JPH02155483A - Emergency stop circuit for ac servo device - Google Patents

Abstract

PURPOSE:To shorten the time required for stoppage by stopping an AC servo motor at a regenerative mode as speed control is left as it is utilized on emergency stop. CONSTITUTION:A main circuit is composed of a converter 1 and an inverter 2, and the speed of a synchronous motor 3 is controlled. An electromagnetic contactor 4 for the main circuit is closed during operation, and a sequence in which the electromagnetic contactor is opened when an emergency stop push-button 7 is pushed is incorporated. When the emergency stop push-button 7 is pushed, an output from a photo-coupler 6 is turned OFF, and a signal EMS is brought to +5V. When the signal EMS is brought to +5V, a changeover switch 8 for a speed command is changed over from (a) to (b), speed is controlled under the state in which a speed command N* input to a proportional- plus-integral circuit 9 is brought to zero, and the synchronous motor 3 is decelerated suddenly at a regenerative mode.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an emergency stop circuit for an AC servo device that quickly stops an AC servo motor in a regeneration mode during an emergency stop.

(Prior Art) An AC servo device is used to control the speed and position of a motor, and FIG. 2 shows its basic configuration.

In FIG. 2, the main circuit section is composed of a converter section 1 that converts alternating current to direct current and an inverter section 2 that converts direct current to alternating current.

The speed command N* is provided by the position detector 15 attached to the motor.
The detected position is compared with a velocity feedback signal N obtained by differentiating it in a position velocity generation circuit 18, and proportionally integrated by a proportional integration circuit 8.

Furthermore, a current command is generated by a current command generation circuit 16 from the output of the proportional-integral circuit 8 and the position of the rotor of the synchronous motor 3 detected by the position detector 15, and the PWM control circuit 17 generates a current command so as to match this current command value. The current of the AC motor 3 is controlled by.

The control is started by inputting an operation command signal from outside the unit, which causes the proportional integral circuit 8 and P
The WM control circuit 17 starts operating.

In this case, the emergency stop has conventionally been performed using a braking resistor as shown in FIG.

That is, at the time of an emergency stop, the AC input is cut off, the operation signal is turned off, the electromagnetic contactor 20 becomes de-energized, all of its B contacts are closed, and the braking resistor 19 is connected to the synchronous motor 3.
The energy possessed by the synchronous motor 3, which is connected to the motor and becomes a generator, is consumed within the braking resistance and the brake is applied, causing the synchronous motor 3 to decelerate and stop.

(Problem to be solved by the invention) In the case of an emergency stop, it is necessary to stop for as short a time as possible, and in the conventional method of consuming the energy of a synchronous motor in braking resistance, the energy is lost as the speed decreases. There is a problem that consumption decreases and deceleration time increases.

An object of the present invention is to provide a high-performance emergency stop circuit for an AC servo device that stops an AC servo motor in regeneration mode while maintaining speed control during an emergency stop, thereby shortening the time required for stopping. .

[Structure of the invention]

(Means and effects for solving the problem) The present invention operates a changeover switch by detecting cutoff of the main circuit power supply and inputting the state of an emergency stop operation switch, and changes the speed reference of the speed control circuit to the speed. In addition to switching from command input to zero, it is detected that the motor speed has been sufficiently reduced by the speed feedback signal, and the inverter's P
This system prohibits WM control to stop the inverter, and by reducing the input to the speed control circuit to zero during emergency stop operation, if the motor is rotating, it enters regeneration mode, and the rotational energy of the motor is reduced. The motor rapidly decelerates due to regeneration by the inverter, and when the rotational speed of the motor drops sufficiently, PWM control is prohibited and the inverter is stopped, so the time required for an emergency stop can be sufficiently shortened.

(Example) An embodiment of the present invention is shown in FIG.

FIG. 1 shows a control circuit for emergency stop according to the present invention, and the speed control circuit is basically the same as that in FIG. 2.

That is, in FIG. 1, converter 1 and inverter 2
The main circuit is configured by the main circuit, and controls the speed of the synchronous motor 3.

A sequence is incorporated in which the main circuit electromagnetic contactor 4 is closed during operation, and is opened when the emergency stop pushbutton 7 is pressed.

When the emergency stop pushbutton 7 is pressed, the output of the photocoupler 6 is turned off and the signal EMS becomes +5V.

Also when the input power to converter 1 is lost.

The output of the power cutoff detection circuit 5 is turned off and the signal EMS is +5.
It becomes v.

When the signal EMS becomes +5V, the speed command selector switch a is switched from a to b, speed control is performed with the speed command N* input to the proportional integral circuit 9 being zero, and the synchronous motor 3 is rapidly decelerated by regeneration mode.

Here, when the speed signal N of the synchronous motor 3 is converted to an absolute value IN+ by the absolute value circuit 10, when the synchronous motor decelerates sufficiently and IN+ becomes a sufficiently low value, the output of the comparator 11 becomes +5V, The output of NAND gate 12 is “0”
"become.

During operation, the operation signal is “1”, so NAND
When the output of the gate 12 becomes "0", the output of the AND gate 13 becomes 110 F+, PWM control is prohibited, and the motor becomes free.

This sudden deceleration and stop operation is also performed when the AC power supply to the converter is interrupted, and the AC motor is decelerated and stopped by a similar logical operation.

Note that although the above embodiment is a case of an AC servo device using a synchronous motor, the present invention can be similarly applied to an AC servo device using an induction motor.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to perform an emergency stop operation in a sufficiently short time with a simple circuit configuration, and it is extremely effective in preventing personal accidents and machine damage.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing one embodiment of the present invention, Figure 2 is an AC
FIG. 3 is a system diagram showing the basic configuration of a servo device. FIG. 3 is a circuit diagram showing an example of an emergency stop circuit of a conventional AC servo device. 1...Converter 2...Inverter 3...Synchronous motor 4.20...Magnetic contactor 5.6...Photocoupler 7...Emergency stop switch 8...Selector switch 9...Proportional Integrating circuit 10... Absolute value circuit 11... Comparator 12... NAND gate 13... AND gate 14... Current detector 15... Position detector 16... Current command adult circuit 17 ... PWM control circuit 18 ... Position speed generation circuit 19 ... Braking resistance (8733) Attorney Akira (and 1 other person) Fig.

Claims (1)

[Claims] In an emergency stop circuit of an AC servo device that rapidly stops an AC servo motor that is driven using an inverter as a power source and whose speed is controlled according to a speed command in response to an emergency stop command, a speed command for speed control in response to an emergency stop command is used. An AC characterized by being equipped with a speed command switching circuit that makes the speed zero, and an operation prohibition circuit that detects that the speed of the AC servo motor has fallen below a predetermined value and stops the inverter.
Emergency stop circuit for servo equipment.