Control device and processing equipment

Abstract

A control device 1 is provided with: a motor control unit (10, 11, etc.) that supplies a drive current to a motor 3, which is a power source of processing equipment, so as to place the motor 3 in a normal operating state, and, in response to multiplexed commands (S1, S2) that are sent from the outside and relate to a safety function operation of the processing equipment, controls the drive current so as to place the motor 3 and the processing equipment in a safety stop state; and a command monitoring unit 16 that monitors whether or not the commands (High / Low of S1, S2) match each other. If the period during which the commands do not match exceeds an allowable value, the command monitoring unit 16 generates a safety stop signal Sd (High) for safely stopping the motor 3, and continuously sends the safety stop signal Sd (High) to the motor control unit. This configuration makes it possible to facilitate the construction of a safety system that uses a control device.

Description

Technical Field

[0001] The present disclosure relates to a control device and a processing apparatus. In a non-limiting specific example, it relates to a control device that controls the operation of a motor in various processing apparatuses or a mechanical drive system equipped with a motor.

Background Art

[0002] In the field of various processing apparatuses (for example, injection molding machines, presses) equipped with motors, in order to ensure the safety of the processing apparatus and the surrounding environment, etc., a safety stop function (hereinafter, may be abbreviated as "safety function") for safely stopping the motor of the apparatus is provided. Specifically, as controls for safely stopping the motor, various controls such as torque-off stop and deceleration stop can be mentioned. This control is executed based on a signal (which may be called a safety signal, etc.) from an external device provided outside the apparatus.

[0003] As a conventional example of performing torque-off control of a motor, for example, there is the technology described in Patent Document 1 below. Patent Document 1 describes a power converter equipped with an STO (Safety Torque Off) function. Also, the safety function of a mechanical drive system using a motor is internationally standardized, and the above STO is also one of the safety functions that are internationally standardized (defined). The STO function can be said to be a function that forcibly cuts off the torque of the motor.

[0004] On the other hand, since the specific configurations of each block such as input, output, and monitoring in the safety function are not standardized, they are left to individual product designs.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in order to enhance the safety function, in individual product designs, it is conceivable to duplicate the safety signal from an external device and thus the signal path (safety path) and configure the same safety signal to be output from the external device simultaneously in parallel. With such a configuration, even if a failure occurs in one of the safety paths, control can be executed to safely stop the motor.

[0007] Monitoring of the dual safety paths can be realized, for example, by externally monitoring the operating state of an output block that outputs a control signal to the drive circuit of the motor. On the other hand, when applying this to an industrial machine system using a plurality of motors and their control devices, such as a servo press machine or a plastic processing machine, there are problems such as an increased monitoring burden in the upper-level system and an increase in the failure rate due to wiring or the like.

[0008] An object of the present invention is to facilitate the construction of a safety system in an industrial machine using a motor by incorporating a monitoring function of a redundant safety system and a protection function according to the monitoring result into a control system that drives and controls the motor.

Means for Solving the Problem

[0009] To achieve the above object, the present invention employs the configurations and methods described in the claims. To give an example, the control device of the present invention includes

[0010] a motor control unit that controls the motor to be in a normal operating state by sending a drive current to the motor and to be in a safe stop state from the normal operating state in response to multiple commands regarding the operation of a safety function sent from the outside; a command monitoring unit that monitors whether each of the commands matches each other, and is provided with

[0011] When the period during which the commands do not match each other exceeds the allowable value, the command monitoring unit generates a safety stop command to safely stop the motor, and continuously sends the generated safety stop command to the motor control unit.

Advantages of the Invention

[0012] According to the present invention, it is possible to easily construct a safety system in a system of an industrial machine in which a motor is used.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0014] <Schematic Configuration> Before explaining each embodiment of the present disclosure, the schematic content common to each embodiment will be described with reference to the drawings as appropriate. The processing equipment system described below mainly consists of the following devices (1) to (3) combined together.

[0015] (1) Motor control device (indicated by reference numerals 1, 1A, 1B in FIGS. 1, 5, and 7, and hereinafter reference numeral 1 will be typically used.)

[0016] The motor control device 1 is a device that controls the operation (start / stop of rotation, rotation direction, rotation speed, etc.) of an electric motor (hereinafter simply abbreviated as motor) 3 used as a power source for processing equipment, and is a main device (control device) in the processing equipment system of the present disclosure. The motor control device 1 includes various block functional parts as shown in FIGS. 1, 5, and 7 in order to control the motor 3 and thus the operation of the processing equipment using the motor 3.

[0017] Note that the processing equipment using the motor 3 and the motor control device 1 is not particularly limited, and examples include various industrial equipment such as plastic processing machines such as servo press machines and injection molding machines.

[0018] (2) External safety device (indicated by reference numerals 2, 2A in FIGS. 1, 5, and 7, and hereinafter reference numeral 2 will be typically used.)

[0019] The external safety device 2 monitors the operation of the motor 3 or the processing equipment, generates multiple commands (any number of signals indicating the same content for Lo / High) regarding the safety function operation of the processing equipment, and sends (inputs) the generated multiple commands to the motor control device 1 through the transmission system.

[0020] This external safety device 2 is an external device separate from the motor control device 1. In this example, it is connected to the motor control device 1 via multiple (double in each figure) signal lines and a wired interface. Note that the connection between the motor control device 1 and the external safety device 2 may be configured to replace part or all of it using communication means (wireless interface). The external safety device 2 can also be referred to as a safety function unit. Also, the transmission system (such as a wired or wireless interface) of the multiple commands sent from the external safety device 2 (safety function unit) to the motor control device 1 can also be referred to as a safety signal transmission unit.

[0021] When these external safety devices 2 detect an abnormality in the operation of the motor 3 or the processing equipment, they send (input) a stop command (for example, a predefined signal (such as a Lo or High signal)) to the motor control device 1 instructing it to safely stop the motor 3 and thus the processing equipment. On the other hand, when the external safety devices 2 do not detect an abnormality in the operation of the motor 3 or the processing equipment, they send (input) an execution command (for example, a High or Lo signal) to the motor control device 1 instructing it to execute the control of the motor 3 by the motor control device 1 as it is. In each figure and below, the above-mentioned stop command and execution command are collectively referred to as safety input signals S1, S2.

[0022] Note that since the configuration and abnormality detection method, etc. of the safety function unit (external safety device 2) which is an external device are well-known, detailed explanations will be omitted as appropriate.

[0023] (3) Safety monitoring device (indicated by reference numeral 16 in FIGS. 1, 5, and 7.)

[0024] The safety monitoring device 16 serves as a "command monitoring unit" that monitors whether the contents (commands, i.e., Lo / High states) of multiple safety input signals S1 and S2 sent (input) from the external safety device 2 to the motor control device 1 match each other. In the illustrated example, the safety monitoring device 16 inputs each of the multiple safety input signals S1 and S2 through a branch line of the signal line through which the safety input signals S1 and S2 are transmitted, monitors and then diagnoses by comparing the contents (commands) of the input signals, and outputs a signal indicating the diagnosis result to the motor control device. Hereinafter, the signal indicating this diagnosis result is referred to as the "diagnosis protection signal Sd".

[0025] Hereinafter, the safety monitoring device 16 will be described on the premise that when each command (Lo / High) included in the multiple safety input signals (S1, S2) output from the external safety device 2 matches each other, it outputs a Lo signal as the diagnosis protection signal Sd, and when they do not match, it outputs a High signal as the diagnosis protection signal Sd.

[0026] Next, the technical significance of the safety monitoring device 16 will be described in relation to other devices. The motor control device 1 described in (1) above, during normal operation, controls the motor 3 and thus the processing equipment to perform operations and functions according to the purpose, etc., by sending a drive current to the motor 3. Hereinafter, this state may be referred to as the "normal operation state". Also, since the operation of the motor 3 and thus the processing equipment in the normal operation state is well-known, a detailed description thereof will be omitted.

[0027] On the other hand, when a stop command (for example, a Lo signal) is input from the external safety device 2 described in (2) above to the motor control device 1, the motor control device 1 performs control such as reducing or cutting off the drive current sent to the motor 3 to safely stop the motor 3 and the processing equipment. By performing such control, the motor 3 (processing equipment) can be shifted from the normal operation state to the safe stop (torque-off or deceleration stop) state.

[0028] Note that the significance of sending multiple commands (safety input signals S1 and S2) from the external safety device 2 to the motor control device 1 is to enhance safety protection. More specifically, for example, when the external safety device 2 sends a stop command and an execution command to the motor control device 1 through two signal lines, even if a trouble occurs in one of the signal transmission systems (such as a circuit, a signal line, or in the case of wireless, the radio wave state) and the above commands cannot be transmitted, the command (safety input signal) can be transmitted through the remaining signal transmission system.

[0029] Therefore, in the above normal operating state, when a safety input signal (S1 or S2) indicating a stop command is input from any of the signal transmission systems of the external safety device 2 to the motor control device 1, the motor control device 1 performs the same control as described above to shift to the safe stop state and safely stop the motor 3 and the processing equipment. By adopting such a configuration that performs the safe stop control in response to the stop command input from any of the signal transmission systems, the safety protection is enhanced.

[0030] On the other hand, as described above, if the processing equipment continues to operate while leaving one of the signal transmission systems of the external safety device 2 malfunctioning, the above-described enhancement of safety protection becomes ineffective. In addition, if a further failure occurs in the external safety device 2, there is a possibility that the safe stop control by the motor control device 1 becomes impossible. Such a case is likely to occur, for example, when the Lo signal is assigned to the execution command and the High signal is assigned to the stop command. Therefore, hereinafter, on the contrary, that is, assuming a configuration in which the High signal is assigned to the execution command and the Lo signal is assigned to the stop command as the safety input signals S1 and S2. In such a configuration, when a trouble such as a disconnection occurs in one of the signal transmission systems, the signal (command) of such a signal transmission system becomes Lo, so it is considered that there is an advantage that it is easy to detect the occurrence of various troubles.

[0031] On the other hand, even when there is no disconnection or the like in all signal transmission systems of the external safety device 2 and the safety input signals S1 and S2 (Lo / High commands) are generally sent normally, a phase shift (for example, the timing of switching from an execution command to a stop command) may occur. In this case, from a safety perspective, the motor control device 1 will perform safety stop control in response to the earlier sent stop command. However, if the signal of the stop command that is the target of the response is an incorrect signal due to a malfunction of the external safety device 2 or the like, disadvantages (such as reducing the operating rate or productivity of the processing equipment) may occur due to the timing of the safety stop being too early.

[0032] Therefore, in the system of the processing equipment, it is necessary to provide the safety monitoring device 16 described in (3), that is, a device that monitors and diagnoses whether multiple commands (Lo / High) sent (input) from the external safety device 2 to the motor control device 1 match each other.

[0033] In other words, the safety monitoring device 16 is a device that plays the role of monitoring and diagnosing whether the external safety device 2 is operating normally. The following is that when the commands (Lo / High) of each of the multiple safety input signals S1 and S2 sent (input) from the external safety device 2 to the motor control device 1 match each other, the safety monitoring device 16 determines that the external safety device 2 is operating normally and outputs a Lo signal (diagnostic protection signal Sd = Lo).

[0034] Also, when the commands (Lo / High) of each of the multiple safety input signals S1 and S2 sent (input) from the external safety device 2 to the motor control device 1 do not match each other, the safety monitoring device 16 determines that the external safety device 2 or the transmission system is not operating normally and outputs a High signal (diagnostic protection signal Sd = High).

[0035] Conventionally, such a safety monitoring device, like the external safety device 2, is an external device similar to it, that is, an external device of the motor control device 1, and is used exclusively during the maintenance of the processing equipment system to diagnose whether each part is operating normally. Such a safety monitoring device is known, for example, as a device that uses a method of monitoring a signal called EDM (External Device Monitoring).

[0036] On the other hand, when using the safety monitoring device as an external device of the motor control device 1, there is a problem that the wiring for the processing equipment system becomes complicated, and there are also problems such as the wiring connection work becoming troublesome depending on the frequency of maintenance, etc.

[0037] In view of the above problems, in each of the embodiments described below, a configuration is adopted in which the safety monitoring device is implemented as an internal device of the motor control device 1. Hereinafter, for the convenience of explanation, etc., the safety monitoring device 16 will be described by substituting it with the safety monitoring unit 16.

[0038] <<Embodiment 1>> FIG. 1 is a diagram showing a configuration example of a motor control device according to Embodiment 1 of the present disclosure. Hereinafter, as a specific example, a configuration example for controlling a three-phase AC motor will be described, but the present invention is not limited thereto and can be applied to the control of various other motors.

[0039] In addition, a plurality of safety functions of a mechanical drive system using a motor are defined in international standards (typically the IEC61800-5 group), and the present invention can be applied to various safety functions including safety torque off (STO). In Embodiment 1 and Embodiment 2 described below, in particular, the case of performing the control of safety torque off (STO), which is an example of a safety stop operation, will be described on the premise.

[0040] As shown in FIG. 1, this motor control device 1 is connected to an external safety device 2, a motor 3, and a main power supply 5 (hereinafter simply referred to as the AC main power supply 5) using three-phase alternating current, and includes various blocks (circuits) for controlling the motor 3 (an encoder 4 is provided on the shaft of the motor 3).

[0041] Here, the main functional blocks (circuits) included in the motor control device 1 are a safe torque off circuit (STO) 10, a three-phase inverter 11, an AC-DC conversion circuit 12, a current detection unit 13, a motor control arithmetic unit 14, a control pulse generation unit (PWM) 15, and a safety monitoring unit 16.

[0042] <Connection to External Blocks, etc.> Among the above, the AC-DC conversion circuit 12 is connected to the AC main power supply 5, converts the three-phase alternating current input from the AC main power supply 5 into direct current, and supplies the converted DC power supply to the three-phase inverter 11. The AC main power supply 5 is an external power supply such as a commercial three-phase 200V AC.

[0043] As shown in FIG. 1, the three-phase inverter 11 includes a switch circuit having six switches (U, V, W, and X, Y, Z) whose on / off states are switched, and is connected to the three terminals of the motor 3 through these switches.

[0044] Hereinafter, the three phases of the three-phase inverter 11 are respectively referred to as the U phase, V phase, and W phase. Symbols U, V, and W are assigned to the upper switches (arms) of the three-phase inverter 11 in FIG. 1, and symbols X, Y, and Z are assigned to the lower switches (arms) in the figure.

[0045] The switches U, V, and W of each phase of the three-phase inverter 11 are connected in parallel to the output line of one pole (for example, the positive pole) of the AC-DC conversion circuit 12 and are connected to the corresponding phase (terminal) of the motor 3. Also, the switches X, Y, and Z of the three-phase inverter 11 are connected in parallel to the output line of the other pole (for example, the negative pole) of the AC-DC conversion circuit 12 and are connected to the corresponding pole (terminal) of the motor 3. Further, the switch U and the switch X are connected in series with each other and are connected to the same pole (the lowermost terminal in FIG. 1) in the motor 3. Similarly, the switch V and the switch Y are connected in series with each other and are connected to the same pole (the second terminal from the top in FIG. 1) in the motor 3. Similarly, the switch W and the switch Z are connected in series with each other and are connected to the same pole (the uppermost terminal in FIG. 1) in the motor 3.

[0046] The three-phase inverter 11 having such a switch circuit (a plurality of switches) can be realized by a power semiconductor. The three-phase inverter 11 performs a switching operation of alternately turning on the switches U / X, V / Y, and W / Z according to a control pulse signal output from the control pulse generation unit 15 via the safe torque off circuit (STO) 10, thereby generating a three-phase alternating current. The alternating current after such a switching operation is sent to the motor 3 as a drive current, whereby the motor 3 rotates and the corresponding processing equipment operates.

[0047] Based on the basic program and various input signals, the motor control arithmetic unit 14 calculates a control operation amount for feedback control of the operation of the motor 3, generates a control signal indicating the calculated control operation amount, and outputs such a control signal to the control pulse generation unit (the "PWM" block in FIG. 1) 15.

[0048] More specifically, the motor control arithmetic unit 14 detects the drive current (such as a voltage waveform) supplied to the motor 3 through the current detection unit 13 disposed at any two of the three poles of the motor 3. Further, the motor control arithmetic unit 14 detects the rotation direction, rotation speed, and rotation position (phase of the rotation axis) of the motor 3 through the encoder 4 attached to the rotation axis of the motor 3. In addition, the motor control arithmetic unit 14 can input and detect the operation instructions of the user through an operation input unit (not shown) including switches and levers of the processing equipment.

[0049] Then, the motor control arithmetic unit 14 calculates the difference (error) between the above-described detection results and the specified operation of the motor 3 (predetermined rotation direction, rotation speed, phase) based on the various input signals described above. Then, the motor control arithmetic unit 14 calculates a control operation amount (here, the mode of the three-phase alternating current to be supplied) such that the motor 3 operates without error corresponding to the basic program and the operation instructions of the user, and outputs a control signal (hereinafter, also simply referred to as "control operation amount") indicating the calculation result to the control pulse generation unit 15.

[0050] The control pulse generation unit 15 performs PWM (Pulse Width Modulation) modulation on the input control signal and outputs a control pulse signal with a modulated pulse width to the safe torque off circuit 10. The control pulse generation unit (PWM) 15 converts the pulse width according to the magnitude of the input control operation amount and generates a control pulse signal from each signal line through a plurality of (in this example, 3 phases × 2 poles = 6) signal lines. The control pulse generation unit (PWM) 15 outputs the generated control pulse signal to the three-phase inverter 11.

[0051] The control pulse generation unit 15 shown in FIG. 1 uses, as a pulse generation method, a triangular carrier wave and a control operation amount input from the motor control arithmetic unit 14

[0052] A pulse width modulation (PWM) method is used to compare them and generate a pulse based on their magnitude relationship. In addition, as a pulse generation method generated (output) by the control pulse generation unit 15, for example, a pulse frequency modulation method that adjusts the pulse generation interval based on the magnitude of the above control operation amount may also be used. Alternatively, as a pulse generation method generated (output) by the control pulse generation unit 15, a method of defining the on / off state of each switch (U, V, W, X, V, Z) of the three-phase inverter 11 in vector coordinates and selecting a predetermined vector for each instantaneous value of the above control operation amount may be used, etc.

[0053] Note that the motor control arithmetic unit 14 and the control pulse generation unit 15 can be implemented by a microcomputer or the like in which a control program is implemented, or an analog-digital circuit. The same applies to the safe torque off circuit 10 and the safety monitoring unit 16. However, in configuring the safety system, the blocks related to the safety function are preferably separated from others in order to minimize the influence from other functional blocks. For example, only the safe torque off circuit 10 may be an analog-digital circuit, and it may be configured to be physically separated from the hardware such as a microcomputer in which other functions (control programs, etc.) are implemented.

[0054] The safe torque off circuit (STO) 10 is a circuit that functions when safely stopping the motor 3 used in the motor control device 1. As shown in FIG. 1, it is connected to an external safety device 2, a control pulse generation unit (PWM) 15, a safety monitoring unit 16, and a three-phase inverter 11. Further, the safe torque off circuit (STO) 10 is connected to the motor control arithmetic block 14 via the control pulse generation unit (PWM) 15.

[0055] The safe torque off circuit 10 of the motor control device 1 is located in the middle of the path for transferring the control pulse signal obtained by the control pulse generation unit 15 to the three-phase inverter 11, and based on the command contents of the safety input signals S1 and S2 separately input from the external safety device 2, it operates or blocks the transfer of the control pulse signal.

[0056] In this embodiment, the safety torque off circuit 10 performs a transfer (supply) / transfer interruption (supply prohibition) operation of the control pulse signal supplied from the control pulse generation unit 15 to the three-phase inverter 11 in accordance with commands of the safety input signals S1 and S2.

[0057] Specifically, when both of the safety input signals S1 and S2 are execution commands, the safety torque off circuit 10 determines that it is in the normal operation state and transfers (supplies) the control pulse signal to the three-phase inverter 11.

[0058] On the other hand, when one of the safety input signals S1 and S2 is a stop command, the safety torque off circuit 10 determines that a safety stop is necessary and interrupts (prohibits) the transfer (supply) of the control pulse signal to the three-phase inverter 11. By this interruption (supply prohibition) operation, a safe torque off (hereinafter referred to as "STO") operation of the motor 3 is performed. More specifically, the STO operation of the motor 3 is realized by turning off the gates of the power semiconductors (corresponding to the respective switches shown in FIG. 1) that constitute the three-phase inverter 11 by interrupting the control pulse signal.

[0059] In a specific example, the safety torque off circuit 10 inputs the signals sent from the above-described external safety device 2 and the safety monitoring unit 16, and when both of the safety input signals S1 and S2 are High and the diagnostic protection signal Sd is Lo, the control pulse signal input from the control pulse generation unit 15 is directly sent (transferred) to the three-phase inverter 11.

[0060] Therefore, according to this system, during normal operation of various devices to which the motor 3 is attached, a rotational operation corresponding to the type of the device, the operation content of the user, etc. is performed by the motor 3, and the accuracy of the operation of the motor 3 and thus the device can be ensured by feedback control.

[0061] On the one hand, when at least one of the safety input signals S1 and S2 is Lo or the diagnostic protection signal Sd is High among the signals sent from and input to the above-described external safety device 2 and safety monitoring unit 16, the safety torque-off circuit 10 blocks (prohibits supply) the transfer of the control pulse signal input from the control pulse generation unit 15. In a specific example of this case, the safety torque-off circuit 10 controls all switches (U, V, W, X, Y, and Z) of the three-phase inverter 11 to turn off in order to turn off the gates of the power semiconductors constituting the three-phase inverter 11 (see FIG. 1).

[0062] For convenience of explanation etc., hereinafter, the diagnostic protection signal Sd in the High state or the safety input signal S1 (S2) in the Lo state may be referred to as an "electric current cut-off signal".

[0063] As described above, by performing safety stop control in response to the output of the electric current cut-off signal, as can be understood from FIG. 1, the drive current is not supplied to the motor 3. Therefore, when the motor 3 is operating, it enters a torque-off state and rotates only by inertia. In practice, due to the frictional resistance etc. of the drive mechanisms in various processing devices connected to the motor 3, the processing devices are quickly stopped when the motor 3 enters the torque-off state, and the safe stop of the devices is achieved.

[0064] By the way, in the above-described international standards (for example, IEC61508 or ISO13849), concepts such as configuring the safety system with dual inputs and dual outputs are shown, but the specific configurations of each block such as inputs, outputs, and monitoring are not shown.

[0065] Therefore, the inventor of the present invention proposes the specific configurations of the various blocks as described below.

[0066] FIG. 2 is a circuit diagram showing a specific configuration example of the safe torque off circuit 10. From another perspective, FIG. 2 is a diagram for explaining a specific example in which the drive current is not supplied to the motor 3 when a current cut-off signal is input to the safe torque off circuit 10.

[0067] In the example shown in FIG. 2, the safe torque off circuit 10 includes a buffer circuit BF0 having a plurality of buffer elements, a gate drive element GD having a plurality (six in this example) of photocouplers, and anode cut-off switches Q1 and Q2. In this example, one end side of the buffer circuit BF0 in the safe torque off circuit STO10 is connected to a reference potential (common) corresponding to 0V. Also, the power supply potential of a constant voltage power supply (not shown) is connected to the other end side of the buffer circuit BF0 and one end sides of the anode cut-off switches Q1 and Q2.

[0068] From the perspective of fail-safe, for example, in case the signal lines of the safety input signals S1 and S2 are disconnected, etc., the level of the reference voltage applied by the signal code or the constant voltage power supply may be selected so that the motor control device 1 reaches the STO operation in the base state of the system.

[0069] The buffer circuit BF0 plays a role of switching the output or non-output of the control pulse signal input from the control pulse generation unit 15 to the subsequent stage through six signal lines (in other words, for six switches) according to the diagnostic protection signal Sd input from the safety monitoring unit 16.

[0070] Specifically, the buffer circuit BF0 has (six) amplification and inversion elements that amplify and invert the current of each of the six signal lines to which the control pulse signal is input, and an inversion amplification element that inverts and amplifies the diagnostic protection signal Sd. The signal lines are connected to the buffer circuit BF0 such that the output of such an inversion amplification element is input to each of the six amplification and inversion elements (before the inversion section). Also, the outputs of the six amplification and inversion elements are connected to the cathodes of the light-emitting diodes in the photocouplers of the gate drive element GD that operates the corresponding switches (U, V, W, X, Y, and Z) of the three-phase inverter 11.

[0071] In the state shown in FIG. 2, since the anode cutoff switches Q1 and Q2 are off and current is not supplied to the light-emitting diodes of the gate drive element GD, no current is output from any of the photocouplers. As a result, the corresponding switches (U to Z) of the three-phase inverter 11 are also off (refer to FIG. 1 as appropriate), and no drive current is supplied to the motor 3.

[0072] Also, even when one of the anode cutoff switches Q1 (or Q2) is turned on based on the safety input signal (either S1 or S2) from the state shown in FIG. 2, if the other anode cutoff switch Q2 (or Q1) is off, current is not supplied to the light-emitting diodes of the corresponding gate drive element GD, and no current is output from the corresponding photocoupler. As a result, the corresponding three switches U, V, W (or X, Y, Z) of the three-phase inverter 11 are also in the off state, and no drive current is supplied to the motor 3.

[0073] In this embodiment, when the state where only one of the anode cutoff switches Q1 (or Q2) is turned on continues for a certain period of time, the diagnostic protection signal Sd becomes High, causing all the switches (U to Z) of the three-phase inverter 11 to turn off, and no drive current is supplied to the motor 3. The specific circuit configuration and the like for realizing this operation will be described later in the description of FIG. 3.

[0074] On the other hand, when both anode cutoff switches Q1 and Q2 are turned on based on the safety input signals S1 and S2 from the state shown in FIG. 2, current from the constant voltage power supply can be supplied to all the light-emitting diodes of the gate drive element GD. In this case, the on / off state or switching of the corresponding switches (U to Z) of the three-phase inverter 11 according to the presence or absence of light emission of each light-emitting diode of the gate drive element GD and thus the output current of each photocoupler is determined by the output (Lo / High) from the corresponding amplifier-inverting element of the buffer circuit BF0.

[0075] In this example, when a High signal is input from the control pulse generation unit 15 and a Lo signal is output from the amplification and inversion element of the buffer circuit BF0, the corresponding light-emitting diode of the gate drive element GD emits light, a current is output from the corresponding photocoupler, and the corresponding switch (any one of U to Z) of the three-phase inverter 11 is turned on. Conversely, when a Lo signal is input from the control pulse generation unit 15 and a High signal is output from the amplification and inversion element of the buffer circuit BF0, the corresponding light-emitting diode of the gate drive element GD does not emit light, no current is output from the corresponding photocoupler, and the corresponding switch (any one of U to Z) of the three-phase inverter 11 is turned off.

[0076] Furthermore, when the diagnostic protection signal Sd input to the enable terminal (inversion amplification element) is High, it is inverted to a Lo signal by the inversion amplification element, and the Lo signal is input to all the amplification and inversion elements of the buffer circuit BF0 and subjected to inversion processing, so that the outputs of all the amplification and inversion elements become High. As a result, all the light-emitting diodes of the gate drive element GD do not emit light, no current is output from all the photocouplers, and all the switches (U to Z) of the three-phase inverter 11 are turned off.

[0077] Thus, according to the circuit configuration shown in FIG. 2, based on the safety input signals S1 and S2 (commands), a state is achieved in which current can be supplied to all the light-emitting diodes, and the drive current is supplied to the motor 3 on the condition that the diagnostic protection signal Sd is Lo (in other words, a safety stop command is not sent).

[0078] On the other hand, when the diagnostic protection signal Sd input to the inverting amplifier element of the buffer circuit BF0 becomes Hi when any photocoupler of the gate drive element GD is in the on state, the Hi signal applied by inverting amplification is inverted to Lo and input to each amplification inversion element of the buffer circuit BF0. As a result, the output of the control pulse signal input from the control pulse generation unit 15 through each signal line to the subsequent stage (gate drive element GD) is blocked, and all photocouplers of the gate drive element GD are turned off. Therefore, in this case, all switches (U to Z) of the three-phase inverter 11 are in the off state (refer to FIG. 1 as appropriate), and no drive current is supplied to the motor 3 (cut off).

[0079] Thus, according to the circuit example shown in FIG. 2, a plurality (six in this example) of pulse signals output from the control pulse generation unit 15 are respectively transferred to the three-phase inverter 11 through the buffer element BF0 and the gate drive element GD in sequence. Then, the three-phase inverter 11 sends (supplies) an alternating current to the motor 3 connected to the outside of the motor control device 1 by switching the built-in power semiconductor.

[0080] Note that when the diagnostic protection signal Sd is lost, the enable terminal of the buffer element BF0 is turned off. As a result, the light emission of the light emitting diodes of all photocouplers (U to Z) of the gate drive element GD is blocked, and similarly, a configuration is achieved in which safe torque off of the motor 3 can be realized.

[0081] <Modification example etc.> Note that the buffer element BF0 may be a multi-channel element. Also in this case, an enable terminal capable of operating the ON / OFF of the output of each channel of the buffer element BF0 may be provided, and the diagnostic protection signal Sd may be input to the enable terminal.

[0082] Also, regarding the gate drive element GD, the circuit configuration using a photocoupler was described in FIG. 2. As another example, the gate drive element GD may be an element capable of switching transfer / transfer prohibition (cut-off) of each pulse signal input from the control pulse generation unit 15, for example, an element incorporating an optical coupler or a magnetic coupler. Further, as another example, the gate drive element GD is not limited to a configuration that transfers each pulse signal input from the control pulse generation unit 15 as it is, and may be a circuit that converts each pulse signal into various digital signals for driving each gate (switches U to Z) of the three-phase inverter 11.

[0083] <Safety monitoring unit> FIG. 3 shows a specific example of the circuit constituting the safety monitoring unit 16 of the present disclosure. Note that although a constant voltage source (not shown) to be connected when driving as an actual circuit is connected to the logic elements in the figure, since it has no influence on the explanation of the function, the explanation regarding the constant voltage source is omitted.

[0084] The safety monitoring unit 16 shown in FIG. 3 branches the safety input signals S1 and S2 sent from the external safety device 2 in parallel to a first processing block B1 and a second processing block B2, respectively, and performs arithmetic processing. Then, the safety monitoring unit 16 performs a logical sum (OR) operation on the arithmetic output of the first processing block B1 and the arithmetic output of the second processing block B2 in a third processing block B3 to generate and output a diagnostic protection signal Sd.

[0085] The first processing block B1 of the safety monitoring unit 16 is configured by serially connecting an XOR unit B11, a charge / discharge unit B12, and a latch unit B13 in this order from the front stage side.

[0086] Among these, the XOR unit B11 compares the secure input signal S1 and the secure input signal S2, detects whether there is a difference in the High / Low polarity of such signals, and outputs a High signal to the subsequent stage when there is a difference. The XOR unit B11 corresponds to the "comparison unit" of the present disclosure. For example, as shown in FIG. 3, the XOR unit B11 can be composed of an XOR element X1 that performs a logical XOR operation on the secure input signal S1 and the secure input signal S2, and a resistor R11 that pulls down the operation result (i.e., the output of the XOR element X1). Here, the pull-down resistor R11 corresponds to the "first resistor" of the present disclosure.

[0087] Note that hereinafter, a resistor having an equivalent function is referred to as a "pull-down resistor", and conversely, a resistor that plays a role of pulling up the output is referred to as a "pull-up resistor".

[0088] One end of the pull-down resistor R11 is connected to the output terminals of the XOR element X1 and the XOR unit B11, and the other end of the pull-down resistor R11 is connected to the reference potential. Such a pull-down resistor R11 has a role of lowering the output potential of the XOR unit B11 to the reference potential when, for example, the safety monitoring unit 16 is activated, and stabilizing the output value. The same applies to the pull-down resistor R14 of the latch unit B13 described later.

[0089] Next, the charge and discharge unit B12 serves as a timer that stores the time information during which the difference continues by charging the High current output when a difference is detected by the XOR unit B11. As such a charge and discharge unit B12, for example, as shown in FIG. 3, a configuration including an RC first-order lag filter circuit (RC time constant circuit) in which a resistor R12 and a capacitor C11 are connected (in series with each other) may be used.

[0090] Here, the resistor R12 corresponds to the "second resistor" of the present disclosure. One end of this resistor R12 is connected to the output terminal of the XOR element (X1), and the other end of the resistor R12 is connected to the output terminal of the charge and discharge unit B12.

[0091] Further, the capacitor C11 has a role of charging and discharging the current supplied to the charge and discharge unit B12. One end (positive voltage terminal) of the capacitor C11 is connected to the other end of the resistor R12 and the output end of the charge and discharge unit B12, and the other end of the capacitor C11 is connected to the reference potential.

[0092] Also, in the example shown in FIG. 3, a circuit of a diode D11 and a resistor R13 connected in series (hereinafter also referred to as a diode circuit) is connected in parallel from the output side to the input side of the above-described resistor R12. Here, the resistor R13 corresponds to the "third resistor" of the present disclosure. And the magnitude relationship of the resistance values between the resistor R12 (second resistor) and the resistor R13 (third resistor) is R12 > R13.

[0093] The above diode circuit does not function during the charging of the capacitor C11 (only the circuit of the resistor R12 functions), and functions as a parallel resistance circuit of the resistors R12 and R13 during the discharging of the capacitor C11. Therefore, due to the difference in the resistance values of the resistors R12 and R13, the charging and discharging currents (time constants) can be adjusted to different values from each other.

[0094] When the output of the previous XOR unit B11 changes from Low to High (in other words, when a difference occurs between the signal S1 and the signal S2), the charge and discharge unit B12 having such a configuration starts charging (charge accumulation) of the capacitor C11. And when the output of the XOR unit B11 returns to Low before the charge accumulated in the capacitor C11 reaches the threshold value (in other words, when the difference between the signal S1 and the signal S2 disappears), the charge accumulated in the capacitor C11 is discharged to the resistors R11, R12, and R13, thereby resetting the capacitor C11 (in other words, the timer).

[0095] On the other hand, when the output of the XOR unit B11 continues to be High for a certain period of time, charge is accumulated in the capacitor C11, and the voltage of the capacitor C11 asymptotically approaches the output voltage of the XOR unit B11.

[0096] Furthermore, the latch unit B13 determines whether the voltage of the capacitor C11 has exceeded a predetermined voltage threshold, and once it has exceeded, it has the function of holding (continuously outputting) the determination result as a High-state output. This operation can be said to have the same effect as determining whether the duration of the difference between the safety input signal S1 and the safety input signal S2 has exceeded a predetermined time limit if the voltage of the capacitor C11 is regarded as a timer. Note that the charge / discharge unit B12 and the latch unit B13 correspond to the "latch unit" of the present disclosure. Hereinafter, the output of the latch unit B13 will be referred to as signal SL.

[0097] For example, as shown in FIG. 3, the latch unit B13 includes a logical OR element O11 and a pull-down resistor R14 that pulls down the output of the logical OR element O11.

[0098] Optionally, the latch unit B13 further includes a capacitor C12 that stores (charges and discharges) the output of the logical OR element O11. One input of the OR element O11 of the latch unit B13 is connected to the output terminal of the timer unit B12 and the voltage terminal (positive voltage terminal) of the capacitor C11, and the other input of the OR element O11 is configured by a circuit that directly feeds back the output of the OR element O11. The voltage of the capacitor C11 is used as a threshold value of the high-level voltage, which is a characteristic value of the logical OR element O11, to determine whether the voltage threshold has been exceeded.

[0099] The second processing block B2 detects (determines) when both the safety input signal S1 and the safety input signal S2 indicate the operation permission state (for example, High) of the motor 3, and outputs the detection result (Lo in the case of the operation permission state). For example, as shown in FIG. 3, the second processing block B2 includes a NAND element N1 that performs a logical NAND operation on the safety input signal S1 and the safety input signal S2, and a resistor R21 that pulls up the output of the NAND element N1.

[0100] The third processing block B3 includes an OR element O3 that performs a logical sum (OR operation) on the input signals, and a pull-up resistor R3 connected to the output terminal of the OR element O3 and the output side of the third processing block B3. The input terminals of the OR element O3 are respectively connected to the output terminal of the first processing block B1 and the output terminal of the second processing block B2.

[0101] Thus, the safety monitoring unit 16 performs an OR operation on the output of the first processing block B1 and the output of the second processing block B2 by the OR element O3 of the third processing block B3, and outputs the result (Lo or High) of the OR operation as a diagnostic protection signal Sd. Then, the Lo or High diagnostic protection signal Sd output from the safety monitoring unit 16 is input to the enable terminal of a buffer element BF0 (see FIG. 2) in the subsequent safety torque off circuit 10.

[0102] Hereinafter, similarly, the case where the diagnostic protection signal Sd is in the Lo state will be described as the operation permission state of the motor 3. In this case, the first processing block B1 outputs a Lo signal by the operation of pull-down resistors R11, 14, etc. at startup. Thereafter, when a difference occurs between the safety input signal S1 input from the external safety device 2 and the safety input signal (the output of the XOR section B11 becomes High), and the difference has elapsed for a predetermined time, the first processing block B1 continuously outputs a High diagnostic protection signal Sd.

[0103] The output of the second processing block B2 will output Lo when both the safety input signals S1 and S2 are High (operation permission state). Also, the third processing block B3 outputs the logical OR of the output of the first processing block B1 and the output of the second processing block B2 as the diagnostic protection signal Sd.

[0104] Therefore, the safety monitoring unit 16 can output a signal different from normal (detect an abnormality between the signals S1 and S2) only when it determines an abnormality such that the difference continues for a certain time in the first processing block B1.

[0105] As described above, in this embodiment, a drive current is sent to the motor 3 to put the motor 3 and thus the processing equipment into the normal operating state, and in response to safety input signals S1 and S2 (multiplexed commands) regarding the safety function operation of the processing equipment sent from the external safety device 2, the drive current sent to the motor 3 is controlled so that the motor 3 and thus the processing equipment are changed from the normal operating state to the safe stop (STO in this example) state. The motor control device 1 includes a motor control unit (a safe torque off circuit 10, a three-phase inverter 11, etc.), and is configured to incorporate a safety monitoring unit 16 (command monitoring unit) that monitors whether or not the safety input signals S1 and S2 (multiplexed commands) match each other.

[0106] Then, as detailed in FIG. 3, when the period during which the safety input signals S1 and S2 (commands) do not match each other exceeds the allowable value, the safety monitoring unit 16 (command monitoring unit) generates a safe stop command (diagnostic protection signal Sd = High) for safely stopping the motor 3, and sends the generated safe stop command (High diagnostic protection signal Sd) to the motor control unit (safe torque off circuit 10).

[0107] Specifically, the safety monitoring unit 16 (command monitoring unit) includes an XOR unit B11 (comparison unit) that compares each of the safety input signals S1 and S2 (commands) and outputs the difference as a High signal, a power storage unit (charge and discharge unit B12) that accumulates the charge of the High signal, and a safe stop command generation unit (charge and discharge unit B12, latch unit B13) that generates and outputs a safe stop command (High diagnostic protection signal Sd) when the voltage of the power storage unit exceeds the threshold value.

[0108] In the motor control device 1 of this embodiment provided with the safety monitoring unit 16 as described above, the safety input signal S1 and the safety input signal S2 are input and compared with each other. When there is an abnormality in one of these two inputs (S1, S2), the abnormality can be detected and the STO of the operation of the motor 3 can be activated.

[0109] Moreover, according to the present embodiment in which the safety monitoring unit 16 is incorporated as an internal device of the motor control device 1, it is possible to monitor whether the external safety device 2 is operating correctly without using an external monitoring device. In other words, it is possible to monitor without wiring. Therefore, there is an advantage that the safety design of the motor control device 1 having a monitoring function for monitoring multiple safety input signals and detecting abnormalities, and thus the entire processing equipment system becomes easier.

[0110] Furthermore, the power storage unit (charge / discharge unit B12) of the safety monitoring unit 16 (command monitoring unit) includes an RC time constant circuit (R12 and C11) that charges the capacitor C11 so as to ensure the time from the output of the High signal of the XOR unit B11 (comparison unit) until the voltage of the capacitor C11 exceeds the threshold value. The safety stop command generation unit includes a latch unit B13 that holds the output of the safety stop signal (High diagnostic protection signal Sd) when the voltage of the capacitor C11 exceeds the threshold value (is discharged from the capacitor C11).

[0111] The above-described RC time constant circuit (R12 and C11) can exhibit the same function as a general timer that measures time based on a clock signal, for example, and can be realized at low cost.

[0112] From another perspective, the safety monitoring unit 16 (command monitoring unit) branches the multiplexed commands (safety input signals S1, S2) in parallel to the first processing block B1 (first signal processing unit) and the second signal processing unit B2 (second signal processing unit), respectively, and based on the logical sum (OR) of the arithmetic output of the first processing block B1 and the arithmetic output of the second processing block B2, outputs the following diagnostic protection signal Sd to the safety torque off circuit 10 (motor control unit).

[0113] That is, when the period during which the safety input signals S1 and S2 (multiplexed commands) do not match each other does not exceed the allowable value due to the above-described timer function, the safety monitoring unit 16 sends Lo as the diagnostic protection signal Sd, and when the period of non-match exceeds the allowable value, it sends Hi (safety stop command) as the diagnostic protection signal Sd.

[0114] As a specific example of the circuit configuration for outputting the diagnostic protection signal Sd as described above, in the first processing block B1 (first signal processing unit), an XOR unit B11, a charge / discharge unit B12, and a latch unit B13 are connected in series in this order, and in the second processing block B2 (second signal processing unit), a NAND unit for performing a NAND operation on the safety input signals S1 and S2 (multiplexed commands) and outputting the result is provided.

[0115] Specifically, the XOR unit B11 includes an XOR element X1 that calculates and outputs the exclusive OR of the safety input signals S1 and S2 (multiplexed commands), and a first resistor (R11) that pulls down the output of the XOR element X1.

[0116] Also, the charge / discharge unit B12 includes an RC time constant circuit composed of a second resistor (R12) whose one end is connected to the output end of the XOR element X1 and a capacitor C11 connected to the other end of the second resistor (R12). When the output of the XOR element X1 is High, the capacitor C11 is charged, and when the output of the XOR element X1 is Low, the charge of the capacitor C11 is discharged.

[0117] Furthermore, the latch unit B13 includes an OR element O11 whose first input end is connected to the output end of the above-described RC time constant circuit (R12, C11), and a pull-down resistor (R14) that pulls down the output of the OR element O11. The output of the OR element O11 is directly connected to the second input end of the OR element O11.

[0118] Furthermore, the NAND section B2 of the second processing block B2 (second signal processing section) includes a logic NAND element (N1) that calculates and outputs the negative logical product (NAND) of the commands (S1, S2), and a resistor (R21) that pulls up the output of the logic NAND element (N1).

[0119] By adopting the above-described circuit configuration, switching between Lo and Hi (safety stop command) of the diagnostic protection signal Sd can be realized. Also, by adopting the above-described circuit configuration, it is possible to provide an accompanying function for dealing with various technical problems described later.

[0120] As described above, according to the present embodiment, by incorporating the monitoring function of the redundant safety system and the protection function according to the monitoring result into a motor control system such as an inverter circuit that drives and controls the motor 3, it is possible to more easily realize the construction of a safety system in a system of industrial machinery such as a processing machine using the motor 3.

[0121] The main circuit configuration and operation in the safety monitoring section 16 shown in FIG. 3 have been described above. Next, the accompanying functions of the safety monitoring section 16 shown in FIG. 3 and the merits obtained from the functions will be described.

[0122] <Configuration corresponding to problems in the charge / discharge section B12> When the safety input signal S1 and the safety input signal S2 are input to the first processing block B1 of the safety monitoring section 16, a case may occur where the XOR section B11 switches the output (High / Lo) of the XOR element X1 at a high frequency. Such a case is, for example, a case where the difference between these two safety input signals (S1, S2) repeatedly occurs instantaneously due to some factor such as an error or minute noise.

[0123] Thus, when the output (High / Lo state) of the XOR element X1 switches frequently, depending on the configuration of the capacitor C11 in the subsequent charge / discharge section B12, particularly when the discharge time constant of the capacitor C11 is large, the following problems may occur. That is, since the time for the output of the XOR element X1 to maintain the Lo state becomes short, the charge of the capacitor C11 in the charge / discharge section B12 is not sufficiently discharged, and the voltage rise characteristic of the capacitor C11 may become non-uniform due to the output of the XOR element X1 repeatedly becoming High.

[0124] To address the above problems, it is required to improve the discharge characteristics of the capacitor C11 in the charge / discharge section B12. Also, in order to improve the discharge characteristics while maintaining the accuracy of the timer measurement time described above, it is necessary to make the discharge time constant smaller than the charge time constant of the capacitor C11.

[0125] Regarding this problem, in the present embodiment, as shown in FIG. 3, a series circuit of the above-described diode circuit, that is, the resistor R13 and the diode D11, is connected in parallel to the resistor R12 of the charge / discharge section B12, and the anode side of the diode D11 is connected to the capacitor C11.

[0126] According to this configuration, by making the resistance values of the resistor R11 of the XOR section B11 and the resistor R13 of the charge / discharge section B12 sufficiently smaller than the resistance value of the resistor R12 of the charge / discharge section B12, the discharge time constant can be made smaller than the charge time constant of the capacitor C11, and the discharge time can be shortened.

[0127] Therefore, according to the circuit configuration of the first processing block B1 in the present embodiment, the discharge characteristics of the capacitor C11 can be improved while keeping the accuracy of the timer measurement time described above constant. Also, according to this circuit configuration, even when the output (High / Lo state) of the XOR element X1 switches frequently, the voltage rise characteristic of the capacitor C11 can be maintained.

[0128] <Problems in the latch section B13 and corresponding configuration> Since the logic OR element O11 of the latch section B13 has a circuit configuration that continues to output High once the output becomes High, it is necessary to pay attention to malfunction due to the inclusion of noise or the like.

[0129] Regarding this problem, in the present embodiment, as shown in FIG. 3, a configuration is adopted in which a capacitor C12 is connected in parallel to the output of the OR element O11. By adopting such a configuration, when noise or the like is included, the noise component can be absorbed by the capacitor C12, so that malfunction caused by the inclusion of noise or the like can be prevented or suppressed.

[0130] <<Embodiment 2>> FIG. 4 is a configuration example of a safe torque off circuit according to Embodiment 2 of the motor control device of the present disclosure. The configuration shown in FIG. 4 is an alternative example of the safe torque off circuit 10 shown in FIG. 2 described above.

[0131] Hereinafter, matters different from the safe torque off circuit 10 shown in FIG. 2 will be described, and for equivalent configurations, the same reference numerals will be given and the description thereof will be omitted as appropriate. Similarly, the description of the constant voltage source connected to the logic element will be omitted.

[0132] As can be seen by comparing FIG. 2 and FIG. 4, the safe torque off circuit 10A shown in FIG. 4 has the anode cutoff switches Q1 and Q2 deleted and the buffer element BF2, the logic AND element A1, and the logic AND element A2 added to the configuration shown in FIG. 2.

[0133] Generally, the main differences between the configuration shown in FIG. 2 and the safe torque off circuit 10A shown in FIG. 4 are that the anode terminals (all of the U, V, W, X, Y, and Z phases) of the gate drive element GD are directly connected in parallel to the constant voltage power supply, and the buffer element BF1 and the buffer element BF2 are connected in series. By adopting such a configuration, the safe torque off of the dual motor can be realized in the safe torque off circuit 10A shown in FIG. 4.

[0134] Also, this safety torque off circuit 10A is also configured such that the STO operation can be performed by the diagnostic protection signal Sd, similar to the configuration shown in FIG. 2. The signal lines of the diagnostic protection signal Sd are branched and connected to the enable terminals of the buffer element BF1 and the buffer element BF2, respectively.

[0135] In the example shown in FIG. 4, the output terminals of the logic AND element A1 and the logic AND element A2 are connected to the enable terminals of the buffer element BF1 and the buffer element BF2 to which the diagnostic protection signal Sd is input. Also, signal lines of the safety input signal S1 and the safety input signal S2 are connected to one ends of the inputs of the logic AND element A1 and the logic AND element A2. Further, inversion units are provided at the other ends of the inputs of the logic AND element A1 and the logic AND element A2 so that the inverted signal of the diagnostic protection signal Sd is input (refer to FIG. 4 as appropriate).

[0136] According to the safety torque off circuit 10A configured as described above, in the same operation as in FIG. 2, that is, when the safety input signal S1 and the safety input signal S2 are High and the diagnostic protection signal Sd is Lo, a signal in the motor operation permission state is output from the buffer element BF1. The operations when each signal (S1, S2, Sd) is other than the above are the same as those in the case of FIG. 2, and the detailed description is omitted.

[0137] <<Embodiment 3>> FIG. 5 is an example of a motor control device according to Embodiment 3 of the motor control device of the present disclosure. The motor control device 1A shown in FIG. 5 has a function of not only monitoring the difference between the safety input signal S1 and the safety input signal S2 by the safety monitoring unit 16 but also inspecting whether the safety monitoring unit 16 that performs such monitoring is functioning normally. The differences from the motor control device 1 described above with reference to FIG. 1 will be described below.

[0138] In Embodiment 3, it is assumed that a monitor device 2B such as an image display is used as an external device of the motor control device 1A. Note that the external safety device indicated by reference numeral 2A in FIG. 5 is equivalent to the external safety device 2 shown in FIG. 1.

[0139] In the motor control device 1A according to the third embodiment, test switches QT1 and QT2 capable of blocking the transmission of the respective signals (S1, S2) are provided on the transmission paths of the safety input signal S1 and the safety input signal S2. In the state shown in FIG. 5, both of these test switches QT1 and QT2 are in the ON state. Further, in the third embodiment, the ON / OFF of these test switches QT1 and QT2 can be operated by the motor control arithmetic unit 14A. Furthermore, the motor control arithmetic unit 14A of the third embodiment is configured to be able to detect the state of the diagnostic protection signal Sd output from the safety monitoring unit 16.

[0140] Specifically, the motor control arithmetic unit 14A additionally includes an operation unit 142 that outputs signals for operating the on / off of the test switches QT1 and QT2. This operation unit 142 has a function of operating so as not to send at least one of the multiple commands (S1, S2) to the motor control unit (the safety torque off circuit 10 in this example).

[0141] Further, the motor control arithmetic unit 14A includes a notification unit 141 that notifies an external monitoring device 2B of the diagnostic protection signal Sd, the state of the device, etc. based on the diagnostic protection signal Sd transmitted from the safety monitoring unit 16. In the illustrated example, the diagnostic protection signal Sd output from the safety monitoring unit 16 is also input to the notification unit 141 and the operation unit 142. Other configurations (functions) of the motor control arithmetic unit 14A are equivalent to those of the motor control arithmetic unit 14 described above with reference to FIG. 1.

[0142] Hereinafter, the significance, advantages, etc. of the circuit configuration shown in FIG. 5 will be described. For example, in the configuration shown in FIG. 1, if the STO state is reached due to the action of the diagnostic protection signal Sd, although the motor 3 is in the torque-off state due to the operation of the STO, there is a possibility that the cause (in this example, whether it was due to the action of the diagnostic protection signal Sd) cannot be determined.

[0143] On the other hand, in the circuit configuration shown in FIG. 5, detection means (the through-value unit 141 and the operation unit 142) for detecting the diagnostic protection signal Sd is mounted inside the motor control arithmetic unit 14A, and through the through-value unit 141, the waveform of the diagnostic protection signal Sd and its transition can be notified to an external monitor device 2B and displayed on the monitor device 2B. Therefore, there is an advantage that the system user can identify the cause thereof.

[0144] Also, in the circuit configuration shown in FIG. 5, since the test switches QT1 and QT2 are configured to be operable from the operation unit 142 provided in the motor control arithmetic unit 14A, there is an advantage that safety is further enhanced.

[0145] More specifically, for example, in a state where the safety input signals S1 and S2 indicate motor operation permission, one of the test switches QT1 or QT2 is artificially (e.g., by user operation) turned OFF to cut off the transmission of one of the safety input signals S1 and S2, and it can be confirmed whether the diagnostic protection signal Sd correctly transitions to High. In other words, according to the circuit configuration shown in FIG. 5, since the safety monitoring unit 16 can self-diagnose whether it is normal, a safer system without failures can be constructed.

[0146] Note that although the test switches QT1 and QT2 shown in FIG. 5 are exemplified as physical switches for cutting off the safety input, any other mechanism such as pull-down / pull-up that can invert the polarity (High / Lo) of the safety input signals S1 and S2 can perform an equivalent self-diagnosis function.

[0147] <<Embodiment 4>> FIG. 6 is a circuit diagram showing a configuration example in the case where an electrical input circuit is provided in the transmission path of the safety input signals S1 and S2 in the motor control device according to Embodiment 4 of the present disclosure.

[0148] In the example shown in FIG. 6, a first-order lag filter composed of a resistor RF and a capacitor CF is provided in front of the safety monitoring unit 16 and the safety torque off circuit 10 in the transmission paths of the safety input signals S1 and S2, and the potential output from such a filter is input to the safety monitoring unit 16 and the safety torque off circuit 10.

[0149] In each first-order lag filter, the output terminal of the resistor RF is connected to one terminal of the capacitor CF and the input ends of the safety monitoring unit 16 and the safety torque off circuit 10. Also, the other terminal of the capacitor CF is connected to the reference potential. Further, the time constant of each first-order lag filter is set to be sufficiently shorter than the time constant of the RC time constant circuit defined by the resistor R12 (second resistor) and the capacitor C11 of the safety monitoring unit (command monitoring unit) 16 described above.

[0150] According to the circuit configuration described above, the STO operation can be obtained by the safety torque off circuit 10 without waiting for the diagnosis (Sd = High) by the safety monitoring unit 16, and a desirable response can be obtained as multiple safety input signals S1 and S2.

[0151] <<Embodiment 5>> FIG. 7 is a diagram according to Embodiment 5, and is a circuit diagram showing an example in which the motor control device of the present disclosure can also be applied to a safety function different from STO.

[0152] The motor control device 1B shown in FIG. 7 is additionally equipped with a safety control unit 20 inside, and the safety input signals S1, S2, the diagnostic protection signal Sd, and the output of the encoder 4 (position information of the rotor of the motor 3) are input to the safety control unit 20. This safety control unit 20 is arranged in front of the motor control arithmetic unit 14 and the safety torque off circuit 10 and behind the external safety device 2 and the safety monitoring unit (command monitoring unit) 16, and inputs the multiple commands, the signal from the command monitoring unit, and the position of the rotor.

[0153] Here, the safety control unit 20 has a function of outputting double deceleration instructions SL1 and SL2 to the motor control arithmetic block 14. Further, the safety control unit 20 has a function of outputting double safe stop (STO) instructions ST1 and ST2 to the safe torque off circuit 10.

[0154] Note that the safety control unit 20 can be realized by an analog and digital circuit, software such as a microcomputer, or a combination thereof.

[0155] Also, the motor control device 1 may be configured such that some functions of the motor control device 1 are separated and added as options. For example, the safety monitoring unit 16 and the safety control unit 20 shown in FIG. 7 may be detachable option blocks via an interface or the like, separate from the main body (that is, the block inside the motor control device 1). With such a configuration, any type of safety function can be added as needed. Therefore, the cost on the main body side of the motor control device 1 can be reduced, and an optimal safety function for the motor 3 can be selected according to the type and operation content of the equipment to which the motor 3 is attached.

[0156] In a certain standard, the safety function Safe Stop1 (SS1) is defined as a safety stop function having a period of deceleration based on a predetermined deceleration pattern as a stage before torque-off stop by STO. As a means for realizing SS1 that secures such a deceleration period, the safety control unit 20 performs the following control.

[0157] When the safety control unit 20 receives a stop command as safety input signals S1 and S2 or a safety stop command (Sd = High) from the safety monitoring unit 16, it sends double deceleration instructions SL1 and SL2 to the motor control arithmetic block 14 and starts monitoring the speed of the motor 3 based on the signal received from the encoder 4. Then, when the speed of the motor 3 becomes equal to or lower than a predetermined speed (threshold speed) as a result of the monitoring, the safety control unit 20 sends an STO instruction to the safety torque off circuit 10. By performing such control, the motor 3 does not suddenly stop when the safety input signals S1 and S2 are output, so it is possible or expected to prevent damage to the corresponding equipment and ensure the safety of workers etc. who are working using the equipment.

[0158] <<Embodiment 6>> FIG. 8 is an example of the internal circuits of the safety control unit 20 and the safety torque off circuit 10 in Embodiment 6. In the circuit configuration shown in FIG. 8, by logically configuring the output of the safety control unit 20 so that ST1 and ST2 become Lo when the diagnostic protection signal Sd is High, the STO can be made to function immediately when the diagnostic protection signal Sd occurs. Even in such a configuration, by utilizing the safety monitoring block 16 and the diagnostic protection signal Sd as the diagnosis of the safety inputs S1 and S2, a safer system with fewer malfunctions can be realized.

[0159] <<Embodiment 7>> FIG. 9 is an example of the internal circuits of the safety monitoring unit 16 and the safety torque off circuit 10 in Embodiment 7. In the circuit configuration shown in FIG. 9, second anode cutoff switches Q1D and Q2D are inserted between the outputs of the anode cutoff switches Q1 and Q2 and the anode of the gate drive element GD inside the safety torque off circuit 10.

[0160] Note that the second anode cutoff switches Q1D and Q2D are normally in the ON (hereinafter referred to as "normally on") polarity, and they are configured to be driven (switched off) by the High output of the diagnostic protection signal SL. With this configuration, when a difference is detected between the safety input signal S1 and the safety input signal S2, the diagnostic protection signal SL outputs a High signal, causing both the second anode cutoff switches Q1D and Q2D to be in the off state, and the motor 3 to be in the torque-off state.

[0161] Among these, the anode cutoff switches Q1 and Q2, which are responsible for cutting off the drive signal supplied to the motor 3 in response to the commands S1 and S2 (safety input signals), correspond to the "first cutoff section" in the present disclosure. On the other hand, the second anode cutoff switches Q1D and Q2D, which are responsible for cutting off the drive signal supplied to the motor 3 in response to the diagnostic protection signal SL (safety stop signal), correspond to the "second cutoff section" in the present disclosure. In this embodiment, the anode cutoff switch Q1 in the first cutoff section and the second anode cutoff switch Q1D are connected in series, and similarly, the anode cutoff switch Q2 in the first cutoff section and the second anode cutoff switch Q2D are connected in series to form a circuit configuration.

[0162] Furthermore, in the circuit configuration shown in FIG. 9, the signal input to the safety monitoring unit 16 is input to feedback the output voltage of the second anode cutoff switches Q1D and Q2D (second cutoff section). As described above, since the second anode cutoff switches Q1D and Q2D are in the normally on polarity, while the diagnostic protection signal SL is Low after the device is started, the input to the safety monitoring unit 16 is the same as in other embodiments, and a signal corresponding to the safety input signals S1 and S2 is input.

