Motor control device and motor control method

Abstract

This motor control device comprises: an abnormality detection unit (30) that detects an abnormality relating to driving of a motor (M); a position control unit (A) that includes a stopping means for stopping the motor (M) by position control; a speed control unit (B, C) that includes a stopping means for stopping the motor (M) by speed control; a dynamic brake circuit (D) that includes a stopping means for stopping the motor (M) by heat consumption; a braking distance calculation unit (31) that calculates braking distances required for stopping the motor (M) by the position control unit (A), the speed control unit (B, C), and the dynamic brake circuit (D), respectively; and a stopping means selection unit (32) that selects the stopping means that obtains the shortest braking distance. When an abnormality is detected by the abnormality detection unit (30), the motor (M) is stopped by the stopping means that obtains the shortest braking distance.

Description

Motor control device and motor control method

[0001] This disclosure relates to a motor control device and a motor control method.

[0002] Conventionally, in motor control devices applied to motor-driven industrial machinery and machine tools, a configuration is known in which the motor is stopped by a predetermined stopping means when some abnormality occurs in the motor's operation. Patent Document 1 discloses a motor control device that stops the motor by using speed control and an electromagnetic brake in combination as stopping means.

[0003] Japanese Patent Publication No. 2007-104869

[0004] However, in conventional configurations, the motor stopping method was uniquely determined according to the type of malfunction. For example, in the case of a malfunction related to position control, stopping control was performed using a position command, and in the case of a malfunction related to hardware, stopping control was performed using a brake circuit. Therefore, depending on the type of malfunction, the braking distance until the motor stops may be longer compared to other stopping methods.

[0005] This disclosure has been made in view of the above-mentioned problems, and aims to provide a motor control device and a motor control method that can automatically select the stopping means that results in the shortest motor braking distance, regardless of the type of abnormality, and perform stopping control.

[0006] One aspect of the present disclosure is a motor control device (1) for controlling a motor (M) that drives a machine tool or industrial machine, comprising: an abnormality detection unit (30) for detecting an abnormality related to the driving of the motor (M); a position control unit (A) including a stopping means for stopping the motor (M) by position control; speed control units (B, C) including a stopping means for stopping the motor (M) by speed control; a dynamic brake circuit (D) including a stopping means for stopping the motor (M) by heat consumption; a braking distance calculation unit (31) for calculating the braking distance required to stop the motor (M) by the position control unit (A), the speed control units (B, C), and the dynamic brake circuit (D), respectively; and a stopping means selection unit (32) for selecting the stopping means that results in the shortest braking distance, wherein when an abnormality is detected by the abnormality detection unit (30), the motor (M) is stopped by the stopping means that results in the shortest braking distance.

[0007] One aspect of the present disclosure is a motor control method for controlling a motor (M) that drives a machine tool or industrial machine, comprising: an abnormality detection means for detecting an abnormality related to the driving of the motor (M); position control means including a stopping means for stopping the motor (M) by position control; speed control means including a stopping means for stopping the motor (M) by speed control; dynamic brake circuit means including a stopping means for stopping the motor (M) by heat consumption; braking distance calculation means for calculating the braking distance required to stop the motor (M) by the position control unit (A), the speed control units (B, C), and the dynamic brake circuit (D), respectively; and stopping means selection means for selecting the stopping means that results in the shortest braking distance, wherein when an abnormality is detected by the abnormality detection unit (30), the motor (M) is stopped by the stopping means that results in the shortest braking distance.

[0008] This is a block diagram showing the configuration of the motor control device according to this embodiment. This is a flowchart showing the procedure for motor stop control 1 according to this embodiment. This is a block diagram showing the configuration of the motor control device when a communication error occurs between the numerical control device and the amplifier. This is a speed-output characteristic graph used to calculate the braking distance by speed control. This is a block diagram showing the configuration of the motor control device according to a modified example of this embodiment. This is a flowchart showing the procedure for motor stop control 2 according to this embodiment. This is a block diagram showing the configuration of the motor control device according to a second modified example of this embodiment. This is a flowchart showing the procedure for motor stop control 3 according to this embodiment. This is a block diagram showing the configuration of the motor control device according to a third modified example of this embodiment. This is a flowchart showing the procedure for motor stop control 4 according to this embodiment.

[0009] An example of an embodiment of the present invention will be described below.

[0010] Figure 1 is a block diagram showing the configuration of the motor control device 1 according to this embodiment. The motor control device 1, which controls a motor M that drives a machine tool or industrial machine, is configured to include a numerical control device 10 and an amplifier 20. The numerical control device 10 has a position control unit A that controls the motor M by position control and a motor control unit 11. The motor control unit 11 has a speed control unit B on the numerical control device side that controls the motor M by speed control.

