JP2002218676A - Motor drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable motor drive unit capable of prolonging a backup time for a servo controller and a control power source so that a robot arm driven by a servo motor may be stopped safely with a big idling angle when an instantaneous interruption or failure of power supply occurs. SOLUTION: The motor drive unit is provided with a large capacitance capacitor 19, as a power source control means 5, which has capacitance calculated from the energy amount necessary for decelerating and stopping the robot driven by the servo motor 1 when detecting a failure of power supply, and supplies a power source voltage for the main circuit power source and the control power source 6 during the failure of the supply. As a result, when the failure of the power supply occurs, a servo driver 3 and a controller 7 are kept under the same condition as before the failure of the power supply, and the robot arm is safely stopped at a decelerated speed of a usual playback operation on an orbit where the arm is being operated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for driving a robot arm and the like, and more particularly, to a motor drive device for stopping a servomotor at a large coasting angle when a momentary power failure or power failure occurs in a power supply line. In the power supply control means.

[0002]

2. Description of the Related Art Conventionally, in a motor driving device for driving a load such as a robot arm, for example, a servomotor is used by effectively utilizing energy regenerated from a servomotor when a power failure or a momentary power failure occurs in a power supply line. FIG. 3 shows a vehicle equipped with a braking device for stopping the operation. FIG. 3 is a block diagram of a conventional motor drive device.
In the figure, D is a driver, L is an AC power supply line that supplies power and serves as a drive source of the driver D, 31 is a servo motor, 32 is an encoder, 33 is an AC power supply, 41 is a counter, 42 is a subtractor, and 43 is a subtractor. A position control unit, 44 is a D / A converter, 45 is an F / V converter, 46 is a subtractor, 47 is a switch, 48 is a speed control unit, 49 is a three-phase sine wave generation circuit,
50 is a drive circuit, 51 is a switch. In such a configuration, first, the encoder 32 outputs an encoder pulse having a number of pulses proportional to the rotation angle of the three-phase servo motor 31 driven by the driver D. In the driver D, the actual position of the servo motor 31 is obtained by counting the number of encoder pulses by the counter 41, and the difference between the externally applied position command value and the actual position obtained by the counter 41 is obtained by the subtractor 42. Later, subtracter 4
A control signal for performing feedback control of the rotational position of the servo motor 31 based on the deviation obtained in Step 2
3 and the D / A converter 44 converts the control signal output from the position control unit 43 from digital to analog. Next, an F / V converter 45 which outputs an analog voltage signal proportional to a pulse command value supplied from the D / A converter 44 via the switch 47 and a pulse rate of the encoder pulse.
The difference from the detected speed value given by the subtractor 46 is calculated by the subtractor 46. The rotational speed of the servo motor 31 is feedback-controlled by the speed control unit 48 based on the deviation obtained by the subtractor 46, and the three-phase sine wave generation circuit 49 performs three-phase sine wave generation based on the control signal of the speed control unit 48. Generates a sine wave signal of
The drive circuit 50 generates a three-phase excitation current based on the three-phase sine wave signal, and drives the servo motor 31. Also, 52
Is a switching circuit that monitors the current flowing through the AC power supply line L, turns on the switch 47 when no power failure occurs in the AC power supply line L, and turns off the switch 47 when a power failure occurs. Reference numeral 53 denotes a delay circuit that delays the switching signal of the switching circuit 52 and switches the switch 51 with the delay signal. 54 is a command value backup circuit,
The resistor R and the capacitor C are connected in parallel,
When a power failure occurs in the AC power line L, the capacitor C
The speed command value is backed up by the energy stored in the controller. Reference numeral 34 denotes a rectifier circuit for rectifying an AC current flowing from the AC power supply 33, and reference numeral 35 denotes a power supply capacitor for storing energy regenerated from the motor when the AC power supply line fails. A control power supply 36 is connected to the power supply capacitor 35 and serves as a backup power supply for the driver D when a power failure occurs. Then, when a power failure occurs in the AC power supply line L, the speed control unit 48 is driven by the energy regenerated from the servo motor 31, and the connection state between the servo motor 31 and the drive circuit 50 is first maintained, and the speed is reduced. The speed command value to be adjusted
, The servo motor 31 is decelerated, and then the servo motor 31 is decelerated for a predetermined time. When the switch 51 is switched by the delay signal generated by the delay circuit 53 and the switch 51 is connected to the contact b, the servo The both ends of the coil of the motor 31 are short-circuited to perform power generation braking and to stop.

