JP7745250B2 - Motor control system and motor control device - Google Patents

Description

This disclosure relates to a motor control system and a motor control device.

In the field of motor control, there is a demand for enhanced safety functions. In relation to this situation, for example, Patent Document 1 discloses a safety device that includes a control board for controlling a motor (electric motor) and a safety function board. By linking the safety function board and the control board, when a safety-related signal is received from an external source, multiple safety functions can be realized in response to the signal, such as stopping the motor by safe torque off (STO: Safe Torque Off) in accordance with safety standards such as IEC 61800-5-2, or stopping the motor after controlling the motor's rotational speed to decelerate (SS1: Safe Stop 1). Patent Document 1 also suggests realizing a safety device as multiple devices.

JP 2011-8642 A

Based on the above suggestions, it is conceivable that, for example, a combination of a motor control device and an external device connected to it (hereinafter referred to as a "safety function device") could enable the execution of other safety functions in addition to STO and SS1, while the motor control device alone could also enable the execution of STO and SS1. This would allow the needs of both users to be met by providing only the motor control device to users who require only the minimum necessary safety functions at low cost, and by providing both the motor control device and the safety function device to users who require a large number of safety functions.

However, if safety functions are realized by combining a motor control device and a safety function device as described above, the number of components that make up the circuits that realize the safety functions and the circuits that affect those circuits (hereinafter referred to as safety-related parts) will increase, which could increase the failure rate of the entire system.

In light of the above circumstances, the purpose of this disclosure is to provide a motor control system, etc., that can reduce the increase in failure rate when implementing safety functions by combining a motor control device and a safety function device.

In order to achieve the above object, a motor control system according to a first aspect of the present disclosure comprises:
The motor control device controls the motor, and a safety function device is provided.
The safety function device is
a first receiving means for receiving a first safety request signal;
a first transmitting means for transmitting the first safety request signal received by the first receiving means to the motor control device;
Equipped with
The motor control device includes:
a second receiving means for receiving a second safety request signal and receiving the first safety request signal from the safety function device;
a selection means for selecting the first safety request signal when the safety function device is connected to the motor control device, and selecting the second safety request signal when the safety function device is not connected to the motor control device;
a cutoff means for cutting off a current flowing through the motor when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating a stop of the motor;
Equipped with.

The motor control device is configured to, when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating the stop of the motor, execute one of stopping the motor by STO (Safe Torque Off) and deceleration control and stopping of the motor by SS1 (Safe Stop 1).
It may also be something.

the motor control device further includes a second transmission means for transmitting an identification signal for identifying a model of the motor control device to the safety function device;
The safety function device further includes a storage means for storing linked model information indicating a model of a motor control device that can be linked with the safety function device,
The first receiving means of the safety function device further receives the identification signal from the motor control device;
the first transmitting means of the safety function device transmits a signal indicating that the safety function device and the motor control device can be interlocked to the selecting means of the motor control device when the model indicated in the identification signal received by the first receiving means is included in the models indicated in the interlocking model information, and transmits a signal indicating that the safety function device and the motor control device cannot be interlocked to the selecting means of the motor control device when the model indicated in the identification signal received by the first receiving means is not included in the models indicated in the interlocking model information;
the selection means of the motor control device selects the first safety request signal when receiving a signal indicating that the safety function device and the motor control device can be interlocked, and selects the second safety request signal when receiving a signal indicating that the safety function device and the motor control device cannot be interlocked.
It may also be something.

In order to achieve the above object, a motor control device according to a second aspect of the present disclosure comprises:
A motor control device that controls a motor,
receiving means for receiving a second safety request signal and a first safety request signal from the safety function device;
a selection means for selecting the first safety request signal when the safety function device is connected to the motor control device, and selecting the second safety request signal when the safety function device is not connected to the motor control device;
a cutoff means for cutting off a current flowing through the motor when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating a stop of the motor;
Equipped with.

This disclosure makes it possible to reduce the increase in failure rate when implementing safety functions by combining a motor control device with a safety function device.

FIG. 1 is a diagram illustrating an overall configuration of a motor control system according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating another example of the overall configuration of a motor control system according to an embodiment of the present disclosure. FIG. 1 is a diagram showing a configuration of a safety function device according to a modified example of an embodiment of the present disclosure. FIG. 1 is a diagram illustrating an overall configuration of a motor control system according to a modified example of an embodiment of the present disclosure.

A motor control system according to an embodiment of the present disclosure will now be described with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals.

(Embodiment)
A motor control system 1 according to an embodiment will be described with reference to Figure 1. In the embodiment, the motor control system 1 is a motor control system that controls a motor 3. The motor control system 1 includes a safety function device 10 and a motor control device 20. The motor control system 1 realizes a safety function by the safety function device 10 and the motor control device 20 working together. The motor control system 1 is an example of a motor control system according to the present disclosure.

The safety function device 10, motor control device 20, and motor 3 are generally described below. The detailed configurations of the safety function device 10 and motor control device 20 will be described later.

The motor control device 20 controls the motor 3 based on signals from a programmable logic controller (not shown) or the like. When the motor control device 20 is not connected to the safety function device 10, it has a safety function of stopping the motor 3 using STO. When the motor control device 20 is connected to the safety function device 10 as shown in FIG. 1, the motor control device 20 works in conjunction with the safety function device 10 to realize multiple safety functions based on safety standards, including not only STO but also SS1, SS2 (Safe Stop 2), SOS (Safe Operating Stop), and SLS (Safety Limited Speed). The motor control device 20 is an example of a motor control device according to the present disclosure.

When the safety function device 10 is connected to the motor control device 20 as shown in Figure 1, it works in conjunction with the motor control device 20 to implement the multiple safety functions described above. The safety function device 10 is an example of a safety function device according to the present disclosure.

Motor 3 is a motor that is driven and controlled by motor control device 20, which is a motor control device. Motor 3 may be operated by receiving three-phase AC power from motor control device 20, for example, or may be a stepping motor. Motor 3 also includes an encoder 31 required for feedback control by motor control device 20. Encoder 31 outputs an encoder signal SE to motor control device 20 that indicates the state of motor 3, such as the rotational speed and position (rotation angle) of the rotor of motor 3. Motor control device 20 drives and controls motor 3 by appropriately varying the voltage applied to motor 3 and the current ID supplied to motor 3 based on current signal SI indicating the current ID supplied to motor 3 and encoder signal SE. Motor 3 is an example of a motor according to the present disclosure.

The motor control device 20 generates a control signal SP for performing deceleration control, etc. of the motor 3 based on the current signal SI and the encoder signal SE. The motor control device 20 can perform deceleration control, etc. of the motor 3 by controlling the motor 3 based on the generated control signal SP.

Next, the configuration of the safety function device 10 will be described. The safety function device 10 includes a receiving circuit 11, an auxiliary control unit 12, and a receiving circuit 13. The auxiliary control unit 12 also includes a safety function module 121 for implementing the safety function.

The receiving circuit 11 receives a first safety request signal SR1 from switches and sensors, such as an emergency stop switch, light curtain, or safety door lock. The first safety request signal SR1 is a signal indicating whether to execute STO or SS1. When the switches and sensors detect a situation in which motor 3 should be stopped, such as an abnormality occurring at a production site where motor 3 is used, they turn on the first safety request signal SR1 and transmit it to the safety function device 10. When the first safety request signal SR1 is on, it indicates that motor 3 should be stopped by executing STO or SS1. For example, the first safety request signal SR1 is on when it is a low signal, and off when it is a high signal. Furthermore, when the receiving circuit 11 is not connected to switches and sensors, a pull-up circuit (not shown) causes the first safety request signal SR1 to be a high signal. The receiving circuit 11 is an example of a first receiving means according to the present disclosure.

Note that while Figure 1 depicts the transmission and reception of signals between the safety function device 10 and the motor control device 20 as if the respective components are directly connected, in reality, signals are transmitted and received via a transmitting circuit or a receiving circuit (not shown). These transmitting and receiving circuits (not shown) are examples of the first transmitting means and first receiving means, respectively, according to the present disclosure.

The receiving circuit 13 receives a third safety request signal SR3 from switches and sensors such as an emergency stop switch, light curtain, and safety door lock. The third safety request signal is a signal that indicates whether or not to execute a safety function based on safety standards such as SS2, SOS, and SLS, which the motor control device 20 cannot execute on its own. As will be described later, when the third safety request signal is on, the auxiliary control unit 12 and the motor control device 20 cooperate to execute safety functions such as SS2, SOS, and SLS. The criteria for turning on the first safety request signal SR1 and the criteria for turning on the third safety request signal SR3 are generally different.

When the safety function device 10 is connected to the motor control device 20 via a connector (not shown), for example, the auxiliary control unit 12 continuously transmits a connection signal SC that is set to a low signal to the processor 232 (described below) of the motor control device 20. This allows the processor 232 to recognize that the safety function device 10 is connected to the motor control device 20. Furthermore, when the first safety request signal SR1 received by the receiving circuit 11 is on, the auxiliary control unit 12 generates a signal to recognize the type of safety function that the safety function module 121 plans to execute in response to the signal SR1 being on, i.e., STO or SS1, and transmits this signal to the motor control device 20.

The auxiliary control unit 12 also transmits a signal SQ indicating the type (on or off) of the first safety request signal SR1 received by the receiving circuit 11 to the motor control device 20. The signal SQ is a low signal if the first safety request signal SR1 is on, and a high signal if the first safety request signal SR1 is off.

Here, if the user selects to execute STO when the first safety request signal SR1 is on, the safety function module 121 immediately sends a signal SQ to the motor control device 20.

On the other hand, when the user selects to execute SS1 when the first safety request signal SR1 is on, the safety function module 121 does not immediately send signal SQ to the motor control device 20, but sends it after a predetermined time has elapsed. The predetermined time is, for example, the time required for the speed of motor 3 to be sufficiently reduced by the deceleration control of motor 3 by the motor control device 20, the details of which will be described later.

The auxiliary control unit 12 also continuously transmits the selection signal SA, which is a Low signal, to the selection circuit 22 (described later) of the motor control unit 20. When the third safety request signal SR3 received by the receiving circuit 13 is ON, the auxiliary control unit 12 generates and transmits to the motor control unit 20 a signal that causes the motor control unit 20 to recognize the type of safety function that is scheduled to be executed in response to the signal SR3 being ON, i.e., the execution of SS2, SOS, SLS, etc.

Next, the configuration of the motor control device 20 will be described. The motor control device 20 includes a receiving circuit 21, a selection circuit 22, a control unit 23, and a current sensor 24. The control unit 23 also includes a cutoff circuit 231, a processor 232, and a drive circuit 233.

The receiving circuit 21 receives the second safety request signal SR2 from switches and sensors, such as emergency stop switches, light curtains, and safety door locks. The second safety request signal SR2 has the same content as the first safety request signal SR1, but the signal transmission path is different. As with the receiving circuit 11 of the safety function device 10, when the switches and sensors detect a situation in which the motor 3 should be stopped, such as an abnormality occurring at the production site where the motor 3 is used, they turn on the second safety request signal SR2 and transmit it to the motor control device 20. When the second safety request signal SR2 is on, it indicates that an STO should be performed, i.e., that the motor 3 should be stopped. As with the first safety request signal SR1, the second safety request signal SR2 is on when it is a low signal, and off when it is a high signal. Furthermore, when the receiving circuit 21 is not connected to the switches and sensors, the second safety request signal SR2 becomes a high signal due to a pull-up circuit (not shown). The receiving circuit 21 is an example of a second receiving means according to the present disclosure.

As with the safety function device 10, the transmission and reception of signals between the motor control device 20 and the safety function device 10 is depicted in FIG. 1 as if the respective components are directly connected to each other, but in reality, signals are transmitted and received via a transmitting circuit or a receiving circuit (not shown). These transmitting circuits and receiving circuits (not shown) are examples of second transmitting means and second receiving means, respectively, according to the present disclosure.

When the input selection signal SA is a low signal, i.e., when the selection circuit 22 receives a low selection signal SA from the safety function device 10, the selection circuit 22 selects the signal SQ received from the safety function device 10 (i.e., the signal SQ indicates the same content as the type (on or off) of the first safety request signal SR1). When the selection signal SA is a high signal, i.e., when the safety function device 10 is not connected to the motor control device 20, the selection circuit 22 selects the second safety request signal SR2 received by the receiving circuit 21. However, when the safety function device 10 is not connected to the motor control device 20, the selection signal SA input to the selection circuit 22 becomes a high signal due to a pull-up circuit (not shown). The selection circuit 22 is, for example, a digital circuit, such as a multiplexer. The selection circuit 22 outputs a shutoff enable/disable signal SB indicating the type (on or off) of the selected signal SQ (first safety request signal SR1) or the second safety request signal SR2 to the shutoff circuit 231. When the selection signal SA is a low signal, the selection circuit 22 does not select the second safety request signal SR2 received by the receiving circuit 21. Therefore, it can be said that the selection circuit 22 disables the receiving circuit 21 when the selection signal SA is a low signal. The selection circuit 22 is an example of a selection means according to the present disclosure.

The drive circuit 233 drives and controls the motor 3 by supplying power to the motor 3 based on a control signal SP received from the processor 232 (described below) via the cutoff circuit 231. More specifically, the drive circuit 233 drives and controls the motor 3 by adjusting the voltage applied to the motor 3 and the current supplied to the motor 3 based on the control signal SP received from the cutoff circuit 231. When the cutoff circuit 231 cuts off the control signal SP, as described below, the power supply to the motor 3 is stopped. This allows STO to be realized.

The current sensor 24 detects the drive current ID supplied to the motor 3 by the drive circuit 233 and outputs a current signal SI indicating the detected drive current ID to the processor 232. The current sensor 24 is, for example, a current sensor using a Hall element provided near the current path between the drive circuit 233 and the motor 3. Note that while the current path is shown as a single line in Figure 1, if the motor 3 is driven by three-phase AC power or is a stepping motor, there will actually be multiple current paths, and the corresponding current sensor 24 will also be composed of multiple elements.

The processor 232 controls the drive control of the motor 3. The processor 232 is, for example, a CPU (Central Processing Unit) that executes programs stored in memory (not shown). Alternatively, the processor 232 may be configured as an ASIC (Application Specific Integrated Circuit).

The processor 232 generates a control signal SP for operating the motor 3 based on a signal from a programmable logic controller (not shown) or the like, the current signal SI output by the current sensor 24, and the encoder signal SE output by the encoder 31, and outputs the generated signal to the cutoff circuit 231. When the safety function device 10 is connected to the motor control device 20, the processor 232 also receives a signal from the auxiliary control unit 12 indicating the type of safety function to be executed in response to the first safety request signal SR1 or the third safety request signal SR3 being turned on. The processor 232 recognizes the safety function to be executed in response to the received signal indicating the type of safety function.

When the signal SQ (first safety request signal) or second safety request signal SR2 selected by the selection circuit 22 is OFF, i.e., when the shutoff/non-shutoff signal SB input from the selection circuit 22 indicates that the signal SQ or second safety request signal SR2 is OFF, the shutoff circuit 231 outputs the control signal SP received from the processor 232 to the drive circuit 233 without shutting it off. On the other hand, when the signal SQ (first safety request signal SR1) or second safety request signal SR2 selected by the selection circuit 22 is ON, i.e., when the shutoff/non-shutoff signal SB input from the selection circuit 22 indicates that the signal SQ or second safety request signal SR2 is ON, the shutoff circuit 231 shuts off the control signal SP received from the processor 232. Examples of such a shutoff circuit 231 include, but are not limited to, a photocoupler. This stops the power supply from the drive circuit 233 to the motor 3, allowing the motor 3 to be stopped by the STO. Furthermore, when the safety function device 10 is connected to the motor control device 20 (the selection circuit 22 selects the signal SQ) and the execution of SS1 is selected by the user, if the first safety request signal SR1 is on, a cutoff possibility signal SB indicating that the signal SQ is on is output to the selection circuit 22 after a predetermined time has elapsed, and the control signal SP is cut off. This makes it possible to execute SS1, a safety function that stops the motor 3 after executing deceleration control. The cutoff circuit 231 is an example of a cutoff means according to the present disclosure.

The motor control device 20 may also be configured as shown in Figure 2. As explained below, by configuring the motor control device 20 as shown in Figure 2, the motor control device 20 can execute SS1 independently, unlike when configured as shown in Figure 1.

In FIG. 2, the motor control device 20 further includes a delay circuit 25. The receiving circuit 21 outputs the received second safety request signal SR2 to the delay circuit 25 and the processor 232. The delay circuit 25 delays the second safety request signal SR2 output by the receiving circuit 21 by a predetermined time and outputs it to the selection circuit 22. The processor 232 starts deceleration control of the motor 3 when the second safety request signal SR2 output by the receiving circuit 21 is ON.

By configuring the motor control device 20 in this manner, when the motor control device 20 and the safety function device 10 are not connected and the second safety request signal SR2 output by the receiving circuit 21 is ON, the selection circuit 22 inputs the second safety request signal SR2 a predetermined time after deceleration control of the motor 3 begins, and outputs a cutoff enable/disable signal SB indicating that the second safety request signal SR2 is ON to the cutoff circuit 231. As a result, the cutoff circuit 231 cuts off the control signal SP to the drive circuit 233 a predetermined time after deceleration control of the motor 3 begins. In other words, the motor control device 20 can execute SS1 independently.

Next, we will explain how configuring the safety function device 10 and motor control device 20 as described above can suppress an increase in the failure rate when implementing safety functions by combining the motor control device and safety function device.

Generally, the failure rate of an entire system consisting of two devices is the sum of the failure rates of the components in each device.

On the other hand, in the motor control system 1, when the safety function device 10 and the motor control device 20 are connected, the selection circuit 22 of the motor control device 20 selects the signal SQ received from the safety function device 10 and outputs a cutoff possibility signal SB indicating the type of signal SQ (i.e., the first safety request signal SR1) to the cutoff circuit 231.

Therefore, in the motor control system 1, the entire system can continue to operate even if the receiving circuit 21 fails, so the failure rate of the receiving circuit 21 does not need to be considered as the failure rate of the entire system. That is, when the safety function device 10 is connected to the motor control device 20 configured as shown in FIG. 1, the receiving circuit 21 is isolated from the circuits that implement the safety functions STO or SS1 and from the circuits that affect those circuits (safety-related components). Therefore, the motor control system 1 can suppress an increase in the failure rate when implementing a safety function by combining the motor control device and the safety function device. Similarly, when the safety function device 10 is connected to the motor control device 20 configured as shown in FIG. 2, the receiving circuit 21 and delay circuit 25 are isolated from the safety-related components, suppressing an increase in the failure rate when implementing the safety function.

(Modification)
To achieve a higher safety level, the receiving circuit 11 and the safety function module 121 of the safety function device 10 may be multiplexed as shown in FIG. 3. Multiplexing may be required depending on the target safety level, and this configuration makes it possible to achieve that safety level. Note that while FIG. 3 omits illustration of signals communicated between the safety function device 10 and the motor control device 20, whether or not the communication lines, transmitting/receiving circuits, etc. for these signals are multiplexed may be determined depending on the target safety level. However, if the communication lines, transmitting/receiving circuits, etc. are multiplexed, the motor control device 20 must also be compatible with multiplexing.

In an embodiment, it is conceivable that the safety function device 10 can be linked to multiple types of motor control devices 20. In this case, the safety function device 10 can be provided with a function to identify the model of the motor control device 20, and configured to transmit a selection signal SA that is a Low signal only if the model of the motor control device 20 identified by the safety function device 10 is a motor control device 20 that can be linked.

4, when the safety function device 10 is connected, the processor 232 of the motor control device 20 receives the connection signal SC output by the auxiliary control unit 12 and transmits an identification signal SD identifying the model of the motor control device 20 itself to the safety function device 10. The auxiliary control unit 12 of the safety function device 10 further includes a memory unit 122. The memory unit 122 stores interlocking model information indicating the model of the motor control device 20 that can be interlocked with the safety function device 10. The auxiliary control unit 121 transmits a selection signal SA that is set to a Low signal to the motor control device 20 only when the model indicated by the identification signal SD received from the motor control device 20 is included in the models indicated by the interlocking model information. Here, the selection signal SA becomes Low only when the model indicated by the identification signal SD is included in the models indicated by the interlocking model information (i.e., only when the model of the motor control device 20 is a model that can be interlocked with the safety function device 10). Therefore, the selection signal SA is a signal that indicates whether the safety function device 10 and the motor control device 20 can be interlocked. This configuration allows the selection circuit 22 to select the signal SQ only if the motor control device 20 is a model that can be interlocked, making it possible to separate (disable) the receiving circuit 21 (and the delay circuit 25, if provided) from the safety-related parts. Therefore, even if a motor control device that cannot be interlocked is mistakenly connected to the safety function device 10, it will not function properly, preventing unauthorized use. The memory unit 122 in this modified example is an example of a memory means according to the present disclosure.

1 Motor control system 10 Safety function device 11 Receiving circuit 12 Auxiliary control unit 121 Safety function module 122 Memory unit 13 Receiving circuit 20 Motor control device 21 Receiving circuit 22 Selection circuit 23 Control unit 231 Shutdown circuit 232 Processor 233 Drive circuit 24 Current sensor 25 Delay circuit 3 Motor 31 Encoder SR1 First safety request signal SR2 Second safety request signal SR3 Third safety request signal SQ Signal SC Connection signal SA Selection signal SB Shutdown OK/NG signal SI Current signal SE Encoder signal SP Control signal SD Identification signal ID Drive current

Claims (4)

The motor control device controls the motor, and a safety function device is provided.
The safety function device is
a first receiving means for receiving a first safety request signal;
a first transmitting means for transmitting the first safety request signal received by the first receiving means to the motor control device;
Equipped with
The motor control device includes:
a second receiving means for receiving a second safety request signal and receiving the first safety request signal from the safety function device;
a selection means for selecting the first safety request signal when the safety function device is connected to the motor control device, and selecting the second safety request signal when the safety function device is not connected to the motor control device;
a cutoff means for cutting off a current flowing through the motor when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating a stop of the motor;
Equipped with
Motor control system. The motor control device is configured to, when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating the stop of the motor, execute one of stopping the motor by STO (Safe Torque Off) and deceleration control and stopping of the motor by SS1 (Safe Stop 1).
The motor control system of claim 1 . the motor control device further includes a second transmission means for transmitting an identification signal for identifying a model of the motor control device to the safety function device;
The safety function device further includes a storage means for storing linked model information indicating a model of a motor control device that can be linked with the safety function device,
The first receiving means of the safety function device further receives the identification signal from the motor control device;
the first transmitting means of the safety function device transmits a signal indicating that the safety function device and the motor control device can be interlocked to the selecting means of the motor control device when the model indicated in the identification signal received by the first receiving means is included in the models indicated in the interlocking model information, and transmits a signal indicating that the safety function device and the motor control device cannot be interlocked to the selecting means of the motor control device when the model indicated in the identification signal received by the first receiving means is not included in the models indicated in the interlocking model information;
the selection means of the motor control device selects the first safety request signal when receiving a signal indicating that the safety function device and the motor control device can be interlocked, and selects the second safety request signal when receiving a signal indicating that the safety function device and the motor control device cannot be interlocked.
3. The motor control system according to claim 1 or 2. A motor control device that controls a motor,
receiving means for receiving a second safety request signal and a first safety request signal from the safety function device;
a selection means for selecting the first safety request signal when the safety function device is connected to the motor control device, and selecting the second safety request signal when the safety function device is not connected to the motor control device;
a cutoff means for cutting off a current flowing through the motor when the first safety request signal or the second safety request signal selected by the selection means is a signal indicating a stop of the motor;
A motor control device comprising: