JPH0352577A - Computer for control voltage of motor - Google Patents

Abstract

PURPOSE:To control a motor with excellent follow-up properties by providing a computing means computing control voltage as the sum of a value obtained by multiplied the difference of the target speed of revolution and the actual speed of revolution by a first constant, a value acquired by multiplying the actual speed of revolution by a second constant and offset voltage, a semple- value measuring means and a means correcting the constants. CONSTITUTION:A DC servo motor 10 is turned and driven by a driver section 11, an optical system 17 is moved, the computation of a control signal and arithmetic processing are conducted by a control section 14, and the speed of revolution of the servo motor 10 is controlled by a PWM unit 6. The control section 14 reads the contents of a capture register 153 and an up counter 154 at the specified sampling time, acquires the difference of the number of counting at this time and the previous time, calculates the accurate number of reference clocks, and computes applied voltage from the difference of the actual number of revolution and the command number of revolution.

Description

[Detailed description of the invention] Industrial application field> The present invention relates to a motor control signal calculation device, and in particular,
The present invention relates to a PWM signal calculation device when controlling the rotational speed of a motor using a PWM signal.

BACKGROUND ART Some motor rotational speed control devices are designed to perform control using PWM signals.

Such a rotation speed control device is also used, 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. , it takes longer to reach the target speed,
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 -V-Ra(10+Tab/Kt)-(1).

Solving this for n, if n=Np at t-0, then , -V-R a (IO + TBL /Kt)
KE Also... It becomes 12KoU 375KTKE dt RaGD2 on the left.

From this formula, the acceleration a during the time when the sampled speed is Ns and the voltage V is given by substituting Np-Ns, t-0 when RaGD2 (4).

By the way, the target speed is sampled N1 and the t2 speed is N1.
S, and if the difference is ΔN, the acceleration a when V-KΔN-K (N-Ns) is applied by normal proportional control is calculated by using V-KΔN, Ns-N-ΔN in equation (4). Substituting: a. ．． ．． 375KTKE RaGD2 (N-ΔN)1 ,,, 3 7 5 KT KE RaGD2 × { (K/KE +1) ΔN-N From this formula, even if ΔN is the same value, if the target speed N is large, the acceleration a will be It can be seen that if N is small, a becomes large.

Therefore, the present invention has been made to eliminate such drawbacks, and an object of the present invention is to provide a control signal calculation device that can control a motor with good followability.

Means for Solving the Problems> The present invention is an apparatus for calculating a control voltage for controlling the rotational speed of a motor, and the control voltage is calculated based on the difference between the target rotational speed and the actual rotational speed. A calculation means that calculates the sum of a value multiplied by a constant, a value obtained by multiplying the actual rotational speed by a second constant, and a predetermined offset voltage, and an optical system is stopped at a predetermined position and the motor is activated by a constant applied voltage. sample value measuring means for accelerating the motor and sampling the speed and time at that time, and then stopping the motor; and correcting means for correcting the first constant and the second constant calculated by the calculating means from the measurement results of the sample value measuring means. A control voltage calculation device for a motor, characterized in that it includes:

When the control voltage is determined by this invention, the acceleration is determined by the speed difference between the target speed and the actual speed, regardless of the target speed, and by selecting the acceleration constant to an arbitrary value, the acceleration is determined by the speed difference between the target speed and the actual speed. A desired acceleration can be obtained for the speed difference.

Further, the theoretically calculated predetermined first constant and second constant are corrected using actually measured data.

Therefore, even if the motor addition differs slightly depending on the model, the first constant and the second constant can be corrected accordingly.

Embodiments Hereinafter, an embodiment of the present invention will be described, taking as an example a case where the present invention is applied to a drive 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 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 is a circuit that uses a PWM signal as the voltage applied to the DC servo motor.

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 low-return 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 an A-phase rotation pulse and a B-phase rotation pulse, and both rotation pulses have an equal number (200 rr! A per motor rotation) and are out of phase with each other. The pulses are shifted by 90 degrees.

The rotation pulse output from the rotary encoder 12 is
The signal is applied to the encoder signal input 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,
It calculates control signals for the servo motor 10 and performs other arithmetic processing.

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 determined by a speed command clock from a control section (not shown) of the main body of the copying machine at a speed command signal input section 15.
The signal is applied to the control section 14, subjected to signal processing, and then sent to the control section 14. The details will be described later.

