JPS589961B2 - Automatic acceleration/deceleration control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an automatic acceleration/deceleration circuit in which acceleration/deceleration control of a motor is performed in an analog manner.

Generally, in the acceleration/deceleration control of a motor used for position control in a machine tool, etc., it is desired to quickly accelerate the motor to a constant speed when accelerating, and to stop the motor smoothly and quickly when decelerating, in order to improve efficiency.

Conventionally, the automatic acceleration/deceleration circuit for the motor described above has been constructed using charging and discharging of a capacitor C, as schematically shown in FIG.

That is, during acceleration, a speed command voltage V corresponding to the command speed is applied to the capacitor C via the resistor R, and the capacitor C
is charged, and during deceleration, the speed command voltage V is set to O to discharge the capacitor C. A pulse train with a frequency corresponding to the voltage of the capacitor C is formed by the V/F converter 2, and this is used to control the speed of the pulse motor 2. It is used as a signal.

In this case, acceleration and deceleration of the motor are determined by the charging/discharging time constant of the capacitor C.

Therefore, the deceleration characteristics of the motor are constant, and if deceleration is started at the same time, the stopping position will be different due to the difference in speed at the start of deceleration.

Therefore, in order to reliably stop a machine driven by a motor at a target position, it is necessary to change the position at which deceleration starts depending on the speed at the start of deceleration.

However, changing the position at which deceleration starts due to differences in speed requires a complicated control device.

Therefore, conventionally, as shown in Figure 2, the deceleration start position is fixed at a value relative to the maximum speed v1, and when the speed is lower than the maximum speed (2), after the speed has decreased to a certain extent, the deceleration start position is automatically activated at a constant low speed. I try to drive to the target position.

For this reason, the time required from the start of deceleration to the stop is longer than that at the maximum speed, which has the drawback that a quick stopping operation cannot be achieved.

SUMMARY OF THE INVENTION An object of the present invention is to provide an automatic acceleration/deceleration circuit that can quickly and reliably control a stop to a target position by an acceleration/deceleration command at a predetermined position regardless of the speed at the start of deceleration.

Hereinafter, the present invention will be described in detail with reference to an embodiment shown in the accompanying drawings.

In FIG. 3, the speed command voltage Vf corresponding to the command speed
i and the voltage Vfc of capacitor 3 are applied to comparator 4.

The comparator 4 compares the speed command voltage Vfi and the voltage Vfc of the capacitor 3, and outputs a high level signal when the voltage Vfc of the capacitor 3 is higher than the speed command voltage Vfi, and the voltage Vfc of the capacitor 3 is higher than the speed command voltage Vfi.
If it is lower or equal, a low level signal is output.

The controller 5 controls charging and discharging of the capacitor 3, and an acceleration/deceleration command is applied to the input, a signal from the comparator 4 is applied to the input E, and the speed command voltage V f is applied to the input F. i is added.

When the acceleration/deceleration command applied to the input of the controller 5 becomes bi-level, the command voltage Vfimax corresponding to the maximum speed is output from the output Q, this voltage is applied to the capacitor 3 via the resistor 6, and the capacitor 3 is set to the voltage Vfimax.
Charge up to.

Further, when the acceleration/deceleration command applied to the input of the controller 5 is at low level and the signal from the comparator 4 applied to the input E is at bi-level, the current flowing through the output Q is proportional to the speed command voltage V f i The current becomes constant in the direction of arrow A, and the capacitor 3 is discharged by this constant current.
Further, when the signal from the comparator 4 applied to the human power E becomes low level, the output Q is grounded and the capacitor 3 is discharged with a time constant R8co determined by the resistance value R8 of the resistor 6 and the capacitance value C8 of the capacitor 3. .

The controller 5 includes, for example, a logic circuit that performs a logical operation between the acceleration/deceleration command applied to the input and the output of the comparator 4 applied to the input E, and a constant voltage source of the voltage Vfimax and a speed command according to the output of this logic circuit. This can be realized by providing a switch circuit that switches between a constant current source corresponding to the voltage Vfi and a short circuit.

The clamp circuit 7 is connected to the speed command voltage Vfi.

Voltage Vfc of capacitor 3 is applied to output voltage Vf.

is clamped to the lower voltage of both forces.

This output voltage Vfo is applied to a voltage/frequency converter 8, converted into a pulse train of a frequency corresponding to the voltage Vfo, and applied to a pulse motor 9 as a speed control signal.

Next, an example of control by the automatic acceleration/deceleration control device of the present invention will be explained with reference to FIG.

First, the speed command voltage Vfi is the maximum speed command voltage Vfi
A case where the voltage Vfil is lower than ax will be explained.

As shown in FIG. 4, when the acceleration/deceleration command becomes bilevel at time t1, the output Q of the controller 5 becomes the voltage Vfima.
x, and the capacitor 3 is connected to the resistor 6 as shown in Figure 4f.
The capacitor 3 is charged to the voltage Vfimax with a time constant R8co determined by the resistance value R8 of the capacitor 3 and the capacitance value C8 of the capacitor 3.

