Motor control device and motor control method

Abstract

The motor control device includes a motor, a current control unit that controls a drive current supplied to the motor, a function safety unit that is a system independent of the current control unit and outputs an STO signal for cutting off the drive current, and a determination unit that determines whether the drive current is cut off or not. The determination unit receives the STO signal output from the functional safety unit, and determines whether or not a current deviation state is present in which a current difference between a current command value transmitted from the current control unit to the motor and an actual current measurement value of the motor is equal to or greater than a first threshold value. When it is determined that the state is the current divergence state (YES in St101) and the STO signal is received (YES in St102), it is determined that an abnormality related to functional safety has occurred.

Description

Technical Field

[0001] The present disclosure relates to a motor control device and a motor control method. Background Art

[0002] Patent document 1 discloses a motor control device including a current estimating unit for estimating the current of the motor, a current abnormality detecting unit for detecting abnormalities in the current, and a stop processing unit. When the current abnormality is detected by the current abnormality detecting unit, the stop processing unit stops the motor based on the estimated current until the motor stops.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-024295 Summary of the invention

[0006] The present disclosure has been made in view of the above-mentioned conventional situation, and an object of the present disclosure is to identify the cause of an abnormality when the abnormality occurs.

[0007] The present disclosure provides a motor control device, comprising a motor, a current control unit, a functional safety unit and a determination unit, wherein the current control unit controls a driving current supplied to the motor, the functional safety unit is a system independent of the current control unit, and outputs an STO signal for cutting off the driving current, the determination unit receives the STO signal output from the functional safety unit, determines whether a current divergence state is in which a current difference between a current command value sent from the current control unit to the motor and an actual current measurement value of the motor is greater than a first threshold value, and when it is determined to be the current divergence state and the STO signal is received, determines that an abnormality related to functional safety has occurred.

[0008] In addition, the present disclosure provides a motor control method, including: controlling a driving current supplied to a motor; outputting an STO signal for cutting off the driving current supplied to the motor; receiving the STO signal; determining whether a current divergence state is in which a current difference between a current command value sent to the motor and an actual current measured value of the motor is greater than a first threshold value; and when it is determined to be the current divergence state and the STO signal is received, determining that an abnormality related to functional safety has occurred.

[0009] In addition, these general or specific methods may also be implemented by systems, devices, methods, integrated circuits, computer programs or recording media, or by any combination of systems, devices, methods, integrated circuits, computer programs and recording media.

[0010] According to the present disclosure, it is possible to determine the cause of an abnormality when the abnormality occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 : is a system configuration diagram of the motor control system involved in this embodiment.

[0012] Figure 2 This is a block diagram of the motor control CPU.

[0013] Figure 3 It is a diagram for explaining an abnormality of the brake.

[0014] Figure 4 This is a diagram for explaining an abnormality detected by the functional safety unit.

[0015] Figure 5 This is a flowchart of a process for determining the cause of an abnormality. DETAILED DESCRIPTION

[0016] (Process of realizing this embodiment)

[0017] As a method of driving a motor, a control method using a PWM (Pulse Width Modulation) instruction is known, and the PWM instruction is used to drive the motor by feeding back various data such as the position of the motor, the speed of the motor, and the actual value of the current flowing in the motor detected by an encoder installed on the motor. The PWM instruction is sent to a servo amplifier connected to the motor, and the current value flowing in the motor is controlled by switching performed by an inverter in the servo amplifier, thereby driving the motor.

[0018] However, for some reason, the current according to the PWM command may not flow through the motor. In this case, the current command value and the measured current value obtained by feedback diverge (so-called current divergence), which is detected as an abnormality. In addition, various means are known for detecting abnormalities, and it is known that an abnormality can be detected early if an abnormality means based on current control is used. Hereinafter, the state in which the current divergence occurs is referred to as the current divergence state.

[0019] The motor control device disclosed in Patent Document 1 estimates the current value flowing in the motor in advance, and stops the motor using the estimated current value instead of the actual current value when an abnormality occurs. However, although the motor control device disclosed in Patent Document 1 can safely stop the motor when an abnormality is detected, there is a problem that it is difficult to determine the cause of the abnormality.

[0020] Hereinafter, with appropriate reference to the accompanying drawings, the embodiments of the motor control device and the motor control method specifically disclosed in the present disclosure are described in detail. However, detailed descriptions beyond necessity are sometimes omitted. For example, detailed descriptions of matters that are already known and repeated descriptions of substantially the same structures are sometimes omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate understanding by those skilled in the art. In addition, the drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recorded in the claims.

[0021] First, refer to Figure 1 , a system configuration of a motor control system 1 according to the present embodiment will be described. Figure 1 2 is a system configuration diagram of the motor control system 1 .

[0022] The motor control system 1 includes a display device 10 , a control device 30 , a brake BR, a motor MT, and an encoder EN.

[0023] The display device 10 includes a display / operation device 11, a display CPU 12, a first memory 13, and a first communication I / F 14. The display device 10 is, for example, a teaching pendant, a personal computer, or a smartphone.

[0024] The display / operation device 11 is a device that displays a signal received from the display CPU 12. Hereinafter, CPU is an abbreviation of Central Processing Unit. The display / operation device 11 is, for example, a touch panel display. The display / operation device 11 may also receive input from a user (for example, a person who manages a motor) with respect to a displayed screen. In addition, the display / operation device 11 may also be incorporated into the control device 30.

[0025] The display CPU 12 generates a screen to be displayed by the display / operation device 11 based on the signal received from the upper CPU 31. The display CPU 12 is, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), a GPU (Graphical Processing Unit) or an FPGA (Field Programmable Gate Array). The display CPU 12 functions as a controller that manages the overall operation of the display device 10. The display CPU 12 performs overall control processing for the operation of each part of the display device 10, data input and output processing between the various parts of the display device 10, and data storage processing. The display CPU 12 operates according to the program stored in the first memory 13. The display CPU 12 uses the first memory 13 when operating, and temporarily stores the data generated or acquired by the display CPU 12 in the first memory 13.

[0026] The first memory 13 is composed of, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory), and temporarily stores programs required for the operation of the display device 10, and temporarily stores data generated during the operation. The RAM is, for example, a working memory used in the operation of the display device 10. The ROM stores and stores, for example, a program for controlling the display device 10 in advance. The first memory 13 may also temporarily store information received from the display CPU 12 for causing the display / operation device 11 to display a screen.

[0027] The first communication I / F 14 is an interface circuit for wireless or wired communication between the display device 10 and the control device 30. Here, I / F represents an interface. The communication between the display device 10 and the control device 30 may also be via a network. The communication method based on the first communication I / F 14 is, for example, mobile communications such as WAN (Wide Area Network), LAN (Local Area Network), LTE (Long Term Evolution), 5G, power line communication, short-range wireless communication (such as Bluetooth (registered trademark) communication), or communication for portable phones.

[0028] The control device 30 is a device that controls the motor MT and includes a host CPU 31 , a functional safety unit 32 , a motor control CPU 33 , and an amplifier 34 .

[0029] When an abnormality occurs in the motor MT (that is, when a current divergence state occurs), the upper CPU 31 receives information related to the cause of the current divergence state from the functional safety unit 32 or the motor control CPU 33. The upper CPU 31 sends the information related to the cause of the current divergence state in the motor MT to the display device 10. The upper CPU 31 is, for example, a CPU, a DSP, a GPU, or an FPGA. The upper CPU 31 operates according to the program stored in the second memory 35. The upper CPU 31 uses the second memory 35 when operating, and temporarily stores the data generated or acquired by the upper CPU 31 in the second memory 35. The upper CPU 31 outputs data to the display CPU 12 via the second communication I / F 36. The upper CPU 31 is connected to the functional safety unit 32 and the motor control CPU 33 so as to be able to communicate.

[0030] The functional safety unit 32 is a device that forcibly cuts off the current drive of the motor MT differently from the motor control CPU 33. For example, in the case of driving an industrial robot that cooperates with a person by means of the motor MT, the functional safety unit 32 stops the motor MT when the relative position, movement speed, and force output of the industrial robot and the person become inappropriate based on the safety standards of the industrial robot. The functional safety unit 32 monitors the position and speed of the motor MT and stops the supply of current from the amplifier 34 to the motor MT. In addition, the functional safety unit 32 can also accept an input from the outside indicating the stop of the motor MT or an input related to the interlock to stop the motor MT. The functional safety unit 32 is composed of, for example, at least one CPU. The functional safety unit 32 is communicatively connected to the host CPU 31, the amplifier 34, and the encoder EN.

[0031] The motor control CPU 33 drives the motor MT according to the position command of the motor MT from the outside and the feedback of the position of the motor MT. In order to control the rotation of the motor MT, the motor control CPU 33 performs current vector control based on the dq axis coordinate system for the current flowing in the motor MT. The dq axis coordinate system is composed of the d-axis, which is the magnetic flux direction of the permanent magnet held by the rotor (rotator) held by the motor MT, and the q-axis orthogonal to the d-axis. More specifically, for example, the motor control CPU 33 performs current control based on the following current vector control: the current vector control sets the input on the d-axis to the d-axis current value to generate a voltage command for the d-axis (hereinafter referred to as the d-axis voltage command), and sets the input on the q-axis to the q-axis current value to generate a voltage command for the q-axis (hereinafter referred to as the q-axis voltage command). In addition, the rotation control of the motor MT performed by the motor control CPU 33 is not limited to the above-mentioned example, and may also be a current control based on current vector control that sets the input on the d-axis as the d-axis current value and generates a d-axis voltage command, and a voltage control control that sets the input on the q-axis as the rotation speed and generates a q-axis voltage command. The motor control CPU 33 is communicatively connected to the host CPU 31, the functional safety unit 32, the amplifier 34, the second memory 35, the brake BR, and the encoder EN. The motor control CPU 33 outputs the instruction of the current to be supplied to the motor MT using the above-mentioned vector control to the amplifier 34. The detailed internal structure of the motor control CPU 33 is described in detail in the following. Figure 2 In the description.

[0032] The amplifier 34 supplies current to the motor MT based on the current command value from the motor control CPU 33. The amplifier 34 is, for example, a servo amplifier. The amplifier 34 supplies current to the motor MT from a power supply unit 334 (see Figure 2 ) amplifies the current supplied and supplies the amplified current to the motor MT. The amplifier 34 is connected to the functional safety unit 32, the motor control CPU 33 and the motor MT.

[0033] The second memory 35 is composed of, for example, a RAM and a ROM, and temporarily stores a program required for the operation of the control device 30, and temporarily stores data generated during the operation. The RAM is, for example, a working memory used in the operation of the control device 30. The ROM stores and stores, for example, a program for controlling the control device 30 in advance. The second memory 35 may also temporarily store the current command value calculated by the motor control CPU 33 and sent to the amplifier 34, and the information on the cause of the current deviation state output by the motor control CPU 33 to the upper CPU 31.

[0034] The second communication I / F 36 is an interface circuit for wireless or wired communication between the display device 10 and the control device 30. The communication between the display device 10 and the control device 30 may also be via a network. The communication method based on the second communication I / F 36 is, for example, mobile communication such as WAN, LAN, LTE, and 5G, power line communication, short-range wireless communication (such as Bluetooth (registered trademark) communication), or communication for a mobile phone.

[0035] The brake BR applies a brake to stop the rotational motion of the motor MT based on a control signal received from the motor control CPU 33. The brake BR has, for example, a friction brake member, and stops the rotational motion of the motor MT by pressing the friction brake member against the rotor of the motor MT. In addition, the method by which the brake BR applies a brake to the motor MT is not limited to the above example.

[0036] The motor MT is a brushless motor such as a permanent magnet synchronous motor (PMSM), and has a rotor (rotator) that can rotate around an axis and holds a permanent magnet (not shown), and a stator (stator) that includes three-phase coils formed by windings corresponding to the three phases wound around a stator core. The rotor is arranged to rotate freely in a manner opposite to the stator. For the motor MT, an amplifier 34 supplies AC power with phases 120 degrees different from each other to each winding (coil) of the U phase, V phase, and W phase, thereby rotating the rotor of the motor MT around the axis. Figure 2 Detailed Description of the Invention In the embodiment of the present invention, a configuration example is given in which the motor MT is driven by three-phase AC power, namely, a U-phase, a V-phase, and a W-phase.

[0037] The encoder EN is mounted on the motor MT. The encoder EN outputs a signal corresponding to the rotational position of the rotor (not shown) of the motor MT to the functional safety unit 32 and the motor control CPU 33. In this way, the encoder EN detects the rotational position of the rotor of the motor MT as an electrical angle. In addition, in the case where the rotational position or rotational speed of the rotor can be detected by estimation, the structure of the encoder EN can also be omitted. In addition, instead of the encoder EN, a Hall element capable of detecting the rotational position of the motor MT can be arranged near the rotor. In this case, a signal representing the position information detected by the Hall element is input as a feedback signal to the functional safety unit 32 and the motor control CPU 33, respectively.

[0038] Next, refer to Figure 2 , the block diagram of the motor control CPU is explained. Figure 2 This is a block diagram of the motor control CPU.

[0039] The motor control CPU 33 includes a brake control unit 331 , a position control unit 332 , a speed control unit 333 , a power supply unit 334 , a current control unit 335 , a processing unit 336 , and an abnormality detection unit 337 .

[0040] The brake control unit 331 controls the switching between on and off of the brake BR. The brake control unit 331 includes a control CPU 3311 (see Figure 3 ) and relay 3312 (refer to Figure 3 ). The brake control unit 331 outputs a signal to the brake BR to apply the brake (that is, to turn on the brake) or release the brake (that is, to turn off the brake) to the motor MT. The brake control unit 331 outputs information about the signal currently being output to the brake BR to the abnormality detection unit 337. The signal currently being output to the brake BR is a signal to turn on the brake BR or a signal to turn off the brake BR. In addition, when an abnormality is detected in the brake control unit 331, the brake control unit 331 outputs a signal indicating that an abnormality has occurred to the abnormality detection unit 337. Regarding the abnormality occurring in the brake control unit 331, Figure 3 In the description.

[0041] The position control unit 332 calculates a speed-related command value (hereinafter referred to as a speed command value) ω* based on at least an external command value (hereinafter referred to as a position command value) θ* related to the position of the motor MT and a feedback signal (hereinafter referred to as a position FB) θ of the position of the motor MT from the processing unit 336. The position control unit 332 outputs the calculated speed command value ω* to the speed control unit 333. FB is an abbreviation for Feedback.

[0042] The speed control unit 333 calculates a current command value (hereinafter referred to as a q-axis current command value) Iq* as a target value of the current for the q-axis and a current command value (hereinafter referred to as a d-axis current command value) Id* as a target value of the current for the d-axis based on the speed command value ω* received from the position control unit 332 and a feedback signal (hereinafter referred to as a speed FB) ω of the speed of the motor MT from the processing unit 336. The speed control unit 333 outputs the calculated d-axis current command value Id* to the first PI control unit 3351. The speed control unit 333 outputs the calculated q-axis current command value Iq* to the second PI control unit 3352.

[0043] The current control unit 335 performs a 2-phase to 3-phase conversion process, which converts the voltage instructions for the d-axis, which is the excitation direction of the motor MT, and the q-axis, which is the direction orthogonal to the d-axis (the q-axis voltage instruction value Vd* and the d-axis voltage instruction value Vq* described later) into 3-phase voltage instructions (PWM instructions) provided to the U phase, V phase, and W phase of the motor MT. The current control unit 335 includes a first PI control unit 3351, a second PI control unit 3352, a PWM instruction generation unit 3353, and a dq conversion unit 3354.

[0044] The first PI control unit 3351 generates a d-axis voltage command value Vd* so that the error of the difference between the value of the d-axis current command value Id* from the speed control unit 333 and the d-axis current Id from the dq conversion unit 3354 becomes zero. The d-axis voltage command value Vd* is a target value for the voltage of the d-axis. The d-axis current Id will be described later. For example, the first PI control unit 3351 performs a proportional integration process on the difference between the value of the d-axis current command value Id* and the value of the d-axis current Id, and uses the result of the proportional integration as the d-axis voltage command value Vd*.

[0045] The second PI control unit 3352 generates a q-axis voltage command value Vq* so that the error of the difference between the value of the q-axis current command value Iq* from the speed control unit 333 and the q-axis current Iq from the dq conversion unit 3354 becomes zero. The q-axis voltage command value Vq* is a target value for the voltage of the q-axis. The q-axis current Iq will be described later. For example, the second PI control unit 3352 performs a proportional integration process on the difference between the value of the q-axis current command value Iq* and the value of the q-axis current Iq, and uses the result of the proportional integration as the q-axis voltage command value Vq*.

[0046] The PWM command generation unit 3353 calculates the voltage commands U1, U2, V1, V2, W1, and W2 of the PWM command corresponding to the drive voltage supplied to each phase of the motor MT based on the d-axis voltage command value Vd* from the first PI control unit 3351, the q-axis voltage command value Vq* from the second PI control unit 3352, and the electrical angle of the rotor (not shown) detected by the encoder EN, and outputs them to the amplifier 34. Here, the voltage commands U1 and U2 correspond to the positive voltage Vp and the negative voltage Vn supplied from the power supply unit 334 to the amplifier 34, respectively, and are voltage commands supplied to the U phase. The voltage commands V1 and V2 correspond to the positive voltage Vp and the negative voltage Vn supplied from the power supply unit 334 to the amplifier 34, respectively, and are voltage commands supplied to the V phase. The voltage commands W1 and W2 correspond to the positive voltage Vp and the negative voltage Vn supplied from the power supply unit 334 to the amplifier 34, respectively, and are voltage commands supplied to the W phase.

[0047] The dq conversion unit 3354 calculates the d-axis current Id and the q-axis current Iq as the detection currents of the d-axis and q-axis based on the U-phase current Iu detected by the first current detection unit DT (not shown in the figure), the V-phase current Iv detected by the second current detection unit DT2 (not shown in the figure), and the electrical angle of the rotor (not shown in the figure) detected by the encoder EN. The U-phase current Iu is the feedback of the current value flowing in the U-phase. The V-phase current Iv is the feedback of the current value flowing in the V-phase. The d-axis current Id is input to the first PI control unit 3351 as the feedback of the d-axis current. The q-axis current Iq is input to the second PI control unit 3352 as the feedback of the q-axis current.

[0048] The power supply unit 334 supplies an AC power supply voltage Ed to the amplifier 34. The power supply unit 334 connects an AC power supply 3341, a diode 3342, a capacitor 3343, and a detection unit 3344 in parallel, and supplies a positive AC voltage Vp and a negative AC voltage Vn to the amplifier 34. The detection unit 3344, which is an example of a power supply voltage acquisition unit, detects the power supply voltage Ed and outputs it to the abnormality detection unit 337.

[0049] Processing unit 336 outputs the electrical angle (that is, position FBθ) detected by encoder EN to position control unit 332. Processing unit 336 calculates speed FBω as the rotation speed of the rotor of motor MT from the amount of change per unit time of position FBθ from encoder EN, and outputs it to speed control unit 333.

[0050] The abnormality detection unit 337, as an example of a determination unit, monitors the actual current measurement value and the current command value actually flowing in the motor MT, and in the case where there is a deviation between the actual current measurement value and the current command value, it is inferred that some abnormality has occurred as a current deviation state. The abnormality detection unit 337 calculates the difference Δiq between the q-axis current Iq from the dq conversion unit 3354 and the q-axis current command value Iq* from the speed control unit 333. The abnormality detection unit 337 receives a signal currently being output to the brake BR or a signal related to an abnormality occurring in the brake control unit 331 from the brake control unit 331. The abnormality detection unit 337 receives the position FBθ and the speed FBω from the processing unit 336. The abnormality detection unit 337 receives the power supply voltage Ed from the detection unit 3344. The abnormality detection unit 337 receives the STO signal from the functional safety unit 32. STO is the abbreviation of Safe Torque Off. The STO signal is a signal that the functional safety unit 32 stops the motor MT when a certain abnormality is detected.

[0051] The amplifier 34 converts the positive AC voltage Vp and the negative AC voltage Vn supplied from the power supply unit 334 into U-phase current Iu, V-phase current Iv and W-phase current Iw based on the voltage commands U1, U2, V1, V2, W1 and W2 received from the PWM command generating unit 3353 and supplies them to the motor MT.

[0052] Next, refer to Figure 3 , indicating an abnormality in the brake BR. Figure 3 It is a diagram for explaining an abnormality of the brake BR.

[0053] The brake control unit 331 includes a control CPU 3311 and a relay 3312. The control CPU 3311 outputs a signal to the relay 3312 to turn the brake BR on or off.

[0054] The relay 3312 switches the circuit on and off based on a signal from the control CPU 3311. The relay 3312 is, for example, a mechanical relay as a contact relay or a MOS FET (Metal Oxide Semiconductor Field Effect Transistor) relay as a contactless relay. In addition, the relay 3312 is not limited to the above examples. If the relay 3312 is turned on, the brake BR is turned on, and if the relay 3312 is turned off, the brake BR is turned off.

[0055] As a case considered as an abnormality of the brake BR, an abnormality occurring in the brake control unit 331 and an abnormality in which the brake BR itself is damaged are listed.

[0056] The abnormality occurring in the brake control unit 331 is described. The control CPU 3311 determines whether the signal sent from the control CPU 3311 to the relay 3312 is consistent with the relay feedback signal indicating the state of the relay from the relay 3312 to the control CPU 3311. When a signal to turn on the brake BR is sent to the relay 3312 and a feedback signal indicating that the relay 3312 is turned off is received from the relay 3312, the relay 3312 fails to turn on according to the control signal, and the control CPU 3311 detects a malfunction of the circuit of the relay 3312 or an incorrect wiring.

[0057] Furthermore, when a signal to turn off brake BR is sent to relay 3312 and a feedback signal indicating that relay 3312 is turned on is received from relay 3312, relay 3312 fails to turn off according to the control signal, and control CPU 3311 detects that the contact of relay 3312 is fused.

[0058] When the control CPU 3311 detects an abnormality in the brake control unit 331, it outputs a signal related to the content of the abnormality to the abnormality detection unit 337. In addition, the control CPU 3311 may also output a signal output to the relay 3312 and a feedback signal from the relay 3312 to the abnormality detection unit 337 (see Figure 2 ). In this case, the abnormality detection unit 337 determines the cause of the current divergence state based on the signal received from the control CPU 3311.

[0059] Next, the abnormality of the brake BR itself being damaged is described. Examples of the abnormality of the brake BR itself include the following: the friction brake member pressed against the rotor of the motor MT is worn, so that the rotation of the motor MT cannot be stopped, the friction brake member is damaged, or the friction brake member cannot be properly separated from the rotor, so that the brake cannot be released.

[0060] The abnormality detection unit 337 receives a signal output for the current brake BR from the brake control unit 331, and receives the position FBθ from the processing unit 336. The abnormality detection unit 337 determines whether there is an abnormality in the brake BR based on the signal from the brake control unit 331 and the position FBθ. When the signal received from the brake control unit 331 is a signal to turn on the brake BR and it is determined from the position FBθ that the motor MT is not stopped, the abnormality detection unit 337 determines that there is an abnormality in the brake BR.

[0061] Hereinafter, an abnormality related to the brake BR will be referred to as a brake abnormality.

[0062] Next, refer to Figure 4 , indicating an abnormality detected by the functional safety department. Figure 4 This is a diagram for explaining an abnormality detected by the functional safety unit.

[0063] The functional safety unit 32 includes two CPUs (a first CPU 321 and a second CPU 322 ). The number of CPUs included in the functional safety unit 32 is not limited to two, and may be three or more.

[0064] The first CPU 321 and the second CPU 322 receive the position FBθ from the encoder EN as encoder data. The first CPU 321 and the second CPU 322 detect an abnormality when the position of the motor MT calculated based on the position FBθ exceeds a given set area. The first CPU 321 and the second CPU 322 detect an abnormality when the speed of the motor MT calculated based on the position FBθ exceeds an abnormal value (referred to as an abnormal speed). The abnormal speed is a predetermined threshold. The functional safety unit 32 outputs an STO signal to the abnormality detection unit 337 indicating that the position or speed of the motor MT is abnormal.

[0065] In addition, the first CPU 321 and the second CPU 322 determine whether the STO signal output to the amplifier 34 is consistent with the feedback signal (hereinafter referred to as the STO signal FB) obtained from the amplifier 34 and indicating the supply state of the current to the motor MT based on the STO signal. When the first CPU 321 and the second CPU 322 determine that the STO signal is inconsistent with the STO signal FB, they detect an abnormality as the amplifier 34 does not stop supplying current to the motor MT based on the STO signal. In other words, the first CPU 321 and the second CPU 322 detect that there is an abnormality in the amplifier 34. The functional safety unit 32 outputs the STO signal indicating that there is an abnormality in the amplifier 34 to the abnormality detection unit 337.

[0066] In addition, the first CPU 321 and the second CPU 322 monitor each other's status at a given time interval (for example, once every 10 seconds, etc.) to monitor whether an abnormality (fault) occurs in the CPU. For example, the first CPU 321 and the second CPU 322 monitor whether the other CPU cannot operate or cannot perform the processing to be executed. When the first CPU 321 or the second CPU 322 detects that an abnormality has occurred in the other CPU, it outputs an STO signal to the abnormality detection unit 337 to indicate that an abnormality has occurred in the first CPU 321 or the second CPU 322.

[0067] In addition, when the first CPU 321 and the second CPU 322 receive an input indicating an emergency stop or an input indicating an interlock from the outside, they monitor each other's status and determine whether the status of the received signals is consistent. When the first CPU 321 and the second CPU 322 determine that the status of the signals received from the outside is inconsistent, they output an STO signal indicating that an abnormality has occurred in the CPU to the abnormality detection unit 337.

[0068] When the functional safety unit 32 detects an abnormality, it outputs an STO signal to the amplifier 34 to stop the supply of current from the amplifier 34 to the motor MT. In addition, when the abnormality detection unit 337 receives the STO signal from the functional safety unit 32, it outputs a signal to turn on the brake BR to the brake control unit 331, thereby mechanically stopping the motor MT by the brake BR. The control device 30 stops the supply of current to the motor MT and further mechanically stops the motor MT by using the brake BR, thereby being able to safely and reliably stop the motor MT when the functional safety unit 32 detects an abnormality.

[0069] Hereinafter, the abnormality detected by the functional safety unit 32 is referred to as an STO abnormality.

[0070] Next, refer to Figure 5, the process of determining the cause of the abnormality is explained. Figure 5 This is a flowchart of a process for determining the cause of an abnormality. Figure 5 Each process of the flowchart is executed by the abnormality detection unit 337.

[0071] The abnormality detection unit 337 calculates the difference Δiq between the q-axis current Iq from the dq conversion unit 3354 and the q-axis current command value Iq* from the speed control unit 333 (step St100). Here, Δiq represents the difference between the current actually flowing in the motor MT and the command value, and the larger the absolute value of Δiq is, the more it indicates that there is a current divergence between the current actually flowing in the motor MT and the command value. In other words, the larger the absolute value of Δiq is, the more it indicates that the current is not flowing in the motor MT as instructed, and the motor MT is in a current divergence state. In addition, the value of Δiq can also be either positive or negative. For example, when Δiq is a positive value, it indicates that only a current smaller than the command value is flowing in the motor MT. In addition, when Δiq is a negative value, it indicates that a current larger than the command value is flowing in the motor MT.

[0072] The abnormality detection unit 337 determines whether the absolute value of Δiq is equal to or greater than a first threshold value ALM1 (step St101 ).

[0073] When determining that the absolute value of Δiq is smaller than the first threshold value ALM1 (step St101 , No), the abnormality detection unit 337 considers that no abnormality has occurred and ends the process.

[0074] When the abnormality detection unit 337 determines that the absolute value of Δiq is greater than or equal to the first threshold value ALM1 (that is, current divergence has occurred) (step St101, Yes), it determines whether the output of the STO signal of the functional safety unit 32 is turned off (step St102). The abnormality detection unit 337 determines whether the STO signal of the functional safety unit 32 is turned off, for example, based on whether the STO signal is received from the functional safety unit 32.

[0075] When the abnormality detection unit 337 determines that the output of the STO signal of the functional safety unit 32 is not turned off (that is, the STO signal is received from the functional safety unit 32) (step St102, yes), it detects an STO abnormality (step St103). The abnormality detection unit 337 performs the process of step St113 after the process of step St103.

[0076] When determining that the output of the STO signal of the functional safety unit 32 is off (that is, the STO signal is not received from the functional safety unit 32 ) (step St102 , No), the abnormality detection unit 337 determines whether the brake BR is normal (step St104 ).

[0077] When the abnormality detection unit 337 determines that the brake BR is abnormal (that is, an abnormality has occurred in the brake BR) (step St104 , No), the abnormality detection unit 337 detects a brake abnormality (step St105 ). After the process of step St105 , the abnormality detection unit 337 executes the process of step St113 .

[0078] When determining that the brake BR is normal (step St104 , Yes), the abnormality detection unit 337 acquires the power supply voltage Ed from the detection unit 3344 (step St106 ).

[0079] The abnormality detection unit 337 determines whether the power supply voltage Ed is an appropriate value relative to the second threshold value ALM2 (step St107). For example, when Δiq is a positive value in the process of step St100, only a current smaller than the command value flows through the motor MT, so the abnormality detection unit 337 determines whether the power supply voltage Ed is greater than the second threshold value ALM2 in the process of step St107. On the other hand, when Δiq is a negative value in the process of step St100, a current larger than the command value flows through the motor MT, so the abnormality detection unit 337 determines whether the power supply voltage Ed is less than the second threshold value ALM2 in the process of step St107.

[0080] When the abnormality detection unit 337 determines that the power supply voltage Ed is not an appropriate value relative to the second threshold value ALM2 (step St107, No), it detects that there is an abnormality in the power supply voltage Ed (step St108). The abnormality of the power supply voltage Ed specifically refers to damage of the detection unit 3344 for detecting the power supply voltage Ed or an abnormality of the power supply unit 334. After the processing of step St108, the abnormality detection unit 337 performs the processing of step St113.

[0081] When the abnormality detection unit 337 determines that the power supply voltage Ed is an appropriate value relative to the second threshold value ALM2 (step St107, yes), the abnormality detection unit 337 obtains the speed FBω from the processing unit 336. In addition, the abnormality detection unit 337 may obtain the position FBθ from the processing unit 336 to calculate the speed FBω. The abnormality detection unit 337 obtains the speed command value ω* from the speed control unit 333. The abnormality detection unit 337 calculates Δω obtained by subtracting the speed FBω from the speed command value ω* (step St109). In addition, Δω may be either positive or negative. When Δω is positive, it indicates that the rotation speed of the motor MT is slower than the command value. When Δω is negative, it indicates that the rotation speed of the motor MT is faster than the command value.

[0082] The abnormality detection unit 337 determines whether the absolute value of Δω is greater than or equal to the third threshold value ALM3 (step St110). When the abnormality detection unit 337 determines that the absolute value of Δω is greater than or equal to the third threshold value ALM3 (step St110, yes), it detects that there is an abnormality in the power line that supplies power to the motor MT (step St111). In other words, the abnormality detection unit 337 infers that there is an abnormality in the power line and that the current cannot be supplied to the motor MT according to the current command value. After the process of step St111, the abnormality detection unit 337 performs the process of step St113.

[0083] When the abnormality detection unit 337 determines that the absolute value of Δω is less than the third threshold value ALM3 (step St110, No), it detects that an overload is applied to the motor MT (step St112). The overload on the motor MT is, for example, a case where a load is applied to the motor MT due to a collision between a machine driven by the motor MT and another machine, a weight being applied, or a locking of the movement by another device. When a load is applied to the motor MT, a current exceeding the current command value may flow through the motor MT.

[0084] After the processing of steps St103, St105, St108, St111, and St112, the abnormality detection unit 337 stops the motor MT as abnormality processing (step St113). As abnormality processing, the abnormality detection unit 337 sends a signal to the amplifier 34 to stop the supply of current to the motor MT. In addition, the abnormality detection unit 337 sends a signal to the brake control unit 331 to open the brake BR. As a result, the abnormality detection unit 337 stops the supply of current to the motor MT and mechanically stops the motor MT using the brake BR.

[0085] After the processing of step St113, the abnormality detection unit 337 outputs the type of abnormality that occurred to the upper CPU 31. For example, when the abnormality detection unit 337 detects an STO abnormality in the processing of step St103, it outputs a signal indicating that an STO abnormality has been detected to the upper CPU 31. In addition, the abnormality detection unit 337 also outputs the content of the detected abnormality to the upper CPU 31 (step St114) for the processing of steps St105, St108, St111, and St112. The upper CPU 31 outputs the content of the abnormality received from the abnormality detection unit 337 to the display device 10 and causes the display / operation device 11 to display it. Thus, the control device 30 can notify the user of the cause of the abnormality that occurred when an abnormality occurs and the motor MT stops. Thus, the control device 30 can assist the user in the operation of eliminating the abnormality that has occurred.

[0086] As described above, when the control device 30 detects the current divergence state, it is possible to quickly and safely stop the motor MT, determine the cause of the current divergence state, and notify the user.

[0087] In addition, the order of determining the cause of the current divergence state is not limited to Figure 5 For example, the abnormality detection unit 337 may first determine the cause of the high possibility of the current divergence state. For example, since the possibility of the abnormality related to the functional safety unit 32 is high, the abnormality detection unit 337 determines from the STO abnormality.

[0088] (Summary of this embodiment)

[0089] Based on the above description of the present embodiment, the following technology is disclosed.

[0090] <Technology 1>

[0091] The motor control device (for example, the control device 30) according to the present embodiment includes a motor (for example, the motor MT), a current control unit (for example, the current control unit 335) for controlling the drive current supplied to the motor, a functional safety unit (for example, the functional safety unit 32) which is a system independent of the current control unit and outputs an STO signal for cutting off the drive current supplied to the motor, and a determination unit (for example, the abnormality detection unit 337) for receiving the STO signal output from the functional safety unit. The determination unit determines whether a current divergence state is in which a current difference between a current command value sent from the current control unit to the motor and a current actual measurement value of the motor is greater than a first threshold value, and when it is determined that the current divergence state is in place and the STO signal is received, it is determined that an abnormality related to functional safety has occurred.

[0092] Thus, the motor control device according to the present embodiment can detect the current divergence state based on the difference between the current command value for the motor and the measured current value, and can determine the cause of the current divergence state based on the reception of the STO signal from the functional safety unit. The motor control device can assist the user in the operation to eliminate the current divergence state by determining the cause of the current divergence state. Thus, when the current divergence state occurs, the motor control device can quickly eliminate the cause and recover.

[0093] <Technology 2>

[0094] In the motor control device described in Technology 1, the functional safety unit obtains the position data of the motor from the encoder installed on the motor, determines whether the position represented by the position data is in an abnormal position state outside a given area, and sends an STO signal to the determination unit if it is determined to be an abnormal position state.

[0095] Thus, the motor control device according to the present embodiment can determine, when detecting the current divergence state, that the current divergence state is caused by an abnormality in the position of the motor.

[0096] <Technology 3>

[0097] In the motor control device described in technology 1 or 2, the functional safety unit obtains the speed data of the motor from the encoder installed on the motor, determines whether the speed represented by the speed data is an abnormal speed state above the abnormal speed, and sends an STO signal to the determination unit when it is determined to be an abnormal speed state.

[0098] Thus, the motor control device according to the present embodiment can determine that the current divergence state is caused by an abnormality in the motor speed when the current divergence state is detected. Thus, for example, the motor control device can notify the user that there is a high possibility that there is an abnormality in the current supply from the amplifier that controls the motor speed because an abnormality is detected in the motor speed.

[0099] <Technique 4>

[0100] In the motor control device described in any one of technologies 1 to 3, the functional safety unit outputs an STO signal to an amplifier that supplies a drive current to the motor, obtains an STO feedback signal from the amplifier, and the STO feedback signal indicates the supply status of the drive current to the motor based on the STO signal. It is determined whether the amplifier is in an abnormal state in which the STO signal and the STO feedback signal are inconsistent. If it is determined that the amplifier is in an abnormal state, the STO signal is sent to the determination unit.

[0101] Thus, the motor control device according to the present embodiment can determine that there is an abnormality in the amplifier when the current divergence state is detected. Thus, the motor control device can notify the user of the abnormality in the amplifier and assist in recovering from the current divergence state as quickly as possible.

[0102] <Technique 5>

[0103] In the motor control device described in any one of technologies 1 to 4, the functional safety unit has a first processor and a second processor that output an STO signal, and the first processor and the second processor monitor each other's processing actions and send the STO signal to the determination unit when the processing actions are inconsistent.

[0104] Thus, the motor control device according to the present embodiment can determine that the cause of the current divergence state is due to an abnormality of the CPU in the functional safety unit. Thus, the motor control device can assist the user in quickly resolving the current divergence state by replacing the CPU, etc., by notifying the user of the abnormality of the CPU in the functional safety unit.

[0105] <Technique 6>

[0106] In the motor control device according to any one of techniques 1 to 5, the functional safety unit transmits the STO signal to the determination unit when the first signal input to the first processor and the second signal input to the second processor do not match.

[0107] Thus, the motor control device according to the present embodiment can determine that the cause of the current divergence state is due to an abnormality in the CPU in the functional safety unit.

[0108] <Technique 7>

[0109] In the motor control device described in any one of technologies 1 to 6, there is also: a brake (for example, brake BR) that limits the drive of the motor; and a brake control unit (for example, brake control unit 331) that supplies a brake signal for operating the brake to the brake and outputs a brake status signal indicating the presence or absence of the brake signal. When it is determined to be a current divergence state and the brake status signal is received, it is determined that an abnormality related to the brake has occurred.

[0110] Thus, when the motor control device according to the present embodiment detects the current divergence state, it is possible to determine that the current divergence state is caused by an abnormality related to the brake by receiving a signal from the brake.

[0111] <Technology 8>

[0112] In the motor control device described in any one of technologies 1 to 7, the brake control unit has a relay for controlling the opening and closing of the operation of the brake, outputs a relay control signal to the relay to set the brake to on or off, obtains a relay feedback signal indicating the state of the relay from the relay, and when the state of the relay indicated by the relay control signal is inconsistent with the state of the relay indicated by the relay feedback signal, it is determined that an abnormality related to the brake has occurred.

[0113] Thus, the motor control device of the present embodiment can identify, when the current divergence state is detected, that the cause of the current divergence state is an abnormality in the relay included in the brake control unit.

[0114] <Technique 9>

[0115] In the motor control device described in any one of technologies 1 to 8, there is also a power supply voltage acquisition unit for acquiring the value of the power supply voltage, and the determination unit determines that an abnormality related to the power supply voltage has occurred when it is determined that a current divergence state is present and that the value of the power supply voltage acquired by the power supply voltage acquisition unit is greater than a second threshold value.

[0116] Thus, the motor control device of the present embodiment can determine that the cause of the current divergence state is due to a failure in the power supply voltage.

[0117] <Technique 10>

[0118] In the motor control device according to any one of techniques 1 to 9, the determination unit causes a display device (eg, the display / operation device 11 ) to display information indicating that an abnormality related to functional safety has occurred.

[0119] Thus, the motor control device of this embodiment can notify the user of the determined cause of the current divergence state by displaying the cause on the display device. Thus, the motor control device can assist the user in eliminating the current divergence state and quickly restore the motor.

[0120] <Technology 11>

[0121] In the motor control device according to any one of techniques 1 to 10, the determination unit determines the cause of the current divergence state from the cause that is most likely to be the cause of the current divergence state.

[0122] Thus, the motor control device according to the present embodiment can efficiently identify the cause of the current divergence state by making a determination starting from the cause with a high probability of occurrence.

[0123] The above embodiments are described with reference to the accompanying drawings, but the present disclosure is not limited to the above examples. It should be understood that those skilled in the art can obviously think of various changes, modifications, substitutions, additions, deletions, and equivalents within the scope of the claims, which also belong to the technical scope of the present disclosure. In addition, the various constituent elements in the above embodiments can be arbitrarily combined within the scope of the main purpose of the invention.

[0124] Industrial Applicability

[0125] The technology disclosed in the present invention is useful as a motor control device and a motor control method for identifying the cause of abnormality when the abnormality occurs.

[0126] Description of Reference Numerals

[0127] 1 Motor control system

[0128] 10 Display device

[0129] 11 Display / operating equipment

[0130] 12 Display CPU

[0131] 13 1st memory

[0132] 35 2nd Memory

[0133] 14 1st communication I / F

[0134] 36 2nd communication I / F

[0135] 30 Control device

[0136] 31 Host CPU

[0137] 32 Functional Safety Department

[0138] 33 Motor control CPU

[0139] 34 Amplifier

[0140] 321 No.1CPU

[0141] 322 2nd CPU

[0142] 331 Brake control unit

[0143] 332 Position Control Unit

[0144] 333 Speed ​​Control Unit

[0145] 334 Power Supply

[0146] 335 Current Control Unit

[0147] 336 Processing Department

[0148] 337 Abnormality Detection Department

[0149] 3311 Control CPU

[0150] 3312 Relay

[0151] 3341 AC Power Supply

[0152] 3342 Diode

[0153] 3343 Capacitor

[0154] 3344 Testing Department

[0155] 3351 No.1 PI Control Department

[0156] 3352 2nd PI Control Unit

[0157] 3353 PWM command generation unit

[0158] 3354 dq conversion unit

[0159] DT1 1st current detection unit

[0160] DT2 Second current detection unit

[0161] MT Motor

[0162] BR Brake

[0163] EN encoder.

Claims

1. A motor control device comprising a motor, a current control unit, a functional safety unit and a determination unit, The current control unit controls the driving current supplied to the motor. The functional safety unit is a system independent of the current control unit, and outputs an STO signal for cutting off the drive current. The determination unit performs the following processing: receiving the STO signal output from the functional safety unit, determining whether a current difference between a current command value sent from the current control unit to the motor and an actual current measurement value of the motor is equal to or greater than a first threshold value in a current divergence state; When it is determined that the current divergence state is present and the STO signal is received, it is determined that an abnormality related to functional safety has occurred.

2. The motor control device according to claim 1, wherein: The functional safety unit performs the following processing: acquiring position data of the motor from an encoder mounted on the motor, and determining whether the position indicated by the position data is in an abnormal position state outside a given area, When it is determined that the abnormal position state is present, the STO signal is transmitted to the determination unit.

3. The motor control device according to claim 1, wherein: The functional safety unit performs the following processing: acquiring speed data of the motor from an encoder mounted on the motor, and determining whether the speed indicated by the speed data is an abnormal speed state exceeding the abnormal speed; When it is determined that the abnormal speed state occurs, the STO signal is sent to the determination unit.

4. The motor control device according to claim 1, wherein: The functional safety unit performs the following processing: outputting the STO signal to an amplifier that supplies the drive current to the motor, acquiring an STO feedback signal from the amplifier, the STO feedback signal indicating a supply state of the drive current to the motor based on the STO signal, Determine whether the amplifier is in an abnormal state in which the STO signal is inconsistent with the STO feedback signal, When it is determined that the amplifier is in an abnormal state, the STO signal is sent to the determination unit.

5. The motor control device according to claim 1, wherein: The functional safety unit includes a first processor and a second processor that output the STO signal. The first processor and the second processor monitor each other's processing operations, and transmit the STO signal to the determination unit when the processing operations do not match.

6. The motor control device according to claim 5, wherein: The functional safety unit transmits the STO signal to the determination unit when the first signal input to the first processor and the second signal input to the second processor do not match.

7. The motor control device according to claim 1, wherein: The motor control device further includes a brake and a brake control unit. The brake limits the driving of the motor, The brake control unit supplies a brake signal for operating the brake to the brake, and outputs a brake state signal indicating the presence or absence of the brake signal. The determination unit determines that an abnormality related to the brake has occurred when it is determined that the current divergence state is in place and the STO signal is not received but the brake state signal is received.

8. The motor control device according to claim 7, wherein: The brake control unit includes a relay, The relay controls the opening and closing of the operation of the brake. The brake control unit outputs a relay control signal to the relay to turn the brake on or off. acquiring a relay feedback signal representing a state of the relay from the relay, When the state of the relay indicated by the relay control signal and the state of the relay indicated by the relay feedback signal do not match, it is determined that an abnormality related to the brake has occurred.

9. The motor control device according to claim 1, wherein: The motor control device further includes a power supply voltage acquisition unit. The power supply voltage acquisition unit acquires the value of the power supply voltage. The determination unit determines that an abnormality related to the power supply voltage has occurred when it is determined that the current divergence state is present and the STO signal is not received and when it is determined that the value of the power supply voltage acquired by the power supply voltage acquisition unit is equal to or greater than a second threshold.

10. The motor control device according to claim 1, wherein: The determination unit causes a display device to display information indicating that an abnormality related to the functional safety has occurred.

11. The motor control device according to claim 1, wherein: The determination unit determines the cause of the current divergence state from a cause that is highly likely to be the cause of the current divergence state.

12. A motor control method, comprising: controlling the drive current supplied to the motor; outputting an STO signal for cutting off the drive current supplied to the motor; Receiving the STO signal; determining whether a current divergence state is in which a current difference between a current command value sent to the motor and an actual current measurement value of the motor is greater than a first threshold value; When it is determined that the current divergence state is present and the STO signal is received, it is determined that an abnormality related to functional safety has occurred.

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