JPH03198679A - Detecting device for arrival at steady range in motor controller - Google Patents

Abstract

PURPOSE:To normally control a motor by determining arrival of a motor rotating speed at a steady range when a difference between maximum data and minimum data of data of plurality of times calculated at each predetermined timing stored in a storage means is a predetermined value or less. CONSTITUTION:When data regarding the rotating speed of a motor 10 is calculated at a predetermined timing, data of past predetermined times stored already in a storage means of a controller 14 are sequentially shifted by one, and data calculated this time is stored in a latest data storage area. Then, when data corresponding to a center of large and small values of data of past predetermined times stored in the storage means for storing latest data is determined to fall within predetermined range, a difference between the maximum data and the minimum data of the data of the predetermined number of times stored in the storage means is calculated. If the difference is a predetermined value or less, it is decided that the speed of the motor 10 arrives at the steady range.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a steady state reaching detection device in a motor control device.

<Background of the Invention> PLL (p-has) is used as a control to maintain the motor at a constant speed after the motor reaches the steady state from the transient response range.
e-1oc, ke', dIo-op) control is known.

There is also a control method using a PWM (Pulse Width Modulation) signal, which is related to an earlier application by the present applicant. This control method obtains a PWM signal based on a control component proportional to the speed difference between the target speed and the detected speed, and a control component proportional to the phase difference between the target speed signal and the detected speed signal, and controls the motor speed. It is something to control.

Each of the above-mentioned control methods is sufficiently effective as constant speed control after the motor reaches a steady state region.

<Problems to be Solved by the Invention> By the way, in the transient response region where the rotational speed of the motor is increased to a steady state region, proportional control is generally performed in which a voltage proportional to the speed difference between the target speed and the detected speed is applied to the motor. It will be done. Then, the detected speed is a predetermined percentage of the target speed,
For example, it may be determined that the motor rotation speed has reached a steady range by reaching within 95%, or an acceleration component may be calculated based on the previous detected speed and the current detected speed, and the motor rotation speed may be determined to be steady based on that value. It was determined that the area had been reached.

However, in the method of determining that the motor rotation speed has reached a steady range when the detected speed has reached a predetermined percentage (for example, 95%) of the target speed, for example, if the load is larger than the set value, the motor rotation speed is lower than the target speed. In some cases, the speed stabilizes at a low speed (for example, 90% of the target speed), and it is not determined that the steady state has been reached for a long time.

Furthermore, in the method of calculating acceleration and determining whether it has reached a steady state based on that value, even in the transient response region, it may be determined that the acceleration component has become almost 0 due to noise, vibration, etc. There were cases where it was erroneously judged that the temperature had entered the steady state region.

If it is determined that the rotational speed of the motor has not reached the steady range as in the former case, control using PWM signals is entered based on PLL control or the proportional component and phase difference component devised by the applicant. I can't.

In addition, as in the latter case, if it is determined that the stationary region has been reached even though it is in the transient response region due to an erroneous judgment, the PLL
Even if control is started, normal control cannot be performed.

Therefore, in the motor control device, it is necessary to be able to accurately detect when the motor rotation speed reaches the steady state range from the transient response range.

This invention was made in view of the above circumstances, and
It is an object of the present invention to provide a steady-state region reaching detection device in a motor control device that can accurately detect when a motor rotation speed has reached a steady-state region.

Means for Solving the Problems> The present invention provides a motor control device that performs feedback control of a motor so that the motor rotation speed becomes equal to a command speed, a means for calculating data regarding the motor rotation speed at each predetermined timing; It has a storage area that can store data related to the motor rotation speed for a predetermined number of times in chronological order, and each time data related to the motor rotation speed is calculated, the already stored data is sequentially shifted one by one, and the current data is shifted one by one. A storage means for storing the calculated data in the latest data storage area, and whether the latest data is within a predetermined range with respect to data corresponding to the center of the magnitude among the plurality of data stored in the storage means. When the first determining means determines that the latest data is within a predetermined range with respect to the data corresponding to the center of the magnitude, the data for the plurality of times stored in the storage means are A means for calculating the difference between the maximum data and the minimum data of the data, and determining whether the difference between the maximum data and the minimum data is less than or equal to a predetermined value, and determining whether the difference is less than or equal to the predetermined value. The present invention is a steady-state region reaching detection device in a motor control device, which includes a second determining means that sometimes determines that the motor rotational speed has reached a steady-state region.

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

When the data regarding the motor rotational speed is calculated, the data for a predetermined number of times in the past already stored in the storage means are sequentially shifted one by one, and the data calculated this time is stored in the latest data storage area.

Next, it is determined whether the latest data is within a predetermined range with respect to data corresponding to the middle of the data stored a predetermined number of times in the past stored in the storage means.

When it is determined that the latest data is within a predetermined range with respect to the data corresponding to the center of magnitude, the difference between the maximum data and the minimum data among the data stored in the storage means for a predetermined number of times is calculated. Ru.

Then, it is determined whether the difference between the maximum data and the minimum data is less than or equal to a predetermined value, and when the difference is less than or equal to the predetermined value, it is determined that the motor rotation speed has reached a steady range. Ru.

<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 10 is of a permanent magnet field type, and is rotationally driven by a driver section 11.
Move 7.

A rotary encoder 12 is installed on the rotating shaft of the servo motor 10.
are connected. As is already well known, the low rotation encoder 12 outputs a speed detection pulse every time the servo motor 10 rotates by a predetermined minute angle. The low-return encoder 12 of this embodiment outputs A-phase and B-phase speed detection pulses (speed detection signals) that have the same period and are out of phase by 90 degrees, and when the servo motor 0 rotates once, , for each phase, for example, 200 speed detection pulses are output.

The speed detection pulse output from the low-resolution 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 sent to the control section 14.
given to.

The control unit 14 is equipped with a CPU, a ROM that stores programs, a RAM that stores necessary data, etc., and performs processing for calculating the difference between the commanded speed and the detected speed, processing for determining whether the speed has reached a steady state, and processing for determining whether the speed has reached a steady state. Calculation process of phase difference between command signal and speed detection signal, PWM for controlling servo motor 0
Performs data calculation processing, etc.

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 speed command clock is signal-processed by the speed command signal input section 15 and then given to the control section 14 .

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 11 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 as a premise.

Therefore, in this control circuit, the encoder signal input section 13
The configuration is as shown in FIG. 2, and the signal reading by the control section 14 is devised to enable accurate speed detection.

To explain with reference to FIG. 2, encoder signal human power section 1
3 includes a rise detection circuit 1 that detects the rise of the A-phase speed detection pulse sent from the low reencoder 12.
31, up-count the reference clock, e.g. 16
The free running counter 133 having a bit configuration and the rising edge detection output of the rising edge detection circuit 0 to 131 are used as a capture signal, and the captured signal is used as a trigger to generate the free running counter 1.
Capture register 1 that reads and holds the count number of 33
34 are 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 unit 135 determines the level of the B-phase rotation pulse when the rise detection output of the A-phase speed detection pulse is given from the rise detection circuit 131,
Depending on whether the B-phase rotation pulse is at a high level or a low level, it is determined whether the servo motor 10 (FIG. 1) is rotating in the forward direction or in the reverse direction. The up/down counter 136 counts up or down the detection output of the rising edge detection circuit 131 based on the discrimination 1 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 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 ΔT, if n rotation pulses are counted by the up-down counter 136 and the number of reference pulses counted by the free running counter 133 during that period is measured, the rotation speed is N can be calculated.

In other words, the rotation speed N [rpm] of the servo motor 10 is determined by the frequency of the reference clock being f [Hz], and the number of A-phase rotation pulses output from the rotary encoder 12 when the servo motor 10 rotates once being 2 C [ ppr], the contents of the current capture register 131 are CPT, the contents of the previous capture register 131 are CPT, the contents of the previous capture register 131 are CPT
If PT is , , , then it can be calculated as (1).