On the other hand, the clamp circuit 7 operates during a period T during which the speed command voltage V f i 1 is at a higher level than the voltage Vfc of the capacitor 3 .

sets the voltage Vfc of the capacitor 3 as the output Vfo, and the motor 9 is gradually accelerated as shown in FIG. 4a in response to the time constant R8co.

Then, when the voltage of the capacitor 3 reaches the speed command voltage Vfil, the output Vfo of the clamp circuit 7 changes to the speed command voltage Vfil.
The motor 9 is clamped to the speed command voltage Vfi.
is operated at a speed corresponding to l.

When the acceleration/deceleration command becomes low level at time t2, the capacitor 3 starts discharging.

At this time, since the charging voltage Vfc of the capacitor 3 is higher than the speed command voltage Vfil, the output of the comparator 4 is bi-level, and the capacitor 3 is discharged with a constant current corresponding to the speed command voltage Vfil.

Therefore, the voltage Vfc of capacitor 3 is line 1 of FIG. 4f.
It decreases as shown by 0.

When the voltage Vfc of the capacitor 3 decreases to the speed command voltage Vfil, the output of the comparator 4 becomes a low level, the output Q of the controller 5 becomes a ground level, and the capacitor 3 is discharged with a time constant R8Co.

As a result, the voltage Vfc of the capacitor 3 becomes the speed command voltage V
Since it is smaller than fil, the output Vfo of the clamp circuit 7
is clamped to the voltage Vfc of capacitor 3, and motor 9
is controlled to be decelerated according to the discharge voltage Vfe of the capacitor 3.

As mentioned above, while the voltage of the capacitor 3 is higher than the speed command voltage Vfil, the capacitor 3 is discharged with a constant current proportional to the speed command voltage Vfil. A value corresponding to the distance can be set, and the motor 9 can be accurately stopped at the target position.

Next, the speed command voltage Vfi is the maximum speed command voltage Vfima
The case of x will be explained.

When the acceleration/deceleration command (see FIG. 4 d) becomes bilevel at time t1, the output Q of the controller 5 becomes Vfimax, and charging of the capacitor 3 is started.

(See Figure 4 f) The voltage Vfc of the capacitor 3 is the voltage Vf
Until Tf reaches imax, the output Vfo of the clamp circuit 8 is clamped to the voltage Vfc of the capacitor 3, the motor 9 is accelerated and controlled according to the charging time constant R0C0 of the capacitor 3, and the voltage of the capacitor 3 reaches Vfimax. Then, the output Vf of the clamp circuit 8.

becomes the voltage Vfimax, and constant speed operation is performed at the maximum speed.

(See FIG. 4a) When the acceleration/deceleration command becomes low level at time t≦, the capacitor 3 starts discharging.

At this time, the voltage Vfc of the capacitor 3 is the speed command voltage Vf
Since it is equal to imax, the output of the comparator 4 is at a low level (see Figure 4 e), the output Q of the controller 5 is grounded, and the capacitor 3 is discharged with a time constant RoCo as shown by line 11 in Figure 4 f. Ru.

Therefore, the motor 9 has a time constant R8co for discharging the capacitor 3.
The deceleration is controlled accordingly.

In this way, the command speed voltage Vfi is changed to the maximum command speed voltage Vf
When set to imax, control is similar to that of a conventional acceleration/deceleration control device.

In the above embodiments, the motor to be controlled is not limited to a pulse motor, but can also be applied to a DC motor or the like.

In the case of a DC motor, a V/F converter may not be provided and the DC output of the clamp circuit may be used as the speed control signal.

As explained above, according to the present invention, the motor can be controlled by acceleration/deceleration commands from a predetermined position, and the motor can be controlled to stop quickly and reliably at the target position regardless of the speed at the start of deceleration. have

[Brief explanation of drawings]

Fig. 1 is a configuration diagram showing a conventional automatic acceleration/deceleration circuit, Fig. 2 is a time-velocity characteristic diagram for explaining the problems of the conventional method, and Fig. 3
The figure is a block diagram showing one embodiment of the automatic acceleration/deceleration circuit according to the present invention, and FIGS. 4a to 4f are graphs for explaining the present invention in detail. 3... Capacitor, 4... Comparator, 5... Controller, 7... Amplifier circuit, 8... Voltage voltage wave number converter, 9... Pulse motor.

Claims (1)

[Claims] 1. In an automatic acceleration/deceleration control device that performs acceleration/deceleration control of a motor in response to charging/discharging of a capacitor, the voltage of the capacitor is compared with a speed command voltage corresponding to a command speed, and the voltage of the capacitor is higher than the speed command voltage. a comparator that outputs a signal when the time is off, and an acceleration command signal that charges the capacitor to a voltage corresponding to the maximum command speed, and a deceleration command signal that charges the capacitor proportional to the speed command voltage while there is a signal from the comparator. A capacitor charge/discharge control circuit that discharges at a constant current and then discharges at a predetermined time constant, and clamps to the lower voltage of the capacitor voltage and the speed command voltage, and uses this as a speed command signal for the motor. Automatic acceleration/deceleration control device equipped with a clamp circuit.