[0003]

The prior art employs a two-stage braking system in which, when a power failure occurs in the AC power supply line L, a position loop is cut off midway to perform power generation braking of the servo motor 31, and a small braking system is used. Since the robot is stopped at the coasting angle, the time required to stop the robot (not shown) with rapid deceleration when a power failure occurs is a numerical value such as at most several tens of ms. In such an operation, the trajectory of the robot arm coasts with no control due to the inertia of the robot arm (not shown) or the like. However, there is a risk that the wafer gripped in the drawing (not shown) may interfere with peripheral devices, or the wafer may be skipped by the acceleration of the robot, and there is a problem in reliability.
For this reason, in order to safely stop the robot arm driven by the above-described servo motor at the position on the trajectory that was previously taught when a power failure occurs, it is necessary to stop the servo motor 31 at a large coasting angle. Therefore, it is important to lengthen the backup time of the servo controller and the control power supply so as to match the coasting angle required for stopping the servomotor 31. The present invention has been made in order to solve the above-described problem. In the case where a robot arm or the like is driven by a servo motor, when a momentary power failure or power failure occurs, the robot arm is moved to a position on a trajectory which has been previously taught. It is an object of the present invention to provide a highly reliable motor drive device capable of extending the backup time of a servo controller and a control power supply so that the motor can be safely stopped at a large coasting angle.

[0004]

In order to solve the above-mentioned problems, the present invention provides a servo drive means for driving the servomotor based on a control signal obtained by feedback-controlling the rotation speed of the servomotor; A motor drive device comprising: a controller for giving a command to a servo drive unit; a power supply unit for supplying AC power; and a power supply control unit for controlling a main circuit power supply and a control power supply based on the power supply unit. The control means has a capacity calculated from the amount of energy required to decelerate and stop the load driven by the servomotor when detecting a power failure,
And a large-capacity capacitor for supplying a power supply voltage for a main circuit power supply and a control power supply at the time of a power failure; a power supply voltage Va rectified by the power-on means; A first diode and a second diode acting to be supplied toward Vp, a third diode acting to supply the control power even when power is not supplied from the power supply means side during a power failure; A smoothing capacitor that suppresses ripples and stores regenerative energy from the servomotor; a first resistor that suppresses charging current to the large-capacity capacitor; and a first resistor that suppresses charging / discharging current of the large-capacity capacitor. A second resistor and a transistor serving as a discharging means for discharging the residual voltage of the large-capacity capacitor. .

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a motor drive device showing an embodiment of the present invention. 1 is a three-phase servo motor driven by a driver D, 2 is an encoder that outputs encoder pulses of a pulse number proportional to the rotation angle of the servo motor 1,
Reference numeral 3 denotes a servo drive unit provided with a counter, a position control unit, a speed control unit, a three-phase sine wave generation circuit, and the like (not shown). Reference numeral 4 denotes a power supply unit serving as a primary side, 5 denotes a power supply control unit serving as a primary side, 6 denotes a control power source, 7
Is a controller for giving a position command or the like to the servo drive means 3. FIG. 2 is a block diagram showing details of the power control means in FIG. First, the power supply means 4 will be described. Reference numerals 9A and 9B denote relay switches serving as main circuit opening / closing means, which are opened / closed by an opening / closing command from the controller 7, an emergency stop signal, or the like. Reference numeral 22 denotes a diode bridge for rectifying the AC power, and reference numeral 24 denotes a smoothing capacitor. The AC voltage is supplied to the primary side of the control power supply 6 as long as the AC power is supplied regardless of whether the relay switches 9A and 9B are opened or closed. Is done. Reference numeral 23 denotes a circulating current suppressing resistor, the operation of which will be described later. Reference numeral 8 denotes a power failure detection means, which includes a level detection circuit, a timer circuit, and the like, and detects whether a power failure has occurred for a predetermined time or more, but detailed description of the circuit is omitted. Reference numeral 10 denotes a diode bridge for rectifying a motor driving main circuit power supply. Reference numeral 12 denotes an inrush current suppressing resistor for suppressing an inrush current when the AC power is turned on. Reference numeral 11 denotes a relay switch, which operates to close after detecting that the main circuit power supply voltage Vp has reached a predetermined voltage by the voltage detection means 21,
The main circuit power is supplied without voltage drop because it is connected in parallel with the inrush current suppressing resistor 12. Next, the power control means 5 will be described. Reference numerals 13, 14, and 15 denote a first diode, a second diode, and a third diode, respectively.
Of the rectified power supply voltage Va and the voltage of the large-capacity capacitor 19 described later, the higher one is supplied toward the motor power supply voltage Vp. The third diode 15 functions so as to supply the control power supply 6 even when the power supply from the diode bridge 22 is stopped during a power failure. Reference numeral 19 denotes a large-capacity capacitor, which can decelerate and stop the robot driven by the servomotor 1 with a deceleration set on a pre-teached trajectory even during a playback operation when a power failure is detected. As described above, a capacity (for example, about 1 Farad) calculated from the amount of energy required for decelerating and stopping is used. Reference numeral 20 denotes a smoothing capacitor that suppresses power ripple and stores regenerative energy from the servo motor 1. 21 is a voltage detecting means, 18 is a large capacity capacitor 1
9. A transistor serving as a discharging means for the residual voltage of No. 9,
Vp can be lowered according to the voltage level detected by the voltage detecting means 21, or it can be discharged rapidly. 16 is a first resistor for suppressing the charging current to the large-capacity capacitor 19, and 17 is a large-capacity capacitor 19
Is a second resistor for suppressing the charge / discharge current of the second resistor. Then, the circulating current suppressing resistor 23 suppresses the circulating current on the plus side of the large capacity capacitor 19 → the second diode 14 → the third diode 15 → the smoothing capacitor 24 → the minus side of the large capacity capacitor 19.