Here, in equation (1), since the reference clock frequency f and the number of rotational pulses C are constants, -A CPT, -CPT.

A (2) However, A:,! -X60 X: CPT, CPTn-+.

FIG. 3 shows a rotation speed detection processing procedure in which the control unit 14 reads out the contents of the capture register 1334 and the up/down counter 136 at every sampling time Δt to calculate the rotation speed N.

The sampling time Δt is set to an appropriate time that satisfies the following: Δt≧X=CPT, CPT, l−+ (3).

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

[Control unit] 4 resets the timer every time the internal timer reaches a certain sampling time Δt (Step S1) (Step S2), and reads out the contents of the capture register 134 and the up/down counter 136 (Step S1).
3).

Then, from the count number CPT of the capture register 134 read this time, the count number CPT□-1 of the capture register 134 read last time which is already stored is calculated.
After the reference clock number X within one sample time Δ is obtained by subtracting CPT, CPT is stored (step S4).

Also, from the count number UDC of the up-down counter 1346 read this time, the count number U of the up-down counter 136 read last time that has already been stored is calculated.
After the number n of rotational pulses within one sample time Δ is obtained by subtracting DC, -+, UDC2 is stored (step S5).

Then, based on the above equation (2), the servo motor 1
The rotation speed N of 0 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 human power 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. A capture register 153 for reading and holding a count number and an up counter 154 for alarm counting the output pulses of the rising edge detection circuit 151 are provided.

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 human power 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 rise detection circuit 151, and the rise of the speed command clock is detected in the rise detection circuit 151. 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, if the contents of the capture register 153 are read out based on a certain rising detection signal, the contents of the capture register 153 are read out based on the next rising detection signal, and the difference is found, the free speed in one cycle of the speed command clock can be calculated. The count number of the running counter 152 can be measured. In other words, it is possible to obtain the rotation speed No. that corresponds to the command speed.

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. 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 number of reference clocks within one cycle of the speed command clock is determined.

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

First, the rising edge detection circuit 13 of the encoder signal human 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 PDT (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 PDTn is a value corresponding to the time from the start of motor control to the current pulse rise detection point. .

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

P P I,,=P P I (n-11+sp D
-(4) Here, PPI (fi-1) 'previously stored phase reference value SPD: number of reference clocks during one period of the speed command clock (SPD is a fixed value).

However, since the initial value of PPI o-11 is zero, the phase reference value PPI corresponding to the first rising edge of the speed detection pulse after the start of motor control is detected in step Sll above. The value will be 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, every time the rising edge of the speed detection pulse is detected (step 511)
, reading the count value of the free running counter 133 and the phase comparison value PDT. Update (step 512)
, phase reference value PPI. calculation and update (step 81
3) and calculation of phase difference PHDT (step 514)
is repeated.

9 After the start of motor control, when the second rise of the speed detection pulse is detected at step Sll, step 3
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. In other words, the value of the phase reference value PPIn calculated in step 813 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 PP calculated in step 813
I 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 corresponding to the time 0 (phase reference value PPI,) from the start of motor control to the rising point of the speed command clock corresponding to the speed detection pulse whose rising edge was detected this time is calculated as the speed command. The phase difference PHDT is obtained by dividing by a value (SPD) corresponding to the clock cycle. Therefore, even if the phase difference between the speed command clock and the speed detection pulse is one cycle or more of the speed command clock, the phase difference PHD
T is detected accurately.

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 −(6) Phase difference P
The control voltage v2 by the HDT is determined as follows, assuming that the maximum value of the predetermined control voltage (2) is V2max.