[0163] On the other hand, after the safety monitoring unit 16 sets the diagnostic protection signal SL to High, the second anode cutoff switches Q1D and Q2D are turned off. Therefore, although the input of the safety monitoring unit 16 may not reflect the input states of the safety input signal S1 and the safety input signal S2, the torque-off state of the motor 3 is maintained by the action of the latch unit B13, so the safety function can be achieved.

[0164] In this way, if the signals downstream of the part where the safety monitoring unit 16 operates to cut off torque (the second anode cutoff switches Q1D and Q2D in this embodiment) are fed back as the input of the safety monitoring unit 16, the second processing block B2 and the third processing block B3 in FIG. 3 can be made unnecessary, contributing to miniaturization of the device and the like.

[0165] As described above, the present invention has been described based on the embodiments. However, the configurations of the above-described embodiments are merely examples and are not limited thereto, and various modifications are possible. In the above-described embodiments, except for the essential components, addition, deletion, replacement, etc. of the components are possible. Unless otherwise specified, each component may be singular or plural. Combinations of various configuration examples are also possible.

Explanation of Reference Numerals

[0166] 1, 1A, 1B Motor control device 2, 2A External safety device 2B Monitoring device 3 Motor 4 Encoder 5 AC main power supply 10 Safety torque-off circuit (motor control unit) 11 Three-phase inverter (motor control unit, power semiconductor) 12 AC-DC conversion circuit 13 Current detection unit 14 Motor control arithmetic unit (motor control unit) 15 Control pulse generation unit (motor control unit) 16 Safety monitoring unit (command monitoring unit) 20 Safety control unit (motor control unit) 141 Notification unit 142 Operation unit A1, A2 Logical AND element B1 First processing block (first signal processing unit) B2 Second processing block (second signal processing unit, NAND unit) B3 Third processing block S1, S2 Safety input signals (multiple commands) Sd Diagnostic protection signal Q1, Q2 Anode cut-off switches BF0, BF1, BF2 Buffer elements GD Gate drive element B11 XOR unit X1…XOR element, R11…Pull-down resistor B12 Charge and discharge unit R12…Resistor (second resistor), C11…Capacitor, R12, C11 (RC time constant circuit), D11…Diode, R13…Resistor, D11, R13 (diode circuit) B13 Latch unit O11…OR element QT1, QT2 Test switches RF, CF First-order lag filter ST1, ST2 Stop (STO) instructions SL1, SL2 Deceleration instructions

Claims

1. A motor control unit that controls a motor to be in a normal operating state by sending a drive current to the motor and to be in a safe stop state from the normal operating state in response to multiple commands regarding a safety function operation sent from the outside; A command monitoring unit that monitors whether each of the commands matches each other; and When the period during which the commands do not match each other exceeds an allowable value, the command monitoring unit generates a safety stop command to safely stop the motor and continuously sends the generated safety stop command to the motor control unit. A control device.

2. In the control device according to Claim 1, The command monitoring unit includes A comparison unit that compares each of the commands and outputs a difference as a High signal; A power storage unit that accumulates the charge of the High signal; and A safety stop command generation unit that generates and outputs the safety stop command when the voltage of the power storage unit exceeds a threshold value. A control device.

3. In the control device according to Claim 2, The power storage unit includes a capacitor, and is provided with an RC time constant circuit that charges the capacitor so as to ensure the time from when the High signal is output until the voltage of the capacitor exceeds the threshold value. The safety stop command generation unit includes a latch unit that holds the output of the safety stop command when the voltage of the capacitor exceeds the threshold value. When receiving the safety stop command, the motor control unit controls to cut off or reduce the drive current supplied to the motor. A control device.

4. In the control device according to Claim 3, Further, It is provided with a notification unit that notifies an external device of the state of the signal output from the latch unit. A control device.

5. In the control device according to claim 4, further, an operation unit that operates so as not to send at least one of the multiple commands to the motor control unit, a control device.

6. In the control device according to claim 1, the command monitoring unit includes an XOR unit, a charge / discharge unit, and a latch unit connected in series in this order, the XOR unit includes an XOR element that calculates and outputs the exclusive logical sum of the commands, and a first resistor that pulls down the output of the XOR element, the charge / discharge unit includes an RC time constant circuit including a second resistor whose one end is connected to the output end of the XOR element and a capacitor connected to the other end of the second resistor, charges the capacitor when the output of the XOR element is High, and discharges the charge of the capacitor when the output of the XOR element is Low, the latch unit includes an OR element whose first input end is connected to the positive voltage terminal of the capacitor, and a pull-down resistor that pulls down the output of the OR element, and the output of the OR element is directly connected to the second input end of the OR element, a control device.

7. In the control device according to claim 1, the command monitoring unit branches the multiplexed commands in parallel to a first signal processing unit and a second signal processing unit respectively, and based on the logical sum of the calculation output of the first signal processing unit and the calculation output of the second signal processing unit, sends a High signal as the safety stop command to the motor control unit, the first signal processing unit includes an XOR unit, a charge / discharge unit, and a latch unit connected in series in this order, the second signal processing unit has a NAND unit that performs a NAND operation on the multiplexed commands and outputs the result, the XOR unit includes an XOR element that calculates and outputs the exclusive logical sum of the commands, and a first resistor that pulls down the output of the XOR element, The charge and discharge unit includes an RC time constant circuit composed of a second resistor with one end connected to the output end of the XOR element and a capacitor connected to the other end of the second resistor. When the output of the XOR element is High, the capacitor is charged, and when the output of the XOR element is Low, the charge of the capacitor is discharged. The latch unit includes an OR element with a first input end connected to the positive voltage terminal of the capacitor and a pull-down resistor for pulling down the output of the OR element. The output of the OR element is directly connected to the second input end of the OR element. The NAND unit includes a logic NAND element that calculates and outputs the negative logical product of the command and a pull-up resistor for pulling up the output of the logic NAND element. Control device.

8. In the control device according to claim 7, In the charge and discharge unit of the first signal processing unit, a series circuit of a third resistor and a diode is connected in parallel to the second resistor. The diode is connected such that the anode is on the output end side of the second resistor and the cathode is on the input end side of the second resistor, thereby rectifying in a direction to discharge a part of the charge accumulated in the capacitor of the RC time constant circuit through the third resistor. Control device.

9. In the control device according to claim 7, A delay filter circuit is provided in front of the motor control unit and the command monitoring unit. The time constant of the delay filter circuit is shorter than the time constant of the RC time constant circuit. Control device.

10. In the control device according to claim 1, The motor control unit is A motor control arithmetic unit that inputs the drive current supplied to the motor and the position of the rotor of the motor, performs an operation to obtain a control operation amount for correctly operating the motor, and outputs the calculated control operation amount. A power semiconductor having a switch circuit that adjusts the drive current sent to the motor based on the control operation amount from the motor control arithmetic unit, A safety stop control unit that performs control to reduce the drive current sent to the motor in response to the safety stop command, and A control device.

11. In the control device according to claim 10, The safety stop control unit is provided after the motor control arithmetic unit and before the power semiconductor, When the safety stop command is not generated from the command monitoring unit, the signal of the control operation amount is transferred to the power semiconductor, When the safety stop command is generated from the command monitoring unit, the switch circuit of the power semiconductor is turned off by blocking the transfer of the signal of the control operation amount, and the drive current sent to the motor is blocked. A control device.

12. In the control device according to claim 11, Furthermore, a safety control unit is provided before the safety stop control unit and the motor control arithmetic unit, and inputs the multiple commands, the signal from the command monitoring unit, and the position of the rotor, When the safety stop command is generated from the command monitoring unit, the safety control unit performs control to gradually reduce the drive current sent to the motor based on the rotational operation of the motor, and then performs control to block the drive current sent to the motor. A control device.

13. In the control device according to claim 6, The motor control unit Inputs the drive current supplied to the motor and the position of the rotor of the motor, performs an operation to obtain a control operation amount for correctly operating the motor, and outputs the calculated control operation amount, a motor control arithmetic unit, A power semiconductor having a switch circuit that adjusts the drive current sent to the motor based on the control operation amount from the motor control calculation unit, A safety stop control unit that performs control to reduce the drive current sent to the motor in response to the safety stop command, The safety stop control unit, A circuit in which a first cutoff unit that cuts off the drive current supplied to the motor in response to the command and a second cutoff unit that cuts off the drive current supplied to the motor in response to the safety stop command are connected in series, and the output of the circuit is input to the XOR unit of the command monitoring unit, and the output of the latch unit of the command monitoring unit is supplied as the safety stop command to the second cutoff unit, Performs control to reduce the drive current sent to the motor in response to the command and the safety stop command, Control device.

14. The control device according to claim 1 is connected, A processing apparatus having a motor controlled by the control device as a power source, Processing equipment.

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