JPH01138986A - Acceleration controller for motor - Google Patents

Abstract

PURPOSE:To minimize the peak value of consumption energy per unit time and enable acceleration or deceleration to be performed in a short time, by setting acceleration for rotating a motor, to be in inverse proportion to a speed. CONSTITUTION:From a CPU 1, the output of an internal speed command value theta2' is generated based on an external speed command value theta2, the control signal of the forward rotation, the reverse rotation, the stop, and the like of a motor, and a slowly incremental/decremental time T for suggesting the acceleration or deceleration time of the motor. Then, from an acceleration or deceleration regulator 3, the output of a current command value is generated according to a deviation between the internal speed command value theta2' and a speed detection value. Besides, by a current regulator 4, a deviation between the current command value and a current detection value is applied to a power converter 5. Then, by the CPU 1, arithmetic is performed on the internal speed command value theta2' so that acceleration may be in inverse proportion to a speed, and the output is generated. As a result, the peak of consumption energy is minimized, and the accelerator deceleration can be performed in a short time.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to an acceleration control device for motor rotation, and more specifically, to an acceleration control device for motor rotation, and more specifically, to achieve economical acceleration/deceleration when accelerating or decelerating a motor during operation, that is, energy consumption per unit time. The present invention relates to an acceleration control device for motor rotation, which minimizes peaks in motor rotation and can perform acceleration and deceleration equivalent to conventional methods in a short time.

[Conventional technology]

For example, DC motors and AC motors used in machine tools, elevators, etc. are controlled to accelerate or decelerate by receiving a final speed command or a final position command from the outside by appropriate means.

The value of the final velocity or the value of the final position may be a constant value until the response of these motors is completed, or may be a value that changes from time to time without waiting for the response to be completed.

Here, a conventional motor speed control device that receives a final speed command will be explained with reference to FIGS. An example of a servo control device that generates a signal, compares it with the motor's constantly changing position detection signal, and applies this position difference signal to the speed command section as if it had received a speed command from the outside is explained with reference to FIG. do.

The speed control device 100 shown in FIG. 9 detects the rotational speed of a motor and controls the rotational speed of the motor.

Speed command unit 1 that issues command signals in response to external commands
The output terminal of 01 is an adder/subtracter 1 consisting of an operational amplifier, for example.
02.

The output end of this adder/subtractor 102 is connected to a regulator 103, and the output end of this regulator 103 is connected to a power converter 104. A source power (not shown) is input to the power converter 104, and this source power is supplied to the motor 105 as controlled power.

The rotational speed of the output shaft of the motor 105 is detected by a suitable speed detector 106, and this detection signal is fed back to the second input terminal of the adder/subtractor 102. In the above device, IO2, 103, and 104 are often referred to as motor drivers. The size of these motors and motor drivers (especially the power converter) depends on the energy they consume per unit time; the larger the peak of energy consumption per unit time is, the larger and more expensive they become. .

And, the speed control device 100 configured in this way
is the new command speed 62. When a signal such as σ3 is applied to the speed command unit 101 from the outside, the speed command unit 101 generates a command signal σ having a temporal slope in order to alleviate sudden changes in command speed and smoothly accelerate and decelerate. It looks like this.

In the first example, speed control is performed by the speed command unit 101 generating a speed (4) having an exponential characteristic as shown in FIG. 11(a), which has a simple circuit configuration.

For example, between time t and xjz, the speed d is calculated by the following formula (
1). Note that α is a time constant.

fl= (/?z #+) (1e-”) +6,
5o-non-...(1) Furthermore, the acceleration i becomes as in equation (2) when equation (1) is differentiated.

f = (7z 4+) αe-... Old, old, old... (21 And the power W per unit time that the motor does to the external drive object is the speed Since it is proportional to the product of σ and acceleration i, it is expressed as equation (3).

Wocf(J=tx (dz-4,+)"e4' (1
−e−”)+α(σ2−σ1)σ, e−σ1...
...(3) Note that the response completion time (the time it takes for the detected speed to reach the command speed) tz is theoretically infinite (practically speaking, it is 98 times 1/α x 4). .5% respond).

The change from 62 to d (time t3 to ta) is also the same as described above. As is clear from Figure 11 (C), acceleration/deceleration control with this exponential characteristic has a large peak energy consumption per unit time (wm) of the system, and it takes a long time to complete acceleration/deceleration. It has the disadvantage of being infinite (theoretically infinite).