(A) Case 1 during the rise from the start of speed control to the steady state (a) When the phase difference is smaller than 3 cycles (-3<PHDT<+3) V2= (V2nax /3) ・PHDT...
(7) (b) When the phase difference is 3 cycles or more and the phase of the speed detection signal is ahead of the phase of the speed command signal (PHDT≦-3) V2--V2max (8) (C
) When the phase difference is 3 cycles or more and the phase of the speed detection signal lags the phase of the speed command signal (PHDT≧+3) V2−+V2max −(9) Therefore, the phase difference between the phase difference PHDT and the control voltage v2 Relationship is the 6th
The relationship shown in the figure is obtained.

(B) In the case of steady region (a) When the phase difference is smaller than 7 periods (-1<PHD
T<+1) V2−V2max ΦPHDT −= (10
)2 (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=-V2max - (11) (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−+V2max −(12) Therefore, the phase difference between the phase difference PHDT and the control voltage v2 Relationship is the seventh
The relationship shown in the figure is obtained.

After the start of motor control, until the speed rises and reaches the steady range, ■2 is calculated based on the above equations (7) to (9), and when the speed reaches the steady range, the above equations (10) to (12) are calculated. Based on v2
is calculated. Therefore, after the start of motor control, the control voltage for the phase difference is relatively low during the rise until the steady state is reached, and during the steady state, the control voltage for the phase difference is relatively high. As a result, it is possible to prevent the motor rotational speed from increasing to a speed considerably higher than the command speed at the time of startup, and it is possible to improve the followability of the speed at steady state and prevent the servo motor 10 from stepping out.

FIG. 8 shows a steady state reaching detection process by the control unit 14 for detecting that the speed has reached a steady state, and FIG. 9 shows two types of memories M1 and M2 used for this process.
It shows.

In FIG. 9, the memory M1 is for storing rotation speed data for five times in order from the newest one, and has an area for storing new rotation speed data to an area for storing old rotation speed data. Five storage areas E1 to E5 are provided in this order. That is,
The current (latest) rotation speed data N, (n is a natural number, and each time the rotation speed data is calculated, 1. 2.
It increases to 3°... ) is the previous rotation speed data N in E2. -1, is stored in E3 as the rotation speed data N(
n-2) is the rotation speed data N(11-3) from three times ago in E4.
1 is the rotation speed data N from 4 times ago in E5. -4, are stored respectively.

The memory M2 is a memory for sorting, that is, rearranging the five rotational speed data N0 to N (11-41) stored in the memory M1 in ascending order, and has five storage areas Ell to E15.

Five rotation speed data Nゎ~N(
. -4) is sorted, for example, five rotation speed data N, to N(.

-4, the second largest one is stored in area E12, the third largest one is stored in area E13, the fourth largest one is stored in area E14, and the smallest one is stored in area E15. be done. Therefore, when sorting is performed, the area E13 stores only the rotation speed data corresponding to the center of the five rotation speed data stored in the memory M1.

Note that the memories M1 and M2 are not used to store rotation speed data for five rotations, but may be used to store any number of rotation speed data of three or more, preferably an odd number.

5. The steady-state region attainment detection process shown in FIG. 8 is performed each time the rotation speed N is calculated, for example in step S6 of the rotation speed detection process in FIG.

When the rotation speed N is calculated, five rotation speed data N are stored in the memory M1. -N(I+-4) is shifted (step 521). As a result, the previous data N
7 is the previous rotation speed data N. -1° is stored in area E2, and the previous data N (ffi-11 is the rotation speed data N two times before (I+-21 is stored in area E3, and the previous data N. -2, is the third rotation speed data N). The number data N.-3 is stored in area E4, and the previous data Ntn-31 is 4.
The previous rotation speed data N (fi-4) is stored in area E5 and is the oldest data N.-4.
, (rotation speed data from five times ago) will no longer be stored.

Also, the latest rotation speed data N calculated this time.

is stored in area E1 (step 522).

Next, five speed data N stored in the memory M1 including the latest rotation speed data N7. -N.

4 are sorted, and five rotation speed data Nn to N(n-
41 are stored in descending order (step 523). As a result, area E13 contains five rotation speed data N7 to
N. −4, rotation speed data corresponding to the center of magnitude (
This will be referred to as "central data N,") is stored.

