KR20220081269A - Power supply measurement control circuit and robot controller - Google Patents

Abstract

Provided is a power measurement control circuit capable of detecting an abnormality in the AC power by monitoring an external AC power supply that supplies power for driving an industrial robot.
The power supply measurement control circuit is between the main circuit relay 23 for supplying and shutting off electric power to the robot and the AC power supply 10, respectively, for detecting a current waveform and a voltage waveform of the AC power from the AC power supply 10. AC A detection processing unit 40 including a current detection unit 21 and an alternating voltage detection unit 22 , and a detection storage unit 41 for storing the detected current and voltage waveforms and calculating currents and voltages from the current and voltage waveforms ) and an abnormality detection unit 46 connected to the detection processing unit 40 to detect an abnormality in the AC power supply 10 .

Description

POWER SUPPLY MEASUREMENT CONTROL CIRCUIT AND ROBOT CONTROLLER

The present invention relates to a power measurement control circuit for an industrial robot and a robot controller having such a power measurement control circuit.

The external power source used for the operation of the industrial robot is generally a commercial AC power, for example, single-phase or three-phase, 200/230V, 50/60Hz commercial AC power is used. However, depending on the installation environment of the robot, a good quality external power source may not be obtained, such as a large voltage drop, noise mixing in the voltage waveform, or large waveform distortion in the voltage waveform. As an example of waveform distortion, there is a thing in which a waveform, which should be originally a sine wave, is cut off in the vicinity of the vertex and is flattened. If the robot is connected to an external power source of poor quality, the robot may not operate normally. So far, with respect to the quality of the external power source to which the robot is connected, it is detected whether the voltage of the AC power supplied to the robot meets a predetermined voltage level (160 V for an AC power of nominal 200 V), If it did not reach the level of , it was judged to be a "reduced voltage" and an alarm was issued.

The electric current supplied to the robot and the electric power consumed by the robot vary greatly depending on the type of robot or what kind of operation the robot is performing. Therefore, when another robot is newly connected and operated with respect to an external power source capable of operating a certain robot normally, the newly connected robot may not operate normally. To prevent problems caused by an external power supply that supplies AC power to the robot, when introducing a new robot, measure the input current or power to the robot using a general-purpose measuring instrument such as an oscilloscope, current probe, or power meter. is being used to measure Even when a problem that is thought to be caused by an external power supply occurs after the robot is installed, a general-purpose measuring instrument is brought to the site to measure the external power supply.

Regarding measurements related to AC power, Patent Document 1 discloses that the phase difference between the voltage and current is calculated based on the zero-cross timing in the voltage and current of the AC power supply, and the power value is calculated from the voltage, current, and phase difference. . Similarly, in Patent Document 2, the power factor is obtained based on the phase difference between the zero-cross timing in the voltage waveform of the power from the AC power supply and the zero-cross timing in the current waveform, and the effective value of the voltage and the effective value of the current and the power factor. Calculation of active power based on it is disclosed.

Japanese Patent Laid-Open No. 2-116759 Japanese Patent Laid-Open No. 2017-9774

In industrial robots, as a mechanism for determining the quality of AC power, which is an external power source used for driving the robot, conventionally, only determining whether the input power voltage has reached a specified value has been provided. Therefore, it was not possible to detect an abnormality in the AC power supply due to, for example, an increase in the current and a large voltage drop, or an abnormality due to a large distortion in the current or voltage waveform. In addition, in order to know the input current or input power from the AC power supply when the robot is actually operated, it is necessary to separately prepare a general-purpose measuring device and perform measurement.

An object of the present invention is a power measurement control circuit capable of detecting an abnormality of the AC power by monitoring the AC power, which is an external power supply that supplies power for driving an industrial robot, and a power measurement control circuit used to control the industrial robot An object of the present invention is to provide a robot controller having a circuit.

The power measurement control circuit of the present invention is a power measurement control circuit that detects abnormalities by monitoring AC power, which is an external power source used for driving an industrial robot, and a main circuit relay and AC that supply and cut off AC power to the industrial robot. Detection means for detecting a current waveform and a voltage waveform of AC power from an AC power source between power sources, and a detection means for storing the current waveform and voltage waveform detected by the detection means, and calculating the current and voltage from the current waveform and voltage waveform It has a memory|storage means and an abnormality detection means which is connected to the detection memory|storage means and detects the abnormality in an AC power supply.