[0006] The operation of the device thus constructed will be described. When the AC power is supplied, first, the control power 6 is supplied, and the controller 7 starts up. The relay switches 9A and 9B are closed by the main circuit power-on command (not shown) from the controller 7, and the AC power is
0, the voltage across the smoothing capacitor 20 is increased through the rush current suppressing resistor 12 and the first diode 13. At the same time, charging of the large capacity capacitor 19 is started through the first resistor 16 and the second resistor 17, and the voltage across the large capacity capacitor 19 is slowed up. When the voltage detected by the voltage detecting means 21 exceeds a predetermined voltage, the controller 7 closes the relay switch 11, and the voltage from the AC power supply is supplied to the main circuit power supply without voltage drop across the inrush current suppressing resistor 12. Robot operation becomes possible. After or during the operation of the robot, the charging of the large-capacity capacitor 19 is completed. On the other hand, when a power failure occurs in the AC power supply line L, the controller 7 that has detected the power failure by the power failure detection
If the robot arm is performing a playback operation, the servomotor is decelerated and stopped at a normal working deceleration while performing trajectory control on a trajectory previously taught. In the event of a power failure, the main circuit power supply voltage is supplied to Vp from the large capacity capacitor 19 and also to the control power supply 6 through the third diode 15. At this time, the first diode 13, the diode bridges 10 and 22 function to prevent backflow.
On the other hand, when the robot is stopped at the time of the power failure, the controller 7 turns on the transistor 18 so that the residual voltage of the main circuit power supply decreases promptly, and the large-capacity capacitor 19 → the second resistor 1
7 → transistor 18 → discharge rapidly in the path of large capacity capacitor 19. When the main circuit power supply is turned off or when an emergency stop is performed, the relay switch is opened, but one of the above two operations is selected as the main circuit power supply voltage except that control power is continuously supplied.

Therefore, in the motor drive device of the present invention, the power supply control means 5 has a capacity calculated from the amount of energy required to decelerate and stop the load of the robot or the like driven by the servomotor 1 when detecting a power failure. And a large-capacity capacitor 19 for supplying a power supply voltage for the main circuit power supply and the control power supply 6 at the time of a power failure, and a higher voltage of the power supply voltage Va rectified by the power supply means 4 and the voltage of the large-capacity capacitor 19 A first diode 13 and a second diode 14 that act to be supplied toward the motor power supply voltage Vp, and a third diode that acts to supply the control power supply 6 even when power is not supplied from the power supply means during a power failure. A diode 15 and a smoothing capacitor that suppresses power supply ripples and stores regenerative energy from the servomotor 1 0, a first resistor 16 for suppressing the charging current to the high-capacity capacitor 19, a second resistor for suppressing discharge current of the large-capacitance capacitor 19 17
And the provision of the transistor 16 serving as a discharging means for the residual voltage of the large-capacity capacitor, the backup time of the servo controller and the control power supply is extended to match the coasting angle required for stopping the servomotor 1 when a momentary power failure occurs. As a result, the servo driver and the controller can be placed in the same control state as before the occurrence of the power failure, and the robot arm can be stopped on the operating track at the deceleration during normal playback operation. Specifically, the time required to stop the robot when a power failure occurs is a numerical value such as several hundred ms, and the robot arm can be stopped at an acceleration during normal wafer gripping.

[0008]

As described above, according to the present invention, as a power supply control means in a motor driving device, a load of a robot or the like driven by a servomotor is calculated from the amount of energy required to decelerate and stop when a power failure is detected. Large-capacity capacitor having a reduced capacity and supplying a power supply voltage for a main circuit power supply and a control power supply at the time of a power failure, and a higher voltage of the power supply voltage Va rectified by the power-on means and the voltage of the large-capacity capacitor. A first diode and a second diode, which act to be supplied toward the motor power supply voltage Vp.
A diode, a third diode that functions to supply control power even when power is not supplied from the power supply means at the time of power failure, and a smoothing capacitor that suppresses power ripple and stores regenerative energy from the servomotor.
Since the first resistor for suppressing the charging current to the large-capacity capacitor, the second resistor for suppressing the charging / discharging current of the large-capacity capacitor, and the transistor serving as the discharging means for the residual voltage of the large-capacity capacitor are provided. In the event of a momentary power failure, the backup time of the servo controller and control power supply can be extended to match the coasting angle required to stop the servo motor, and as a result, the servo driver and controller return to the same control state as before the power failure occurred. The robot arm can be safely stopped on the running track at the deceleration during normal playback operation. Also, from this, when the robot has a combined operation of the composite axis, the robot arm was taught in advance without being affected by the difference in the rotation speed of each axis servo motor at the moment of a momentary power failure, the difference in the motor load inertia, etc. Needless to say, it can be stopped on orbit.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motor drive device showing an embodiment of the present invention.

FIG. 2 is a block diagram showing details of a power supply control unit on a primary side in FIG. 1;

FIG. 3 is a block diagram of a conventional motor drive device.

[Explanation of symbols]

 1: Servo motor 2: Encoder 3: Servo drive means 4: Power supply means 5: Power supply control means 6: Control power supply 7: Controller 8: Power failure detection means 9A, 9B: Relay switch 10: Diode bridge 11: Relay switch 12: Inrush current suppressing resistor 13: First diode 14: Second diode 15: Third diode 16: First resistor 17: Second resistor 18: Transistor 19: Large capacity capacitor 20: Smoothing capacitor 21: Voltage detecting means 22: Diode Bridge 23: Circulating current suppression resistor 24: Smoothing capacitor L: AC power line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3F059 CA00 FC11 5G015 GB03 JA06 JA27 JA32 JA35 JA61 5H530 AA05 BB33 CC26 CD24 CE16 DD22 DD29

Claims (1)

[Claims] A servo drive means (3) for driving the servo motor (1) based on a control signal obtained by feedback-controlling the rotation speed of the servo motor (1).
A controller (7) for giving commands to the servo drive means (3); a power supply means (4) for supplying AC power; and a main circuit power supply and a control power supply (6) based on the power supply means (4). ) For controlling the power supply (5)
Wherein the power control means (5) has a capacity calculated from the amount of energy required to decelerate and stop the load driven by the servomotor (1) upon detection of a power failure, and A large-capacity capacitor (1) that supplies the power supply voltage for the main circuit power supply and control power supply during a power outage
9) and the higher voltage of the power supply voltage Va rectified by the power supply means (4) and the voltage of the large-capacity capacitor (19) is supplied to the motor power supply voltage Vp. A first diode (13) and a second diode (14), and a third diode (1) that functions to supply the control power (6) even when power is not supplied from the power supply means (4) during a power failure.
5), a smoothing capacitor (20) for suppressing power supply ripple and storing regenerative energy from the servomotor (1), and a first resistor (20) for suppressing a charging current to the large-capacity capacitor (19). 16) and a second method for suppressing the charge / discharge current of the large-capacity capacitor (19).
A motor drive device comprising a resistor (17) and a transistor (16) serving as a means for discharging a residual voltage of the large-capacity capacitor (19).