Next, the current rotational speed data N1 stored in area E1 of memory M1 is compared with the central data N□ stored in area E13 of memory M1, and it is determined whether or not it is within a certain range of No. It is determined (step 524). 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-α)≦N,≦N, (1+β)... (1
3) However, α and β are values by which it can be accurately determined by experiment or calculation that the preset motor rotation speed has reached a steady range.

That is, in this step S24, the current rotation speed data N. It is determined whether or not the data is within a certain range of data N□ corresponding to the center of the size of the five 7 data of the current and past four times.

If the current rotational speed data Nゎ is not within the range shown by the above equation (13) (NO in step S24), the speed change, that is, the acceleration is relatively large, and the motor rotational speed is still rising. state, and the phase difference P
The current process is ended without switching the relational expression of control voltage (2) for HDT.

If the current rotational speed data Nn is within the range shown by the above formula (13) (YES in step S24),
The change in speed, that is, the acceleration, is relatively small, and it is tentatively determined that the speed has reached a steady range (the first stage of determination is made).

However, in this method, the speed detection signal is
When vibrations such as those indicated by symbol A in Figure A occur, it may be erroneously determined that the steady state region has been reached even though the steady state region has not been reached.

8 To explain with reference to FIG. 12B, which shows an enlarged view of the vibration A in FIG. 12A, rotation speed data N is obtained at time point 1n. is calculated, time t. Data N regarding the motor rotation speed for 5 times of ~ttn-41. -N(.-4, will be stored in the memory M1. Then, the latest data N, , will be the data corresponding to the middle of the magnitude among these data, so in the first stage determination, It is incorrectly determined that the steady state has been reached.

Therefore, in this embodiment, the determination in step S25 is made in order to prevent the above-mentioned erroneous determination.

In step S25, the maximum data Nmax (stored in area Ell of memory M2) and the minimum data Nm1n of the five data for the current time and the past four times are selected.
(It is stored in area E15 of memory M2.)
It is determined whether the difference (Nmax - Nmjn) is within a predetermined range W or not.

Difference between maximum data N max and minimum data Nl1in (
If Nmax - Nmin ) is not within the predetermined range W, it is determined that the speed detection signal is only experiencing vibrations such as those shown in FIGS. 12A and 12B and has not reached a steady state, Control voltage V for phase difference PHDT
The current process is ended without switching the relational expression 2.

If the difference (Nmax - Nmjn) between the maximum data N max and the minimum data NrLlin is within the predetermined range W, it is determined that the determination that the speed has reached the steady range in step S24 is not an erroneous determination due to vibration. The relational expression of the control voltage v2 with respect to the phase difference PHDT is expressed by the above equation (10
) to (12) (step 526), and this process is ended.

In this steady state reaching detection process, data N, which corresponds to the middle of the size of the five data for this time and the past four times, is...
The current rotational speed data N is within a certain range of . The first step is to determine whether or not the motor rotation speed has reached a steady range by determining whether or not the motor rotation speed is in the steady state. 0 - Even if the detected signal changes significantly over time, the signal affected by this is not used for comparison judgment.

Also, this rotation speed data N. However, the motor rotation speed is determined to be steady depending on whether the difference between the maximum data Nmax and the minimum data Nmjn (Nmax - Nmjn) of the five data for this time and the past four times is within a predetermined range W. The second step is to determine whether or not the steady state has been reached, so even if vibrations occur in the speed detection signal between the start of control and the time the steady state has been reached, it is determined that the steady state has been reached. There is no misjudgment, and the detection of reaching the steady state region is performed accurately.

In the above control, the first stage determination in step S24 and the second stage determination in step S25 may be for forward or backward movement.

The control voltage v1 based on the speed difference ΔN is expressed by the following equation.

V1=Ra(GD2　ΔNTBL 9 +Io+ 1 375KT Δt K.

+KeN 1 =RaGD'・AN+KeN 375KT Δt +Ra (IO+TBL/KT) −(1
4) However, Ra: Amateur resistance [Ω]: Torque constant [kgm/A] Ke: Induced voltage constant [V/rpm Io: No-load current [A] GD2: Moment of inertia due to load and motor [kg
m2] TBL two sliding load [kgm].

The control unit 14 detects the rotation speed N of the servo motor 10 (step S6 in FIG. 3) and calculates the speed difference Δ from the command speed N0.
Each time N is calculated or the phase difference PHDT is calculated (step 514 in FIG. 5), the above equations (6) to (1
Based on 4), calculate VO and adjust PWM accordingly.
Output data. This PWM data is sent to the PWM unit 16, and the servo motor 2 is controlled via the driver section 11.

FIG. 10 is a block diagram showing a specific example of the configuration of the PWM unit 16, and FIG. 11 is a timing chart for explaining the operation of the PWM unit 16.

The PWM 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 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.

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 expressed by the above-mentioned formula (6
) is the voltage data determined by That is, it is the voltage vO obtained by correcting the voltage V1 in equation (14) 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 sent to the down counter 16.
3, and the flip-flop 164 is turned on by the set signal. Therefore, the output of the flip-flop 64, 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", the flip-flop 16
4 Heliset signal is given. Therefore, the output of flip-flop 164 is inverted to low level.

As a result, the duty is determined from the value held in the PWM data register 162, that is, the voltage data calculated by equation (6), and a PWM signal is derived from the PWM unit 16.

The present invention is applicable not only to control of the optical system of a copying machine 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 reliably detect when the motor rotation speed reaches the steady state from the transient response range, regardless of the magnitude of the load.

In addition, even if the speed detection signal is temporarily adversely affected by instantaneous load fluctuations or noise, the influence will not appear in the discrimination results, and it will be possible to accurately detect when the rotation speed has reached a steady state. can.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the electrical configuration of a drive control circuit for a DC servo motor for driving an optical system 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 block diagram showing an example of the electrical 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. FIG. 6 is a graph showing the relationship between the control voltage V2 and the phase difference PHDT used at the time of speed rise. FIG. 7 is a graph showing the relationship between the control voltage v2 and the phase difference PHDT used in steady state. 6. FIG. 8 is a flowchart showing the steady-state region arrival detection processing procedure in the embodiment of the present invention. FIG. 9 is a diagram showing two memories M1 and M2 used for the steady state reaching detection process. FIG. 10 is a block diagram showing a specific electrical configuration of the PWM unit. FIG. 11 is a timing chart showing the operation of the PWM unit. FIG. 12A is a diagram for explaining the problem solved by one embodiment of the present invention, and is a time chart of the speed detection signal when vibration occurs in the speed detection signal. FIG. 12B is an enlarged view of the vibrating portion indicated by the symbol A in FIG. 12A. 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 human power section, 16...PWM unit, M
1, M2...indicates memory. 7

Claims (1)

[Claims] 1. In a motor control device that performs feedback control of a motor so that the motor rotation speed becomes equal to a command speed, means for calculating data regarding the motor rotation speed at each predetermined timing; data regarding the motor rotation speed; It has a storage area that can store a predetermined number of times in chronological order, and each time data related to the motor rotation speed is calculated, the already stored data is sequentially shifted one by one, and the currently calculated data is stored. A storage means for storing the latest data in the latest data storage area; 1 Discrimination means: When the first discrimination means determines that the latest data is within a predetermined range with respect to the data corresponding to the center of magnitude, the maximum of the data of multiple times stored in the storage means A means for calculating the difference between the data and the minimum data, a means for determining whether the difference between the maximum data and the minimum data is less than or equal to a predetermined value, and when the difference is less than or equal to the predetermined value, the motor is rotated. A steady-state region reaching detection device in a motor control device, comprising: second determining means for determining that the speed has reached the steady-state region.