In the power supply measurement control circuit of the present invention, the detection means for detecting the current waveform and the voltage waveform is provided at a position on the AC power supply side rather than the main circuit relay, and the current waveform and the voltage waveform detected by the detection means are stored, and the current waveform and By providing a detection storage means for calculating current and voltage from the voltage waveform, and an abnormality detection means connected to the detection storage means to detect an abnormality in the AC power supply, the AC power supply, which is an external power supply, can be measured without using a general-purpose measuring instrument. By evaluating the quality, it becomes possible to detect abnormalities in the AC power supply.

The power supply measurement control circuit of the present invention may further include a power calculation means for calculating power based on the current and voltage waveforms or based on the current and voltage. By providing the electric power calculation means, the input electric power to the industrial robot can be known, and the approximate electric power consumption in the robot can be known.

In the power supply measurement control circuit of the present invention, the abnormality detection means may be configured to notify the host device when an abnormality is detected. When there is a host device used to control the industrial robot, the occurrence of an abnormality can be notified to the host device, so that the occurrence of an abnormality in the AC power source, which is an external power source, can be known on the host device side, so that the abnormality can be appropriately addressed. be able to respond.

In the power supply measurement control circuit of the present invention, the detection and storage means preferably detects the zero-crossing point in AC power. By detecting the zero-crossing point, it becomes possible to open and close the contacts of various relays including the main circuit relay in the vicinity of the zero-crossing point of AC power, and it becomes possible to reduce wear and tear of the contacts.

The robot controller of the present invention is a robot controller that drives and controls an industrial robot by receiving AC power from an AC power source, and includes a main circuit relay that supplies and cuts off electric power to the industrial robot, and between the main circuit relay and the AC power supply. a detection means for detecting a current waveform and a voltage waveform of AC power; a detection means for storing the current waveform and the voltage waveform detected by the detection means and calculating the current and voltage from the current waveform and the voltage waveform; It connects and has abnormality detection means which detects the abnormality in an AC power supply.

In the robot controller of the present invention, detection means for detecting the current waveform and voltage waveform of AC power from the AC power supply are provided at a position on the AC power supply side rather than the main circuit relay, and the current waveform and voltage waveform detected by the detection means are stored And, by providing a detection storage means for calculating current and voltage from the current waveform and voltage waveform, and an abnormality detection means connected to the detection storage means to detect an abnormality in an AC power supply, without using a general-purpose measuring instrument, By evaluating the quality of the AC power source, which is an external power source, abnormalities in the AC power source can be detected.

The robot controller of the present invention may further include a power calculation means for calculating power based on the current waveform and the voltage waveform or based on the current and voltage. By providing the electric power calculation means, the input electric power to the industrial robot can be known, and the approximate electric power consumption in the robot can be known.

In the robot controller of the present invention, the abnormality detecting means may be configured to notify the host device when an abnormality is detected. When there is a host device that controls the industrial robot by sending a command to the robot controller, it is possible to notify the host device of the occurrence of an abnormality, so that the occurrence of an abnormality in the AC power source can be known on the host device side, You can respond appropriately to the above.

In the robot controller of the present invention, furthermore, a rectifier circuit for rectifying AC power, a power supply circuit provided on the output side of the rectifier circuit, a resistor for preventing inrush current provided between the main circuit relay and the power supply circuit, and a short circuit relay for shorting both ends of the resistor; , a power supply control means for controlling the short circuit relay is provided, the detection and storage means detects a zero cross point in at least one of the current waveform and the current waveform, and the power supply control means synchronizes the zero cross point with the short circuit relay. You may make it perform control which closes a contact point. By configuring in this way, while it is possible to limit the inrush current flowing through the smoothing capacitor when the power is turned on, the contact of the short-circuit relay is closed in accordance with the zero-cross point, so that it is possible to reduce wear and tear on the contact of the short-circuit relay.