Therefore, in order to improve such drawbacks, the speed command section 10
A case where so-called linear acceleration/deceleration is used in which the output of 1 changes at a constant rate over time (acceleration i is constant) with respect to external command human power j1-σ2 will be explained with reference to FIG.

That is, at times t to t2, the speed σ becomes as shown in equation (4).

Further, the acceleration i is as shown in equation (5).

Furthermore, the power W is as shown in equation (6).

In this speed control method, as shown in FIG. 12(c), the peak value of the power is Wc, which is smaller than the power W shown in FIG. 11. Moreover, t2 in FIG. 12 can be made much smaller than t2 in FIG. 11.

However, the power required for acceleration and deceleration increases at high speeds depending on the kinetic energy, and the energy consumption capacity per unit time of the system is required to be large.

On the other hand, the motor speed control device using the position control device (usually called a servo control device) shown in FIG. 10 is used to perform speed control with higher precision than the device shown in FIG. works like this.

A command indicating a new position is issued from the outside to the command position generation unit 107.
, the generator 107 outputs a position command signal that changes from time to time to the adder/subtractor 108 when there is a difference in position from the previously given command position; from time to time depending on the rotation of the motor. The constantly changing position detection signal is detected by the position detector 109 and fed back to the adder/subtractor 108.

The output of the adder/subtractor 108 is a signal indicating the position difference between the commanded position and the detected position, and this signal is given to the speed command unit 101 shown in FIG. 10 instead of the external command shown in FIG. 9. The signal forming the position difference takes a smooth temporal change depending on the response performance of the position feedback control system shown in FIG.

Therefore, the command section 101 simply operates as a regulator that multiplies the position difference signal by gain.
The operation of each part is similar to that shown in the figure. The device shown in FIG. 10 has the ability of a position control device because the command is a position and the detection is also a position, and is usually called a servo control device. This position control device controls the speed of rotation of motor 105.

The command position generation unit 107 generates the generated speed based on an external command (command indicating positional movement per unit time, that is, speed) so that the position changes from time to time, for example, with one pulse as a unit of movement amount. A position command pulse train corresponding to the command speed is applied to the addition side of the adder/subtractor 108. In this case, the adder/subtractor 10B is composed of a reversible counter and a DA converter that converts the accumulated value (digital data) of the counter into analog data. The pulse encoder is a pulse generator, and is fed back in the form of a pulse train in which one pulse is a unit movement amount, and is applied to the subtraction side of the 108 counters (addition/subtraction units).

Now, this position control device can achieve a steady speed deviation of zero when the command speed is constant using well-known control capabilities. Therefore, it is often used for more accurate speed control circuits than the device of FIG.

When the gain of the position feedback loop of this position control device is high, although the change in the position difference signal that is input to the command section 101 is smooth as described above, it has the following characteristics. That is, (1) when the temporal occurrence rate of position command pulses changes stepwise, the temporal change pattern of the position difference signal becomes an exponential pattern shown in FIG.

(2) When the temporal rate of occurrence of position command pulses increases or decreases in a linear manner, the temporal change pattern of the position difference signal becomes approximately the linear acceleration/deceleration pattern shown in FIG.

Therefore, even when the speed is controlled with high precision by the position control device shown in FIG. 10, the problems described above with reference to FIGS. 11 and 12 still exist.

That is, in the conventional speed control operations shown in FIGS. 11 and 12, the energy consumption per unit time is large, so the size of the motor and power converter is extremely large. .

[Means for solving problems]

In order to solve the above problems, the present invention makes the acceleration of motor rotation inversely proportional to the speed.

Next, the present invention will be explained in detail.

Generally, kinetic energy (1/2Ji 2 in a rotating system
) is equal to the work done during that time.

This is derived from Newton's equation of motion. however,
J is the moment of inertia of the rotation type including the motor.

Let W be the work done per unit time (work rate) for the outside of a certain system. If this system is to reduce the maximum value of the power W as much as possible and perform a large amount of work during a certain period of time, it suffices if the power W is constant during this period.

That is, since the energy consumed by the system is proportional to the work done outside the system, if W=constant, the maximum value of the energy consumed by the system per unit time is the minimum.

If this is expressed as a differential equation, it will be as shown in equation (7).

Solving this equation yields equation (8).

From equation (9), W/J is a constant, so 11, that is, the acceleration, may be set to a value inversely proportional to the magnitude of the velocity j at that time.

From formula (7), σ"=2 - t + C... Old... αψ Here is 6, Z as the value of 6z at Crt=O.

Therefore, Ql), from equation (2), equation (8) is f tj = - (= constant) It has been established as follows.

The state of velocity and acceleration at this time is illustrated in Figure 1 (
The results are as shown in a), (b), and (c).

In the case shown in Fig. 1, the speed increases from d, to σ8, and then j
, shows the case where it changes to .

The method shown in Fig. 1 has a much shorter completion time than the exponential method shown in Fig. 11, even though the same acceleration/deceleration is performed, and the energy consumption capacity of the system is minimized. As a result, the system configuration can be realized in the most economical manner.

That is, the power WA shown in FIG. 1(c) is WA less WIl than the power W shown in FIG. 11. Furthermore, compared to the linear accelerator/decelerator shown in Figure 12, the system shown in Figure 1 takes a little longer to complete in the high-speed range, but in the low-speed range it makes full use of the consumed energy. The completion time will be drastically shortened. In addition, the energy consumption capacity of the system per unit time is minimal, and the power WA is Wc smaller than the power W in FIG.

In particular, the method shown in FIG. 1 does not require provision for wasteful energy consumption for systems with large J, and its economical effects are significant.

Additionally, ranges where the kinetic energy is small (e.g., at rest -
The time required for acceleration and deceleration at low speeds can be made shorter than in the systems shown in FIGS. 11 and 12 by making full use of the energy consumption capacity. For this reason, in production systems such as factories that normally operate and stop frequently, this method is superior to the methods shown in Figures 11 and 12 by making full use of the small consumption capacity and consuming energy. You can gain productivity.

Furthermore, as energy to be utilized when decelerating the motor, in addition to the power source as the source energy, kinetic energy of the rotational system (because the motor acts as a generator) can also be utilized. Therefore, it is possible to achieve a larger acceleration during deceleration than during acceleration. The limit is the electrical strength of the motor driver (mainly the voltage and current strength of the power converter).

Next, in a motor speed acceleration/deceleration device that makes the acceleration inversely proportional to the command speed in order to minimize the maximum energy consumption per unit time, when the speed is zero or extremely low, the acceleration 6° is calculated by the formula (9 ), it becomes an extremely large value, and it is necessary to limit it in a finite signal and power range. Practically speaking, the following means may be added.

That is, the torque control current of the motor driver that drives the motor is proportional to i, and it is necessary to avoid saturation of the current within the motor driver to perform normal control. For this reason, in order to suppress the peak of the torque control current by sacrificing (extending) some acceleration/deceleration time, when the command speed at the start of acceleration/deceleration is below a predetermined value, the command speed after the start of acceleration/deceleration will reach the predetermined value. The commanded speed is controlled so that it is accelerated or decelerated in a time-wise manner, for example, linearly (see the circled area in FIG. 2(a)).

By doing this, during the speed change, the peak of i in FIG. 1 is made smaller and flattened as shown in FIG. 12. In this way, the time 6
The peak values of d and torque current can be suppressed by as much as 10% just by extension.

That is, as shown in FIGS. 2(a) and (b), 1°~
At σ1~f1° corresponding during t'+1,
The peak of fI is changed from the dotted line portion (corresponding to the solid line portion in FIG. 1) to the solid line portion in FIG.

In this way, the power WA can be reduced by only slightly sacrificing acceleration/deceleration time, as shown in FIG. 2(C).

〔Example〕

The present invention will be explained below based on illustrated embodiments.

FIG. 3 is a block configuration diagram showing a first embodiment (speed control device) of the motor rotation acceleration control device of the present invention,
Figure 5.6 is a flowchart showing the command operation for this speed feedback looseness, Figure 7 is a diagram showing the operation pattern of acceleration/deceleration of the motor, and Figure 8 is a flowchart showing the operation pattern of the acceleration/deceleration of the motor. ) is an operation explanatory diagram showing an enlarged version of FIG.

First, the block configuration of FIG. 3 will be explained. The embodiment shown in FIG. 3 corresponds to the conventional motor speed control device shown in FIG. 9.

The CPU, which is made up of a microcomputer, etc., receives an external speed command value (d2) that is the final attained speed of the motor, and control signals for forward rotation, reverse rotation, stop, etc. of the motor.

The slow-up/down time (T), etc. that specify the acceleration/deceleration time of the motor is input.

When various signals such as those mentioned above are input to the CPUI, this C
The process shown in FIG. 5.6 is performed in the PU 1, and the internal speed command value (σ) is supplied to the D/A converter 2. An analog signal is supplied from this D/A converter 2 to a first input terminal (addition side) of an addition/subtraction/speed regulator 3.

A current regulator 4 is connected from the output end of this addition/subtraction/speed regulator 3.
A signal is output to the power converter 5, and this signal is supplied to the power converter 5.

The output end of this power converter 5 is connected to a motor 105, and the output shaft of this motor 105 is connected to a tacho generator 6 that generates a voltage proportional to the number of rotations. This tacho generator 6 is connected to the second input terminal (subtraction side) of the speed regulator 3, and feeds back the speed. Further, the current of the converter 5 is detected via the current detector 104 and fed back to the current regulator 4.

In the motor rotation acceleration control device configured as described above, when the slow-up time T is specified, the CPUI determines the start-up/fall operation pattern of the motor 105. An example of this driving pattern is the one shown in FIG. 7 in which a curve such as dl shown in Equation 10 or d in FIG. 1 is returned with an easy-to-memorize broken line.

Curve C2 is a general driving pattern that does not involve rapid acceleration or deceleration, curve C1 is a driving pattern that is within the permissible speed limit, and curve C3 is a driving pattern that involves rapid acceleration and deceleration that exceeds the permissible limit in some parts. This is the driving pattern for this case. That is,
It is understood that the curve shown in Fig. 7 corresponds to Fig. 1 (a) described in the explanation of the principle, and the time-velocity characteristics show the same tendency as a whole (a part of the bowl shape). be done.

Then, in accordance with the various driving patterns described above, control as shown in FIG. 8 is performed in order to avoid excessive acceleration and saturation of the torque control current to perform normal control.

In the case of curve C3, since it exceeds the maximum slope value that indicates the limit value, some parts of C3 that are too steep (C3A) are modified (suddenly It is necessary to alleviate the sudden rise in temperature. This way C3B
The subsequent parts do not need to be modified as they are since the slope is less than the maximum slope.

C3A' corresponds to a modified version of C3A.

Next, the operation of the speed control device shown in FIG. 3 will be explained with reference to FIGS. 5 and 6. It should be noted that what is shown in FIG. 5 is a main flowchart, which is also commonly used in the case of the position control device described below (FIG. 4, etc.).

As shown in FIG. 5, first, the entire device is system initialized (initial state setting) (symbol Sl). Next, the slow-up/down time T is input to the CPU, and this C and PUI determine the operation pattern of the motor 105 (see curves 01 to C3 in FIG. 7).
code S2).

In this state, the external speed command value (σ2) is
is input (symbol S3). Furthermore, in this state, CP
An interval interrupt Δt is input and checked for LI 1 as shown in FIG. 6, which will be described below.

Next, according to FIG. 6, S4 (speed command operation) shown in FIG.
Explain the operation.

At step 311, σ2 (external speed command value, corresponding to σ2 in FIG. 1(a)) is compared with σ1 (speed before change, current speed).

If σ2=, then CPU1 sets the conventional speed value to D.
Output to the A converter 2 (S12. This section ends).

If jt>σ1, then n=Q+1=1 and t=Δt(S
13), using this t, calculate σ from formula 00 (314
). Also, i is determined (S15).

First, compare i and 1ft=, (allowable upper limit value of f) (316), and if f≦9 Lie, then further compare d2 and d (S 17 ), if a'z≦0, σ=7
Output z (S18. This section ends). Also, σ
2>, output σ obtained in S14 (S19)
.

On the other hand, in S16, if /j>/lFtim, tI
o and corresponds to Figure 8 C3A-C3A'), d
Compare the magnitude of 2 and 6.521), if #2≦d, then 6
=σ2 (S22. This section ends). Further, if σ2>d, J ft=- process returns to S13 and this process is realized by repeating this section until reaching S18 or S22.

As described above, in an acceleration control device using only a velocity feedback loop, control as shown in FIGS. 7 and 8 is performed.

Next, a position control device according to a second embodiment of the present invention will be explained with reference to FIGS. 4 and 6.

