JP7281699B2 - BRAKE DRIVE CONTROL CIRCUIT AND ITS FAILURE DETECTION METHOD - Google Patents

Description

The present invention relates to a brake drive control circuit for controlling the drive of an electromagnetic brake attached to a motor or the like, and a failure detection method thereof.

In robots, electromagnetic brakes are attached to the motor shafts in order to ensure safety by preventing the robot arm from moving or falling when the power of the motors that drive each shaft is interrupted. Electromagnetic brakes provided in robots are generally of the non-excitation type. When the electromagnetic brake is energized, the brake is released (released). is configured to lock In addition, the safety standards (UL1740, ISO10218) for robots require electromagnetic brakes provided in robots to be able to release the brakes when power for driving the motors is lost. Patent Literature 1 discloses a device in which a motor brake power supply unit for energizing an electromagnetic brake to release the brake is provided, and the brake can be released by operating a switch provided in the motor brake power supply unit. ing.

Electromagnetic brakes provided in robots are mechanisms related to safety and require high reliability. If the switch is controlled by only one switch as shown in Patent Document 1, if the switch fails in the form of a short circuit, the brake will always be released, making it impossible to ensure safety. There is a risk. Therefore, Patent Document 2 discloses a brake drive control circuit in which switching control means are connected to both ends of the electromagnetic brake so as to be electrically in series with the electromagnetic brake, respectively, in order to improve safety. A switching transistor is used as the switching control means. The brake drive control circuit described in Patent Document 2 also includes voltage detection means for performing failure detection by detecting the voltage across the electromagnetic brake.

JP-A-2000-296492 JP-A-2006-123118

In the brake drive control circuit of Patent Document 2, one of the two switching control means is a low-side switch provided between the electromagnetic brake and the ground potential, and the other is between the electromagnetic brake and the power supply voltage for driving the brake. It becomes a high side switch provided in. If the power supply voltage for driving the brake is low, the problem is unlikely to occur. In addition, when the power supply voltage is high, the following problems arise depending on the type of device used as the high-side switch. That is, when an N-channel FET (Field Effect Transistor) is used, the drive circuit becomes large, the number of parts increases, the cost increases, and the mounting area increases. When a P-channel FET is used, the size of the device increases, the on-resistance increases, and the loss increases. When a bipolar transistor is used, the device size increases and the loss also increases.

Electromagnetic brakes require a considerable amount of current to release them, so if the number of robot axes increases and the number of electromagnetic brakes increases, the power supply circuit for the electromagnetic brakes must also have a large capacity. There is a need to. In a robot, a large-capacity, relatively high-voltage power supply circuit is provided to drive the motor. The above-mentioned problems involved cannot be solved. If a relatively low-voltage power supply circuit is separately prepared for driving the brake, the separately prepared power supply circuit also requires a certain amount of capacity, which causes an increase in cost. The robot is also provided with a relatively low-voltage power supply circuit for its control circuit, but since the control circuit does not consume much power, the power supply circuit for the control circuit has a relatively small capacity, and multiple axes can be operated. It is not realistic to use a small-capacity power supply circuit for a control circuit as a power supply circuit for driving a brake in a robot that requires a large current for brake release.

An object of the present invention is to enable a relatively low voltage to be applied to a switching element used as a high-side switch without compromising safety, and to eliminate the need to provide a large-capacity separate power supply circuit. and a failure detection method for such a brake drive control circuit.

A brake drive control circuit according to the present invention is a brake drive control circuit that controls an electromagnetic brake that releases a brake when energized, wherein a first power supply for a first circuit voltage and one terminal of the electromagnetic brake are connected to the brake drive control circuit. between a first rectifying element provided, a cutoff switch inserted in a line for supplying power to the first power supply to operate the first power supply, and the other terminal of the electromagnetic brake and a ground point; a first switching element provided, a second switching element provided in series between a second power supply having a second circuit voltage different from the first circuit voltage, and the one terminal of the electromagnetic brake; and a rectifying element, wherein the second circuit voltage is lower than the first circuit voltage.

A brake drive control circuit according to the present invention is a brake drive control circuit that controls an electromagnetic brake that releases a brake when energized, wherein a first power supply for a first circuit voltage and one terminal of the electromagnetic brake are connected to the brake drive control circuit. between a first rectifying element provided, a cutoff switch inserted in a line for supplying power to the first power supply to operate the first power supply, and the other terminal of the electromagnetic brake and a ground point; a first switching element provided, a second switching element provided in series between a second power supply having a second circuit voltage different from the first circuit voltage, and the one terminal of the electromagnetic brake; and a rectifying element, wherein the first power supply is a power supply for driving a motor that is subjected to a braking operation by the electromagnetic brake, and the cutoff switch is provided in a safety circuit for the motor.

The monitoring means includes a first monitor circuit for detecting a voltage at a connection point between the other terminal of the electromagnetic brake and the first switching element, and a connection point between the second switching element and the second rectifying element. and a second monitor circuit for detecting the voltage.

When the cut-off switch is open and the first power supply is inoperative, the first switching element and the second switching element are activated based on the operation of the brake release switch or the input of the brake release command. Electromagnetic brake is released

In such a brake drive control circuit, the cut-off switch and the first switching element are connected in series with the electromagnetic brake interposed therebetween. and the locked state of the electromagnetic brake can be maintained. On the other hand, since the electromagnetic brake can be released by using the second power supply and the second switching element, the safety standard states that "the brake can be released when the power supply for driving the motor is lost." can satisfy the requirements based on As the first switching element and the second switching element, for example, semiconductor elements such as transistors can be used.

In the brake drive control circuit of the present invention, the second circuit voltage can be made lower than the first circuit voltage. The second switching element corresponds to a high-side switch, but since the second circuit voltage is low, compared to the case of operating at the same voltage as the first circuit voltage, the second switching element has a low withstand voltage and a small semiconductor. element can be used, and the drive circuit for the second switching element can also be simplified.

In the brake drive control circuit of the present invention, the power source for driving the motor, which is the target of the braking operation by the electromagnetic brake, can be used as the first power source, and the switch generally provided in the safety circuit for the motor can be used as the cutoff switch. Safety circuits for motors are required to have high reliability. By using a switch for shutting off the power supply for driving the motor in the safety circuit as a shutoff switch in the present invention, the power to the motor is shut off and the brake is applied. It is possible to configure a highly reliable brake drive control circuit that complies with safety standards for reliable operation.

The brake drive control circuit of the present invention may include monitor means for monitoring voltages at one terminal and the other terminal of the electromagnetic brake. By providing such monitoring means, failure of the switching element can be detected and safety can be improved. This monitor means includes, for example, a first monitor circuit for detecting the voltage at the connection point between the other terminal of the electromagnetic brake and the first switching element, and the voltage at the connection point between the second switching element and the second rectifying element. and a second monitor circuit. By using such a first monitor circuit and a second monitor circuit, it is possible to monitor voltages across the electromagnetic brake, and independently detect failures of the first switching element and second switching element. .

Alternatively, the brake drive control circuit of the present invention may comprise monitoring means having a circuit for monitoring the voltage across the electromagnetic brake. By providing such monitoring means, failure of the switching element can be detected and safety can be improved.

When the monitoring means is provided in the present invention, it is preferable to further provide a failure detection circuit that outputs a failure detection signal based on the monitoring result of the monitoring means and keeps the cutoff switch in an open state. By providing such a fault detection circuit, it is possible to prevent the first power supply from operating when the switching element is faulty, and to prevent the brake from being released, thereby further enhancing safety. can. When the cut-off switch is opened based on the output of the failure detection signal, the output voltage of the first power supply does not necessarily become zero immediately if a capacitor is provided at the output of the first power supply. Therefore, in the present invention, when a failure detection signal is output, the output of the first power supply is forcibly discharged by, for example, flowing a D-axis current to the motor or using a discharge resistor, so that the brake can be quickly applied. It is preferable to make it work.

In the brake drive control circuit of the present invention, when the cutoff switch is open and the first power supply is not operating, the first switching element and the second switching element operate based on the operation of the brake release switch or the input of the brake release command. It can be configured such that the electromagnetic brake is released when the state is set. By inputting a brake release command from a brake release switch provided for each axis of the robot or a pendant for robot teaching, the electromagnetic brake can be reliably released in an emergency.

In the brake drive control circuit of the present invention, the first switching is performed so that the voltage applied to the electromagnetic brake when maintaining the electromagnetic brake in the released state is lower than the voltage applied to the electromagnetic brake when shifting the electromagnetic brake to the released state. It is preferred to PWM drive the device. Power can be saved by changing the voltage required for releasing the electromagnetic brake and maintaining the released state, and further power saving can be achieved by performing PWM drive. In particular, when a robot or the like is in normal operation, the electromagnetic brake must be kept in the released state for a long time. is possible.

The failure detection method of the present invention includes a first rectifying element provided between a first power supply for a first circuit voltage and one terminal of an electromagnetic brake, and a first rectifying element provided between the other terminal of the electromagnetic brake and a ground point. a second switching element and a second rectifying element provided in series between a second power supply having a second circuit voltage different from the first circuit voltage and one terminal of the electromagnetic brake; and a failure detection method in a brake drive control circuit that controls an electromagnetic brake that releases the brake by energizing, the method using a pulse of a length that the electromagnetic brake does not respond when the first power supply is inactive to drive the second switching element, and monitor the voltage at the connection point between the other terminal of the electromagnetic brake and the first switching element and the voltage at the connection point between the second switching element and the second rectifying element.

According to the failure detection method of the present invention, the failure of the first switching element and the failure of the second switching element can be detected separately, and furthermore, the circuit for monitoring the voltage or the disconnection of the electromagnetic brake (or It is also possible to detect failures such as unconnected).

In the failure detection method of the present invention, the first switching element is PWM-driven while the electromagnetic brake is released, and the connection point between the other terminal of the electromagnetic brake and the first switching element is driven in synchronization with the PWM drive. voltage may be monitored. By performing such monitoring, it is possible to detect a failure of the first switching element or disconnection of the electromagnetic brake even when the electromagnetic brake is energized and released.

According to the present invention, in a brake drive control circuit, a relatively low voltage can be applied to a switching element used as a high-side switch without impairing safety. The provision of circuitry can be dispensed with. Also provided is a failure detection method capable of reliably detecting a failure of a switching element or the like in such a brake drive control circuit.

1 is a circuit diagram illustrating a brake drive control circuit according to an embodiment of the invention; FIG. 2 is a state transition diagram showing the operation of the brake drive control circuit shown in FIG. 1; FIG. It is a figure explaining the electric current which flows into an electromagnetic brake. 1 is a circuit diagram illustrating a brake drive control circuit according to an embodiment of the invention; FIG.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining a brake drive control circuit according to one embodiment of the present invention, and shows a state in which this brake drive control circuit is incorporated in a robot. The robot is provided with a plurality of motors 13 that are servo-controlled by the robot controller, and the figure shows the motors 13 for one axis, the electromagnetic brake 31, and the brake drive control circuit in the robot.

An electromagnetic brake 31 is mechanically connected to the rotating shaft of the motor 13, as indicated by double lines. A solenoid (coil) of the electromagnetic brake 31 is provided in parallel with a surge absorber 32 for absorbing a large back electromotive force generated when the current to the solenoid is interrupted. A varistor, a diode, or the like, for example, is used as the surge absorber 32 . A driver 12 is provided for each motor 13 for each axis. A motor drive power supply 11 is provided in common to each axis to convert an AC motor power supply into a DC power supply. Based on this, the corresponding motor 13 is driven.

A safety circuit 20 is provided between the motor power supply and the motor drive power supply 11 . This safety circuit 20 is generally provided in a robot to ensure safe operation of the robot, and is provided in a line that supplies power from the motor power supply to the motor drive power supply 11 to prevent the supply of power. It has a cut-off switch 21 that cuts off and a safety control section 22 that controls the cut-off switch 21 . The safety circuit 20 is configured to supply power to the motor drive power supply 11 only when it can be confirmed that the robot is safe. The safety control unit 22 receives a signal from the operation switch and an abnormal shut-off signal. The safety control unit 22 closes the cut-off switch 21 to supply power to the motor drive power source when the robot operation is instructed by the operation switch, and immediately opens the cut-off switch 21 when an emergency cut-off signal is input. , the power supply to the motor drive power supply 11 is stopped, and the motors 13 of all axes are stopped. Furthermore, the safety control unit 22 outputs a safety circuit monitor signal indicating the state of the safety circuit 20 to the outside. The motor drive power supply 20 and the safety circuit 20 are provided inside a robot controller that is connected to and controls the robot.

Since the safety circuit 20 is directly connected to the safety of the robot, it is a highly reliable circuit conforming to various safety standards. Also, when the power to the motor 13 is cut off, the electromagnetic brake 31 of each shaft must operate to lock the motor shaft. Therefore, in this embodiment, the cutoff switch 21 in the safety circuit 20 is used instead of the high side switch in the conventional brake drive control circuit as shown in Patent Document 2. This means that the motor drive power supply 11 is used as a power supply for the electromagnetic brake 31. When the motor drive power supply 11 is inoperative and the motor 13 is in a non-driving state, the electromagnetic brake 31 is applied to the motor shaft. can be securely locked. However, simply using the motor drive power supply 11 as the drive power supply for the electromagnetic brake 31 does not satisfy the safety standard requirement that the brake can be released even when the power supply for driving the motor is lost. can't Therefore, in this embodiment, a brake power supply is prepared separately from the motor drive power supply 11 so that the electromagnetic brake 31 can be released even when the power supply for driving the motor 13 is lost. It is an emergency to release the electromagnetic brakes 31 when the power for driving the motor is lost. , the electromagnetic brakes 31 are released one by one for the axes requiring brake release. Therefore, the capacity required for the power supply for the brake is a capacity that can release the electromagnetic brake 31 of one axis at most. A power supply provided separately from the power supply 11 can be used.

When the electromagnetic brake 31 is driven by the brake power supply, the cutoff switch 21 in the safety circuit 20 cannot be used in place of the high side switch. A high-side switch must be provided. Also, the motor drive power supply 11 and the brake power supply must be separated. Therefore, in the brake drive control circuit of this embodiment, both ends of the electromagnetic brake 31 are connected to the connection points 33 and 34, respectively, and the transistor Tr1 provided as a low-side switch between the connection point 34 and the ground point is connected to the brake power supply. a transistor Tr2 provided as a high-side switch to switch between the motor driving power source 11 and the connection point 33 for reverse voltage blocking; and a reverse voltage blocking diode D1 provided between the transistor Tr2 and the connection point 33. and a diode D2. In this configuration of the brake drive control circuit, the cutoff switch 21 is commonly provided for all the electromagnetic brakes 31 in the robot, but the transistors Tr1 and Tr2 and the diodes D1 and D2 are provided for each electromagnetic brake 31. FIG. The transistor Tr1 is, for example, an N-channel FET whose gate is supplied with a brake signal, and the transistor Tr2 is, for example, a P-channel FET whose gate is supplied with an emergency brake signal. Here, the motor drive power supply 11 corresponds to the first power supply, the brake power supply corresponds to the second power supply, the transistor Tr1 corresponds to the first switching element, the transistor Tr2 corresponds to the second switching element, and the diode D1 corresponds to It corresponds to the first rectifying element, and the diode D2 corresponds to the second rectifying element. Here, N-channel and P-channel FETs are used as the first and second switching elements, respectively, but the devices used for each switching element are not limited to this.

In the circuit of this embodiment, when the electromagnetic brake 31 is released as the motor 13 is driven, it is necessary to supply a current proportional to the number of axes of the robot. A drive power supply 11 is used. When the electromagnetic brake 31 is released in an emergency while the motor 13 is not driven, it is sufficient to have a capacity necessary to release the electromagnetic brake 31 for one axis. Assuming that the voltage of the motor drive power supply 11 is the first circuit voltage and the voltage Vcc of the brake power supply is the second circuit voltage, the first circuit voltage and the second circuit voltage are different, and the second circuit voltage is the first circuit voltage. It can be a voltage lower than the circuit voltage. The second circuit voltage is lower than the first circuit voltage, and the current required to flow through the transistor Tr2 is the current for driving the electromagnetic brake 31 for one axis. Devices with low withstand voltage and small size can be used, and their drive circuits can also be small.

Further, the brake drive control circuit shown in FIG. 1 includes monitor circuits 41 and 42 and a fault detection circuit 45 for monitoring the drive voltage of the electromagnetic brake 31 and detecting faults in the transistors Tr1 and Tr2. The monitor circuit 41 is connected to a connection point 34 between the transistor Tr1 and the electromagnetic brake 31 to output a Tr1 monitor signal, and the monitor circuit 42 is connected to a connection point 35 between the transistor Tr2 and the diode D2 to output the Tr2 signal. Outputs the monitor signal. The monitor circuits 41 and 42 can be composed of, for example, resistor voltage dividing circuits, level shift circuits, photocouplers, and the like. In the illustrated one, each of the monitor circuits 41 and 42 is composed of a resistive voltage dividing circuit in which two resistors are connected in series and a monitor signal is output from the midpoint thereof. The Tr1 monitor signal and Tr2 monitor signal are input to the failure detection circuit 45 .

Next, the operation of the brake drive control circuit shown in FIG. 1 will be explained using the state transition diagram shown in FIG. Here, the standby state is a state in which only a control circuit (not shown) in the robot controller is energized and power is not supplied to the motor drive power supply 11, and the motor 13 is in a free state or a dynamic brake state. is. In the standby state, no current is supplied to the electromagnetic brake 31 and the motor shaft is locked by the electromagnetic brake 31 . The transistor Tr1, which is a low-side switch, remains in an off state (cutoff state). On the other hand, the servo-on state is a state in which power is supplied to the motor drive power source 11 and the motor 13 is servo-driven (servo lock state). It is in release state.

In normal operation, in the standby state, monitor circuits 41 and 42 are used to detect failures of transistors Tr1 and Tr2. Since the electromagnetic brake 31 does not operate when a very short pulse is energized, a very short pulse (for example, 0.5 milliseconds) is applied from the failure detection circuit 45 to the transistor Tr2 at a constant period (for example, 100 milliseconds). The voltage is applied to drive the transistor Tr2 and the failure is monitored. If the voltage of the Tr1 monitor signal does not change to a pulse-like high level in response to the application of the pulse, it can be determined that the transistor Tr1 is not turned off, that is, the monitor circuit 41 is out of order. On the other hand, unless the voltage of the Tr2 monitor signal pulse-like changes to a high level in response to the application of the pulse, the transistor Tr2 is not turned on (conducting state), that is, it is out of order, or the monitor circuit 42 is out of order. can be judged. When any failure is detected, the failure detection circuit 45 outputs a failure detection signal, and the failure detection signal is supplied to the safety circuit 20 as one of the emergency shutdown signals. As a result, when a failure is detected, transition to the servo-on state is prohibited, and the state shifts to the error state.

A transition from the standby state to the servo-on state occurs when the user operates the operation switch of the robot. In the transition to the servo ON state, the cutoff switch 21 in the safety circuit 20 is turned on by operating the operation switch, and power is supplied to the motor drive power source 11 . At this stage, the brake signal keeps the transistor Tr1 off. Also, the failure detection operation of the transistors Tr1 and Tr2, which has been performed in the standby state, is stopped. A control circuit (not shown) in the robot controller detects a transition command to the servo-on state by a signal similar to that of the safety circuit. At this stage, if the Tr1 monitor signal does not go high, the transistor Tr1 cannot be turned off, the electromagnetic brake 31 itself is not connected (or disconnected), or the monitor circuit 41 is out of order. It is judged to be either "Yes" or "Yes", and the failure detection circuit 45 sends out a failure detection signal.

If there is no error (for example, detection of a failure by the failure detection circuit 45) in the transition to the servo-on state, the robot enters the servo-on state. In the servo ON state, the brake signal drives the transistor Tr1 to the ON state in order to release the electromagnetic brake 31 . At this time, the transistor Tr1 may be driven so as to be always on, but is preferably driven by pulse width modulation (PWM) in order to save power. FIG. 3 is a diagram for explaining the voltage applied to the electromagnetic brake 31. As shown in FIG. A state in which the electromagnetic brake 31 locks the motor shaft is called a brake clamp state. In order to shift from the brake clamped state to the brake released state, it is necessary to apply a relatively large voltage to the solenoid of the electromagnetic brake 31 to move the actuator (not shown) within the electromagnetic brake 31 . This is called a suction operation. Once the actuator has moved to the brake-released position, the brake-released state can be maintained by continuing to apply a smaller voltage than during the suction operation. This is called a hold operation. In order to operate the brake and enter the brake clamp state, the brake voltage should be set to zero. In practice, a small amount of current is supplied so that the electromagnetic brake 31 is not released even in the brake clamp state in order to determine the failure of the transistor Tr1. In this embodiment, by PWM-driving the transistor Tr1, the average voltage applied to the electromagnetic brake 31 is set to one of the value in the attracting operation, the value in the holding operation, or the value in the brake clamp state. The electromagnetic brake 31 is operated and released. Even if the purpose is not to save power, if the voltage of the motor drive power supply 11 is higher than the rated voltage of the electromagnetic brake 31, PWM drive is performed. When the transistor Tr1 is always turned on in the servo-on state for failure detection, the transistor Tr1 is driven with a short test pulse that does not cause the electromagnetic brake to respond.

The failure detection circuit 45 monitors the Tr1 monitor signal in synchronization with driving of the transistor Tr1. At this time, if the monitor signal does not go high in synchronization with the driving of the transistor Tr1, the failure detection circuit 45 detects that the electromagnetic brake 31 itself is disconnected (or disconnected), which is a failure in which the transistor Tr1 is not turned off. ) or that the monitor circuit 41 is out of order, and outputs a failure detection signal. Similarly, when the monitor signal does not go low in synchronization with the driving of the transistor Tr1, the failure detection circuit 45 determines that the transistor Tr1 has failed to turn on, and outputs a failure detection signal. When any failure is detected, or when an emergency stop is instructed to the robot controller, the safety circuit 20 is supplied with an abnormal cutoff signal, and the cutoff switch 21 is cut off. , transition to the error state. The electromagnetic brake 31 must be actuated immediately when the error state occurs. The output voltage of the motor drive power supply 11 does not always become zero immediately. At this time, if the transistor Tr1 does not turn off due to a failure, the electromagnetic brake 31 will not lock the motor shaft, which is dangerous. Therefore, when shifting from the servo-on state to the error state, the output voltage of the motor drive power supply 11 is forcibly reduced by forcibly discharging the D-axis current to the motor 13 or using a regenerative voltage discharging resistor. It can be set to zero to prematurely apply the brakes.

If the normal stop of the robot is instructed by operating the operation switch or the like without the occurrence of an error, the transition from the servo-on state to the standby state occurs. This transition is a transition to the servo off state. In the transition to the servo off state, the cutoff switch 21 is turned off by operating the operation switch or the like, and the control circuit (not shown) in the robot controller transitions to the standby state by the safety circuit monitor signal from the safety circuit 20. Detect directives. Further, in the transition to the servo-off state, the transistor Tr1 is turned off to enable the error detection in the standby state by the test pulse, thereby shifting to the standby state.

Next, operation in an emergency will be described. Assuming that the servomechanism breaks down when a person or object is caught, the electromagnetic brake 31 can be operated even when the power supply for driving the motor 13 is lost, as stipulated in safety standards. A release function is provided. In the brake drive control device of the present invention, as described above, this function is realized by using the brake power supply and the transistor Tr2, and the brake operation command is issued from the operation pendant (not shown) connected to the robot controller. The electromagnetic brake 31 is released by electric power from the brake power source by input or operation of a brake operation switch provided for each axis of the robot. This emergency brake release operation can be executed when the cutoff switch 21 in the safety circuit 20 is in the OFF state and the motor drive power supply is in the OFF state.

As shown in the state transition diagram of FIG. 2, the operation of the brake release switch or the brake release command On causes a transition to the brake release preparation stage. At this stage, the emergency brake signal turns on the transistor Tr2 connected to the brake power supply. Next, the transistor Tr1 is turned on by PWM driving in the same manner as in the above-described servo-on state, or the transistor Tr1 is turned on by mixing a test pulse. As a result, current flows through the electromagnetic brake 31 and the brake is released. When the voltage Vcc of the brake power supply is lower than the output voltage of the motor drive power supply 11, whether the transistor Tr1 is PWM-driven or always on depends on the specifications of the electromagnetic brake 31 and the voltage Vcc. When PWM driving is performed, the transistor Tr2 may be PWM-driven and the transistor Tr1 may be kept on at all times. The failure detection circuit 45 detects a failure of the transistor Tr1 based on the Tr1 monitor signal in synchronization with the driving of the transistor Tr1 as described above, and when a failure is detected, the robot transitions to an error state. In this error state, the transistor Tr2 is turned off and the brake release operation is prohibited.

In an emergency brake release operation, the power supply to the electromagnetic brake 31 is terminated after the brake has been released for a certain period of time, thereby preventing the axis from dropping due to the robot's own weight or the like. Therefore, when the brake release switch is turned off, when the brake release command is turned off, and when the set time elapses, the robot returns from the brake release state to the original standby state.

[Effect of the present embodiment] According to the above-described present embodiment, normally, the electromagnetic brake 31 is released by the power from the motor drive power supply 11 without going through the high side switch, and the power for driving the motor 13 is lost. Since the electromagnetic brake 31 can be released with electric power from a brake power source with a relatively low voltage and small capacity when it is switched on, the high-side switch and the drive circuit therefor can be made small-sized and with low withstand voltage. , the cost can be reduced without compromising safety. Further, by providing the monitor circuits 41 and 42 and the failure detection circuit 45, failures of the transistors Tr1 and Tr2, which are switching elements for releasing the electromagnetic brake 31, can be reliably detected, and safety can be further enhanced.

[Another Embodiment of the Invention] FIG. 4 shows a brake drive control circuit of another embodiment of the invention. The brake drive control circuit shown in FIG. 4 is obtained by removing the monitor circuits 41 and 42 in the circuit shown in FIG. 1 and providing a resistor R and a photocoupler 43 instead. The resistor R and the light emitting element in the photocoupler 43 are connected in series, and both ends of this series connection are connected to both ends (connection points 33 and 34) of the electromagnetic brake 31, respectively. A detection signal from the light receiving element side in the photocoupler 43 is input to the failure detection circuit 45 . The configuration consisting of the resistor R and the photocoupler 43 is the same as the configuration used for failure detection in Patent Document 2, and when the transistor Tr1 and the transistor Tr2 are separately turned on and simultaneously turned on, Failure detection is performed based on the change in the detection signal. In the configuration shown in FIG. 4, failure detection is performed by the same procedure as that described for the circuit shown in FIG. If the transistor Tr1 is driven by PWM when the brake is released, the failure of the transistor Tr1 can be detected while the brake is released by appropriately setting the allowable range of current discontinuity in the electromagnetic brake 31 and the operating point of the photocoupler 43. .

[Effect of the present embodiment] Also in this embodiment, the high-side switch and the drive circuit therefor can be made small-sized and have a low withstand voltage, and the cost can be reduced without impairing the safety. Furthermore, in this embodiment, the simple configuration using a photocoupler can detect failures of the transistors Tr1 and Tr2, which are switching elements for releasing the electromagnetic brake 31, and further improve safety.

(Reference Example 1) As another embodiment of the present invention, there is provided a brake drive control circuit for controlling an electromagnetic brake that releases the brake when energized, wherein a first power source of a first circuit voltage and one of the electromagnetic brake a first rectifying element provided between the terminal, a cut-off switch inserted in a line for supplying power to the first power supply in order to operate the first power supply, and a terminal connected to the other terminal of the electromagnetic brake. a first switching element provided between a point and a second switching element provided in series between a second power supply having a second circuit voltage different from the first circuit voltage and the one terminal of the electromagnetic brake; A brake drive control circuit having a switching element and a second rectifying element.

(Reference Example 2) As another embodiment of the present invention, the brake drive control circuit according to claim 1, wherein said second circuit voltage is lower than said first circuit voltage.

(Reference Example 3) According to Reference Example 1 or 2, the first power supply is a power supply for driving a motor that is subject to braking operation by the electromagnetic brake, and the cut-off switch is provided in a safety circuit for the motor. brake drive control circuit.

(Reference Example 4) The brake drive control circuit according to any one of Reference Examples 1 to 3, comprising monitor means for monitoring voltages of the one terminal and the other terminal of the electromagnetic brake.

(Reference Example 5) The monitor means includes a first monitor circuit for detecting a voltage at a connection point between the other terminal of the electromagnetic brake and the first switching element, the second switching element, and the second rectifying element. and a second monitor circuit that detects the voltage at the connection point with the brake drive control circuit according to Reference Example 4.

(Reference Example 6) A brake drive control circuit according to Reference Examples 1 to 3, comprising monitor means having a circuit for monitoring the voltage across the electromagnetic brake.

(Reference Example 7) A device according to any one of Reference Examples 4 to 6, further comprising a fault detection circuit that outputs a fault detection signal based on the monitoring result of the monitor means and maintains the cutoff switch in an open state. Brake drive control circuit.

(Reference Example 8) A brake drive control circuit according to Reference Example 7, wherein the output of the first power supply is forcibly discharged when the failure detection signal is output.

(Reference Example 9) When the cut-off switch is open and the first power supply is non-operating, the first switching element and the second switching element operate based on the operation of the brake release switch or the input of the brake release command. 9. The brake drive control circuit according to any one of Reference Examples 1 to 8, wherein the electromagnetic brake is released by setting the state.

(Reference Example 10) The first electromagnetic brake is arranged so that the voltage applied to the electromagnetic brake when the electromagnetic brake is maintained in the released state is lower than the voltage applied to the electromagnetic brake when the electromagnetic brake is shifted to the released state. The brake drive control circuit according to any one of Reference Examples 1 to 9, wherein the switching element is PWM-driven.

(Reference Example 11) A first rectifying element provided between a first power supply for a first circuit voltage and one terminal of an electromagnetic brake, and a rectifying element provided between the other terminal of the electromagnetic brake and a ground point a first switching element, and a second switching element and a second rectifying element provided in series between a second power supply having a second circuit voltage different from the first circuit voltage and the one terminal of the electromagnetic brake. and a failure detection method in a brake drive control circuit that controls the electromagnetic brake that releases the brake when energized, wherein the electromagnetic brake does not respond when the first power supply is inactive. to drive the second switching element using the pulse of, the voltage at the connection point between the other terminal of the electromagnetic brake and the first switching element, and the connection between the second switching element and the second rectifying element A fault detection method that monitors point voltages and voltages.

(Reference Example 12) While the electromagnetic brake is released, the first switching element is PWM-driven, and a connection point between the other terminal of the electromagnetic brake and the first switching element is synchronized with the PWM drive. 12. The failure detection method according to Reference Example 11, wherein the voltage of is monitored.

11... Motor drive power supply 13... Motor 20... Safety circuit 21... Cutoff switch 22... Safety control unit 41, 42... Monitor circuit 43... Photocoupler 45... Failure detection circuit D1, D2... Diode ( rectifier), Tr1, Tr2...transistors.

Claims (4)

A brake drive control circuit that controls an electromagnetic brake that releases the brake when energized,
a first rectifying element provided between a first power supply for a first circuit voltage and one terminal of the electromagnetic brake;
a cut-off switch inserted in a line supplying power to the first power supply to operate the first power supply;
A first switching element provided between the other terminal of the electromagnetic brake and a ground point, a second power supply having a second circuit voltage different from the first circuit voltage, and the one terminal of the electromagnetic brake. a second switching element and a second rectifying element provided in series between,
A brake drive control circuit, wherein the second circuit voltage is lower than the first circuit voltage. A brake drive control circuit that controls an electromagnetic brake that releases the brake when energized,
a first rectifying element provided between a first power supply for a first circuit voltage and one terminal of the electromagnetic brake;
a cut-off switch inserted in a line supplying power to the first power supply to operate the first power supply;
A first switching element provided between the other terminal of the electromagnetic brake and a ground point, a second power supply having a second circuit voltage different from the first circuit voltage, and the one terminal of the electromagnetic brake. a second switching element and a second rectifying element provided in series between,
A brake drive control circuit, wherein the first power supply is a power supply for driving a motor that is subject to braking operation by the electromagnetic brake, and the cut-off switch is provided in a safety circuit for the motor. The brake drive control circuit according to any one of claims 1 and 2,
a first monitor circuit for detecting a voltage at a connection point between the other terminal of the electromagnetic brake and the first switching element; and a second monitor circuit for detecting a voltage at a connection point between the second switching element and the second rectifying element. 2 monitor circuits for monitoring the voltages of the one terminal and the other terminal of the electromagnetic brake. When the cut-off switch is open and the first power supply is inoperative, the first switching element and the second switching element are activated based on the operation of the brake release switch or the input of the brake release command. 4. The brake drive control circuit according to any one of claims 1 to 3, wherein the electromagnetic brake is released.

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