In the robot controller of the present invention, when the detection and storage means detects the zero-crossing point, the power supply control means synchronizes with the zero-crossing point to control to close the contact of the main circuit relay and control to open the contact of the main circuit relay. You may control at least one of them. The wear and tear of the main circuit relay can be reduced by opening and closing the contacts of the main circuit relay in synchronization with the zero cross point. In particular, when performing control to open the contact of the main circuit relay, it is preferable to perform control to open the contact of the short circuit relay in synchronization with the zero cross point, and then perform control to open the contact of the main circuit relay in synchronization with the zero cross point . By performing such control, wear and tear of the contacts of both the main circuit relay and the short circuit relay can be reduced.

According to the present invention, a power measurement control circuit capable of detecting an abnormality of an AC power supply by monitoring an external power supply that is an AC power supply for driving an industrial robot, and a robot controller having such a power measurement control circuit can

1 is a block diagram showing the configuration of a robot controller according to an embodiment of the present invention.

EMBODIMENT OF THE INVENTION Next, embodiment of this invention is described with reference to drawings. The power measurement and control circuit based on the present invention monitors AC power, which is an external power source that supplies power for driving an industrial robot to detect an abnormality in the AC power, and is usually used for driving and controlling industrial robots. is provided inside the robot controller. Fig. 1 shows the configuration of a robot controller according to an embodiment of the present invention.

The robot controller shown in FIG. 1 is supplied with AC power from, for example, an AC power supply 10 that is a commercial power source, and controls the motor 60 of each axis of the industrial robot based on a command input from the outside. A power supply circuit 26 is provided inside the robot controller to which AC power is supplied from the AC power supply 10 and outputs DC power. The power supply circuit 26 is provided with a full-wave rectifying circuit 27 for rectifying by supplying AC power, and a smoothing capacitor 28 for smoothing the pulsating current output from the full-wave rectifying circuit 27 . The DC power obtained from the power supply circuit 26 is supplied to the servo driver 51 which drives the motor 60 and performs servo control via the short-circuit protection fuse 29 . Moreover, the robot controller is provided with the main control part 50 which performs basic control as a robot controller. The main control unit 50 is connected to a host device, for example, a device used by a user of an industrial robot, and is configured by, for example, a CPU (central processing unit) or a microprocessor. The servo driver 51 drives the motor 60 by servo control using DC power supplied by a command from the main control unit 50 that performs drive control of the motor 60 based on an external command. .

In order to consume regenerative energy when a regenerative current flows from the motor 60 through the servo driver 51 to the power supply circuit 26 side, a discharge resistor 32 against the input of DC power in the servo driver 51 A switch element 33 provided in parallel and intermittent with the current flowing through the discharge resistor 32 is provided. In the illustrated example, an NPN-type bipolar transistor is used as the switch element 33 , and one end of the discharge resistor 32 is connected to the positive (+) side conducting wire of the DC input of the servo controller 51, and discharges The other end of the resistor 32 is connected to the collector of the transistor which is the switch element 33 . The emitter of this transistor is connected to the conducting wire on the negative (-) side of the DC input of the servo controller 51 . Further, in order to detect a voltage on the output side of the power supply circuit 26 , a DC voltage detector 30 is provided on the servo driver 51 side rather than the short circuit protection fuse 29 .

Between the AC power supply 10 and the power supply circuit 26 , a main circuit relay 23 for supplying and interrupting AC power to the power supply circuit 26 is provided. In the industrial robot, since the motor should not be driven unless a predetermined condition for safety is met, the main circuit relay 23 is provided with a safety judgment circuit (not shown) that determines whether or not the predetermined condition for safety is satisfied. ), the contact is closed according to the safety output signal from ) and the AC power from the AC power supply 10 is supplied to the power supply circuit 26 . The safety output signal is applied to the coil 23a of the main circuit relay 23 via a delay element 31 that gives a predetermined delay time. Between the main circuit relay 23 and the power supply circuit 26, a resistor 24 is provided in order to limit the inrush current flowing through the smoothing capacitor 28 when the power supply circuit 26 is started, and the resistor 24 A short-circuit relay 25 having a contact for short-circuiting both ends is provided.

At a position closer to the AC power supply 10 than the main circuit relay 23, an AC current detection unit 21 for detecting a current waveform and a voltage waveform of AC power supplied from the AC power supply 10 to the power supply circuit 26, respectively, and An AC voltage detection unit 22 is provided. The AC current detection unit 21 and the AC voltage detection unit 22 correspond to detection means. The AC current detection unit 21 is constituted by a shunt resistor inserted into a conducting wire from the AC power supply 10 toward the main circuit relay 23, and is a current waveform detected by a voltage signal that is a voltage between both ends of the shunt resistor. to output On the other hand, the AC voltage detection unit 22 is constituted by a voltage dividing resistor disposed between a pair of conducting wires connecting the AC power supply 10 and the main circuit relay 23 , and is a voltage divided by the dividing resistor. The detected voltage waveform is output by the signal. Here, it is assumed that the AC power supply 10 is single-phase, but in the case of three-phase, the AC current detection unit 21 is constituted by two shunt resistors respectively inserted into two of the three conductors, and one of the three conductors. The AC voltage detection unit 22 is constituted by two sets of voltage dividing resistors provided between each of the dog and the remaining two. A detection processing unit 40 is provided to which the current waveform and voltage waveform detected by the AC current detection unit 21 and the AC voltage detection unit 22, respectively, are input. Although the case where the current waveform of AC power is detected by the shunt resistor inserted into the conducting wire is described here, the method for detecting the current waveform usable in the present invention is not limited to using a shunt resistor. As the AC current detection unit 21, one that detects a current waveform by using a Hall element or one that detects a current waveform by a current transformer or the like can also be used.

The detection processing unit 40 is constituted by a CPU <central processing unit> or a microprocessor having an analog/digital (A/D) conversion function, and logically includes a detection storage unit 41 and a power calculation unit 42 . are doing The detection storage unit 41 and the power calculation unit 42 correspond to the detection storage unit and the power calculation unit, respectively. The detection and storage unit 41 performs analog/digital conversion of a voltage signal representing a current waveform and a voltage signal representing a voltage waveform, respectively, and calculating respective rms values of current and voltage from those current waveforms and voltage waveforms, Memorize current and voltage waveforms. In the calculation of the rms value, in order to avoid the influence of waveform distortion, it is preferable not to simply obtain the rms value based on the crest value, but to obtain the rms value by accumulating instantaneous values. The detection storage unit 41 may detect a zero cross point in each of the current waveform and the voltage waveform. The electric power calculation unit 42 calculates and stores the electric power input from the AC power supply 10 by multiplying the detected current by the voltage or by integrating the product of the instantaneous value in the current waveform and the instantaneous value in the voltage waveform. . When it is unnecessary to calculate the input power, it is not always necessary to provide the power calculation unit 42 .

The robot controller of this embodiment is further provided with the power supply control part 45 which controls the main circuit relay 23, the short circuit relay 25, and the switch element 33. As shown in FIG. The power supply control unit 45 is constituted by, for example, a CPU or a microprocessor, and is connected to the detection processing unit 40 and the main control unit 50 via a signal line. In particular, in the present embodiment, the power supply control unit 43 controls the AC power supply 10 based on the current, voltage, and power detected by the detection processing unit 40 and the current waveform and voltage waveform stored in the detection processing unit 40 . ) is provided with an abnormality detection unit 46 that detects an abnormality. The abnormality detection unit 46 corresponds to an abnormality detection means. When an abnormality in the AC power supply 10 is detected, the abnormality detection unit 46 can notify the occurrence of an abnormality to the host device via the main control unit 50 . In addition, according to a request input from the host device through the main control unit 50 , the calculated values of current, voltage, and power or the current waveform, voltage waveform or power waveform stored in the detection processing unit 40 are transmitted to the host device. output toward The AC current detection unit 21 , the AC voltage detection unit 22 , the detection processing unit 40 , and the abnormality detection unit 46 constitute a power supply measurement control circuit based on the present invention.

By providing the power measurement control circuit in the robot controller in this way, the effective power input voltage from the AC power supply 10 is not used for each robot and further for each robot operation without using a general-purpose measuring instrument such as an oscilloscope, a current probe, or a power meter. It becomes possible to obtain the value, the maximum value and the waveform, the rms value, the maximum value and the waveform of the power supply input current, and the input power. By detecting the power supply input current or the power supply input voltage, it is possible to detect an excess of an allowable input current, occurrence of an overvoltage or a reduced voltage, and the like. If the input power is used, an estimate of heat generation or power consumption in the motor 60 of the robot can be obtained, and further, it is possible to detect, for example, that the allowable power is exceeded. When the effective value expected from the peak value deviates greatly from the effective value obtained by integrating the instantaneous values in the waveform, it can be determined that the waveform distortion in the AC power supply 10 is large.

Next, the control of the main circuit relay 23, the short circuit relay 25, and the switch element 33 by the power supply control part 45 in this embodiment is demonstrated. First, the control of the switch element 33 is demonstrated. When the regenerative current from the motor 60 flows from the servo driver 51 to the power supply circuit 26 side, the DC voltage on the output side of the power supply circuit 26 rises. When this DC voltage rises too much, there exists a possibility that the withstand voltage of the element or apparatus connected to the power supply circuit 26 may be exceeded. The voltage detected by the DC voltage detector 30 provided on the output side of the power supply circuit 26 is input to the power supply control part 45, and the power supply control part 45 sets the voltage detected by the DC voltage detector 30 to a threshold value. When it exceeds, a signal is output to the base of the transistor which is the switch element 33 to put the transistor into a conductive state, and regenerative energy is consumed by the discharge resistor 32 . Since the voltage on the output side of the power supply circuit 26 is lowered by the consumption of regenerative energy, when the voltage detected by the DC voltage detector 30 is lowered, the power control unit 45 controls the transistor to a cut-off state, and the discharge resistor ( 32) to stop the consumption of regenerative energy. Thereby, the DC voltage on the output side of the power supply circuit 26 is always maintained below the threshold value.

When the contact of the main circuit relay 23 is closed and the power supply circuit 26 is started, there is a fear that a large inrush current may flow in the smoothing capacitor 28 of the power supply circuit 26, and it rushes to the input side of the power supply circuit 26 A current limiting resistor 24 is provided. After the charging voltage of the smoothing capacitor 28 rises sufficiently, it becomes unnecessary to limit the inrush current, so it is necessary to short-circuit both ends of the resistor 24 with the short circuit relay 25 . The power supply control part 45 is comprised so that the coil 25a of the short circuit relay 25 can be driven, After the contact of the main circuit relay 23 is closed, for example, after a certain time passes, or a DC voltage detector, When the charging voltage of the smoothing capacitor 28 detected in (30) exceeds a certain value, control to close the contact of the short circuit relay 25 is performed. Since the power control unit 45 can know the zero-cross timing in the voltage waveform or current waveform of the AC power from the AC power supply 10 through the detection processing unit 40 , the zero-cross in the AC power waveform Control can be performed so that the contact of the short circuit relay 25 may be closed at the timing of the vicinity of a point. By closing the contact point of the short circuit relay 14 at the timing in the vicinity of the zero-cross point in the waveform of the AC power, the current flowing through the contact point at the moment of closing the contact point becomes small, so that wear and tear of the contact point can be reduced.

From a viewpoint of ensuring safety in an industrial robot, the contact point of the main circuit relay 23 is controlled by a safety output signal as a principle. In the present embodiment, since the safety control signal is also supplied to the power supply control unit 45 , the power supply control unit 45 passes through the detection processing unit 40 to zero in the voltage waveform of the AC power from the AC power supply 10 . Cross timing is known. Therefore, instead of controlling the closing of the contact of the main circuit relay 12 by the safety output signal itself, the safety output signal is output and the power supply is synchronized with the zero-cross point in the voltage waveform of AC power. You may make it control that the control part 45 closes the contact of the main circuit relay 23. As shown in FIG. By closing the contact point of the main circuit relay 23 at the timing in the vicinity of the zero cross point in the voltage waveform of AC power, the current flowing through the contact point at the moment of closing the contact point becomes small, so the contact point of the main circuit relay 23 wear and tear can be reduced.

Even when the safety output signal is turned off for reasons such as emergency stop and the contact of the main circuit relay 23 has to be opened, by opening the contact in the vicinity of the zero cross point, the current to be interrupted by opening the contact is reduced. Since it becomes small, generation|occurrence|production of the arc discharge at a contact can be suppressed, and wear and tear of a contact can be reduced. When the contact of the main circuit relay 23 has to be opened due to an emergency stop or the like, the power supply control unit 45 first opens the contact of the short circuit relay 25 in the vicinity of the zero cross point in the waveform of the AC power, and then Control of opening the contact of the main circuit relay 23 in the vicinity of the zero cross point in the waveform of AC power can be performed. By controlling in this way, it is possible to prevent wear and tear of the contacts of the relays 23 and 25 on both sides. In addition, this control can be completed within the time equivalent to one cycle of AC power, and there is no impediment to ensuring safety during an emergency stop.

As described above, according to the present embodiment, current and voltage are obtained by detecting the current and voltage waveforms in the AC power input from the AC power supply 10, and these waveforms are stored and the power can be detected. By doing so, it becomes possible to detect abnormalities and the like of the AC power supply 10 used for driving the industrial robot without bringing a general-purpose measuring instrument or the like. In addition, it is possible to know the approximate power consumption of the robot and to open and close the contacts of the relays 23 and 25 at the zero-cross timing, thereby reducing wear and tear of the contacts of the relays 23 and 25. can

10: AC power
21: AC current detection unit
22: AC voltage detection unit
23: main circuit relay
24: resistance
25: short circuit relay
26: power circuit
27: full-wave rectification circuit
28: smoothing capacitor
29: short circuit protection fuse
30: DC voltage detector
31: delay element
32: discharge resistance
33: switch element
40: detection processing unit
41: detection storage unit
42: power output unit
45: power control
46: abnormality detection unit
50: main control
51: servo driver
60: motor

Claims (12)

It is a power measurement control circuit that detects abnormalities by monitoring AC power, which is an external power source used to drive industrial robots.
detecting means for detecting a current waveform and a voltage waveform of the AC power from the AC power source between a main circuit relay for supplying and blocking AC power to the industrial robot and the AC power supply;
detection storage means for storing the current waveform and the voltage waveform detected by the detection means, and calculating a current and a voltage from the current waveform and the voltage waveform;
and an abnormality detection unit connected to the detection storage unit and configured to detect an abnormality in the AC power supply. The power supply measurement control circuit according to claim 1, further comprising power calculation means for calculating power based on the current waveform and the voltage waveform or based on the current and the voltage. The power supply measurement control circuit according to claim 1, wherein the abnormality detection means notifies a host device when the abnormality is detected. The power supply measurement control circuit according to claim 2, wherein the abnormality detection means notifies a host device when the abnormality is detected. The power supply measurement control circuit according to any one of claims 1 to 4, wherein the detection and storage means detects a zero-crossing point in the AC power. It is a robot controller that drives and controls industrial robots by receiving AC power from an AC power source,
a main circuit relay that supplies and cuts power to the industrial robot;
detection means for detecting a current waveform and a voltage waveform of the AC power between the main circuit relay and the AC power supply;
detection storage means for storing the current waveform and the voltage waveform detected by the detection means, and calculating a current and a voltage from the current waveform and the voltage waveform;
and an abnormality detection unit connected to the detection storage unit and configured to detect an abnormality in the AC power supply. The robot controller according to claim 6, further comprising power calculation means for calculating power based on the current waveform and the voltage waveform or based on the current and the voltage. The robot controller according to claim 6, wherein the abnormality detecting means notifies a host device when the abnormality is detected. The robot controller according to claim 7, wherein the abnormality detecting means notifies a host device when the abnormality is detected. The power supply circuit according to any one of claims 6 to 9, further comprising: a rectifier circuit for rectifying the AC power and a power supply circuit provided on an output side of the rectifier circuit;
a resistor for preventing inrush current provided between the main circuit relay and the power circuit;
a short circuit relay for shorting both ends of the resistor;
Power control means for controlling the short circuit relay
have more,
the detection and storage means detects a zero cross point in at least one of the current waveform and the current waveform;
The power supply control means performs control to close the contact point of the short circuit relay in synchronization with the zero cross point. The robot controller according to claim 10, wherein the power supply control means performs at least one of a control for closing a contact of the main circuit relay and a control for opening a contact of the main circuit relay in synchronization with the zero crossing point. The power supply control means according to claim 11, wherein when performing control to open the contact of the main circuit relay, after performing control to open the contact of the short-circuit relay in synchronization with the zero-crossing point, synchronizing with the zero-crossing point to control to open the contact point of the main circuit relay, the robot controller.

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