JPH10271866A - Power supply circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply circuit capable of controlling the deceleration of a motor at the time of service interruption. SOLUTION: A three-phase full-wave rectifier circuit 7 is connected in parallel with a single-phase full-wave rectifier circuit 1 through a thyristor 5, and a control power supply circuit 2 is supplied with power. When service interruption is generated, service interruption is detected by a service-interruption detector 6, the thyristor 5 is ignited, and the control power supply circuit 2 is supplied with power accumulated in an electrolytic capacitor C1 for the three-phase full-wave rectifier circuit 7. Accordingly, the control operation is carried out even after service interruption in a servomotor control circuit 9 and a main-shaft motor control circuit 12 by power for control output from the control power supply circuit 2, a servomotor Mx and a main-shaft motor Ms can be decelerated and controlled by a large torque by setting a speed command in [0], and the movement of the motors after service interruption can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit for a machine, such as a machine tool or a robot, which drives a movable part by a motor. In particular, the present invention relates to a power supply circuit for a machine that controls the position and speed of a movable section driven by the motor.

[0002]

2. Description of the Related Art When a power failure occurs in a machine tool, an industrial machine, a robot or the like driven by a motor,
The motor is stopped by free running due to inertia or by operating a dynamic brake. For example, in a machine tool, when a power failure occurs, a spindle motor that drives a spindle is free-run and waits for a natural stop.
The servomotor for driving the feed shaft is stopped by applying a dynamic brake.

[0003]

When a power failure occurs, the motor rotates by free running, and it takes time to stop. For example, if a momentary power failure occurs on a machine tool and you want to start the machine immediately, if the spindle is free running,
For safety reasons, a normal stop is a condition for starting the machine, so you have to wait for the stop.
The disadvantage is that it takes time to start up the machine. In the case of a servomotor or the like that drives the feed shaft, when a power failure occurs, the braking is stopped by applying a dynamic brake. There is a possibility that the movable portion of the camera may collide with another object, which is not preferable.

For machines such as machine tools and robots,
It has a control circuit for controlling the position and speed of a shaft (movable part) driven by a motor. If deceleration control of the motor is performed using this control circuit, a large torque (maximum torque) is output to the motor to perform deceleration control and stop its rotation. By performing this deceleration control, the braking distance is shortened, and the above problem is improved. However, when a power failure occurs, the power supply for driving the motor and the control power supply for supplying power to the control circuit for controlling the motor are to be powered down, so that the above-described motor deceleration control cannot be performed. SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply circuit that enables deceleration control of the motor when a power failure occurs.

[0005]

According to the present invention, there is provided a power supply circuit for a machine having a motor for driving and controlling the position or speed of a movable part, comprising a single-phase AC power supply for supplying power to a control circuit for controlling the motor. A diode is provided to connect a full-wave rectifier circuit and a three-phase rectifier circuit for rectifying a three-phase alternating current that supplies power to the motor in parallel. Thereby, at the time of a power failure, power is supplied from the smoothing capacitor in the three-phase rectifier circuit to the control circuit via the diode. Further, a switching thyristor is used in place of the diode, and when a power failure occurs, the thyristor is ignited to supply power from the smoothing capacitor in the three-phase rectifier circuit to the control circuit. .

[0006]

FIG. 1 is a block diagram showing an embodiment in which a power supply circuit according to the present invention is applied to a power supply section of a machine tool. In the figure, reference numeral 1 denotes a single-phase full-wave rectifier circuit for converting a single-phase alternating current into full-wave rectifier and converting it to direct current. C2 smoothes a rectified voltage provided in the single-phase full-wave rectifier circuit 1. The smoothing capacitor C2 is shown in FIG. 1 separately from the single-phase full-wave rectifier circuit 1 for explanation. Reference numeral 2 denotes a control power supply circuit for adjusting the DC voltage from the single-phase full-wave rectifier circuit 1 to supply DC power to the servo motor control circuit 9 and the spindle motor control circuit 12. Numeral 3 denotes a numerical controller (CNC) for controlling the machine tool, which outputs a movement command to the servo motor control circuit 9 and a speed command to the spindle motor control circuit 12.

Reference numeral 7 denotes a three-phase full-wave rectifier circuit for converting three-phase alternating current into direct current by a bridge of a diode D. C1 denotes a smoothing capacitor in the three-phase full-wave rectifier circuit 7 for smoothing the rectified voltage. It is. 6 is a power failure detection circuit for detecting a power failure of the three-phase AC power supply, 5 is a three-phase full-wave rectifier circuit 7
And a switching thyristor connected to the plus side of the single-phase full-wave rectifier circuit 1 and a thyristor firing circuit 4 for controlling the firing of the thyristor. 14
Is a conductor connecting the negative side of the three-phase full-wave rectifier circuit 7 and the negative side of the single-phase full-wave rectifier circuit 1, whereby the three-phase full-wave rectifier circuit 7 and the single-phase full-wave rectifier circuit 1 are connected to the thyristor 5. Are connected in parallel.

Reference numeral 8 denotes a regenerative discharge circuit, and reference numeral 10 denotes an inverter as an amplifier for driving a servomotor (permanent magnet type synchronous motor) Mx for driving a feed shaft of the machine tool. A transistor Tr as a switching element is turned on / off to drive and control a servomotor. 13 is a spindle motor Ms
The transistor Tr as a switching element is turned on / off by the spindle motor control circuit 12 so that the spindle motor M
s is driven and controlled. 11 is a dynamic brake circuit. Although only one servo motor Mx is shown in FIG. 1, if there are a plurality of feed axes, a servo motor, an inverter, and a servo motor control circuit for the feed axes are provided.

In the circuit of the power supply section, a thyristor 5 and a conductor 14 for connecting the three-phase full-wave rectifier circuit 7 and the single-phase full-wave rectifier circuit 1 in parallel, a thyristor call circuit 4 for firing the thyristor, and a power failure detection The point that the circuit 6 is provided is different from the conventional power supply unit only, and the others are the same.

FIG. 3 is a circuit diagram of the power failure detection circuit 6.
The three-phase alternating current is rectified by the bridge circuit of the diode D, the voltage divided by the resistor R is detected, and the detected voltage is compared with the power failure detection voltage Vs by the comparator 20, and the detected voltage becomes lower than the power failure detection voltage Vs. Then, a power failure detection signal S1 is output. Note that C in FIG. 3 is a noise absorbing capacitor.

FIG. 4 shows another embodiment of the power failure detection circuit. Instead of dividing the voltage obtained by rectifying the three-phase AC in the power failure detection circuit shown in FIG. 3, the power failure detection circuit shown in FIG. The difference is that the direct current voltage (DC link voltage) VDC on the output side of the full-wave rectifier circuit 7 is divided and compared by the comparator 20.

FIG. 5 is a detailed circuit diagram of the thyristor firing circuit 4. The power failure detection signal S1 from the power failure detection circuit 6 is input to the base of the transistor Tr via the resistor R5.
The emitter of the transistor Tr is grounded, and the collector is applied with a bias voltage + V via resistors R7 and R8 connected in series. The collector of the transistor Tr is connected to the cathode of the thyristor 5, and the connection point between the resistors R7 and R8 is connected to the gate of the thyristor 5. Note that the capacitor C3 and the resistors R5 and R6 constitute a noise absorbing filter. When the power failure detection signal S1 is output from the power failure detection circuit 6, the transistor Tr is turned on, a voltage difference is generated between the cathode and the gate of the thyristor 5, a gate current flows, and the thyristor 5 is turned on.

Next, the operation of the power supply unit will be described. The three-phase AC is subjected to full-wave rectification by the three-phase full-wave rectifier circuit 7 and smoothed by the electrolytic capacitor C1.
3 is supplied. The single-phase AC is subjected to full-wave rectification by the single-phase AC full-wave rectifier circuit 1 and smoothed by the electrolytic capacitor C2, and is supplied to the control power supply circuit 2 where the voltage is adjusted and the servomotor control circuit 9 is controlled. The control power is supplied to the spindle motor control circuit 12.

On the other hand, the numerical controller 3 outputs a speed command Vc to the spindle motor control circuit 12 and a movement command Pc to the servo motor control circuit 9 based on a machining program or the like. The spindle motor control circuit 12 performs speed loop control based on the speed command Vc and a speed feedback signal from a speed detector (not shown) provided on the spindle motor Ms, and controls the transistor Tr of the inverter 13 on / off to control the spindle. Is controlled so that the actual speed of the motor is equal to the command speed Vc. Further, the servo motor control circuit 9 performs a loop control of the position and speed based on the movement command Pc and the position and speed feedback signals from the position / speed detector provided for the servo motor Mx, and turns on / off the transistor Tr of the inverter 10. By performing the off control, the position and speed of the servo motor Mx are controlled. When the servo motor Mx and the spindle motor Ms are decelerated, the regenerative energy generated by the deceleration is consumed by the regenerative discharge circuit 8.

The above is a normal operation and is the same as the operation of the conventional power supply unit. Conventionally, when a power failure occurs, conventionally, it is not possible to supply sufficient power from the control power supply circuit 2 to drive the servo motor control circuit 9 and the spindle motor control circuit 12 with only the energy stored in the electrolytic capacitor C2. , The transistors Tr of the inverters 10 and 13 are all turned off, no power is supplied to the spindle motor Ms and the servomotor Mx, and the spindle motor Ms rotates by inertia and then stops. Further, the dynamic brake circuit 11 operates to apply a dynamic brake to the servo motor Mx, and braking is stopped.

On the other hand, in this embodiment, when a power failure occurs, the power failure detection circuit 6 detects the power failure as described above, and outputs the power failure detection signal S1 to the thyristor firing circuit 4, the servo motor control circuit 9, and the spindle motor control circuit 12 Output to As described above, the thyristor firing circuit 4 outputs the power failure detection signal S1
Is input, the thyristor 5 is fired to conduct. As a result, the electric power stored in the electrolytic capacitor C1 of the three-phase full-wave rectifier circuit is supplied to the control power supply circuit 2 through the thyristor 5, and the control power supply circuit 2 supplies the servo motor control circuit 9 and the spindle motor control circuit. The control power is continuously supplied to the circuit 12.

The spindle motor control circuit 12 and the servo motor control circuit 9 receiving the power failure detection signal S1 ignore the speed command Vc and the movement command Pc output from the numerical controller 3, and The motor control circuit 9 controls the speed loop by setting the speed command to "0" (the servo motor control circuit 9 sets the position and speed loop control by setting the movement command to "0" instead of setting the speed command to "0"). The driving of the inverters 13 and 10 is controlled.

Even if the speed command becomes "0", the spindle motor M
s, the servo motor Mx tries to keep rotating by the command immediately before the power failure, but a speed feedback signal is input to the speed loop, and the speed loop sets the speeds of the spindle motor Ms and the servo motor Mx to the command speed “0”. To this end, a drive current in the opposite direction is commanded to the spindle motor Ms and the servo motor Mx to decelerate with a large torque and stop.

If the movement command is set to "0" at the input of the power failure detection signal S1 in the servo motor control circuit 9, the position deviation in the position loop in the servo motor control circuit 9 is as follows. Even if the movement command becomes “0”, the position and speed detector (not shown) attached to the servomotor Mx returns a position feedback signal in the direction of rotation just before the power failure. , The position deviation has the opposite sign immediately before the power failure, and a speed command in the reverse rotation direction is output from the position loop. Also in the speed loop, the reverse rotation direction torque command is output by the reverse rotation direction speed command and the rotation direction speed feedback signal immediately before the power failure fed back from the position / speed detector, and the servo motor Mx Means that deceleration control is performed with a large torque.

The spindle motor Ms and the servo motor Mx
Is reduced, a regenerative current is generated, and this regenerative current is consumed by the regenerative discharge circuit 8. Motor Ms, M
When the power failure occurs, the energy stored in the electrolytic capacitor C1 of the three-phase full-wave rectifier circuit 7 that supplies power for power to the motor x does not control the motors Ms and Mx to decelerate, but through the thyristor 5, It is also supplied to the control power supply circuit 2 and used to control the motors Ms and Mx.

FIG. 2 shows a second embodiment of the present invention, which is different from the above-described first embodiment in that a diode 30 is used in place of the switching thyristor 5. Therefore, the thyristor firing circuit 4 required in the first embodiment is not required. This second
Also in the embodiment, the operation at the time of the power failure or the like is the same as that of the first embodiment.
Since the embodiment is the same as that of the first embodiment, the description is omitted.

However, in the second embodiment, the control power supply circuit 2 is connected to the single-phase full-wave rectifier circuit 1 and the three-phase full-wave rectifier circuit 7 by the diode 30. The fluctuation of the DC voltage which is the output of the phase full-wave rectifier circuit 7 affects the control power supply circuit 2 and causes the voltage of the output of the control power supply circuit 2 to fluctuate, adversely affecting the control power output requiring high accuracy. May be given. Therefore, the control power supply circuit 2 may need to be provided with a means for preventing a new output voltage fluctuation.

[0023]

According to the present invention, even when a power failure occurs, power can be supplied to the control circuit for controlling the motor for a while, so that the motor can be decelerated with a large torque and stopped.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment in which a power supply circuit of the present invention is applied to a power supply unit of a machine tool.

FIG. 2 is a block diagram of a second embodiment in which the power supply circuit of the present invention is applied to a power supply unit of a machine tool.

FIG. 3 is a circuit diagram illustrating an example of a power failure detection circuit according to the embodiment;

FIG. 4 is a circuit diagram of another example of the power failure detection circuit.

FIG. 5 is a detailed circuit diagram of a thyristor firing circuit in the embodiment.

[Explanation of symbols]

 Reference Signs List 1 single-phase full-wave rectifier circuit 2 control power supply circuit 3 numerical controller (CNC) 4 thyristor firing circuit 5 thyristor 6 power failure detection circuit 7 three-phase full-wave rectifier circuit C1, C2 electrolytic capacitor 10, 13 inverter Ms spindle motor Mx Servomotor

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[Procedure amendment]

[Submission date] March 12, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

SUMMARY OF THE INVENTION The present invention controls a motor.
In the power supply circuit for connecting a three-phase rectifier circuit for rectifying the three-phase AC for supplying power to a full wave rectifier circuit and the motor of the single-phase AC supplies power to the control circuit for controlling the motor in parallel A diode is provided. Thereby, at the time of a power failure, power is supplied from the smoothing capacitor in the three-phase rectifier circuit to the control circuit via the diode. Further, a switching thyristor is used in place of the diode, and when a power failure occurs, the thyristor is ignited to supply power from the smoothing capacitor in the three-phase rectifier circuit to the control circuit. .

Claims (2)

[Claims] 1. A power supply circuit for a machine having a motor for controlling the position and / or speed of a movable part, comprising: a single-phase AC full-wave rectifier circuit for supplying power to a control circuit for controlling the motor. Supply power to the motor 3
A three-phase rectifier circuit for rectifying a phase alternating current is connected in parallel via a diode, and when a power failure occurs, power is supplied from a smoothing capacitor in the three-phase rectifier circuit to the control circuit via the diode. Power supply circuit. 2. A power supply circuit for a machine having a motor for controlling the position and / or speed of a movable part, comprising a single-phase AC full-wave rectifier circuit for supplying power to a control circuit for controlling the motor. Supply power to the motor 3
A three-phase rectifier circuit for rectifying phase alternating current is connected in parallel via a switching thyristor, and when a power failure occurs, the thyristor is ignited to supply power from the smoothing capacitor in the three-phase rectifier circuit to the control circuit. A power supply circuit that also supplies power to