The control unit 14 executes arithmetic processing based on each of these input signals, and calculates PWM (pulse width mod
ulation) data and calculates the PWM unit 16
At the same time, a driver unit drive signal is also applied to the driver unit 11 described above.

The PWM unit 16 is a unit for changing the pulse width (output 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 input 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 the A-phase rotation pulse outputted from the rotary encoder 12 is applied. The edge detection circuit 131 detects the rising edge of the applied rotation pulse and derives its detection output.

The encoder signal input section 13 also includes a free running counter 133 of, for example, 16 bits that counts up the applied reference clock, and a capture register 134. The capture register 134 is
The edge detection output of the edge detection circuit 131 is used as a capture signal, and the count number of the free running counter 133 is read and held using the capture signal as a trigger.

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 composed of a microcomputer, a machine clock is used.

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

The 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 16 1 3 1 based on the determined 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 A-phase rising edge detection signal. Further, the updown counter 136 counts the edge detection signal (number of rotation pulses).

Therefore, while the up/down counter 136 counts n rotation pulses, the free running counter 1
The number of reference pulses counted at 33 can be measured, and the rotation speed N can be calculated based on it. The number of rotations N is expressed as N-Constitutional X (6), and the relationship between the number of rotations N and the error N'' is as follows.

If these relationships are represented in a graph, it will be as shown in FIG. 3A.

In this embodiment, focusing on the relationship between the rotation speed N and the error N', the control section 14 devises the sample timing for reading the counts of the capture register 134 and the up-down counter 136, so that the rotation speed N is By increasing the number of rotational pulses n used to calculate the rotational speed N as the rotational speed N increases, the error N', which tends to increase at a square rate as the rotational speed N increases, can be calculated using equation (7). As shown, the error N' is limited to increasing at the rate of the first power.
This makes it possible to accurately detect the rotational speed N.

To explain more specifically, if one sample time from one sample timing to the next sample timing is Δt, in order to detect the rotation speed N, the sample time Δ
At least one rotation pulse, ie, the output of the edge detection circuit 131, must be derived within t.

In order to do so, the above equation (6) must satisfy the requirement of X≦Δt, and in the end, the rotation speed N and the error N′ are N′′(1/Δt)N...(8 ) is necessary. The relationship of equation (8) is
As shown in FIG. 3B, it is above the straight line N--(1/Δt)N.

Therefore, by setting the sampling time Δt to an appropriate constant time that satisfies the relationship of equation (8), the thick line portion in Fig. 3B, that is, the range where the error N' is relatively small for the rotation speed N, can be effectively utilized. Thus, the rotational speed N can be detected.

FIG. 4 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.

Next, explanation will be given with reference to FIG. 2, FIG. 3B, and FIG. 4.

The control unit 14 has an internal timer 1 set to a constant sampling time Δ.
Each time the timer 1 reaches t (step S1), the timer 1 is reset (step S2), and the contents of the capture register 134 and the up/down counter 136 are read (step S3).

Then, from the read count number CPTn of the capture register 134, the count number CPTn of the previously read capture register 134 stored in the memory A is calculated.
After subtracting h-+ to find the number of reference clocks X within one sample time Δt, CPTn is stored in memory A (step S4).

Also, from the read count number UDCn of the up/down counter 136, the count number UDCn of the up/down counter 136 read last time stored in the memory B
After subtracting n-+ to find the number of rotational pulses within one sample time Δt, UDCn is stored in memory B (step S5).

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

Note that in steps S5 and S6, the servo motor 1
As mentioned above, if the rotational speed N of the servo motor 10 increases, the rotational pulse number n also increases stepwise within the sample time Δt, so the rotational speed N of the servo motor 10 can be detected using the thick line part in FIG. 3B. It is as follows.

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

FIG. 5 is a block diagram showing a specific horizontal example of the speed command signal manual 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 a 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 reference 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
By reading the contents of 3 and reading the contents of the capture register 153 based on the next edge detection signal and finding the difference, 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, target rotational speed data can be obtained.

Note that in this embodiment, each time the contents of the capture register l53 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 the detection accuracy. , 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 number of reference clocks within one cycle of the speed command clock is obtained by dividing the value by the difference between the count number read this time and the count number read last time in the up counter.

Next, a method of calculating the output voltage V will be explained.

The control unit 14 calculates the applied voltage expressed by the following formula from the difference between the actual rotation speed NS of the servo motor 10 detected as described above and the command rotation speed N given from the speed command signal human power unit. do.

+KENs 375KT Δt +R a (10 +Tg t./KT)
- (9) The acceleration when the voltage expressed by this formula is applied is calculated by substituting formula (9) into the above formula (4) and calculating N
Replaced with SN-ΔN, a=375KvKE Ra GD2 10KE NB -Ra (10 +TB L /KT
) 1÷KE-Ns] 375K7 KE, Ra, GD2. ΔNR
aGD2 375KT ΔtKE ΔN Δt (10) The value obtained by dividing the speed difference ΔN by Δt is the acceleration,
By optimizing Δt, a constant optimum acceleration can be obtained for ΔN.

Next, the process of deriving the above equation (9) will be explained.

FIG. 6 is an equivalent circuit diagram of a permanent magnet field type DC servo motor.

When a signal voltage V is applied to the motor armature and the angular displacement θ of the rotating shaft is obtained as an output, the motor transfer function is L a-! -L1RaI +EV-
It is derived as (1 1)dt.

The induced voltage E of the motor is proportional to the angular velocity ω of the rotating shaft, so dt However, KE: Induced voltage constant The generated torque is proportional to the armature current I, so T''-K
T I ... (13) However, KT: Torque constant Now, if the sum of the sensitive moment of rotor and load is J, and the braking load of the motor including bearing loss is B, then the load torque TL is dt Motor Since the generated torque and the load torque are equal, dt is obtained.

Generally, the inductance La of an amateur circuit is designed to be small compared to the moment of inertia J, so La-0
, In addition, since the braking load B can also be ignored, if it is set as B-0, then Equation (11) becomes V-Ra I+E - Equation (16) (
14) becomes dt.

Moment of inertia] [KgIIlsec2] is actually GD2 It is more convenient to use [Kgm2], so GD
Change to 2.

GD2=Mg (2k) 2...(18
) Here, G-Mg: Weight of object [Kg] M: Mass g: Gravitational acceleration [9. 8ml see2] k: radius of rotation Physical moment of inertia J [Kgmsec2] is
Considering that all the mass is concentrated at a certain distance, J-
Mk2 is expressed as (19). Therefore, GD2-4gJ...(20)
becomes.

From equations (17) and (20), 4g From equations (21) and (22), TL-GD2.2π　ΔN 4g 60 Δt 2"・Lord's Day・GD2 4gX60 Δt therefore, becomes.

This equation (23) represents the torque required to obtain the amount of change ΔN in the rotational speed during the time Δt.

Since the required load torque is the torque generated by the motor, KTI-GD2 ΔN 375 Δt can be obtained from equations (13) and (23).

Here, from equation (13), the generated torque and current are proportional equations with K as a constant, but the required current (
(no-load current).

Now, if the no-load current is IO, becomes.

Next, since the actual drive control method is a voltage drive type using PWM, from equations (16) and (25), (26) is obtained.

Here, the induced voltage E is E-KEN However, KE: induced voltage constant Therefore, equation (26) is (27) becomes.

By the way, equation (27) does not include terms of sliding load and braking load on the motor. Therefore, if this sliding load and braking load are TEIL, then the braking load TBM of the motor calculated from the no-load current IO is as follows, and the braking load T (Bω) in equation (14) is between TB TBL + TB. Become.

This results in Formula (27) teeth, Ten Ra (TBL/KT) +KE N +KEN (31) becomes.

From the above, if a speed difference ΔN occurs with respect to the target speed N, +KEN 3 7 5 KT Δt +Ra (10 +TBL/KT) −
The voltage V obtained in (9) may be applied to the motor.

Note that the constants determined by the load and motor actually used are: Ra: Amateur resistance [Ω] KT: Torque constant [kg+ll/A] KE: Induced voltage constant [V/rpm] ■ o: No-load current [A] GD2: Moment of inertia due to load and motor [kg
rs2] TRL: sliding load [kg+a].

Therefore, N, ΔN1Δt become variables during control.

By the way, in the above equation (9), the first term is the first constant that is multiplied by the difference between the target rotation speed and the actual rotation speed, the second term is the second constant that is multiplied by the actual rotation speed, and the third term is Each offset voltage is a calculated value, and although it is theoretically constant, it actually changes slightly.

This is because, if the servo motor 10 is a servo motor for driving the optical system of a copying machine, for example, there will be slight variations in the dimensions of the optical system depending on the model, and differences in wire tension and sliding friction included in the optical system. This is because the motor load varies slightly due to factors such as.

Furthermore, even when the optical system moves, the sliding resistance and other factors differ slightly depending on the position of the optical system, which causes the motor load to change slightly.

Therefore, in this embodiment, the first constant, second constant, and offset voltage calculated as described above are actually measured by performing the control described below, and corrected for each actual device.

FIG. 7 first shows a flowchart of the offset voltage measurement operation.

The control unit 14 determines whether the sample speed n of the servo motor 10 is 0 or not based on the output from the encoder signal input unit 13 (Step S11), and if the servo motor 10 is rotating, performs braking. (Step S1
2) The sampling rate n detected by the encoder signal input section 13 is set to 0 (step S13).

Next, the control section applies the PWM signal to the PWM unit 16.
After resetting the data VPWM to O (step S14
), set timer 2 to 0, and set PWM data VPW
M is increased by the minimum unit voltage (step S15), the PWM data VPWM is given to the PWM unit 16, and the voltage V is applied to the servo motor 10 for the time t1 measured by the timer 2.
Apply PWM (steps S16, 517, S18)
Then, if the sampling speed n of the servo motor 10 remains 0, the PWM data VPWM is further increased by the minimum unit voltage, and the servo motor 10 is attempted to be driven for a time t1 based on the increased PWM data VPWM, and the following steps are performed. Similar control is repeated (steps S15 to S19).

When the servo motor 10 starts rotating, the servo motor 10 is braked to stop its rotation (steps S20, S21), and the minimum unit voltage is subtracted from the PWM data VPWM at the moment when the servo motor 10 starts rotating. The value obtained is set as the offset voltage vO (step S22).

Next, a method of correcting the first constant and the second constant will be explained.

The correction is l. Actually, the servo motor 10 is driven in the control circuit shown in FIG. 1, and a predetermined sample value is sampled.

■． The procedure is to perform calculations to correct the first and second constants based on the sampled values.

Next, I. and ■. Let me explain.

I. The sample method will be described with reference to FIG. 8. ■ From the state where the servo motor 10 is stopped,
A WM signal is applied to the servo motor 10.

■The time when the PWM signal is output is set as 1-0, and the minute time t
Measure the motor speed nQ after o seconds.

(2) Determine the motor speed n1 after t1 seconds from time 1-0 (t1 >> to).

■Speed n after t2 seconds from time to (t2-t1+to)
Find 2.

■ Apply braking to stop the servo motor 10.

■． The rotational speed n and acceleration a=(dn/dt) of the correction calculation motor are expressed by the equations (2) and (3) explained above, respectively, so V(1 −Ra (10 +TlIL/KT)) Then, Equation (2) and Equation (3) become n−■” [1−exp (− (y/x) tl
]y (32) a−v” exp ((y/x) t)X (33)

? Calculating 8■, a1 from the values sampled in , ao - no / t (3 (34) a1 (n2 - n1 ) /to (35) and substituting this into equation (33), a0 V - V0 X ( 36) V-Vo a1 ″'-e x p exp (- (x2/x1)t+)
l]... (38) Formula (36). From equation (37), exp (- (y/x)t1)=a1/ao Substituting this into equation (38), y. '． y=v−VO(1−81/ao) −
(39)n1 Also, from equation (36), x-V-Vo...(40)a0.

The control unit 14 performs the sampling method and correction calculation described above.
The operations executed by the controller are shown in the flowchart of FIG.

Next, the control operation shown in FIG. 9 will be explained.

The control unit 14 receives signals from the encoder signal input unit 13? Based on the signal, it is determined whether or not the servo motor 10 is rotating (step S31), and if it is rotating, the rotation of the servo motor 10 is stopped (steps S32 and S3).
3).

In this state, set the timer 3 that measures the sample time to O, output v1 as PWM data, start the timer 3, and wait for the timer 3 to measure the time to (steps S34, S35, S36, S37). ). When the timer 3 counts to, the motor speed given from the encoder signal input section 13 is sampled as speed n■ (step S38).

Next, the speed n of the servo motor 10 when the timer 3 measures time t1 is sampled as the sample speed n1 (steps S39 and S40).

Furthermore, a sample is made assuming that the timer 3 has timed the time t2 (step S41.342).

After that, the control unit 14 stops the servo motor 10 (
Step 343, S44), a expressed by the above-mentioned formula (36), formula (37), formula (3), and formula (40)
. + aj+ x+! / is calculated (step S
45, S46).

Then, based on this calculation result, the first
Correct the constant and second constant.

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 (9
) is the voltage data determined by 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 also set by the set signal. Therefore, the output of the flip-flop 164, that is, the PWM output signal becomes high level.

Next, the down counter 163 performs down counting based on the PWM reference clock, and when the set count value reaches "0", a reset 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 from the value held in the PWM data register 162, that is, the voltage data calculated by equation (9), and a PWM signal is derived from the PWM unit 16.

FIG. 12 is a circuit diagram showing an example of the driver section 11. The driver section 11 includes, for example, a transistor bridge circuit as shown in FIG.
0 can be rotated forward and reverse.

The driver unit drive signal from the control unit 14 is input to the input terminal 11.
1, when the driver part drive signal is at a high level, the servo motor 10 rotates in the normal direction, and when it is at a low level, the servo motor 1
0 is reversed.

Further, the PWM signal from the PWM unit 16 is applied to the input terminal 112, and the motor is turned on/off by switching the PWM signal between high level and low level.

To briefly explain the operation, human power terminals 111 and 1
When a high level signal is applied to transistor 12, transistor 1
14 and 115 are turned on, current flows in the direction of arrow a to the servo motor 10, and the servo motor 10 rotates normally.

On the other hand, input terminal 111 receives a low level signal, input terminal 11
When a high level signal is applied to transistor 11
6 and 117 are turned on, and the servo motor 10 moves to arrow b.
A current flows in the direction, and the servo motor 10 rotates in the reverse direction.

Further, when the input terminal 112 is at a low level, energization of the servo motor 10 is prohibited.

The present invention is not limited to the control of the optical system of the copying machine described above, but can be applied to a motor for controlling a reading device of a facsimile machine and other general motor control circuits. Also, PWM
It can also be applied when calculating applied voltages in forms other than signals.

Effects of the Invention Since the present invention is configured as described above, it is possible to calculate a control signal that can keep the acceleration at a constant value regardless of the target speed. Therefore, the speed of the motor can be controlled with good followability regardless of the target speed.

The first constant and the second constant are corrected regardless of the load fluctuation of the master motor, and the speed of the motor can be controlled with good followability.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall 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 shows a DC for driving an optical system according to an embodiment of the present invention.
FIG. 2 is a circuit block diagram showing the main part configuration of a rotational speed detection device for a servo motor. Figures 3A and 3B show the motor rotation speed N and the error N.
This is a graph showing the relationship between FIG. 4 is a flowchart showing the rotational speed detection operation in one embodiment of the present invention. FIG. 5 is a block diagram showing a specific example of the structure of the speed command signal manual section. FIG. 6 is an equivalent circuit diagram of a permanent magnet feed type DC servo motor. FIG. 7 is a flowchart of the offset voltage measurement operation. FIG. 8 is a diagram for explaining the principle of sampling speed data and time data. FIG. 9 is a flowchart of control operations for sampling speed data and time data. FIG. 10 is a block diagram showing a specific configuration of the PWM unit. FIG. 11 is a timing chart showing the operation of the PWM unit. FIG. 12 is a circuit diagram showing an example of a driver section.

Claims (1)

[Claims] 1. A device for calculating a control voltage for controlling the rotational speed of a motor, the control voltage being a value obtained by multiplying the difference between the target rotational speed and the actual rotational speed by a first constant. , an arithmetic means for calculating the sum of the actual rotational speed multiplied by a second constant and a predetermined offset voltage, and an optical system that is stopped at a predetermined position, and the motor is accelerated by a constant applied voltage. sample value measuring means for stopping the motor after sampling the speed and time of the motor; and correction means for correcting the first constant and the second constant calculated by the calculation means from the measurement results of the sample value measuring means. A motor control voltage calculation device characterized by: