obtained and the hunting phenomenon can be prevented from occurring.

In addition, each time a speed detection pulse is output, the count number CPT, . The rotation speed data N may be obtained based on the following.

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

FIG. 5 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,
A rise detection circuit 151 for detecting the rise of the speed command clock, a free running counter 152 for up-counting the reference clock, and a rise detection output of the rise detection circuit 151 are used as a capture signal, and the capture signal is used as a trigger to control the free running counter 152. It includes a capture register 153 that reads and holds a count number, and an up counter 154 that counts up the output pulse of the rising edge detection circuit 151.

Free running counter 152 is, for example, a 16-bit counter. 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 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 a rising edge detection circuit 151, and a rising edge is detected. Since the output of the rising 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, the contents of the capture register 153 are read based on a certain rising detection signal, and the contents of the capture register 153 are read based on the next rising detection signal.
By reading out the contents of and finding the difference between them, it is possible to measure the count number of the free running counter 152 in one cycle of the speed command clock. In other words, the rotation speed N is the command speed.

can be obtained.

Note that in this embodiment, each time the contents of the capture register 1563 are updated, the difference between the counted number after updating and the counted number before updating is not calculated, but in order to further improve detection accuracy. , the capture register 15 in the encoder signal input section 13
A reading method similar to the count reading in step 3 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. By dividing the difference by the difference between the count number read this time and the count number read last time in the up counter, a more accurate reference clock number within one cycle of the speed command clock is obtained.

FIG. 6 shows a procedure for calculating the phase difference between the speed command clock and the speed detection pulse by the control unit 14.

First, when the rising edge of the speed detection pulse is detected by the rising edge detection circuit 131 of the encoder signal input section 13 (step 521), the free running counter 1
33 count value is read, and that value is the phase comparison value PD.
T, (step 522). Since the free running counter 133 starts counting the reference clock from the start of motor control, the phase comparison value PD
The value of To is a value corresponding to the time from the start of motor control to the current pulse rise detection time.

Next, the phase reference value PPI. is calculated and stored according to the following equation (step 823).

PPll1=PPI,,-1)+SPD-(5)
Here, P P I (, -1): Previously stored phase reference value SPD: Number of reference clocks during one period of speed command clock (SPD is a fixed value).

However, PPII. The initial value of -1) is zero, so
In step S21, the value of the phase reference value PPI corresponding to when the first rising edge of the speed detection pulse is detected in section 8 after the start of motor control becomes SPD.

Thereafter, the phase difference PHDT is calculated using the following equation and stored (step 524).

SPD Then, the above processing is repeated. That is, every time the rising edge of the speed detection pulse is detected (step 521)
, reading the count value of the free running counter 133 and the phase comparison value PDT. update (step 522)
, phase reference value PPI. calculation and update (step 82
3) and calculation of phase difference PHDT (step 524)
is repeated.

After the start of motor control, when the second rise of the speed detection pulse is detected in step S21, step 8
Phase reference value PP calculated in 23. The value becomes 2SPD, and when the third rising edge of the speed detection pulse is detected, it becomes 3SPD and 9. In other words, the value of the phase reference value PPI calculated in step 823 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 323
, 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 PP1.) 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 0 for one cycle or more of the speed command clock, the phase difference PHDT is accurately detected.

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

The rotation speed N of the servo motor 10 is the command speed N.

The voltage vO that should be output to the servo motor 10 to make it follow
It is expressed by the following formula.

VO=V1+V2-(7) That is,
In this example, the speed difference ΔN (=N.

The control voltage V1 based on the phase difference PHDT is corrected by the control voltage V1 based on the phase difference PHDT. The reason for this is that with only proportional control based on the speed difference ΔN, 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. This is because it takes a long time to reach the target position and the followability is not good.

Therefore, in order to improve followability, in this embodiment, 1 is the control voltage V1 due to the speed difference ΔN (""No-N).
is corrected using the control voltage V2 based on the phase difference PHDT.

The control voltage v2 due to the phase difference PHDT is obtained, for example, as follows, assuming that the predetermined maximum value of the control voltage v2 is α.

(a) When the phase difference is smaller than one cycle (-1<PHDT<+1) V2-α・PHDT...(8)(
b) When the phase difference is one cycle or more and the phase of the speed detection signal is ahead of the phase of the speed command signal (PHDT≦-1) V2--α ... (9) (C
) When the phase difference is one cycle or more and the phase of the speed detection signal lags the phase of the speed command signal (PHDT≧+1) V2-+α (10) Therefore, the phase difference PHDT and the control voltage v2 The relationship between 2 and 2 is shown in FIG.

In addition, the control voltage ■1 due to the speed difference ΔN is calculated using the following formula (%) (11) Ra: amateur resistance [Ω] KT: torque constant [kgm] Ke: induced voltage constant [V/rpm ■o: nothing Load current [A] GD2: Moment of inertia due to load and motor [kg
m2] TBI and sliding load [kgml].

The control unit 14 detects the rotational speed N of the servo motor 10 (step S6 in FIG.
Each time DT is calculated (step 524 in FIG. 6), vO is calculated based on the above equations (7) to (11), and PWM data corresponding to this is output. This PWM data is sent to the PWM unit 16, and the servo motor 10 is controlled via the driver section 11.

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 PWM unit 16 includes a set signal generating section] 61,
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 16]
is composed of, for example, a ring counter, and is configured to generate a set signal every time a certain number of reference clocks are counted.

4. The PWM data register 162 is for holding PWM data given from the control section 14. The PWM data given from the control unit 14 is expressed by the above-mentioned formula (7
) is the voltage data determined by That is, it is the voltage vO obtained by correcting the voltage v1 of equation (11) with the control voltage v2 based on the phase difference data PHDT. This PWM data is used to determine the duty of the PWM output signal output from the PWM unit 16.

The down counter 163 counts down every time a PWM reference clock (in this embodiment, the PWM reference clock is a reference clock used in the encoder signal input section 13 and the speed command signal input section 15) is provided. When the set number is counted, a reset signal is output.

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 set in the 5 down counter 163, and the flip-flop 164 is 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 calculated by equation (7), and a PWM signal is derived from the PWM unit 16.

The present invention is applicable not only to the optical system control of a copying machine, but also to a motor for controlling a reading device of a facsimile machine, a motor for controlling the operation of a robot, 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.

6 <Effects of the Invention> Since the present invention is configured as described above, even if the speed detection signal fluctuates over time due to noise etc., it is possible to accurately determine the speed without being affected by the fluctuation. good motor control is possible.

Further, according to the present invention, good motor control can be performed even when the motor rotational speed changes in one direction over a long period of time.

[Brief explanation of drawings]

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 the encoder input section according to the embodiment of the invention. FIG. 3 is a flowchart showing the rotational speed detection processing procedure in the embodiment of the present invention. FIG. 4 is a diagram showing two memories M1 and M2 used for rotational speed detection processing in the embodiment of the present invention. 7 FIG. 5 is a block diagram showing the electrical configuration of the speed command signal input section. FIG. 6 is a flowchart showing a phase difference detection processing procedure in an embodiment of the present invention. FIG. 7 shows the phase difference PHDT and the control voltage v based on the phase difference.
2 is a graph showing the relationship with 2. 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. FIG. 10 is a diagram for explaining one of the problems solved by this embodiment, and shows the contents of the motor detection signal when the motor rotation speed changes in one direction over a long period of time. FIG. FIG. 11 is a diagram for explaining the hunting phenomenon. In the figure, 10...DC servo motor, 11...
Driver section, 12...Low reencoder, 13...
・Encoder signal input section, 14...control section, 15...
・Speed command signal input section, 16...PWM unit, M
l, 8 M2...Memory. (2 others)

Claims (1)

[Scope of Claims] 1. In a motor control device that performs feedback control of the motor so that the motor rotation speed becomes equal to the command speed, a calculation means for calculating data regarding the motor rotation speed at each predetermined timing, a motor rotation speed. A storage means having a plurality of storage areas capable of storing data related to the motor rotation speed for a predetermined plurality of times in order of the newest; If the data calculated last time was not determined to be incorrect data, the data already stored in the storage means is shifted one by one, the oldest data is discarded, and the data calculated this time is The first data to be stored in the latest data storage area.
Storage control means, when the data calculated last time was determined to be incorrect data, stores the latest data by replacing the data calculated this time with the previous data without shifting the data already stored in the storage means. A second storage control means for storing the current calculated data in the latest data storage area corresponds to the data corresponding to the middle of the plurality of data stored in the storage means; A determination means for determining whether or not the data corresponding to the center of magnitude is within a predetermined range; When it is determined that it is within the range, means for extracting the currently calculated data as speed data to be used for motor control, and determining that the currently calculated data is outside a predetermined range with respect to data corresponding to the center of the magnitude. A motor control device comprising: means for determining that the current calculated data is erroneous data and extracting data corresponding to the center of magnitude as speed data to be used for motor control.