As shown in Figure 4, the external speed command value (
σ2), control signals, slow-up/down time, and other signals are input and output as an internal speed command value (σ). σ2
The process to obtain d from is as shown in FIG. 6 and related explanation. The rate multiplier 1 converts the thus obtained σ into a pulse train whose generation rate is proportional to the value of σ.
This pulse train is further input to the synchronization circuit 14 via the flip-flop circuit 13. Furthermore, this pulse train is connected to NAND circuits 15, 16 and N.

It is input to the droop counter 20 via the R circuits 18 and 19. The output of the droop counter 20 is converted into an analog signal by the D/A converter 2 and inputted to the speed regulator 3, whose output is inputted to the current regulator 4. Further, a drive current is supplied from the power converter 5 to the motor 105.

A tachometer generator 6 and a pulse encoder 28 are connected to the output shaft of the motor 105, and the output of the tachometer generator 6 is input to the second input terminal of the speed regulator 3, forming a speed feedback loop. There is.

Further, the output terminal of the encoder 28 is connected to a synchronization direction discrimination circuit 27, and from the output terminal of this discrimination circuit 27, rotation signals Pω and -Pω in the child direction are respectively outputted, and the NOR It is input to circuits 18 and 19.

In addition, a clock pulse (
CPI) is input to the rate multiplier 12, and a clock pulse (CF2) is input to the synchronization pulse generation circuit 26. Then, the synchronization pulse generation circuit 26 generates synchronization pulses P1, P2. P3. P4 occurs respectively, P
l and P2 are supplied to the synchronization circuit 14, and P3 and P4 are supplied to the synchronization direction discrimination circuit 27. These clock pulses cause a droop counter and other related logic circuits that receive a plurality of pulse trains to perform planned operations.

Further, the operation of the acceleration control device having the position feedback loop configured as described above will be explained with reference to the flowchart shown in FIG. 6 in the same manner as in the first embodiment.

〔effect〕

According to the present invention, it is possible to minimize the peak energy consumption per unit time when accelerating and decelerating a motor during operation, and to perform acceleration and deceleration equivalent to conventional motors in a short time.

Therefore, it is possible to construct the motor itself and the motor drive device used to control the motor to be reasonably smaller than conventional ones, and to realize economical acceleration and deceleration.

[Brief explanation of the drawing]

Figures 1 (a), (b), and (c) are diagrams showing the control characteristics used in the motor rotation acceleration control device of the present invention, and Figure 2 is a diagram showing the control characteristics shown in Figure 1 for practical use. FIG. 3 is a characteristic diagram with corrected control characteristics; FIG. 3 is a block configuration diagram showing the first embodiment of the motor rotation acceleration control device of the present invention;
The figure is a block diagram showing a second embodiment of the motor rotation acceleration control device of the present invention, FIG. 5 is a main flowchart used for the control operation of the motor rotation acceleration control device of the present invention, and FIG. , a flowchart of the process of internal command speed generation in the case of the embodiment shown in FIG. 4, FIG. 7 is a diagram showing the operation pattern of the motor rotational acceleration control device of the present invention, and FIG. FIGS. 9 and 10 are block diagrams showing a conventional acceleration control device, and FIGS. 11 and 12 are diagrams showing control characteristics used in the conventional acceleration control device. 1.11...CPU. 3.22... Speed regulator, 4.23... Current regulator, 5.24... Power converter, 6... Tacho generator, 28... Pulse encoder, 105... Motor.

Claims (1)

[Scope of Claims] 1. An acceleration control device for motor rotation, characterized in that the acceleration of motor rotation is made inversely proportional to the speed. 2. The motor rotation acceleration control device according to claim 1, wherein the rate of change of the command speed is set to be below a predetermined value in a range where the initial speed of acceleration/deceleration is above a predetermined value. 3. When the motor is decelerating, the kinetic energy of the motor rotation system is also used as deceleration energy compared to when the motor is accelerating, and the motor is decelerated at a high acceleration according to the voltage and current allowed by the motor driver's power converter. An acceleration control device for motor rotation according to claim 1. 4. The motor rotation acceleration control device according to claim 1, wherein the rate of change of the commanded speed follows an approximate curve obtained by approximating a curve inversely proportional to the value of the commanded speed in multiple stages. 5. A curve that is inversely proportional to the command speed is determined independently during acceleration and deceleration, and during acceleration, the curve depends on the voltage and current of the motor driver's power supply, and during deceleration, it depends on the voltage and current of the motor driver's power converter. 5. The motor rotation acceleration control device according to claim 4, wherein the value corresponds to voltage and current.