[0011] The amplifier 20 includes an amplifier control unit 22 that is driven in response to a control signal from the motor control unit 11. The amplifier control unit 22 includes a switching control unit 21 that is driven in response to a control signal from the motor control unit 11 and switches the power element 23 using a PWM signal, and an amplifier-side speed control unit C that controls the motor M by speed control. The motor M is driven by the switching signal output by the power element 23. Furthermore, the amplifier 20 includes a dynamic brake circuit D that enables stopping control of the motor M by dynamic braking.

[0012] The motor control device 1 according to this embodiment is characterized in that, when it detects an abnormality related to the driving of the motor M, it is configured to automatically select the stopping means among a plurality of stopping means that has the shortest braking distance required for stopping, and to execute motor stopping control. In this embodiment, the position control unit A and speed control unit B included in the numerical control device 10, and the speed control unit C and dynamic brake circuit D included in the amplifier control unit 20 each function as stopping means for the motor M.

[0013] More specifically, the position control unit A includes a stopping means for stopping the motor M by position control, the speed control units B and C include a stopping means for stopping the motor M by speed control, and the dynamic brake circuit D includes a stopping means for stopping the motor M by heat consumption.

[0014] When the abnormality detection unit 30 detects an abnormality related to the drive of the motor M, the braking distance calculation unit 31 calculates the braking distance required for each stopping means to stop the motor M with full torque. Then, the stopping means selection unit 32 selects the stopping means that results in the shortest braking distance, and the motor control unit 1 executes motor stopping control using the selected stopping means. The abnormality detection unit 30, the braking distance calculation unit 31, and the stopping means selection unit 32 may be provided in either or both of the numerical control device 10 and the amplifier 20.

[0015] Figure 2 is a flowchart showing the procedure of the motor stop control 1 according to this embodiment. In step S10, the abnormality detection unit 30 determines whether or not an abnormality has been detected in the motor control device 1. If the determination in step S10 is positive, the process proceeds to step S11, where the braking distance calculation unit 31 calculates the braking distance for each of the stopping means.

[0016] In the following step S12, the stopping means selection unit 32 selects the stopping means with the shortest braking distance from among the applicable stopping means, and the process proceeds to step S13. In step S13, the motor control unit 1 executes motor stopping control using the selected stopping means, and the series of controls is completed. If a negative determination is made in step S10, the control is terminated immediately.

[0017] As described above, according to the motor control device 1 of this embodiment, when an abnormality is detected by the abnormality detection unit 30, the motor M is stopped by the stopping means that provides the shortest braking distance. Therefore, when an abnormality occurs, it is always possible to perform stop control using the stopping means that provides the shortest braking distance for the motor. This reduces the probability of secondary damage occurring, such as contact with the machine end or other shafts or tools due to movement until stopping, depending on the shaft position at the time of the abnormality, when the braking distance is longer compared to other stopping means. This contributes to improving the reliability, lifespan, and durability of the machine tool.

[0018] Figure 3 is a block diagram showing the configuration of the motor control device 1 when a communication error occurs between the numerical control device 10 and the amplifier 20. The same reference numerals indicate the same or equivalent parts. In this embodiment, while the numerical control device 10 is operating normally, the speed control unit C and the dynamic brake circuit D included in the amplifier 20 do not operate as stopping means. The stopping means included in the amplifier 20 operate when a communication error occurs between the numerical control device 10 and the amplifier 20, such as a broken communication cable or corruption of communication data. Even in this case, the stopping means that shortens the braking distance of the motor M is selected from among the speed control unit C and the dynamic brake circuit D.

[0019] Here, we will explain how to calculate the braking distance using the dynamic brake circuit D. When decelerating from speed ω0 to ω1 with braking resistance, the time t [sec] required for deceleration is approximately calculated using the following formula: t = Jall / Tf * {((ω0-ω1) + P * ln((ω0-α) / (ω1-α)) + Q * ln((ω0-β) / (ω1-β))}

[0020] Here, Jall: Total inertia at the motor end [kgfcms 2 Let Tf be the mechanical friction torque [kgfcm], angular velocity ω0, ω1 [rad / sec], p be the number of poles of the motor, La be the motor inductance [H], Kv be the motor back electromotive force constant [Vp.sec / rad], Kt be the torque constant [kgf.cm / Ap], and Rall be the total resistance of the motor including winding resistance and brake resistance [Ω]. In this case, the calculation coefficients are defined as follows.

[0021] C = (p 2 *La 2 ) / 4 A = Kv*Kt*Rall / C / Tf B = Rall<00°0004> / C, α = (-A+√(A 2 -4*B)) / 2 β = (-A-√(A 2 -4*B)) / 2 P = -α / (α-β)*A Q = β / (α-β)*A

[0022] And from the obtained t, the moving distance D [rev] when decelerating from ω0 to ω1 is calculated by D = (ω0 + ω1) / 2 * t / 2 / π. This is performed with an appropriate number of divisions from ω0 to stop (ω0, ω1, ω2... ωn-1, ωn, 0).

[0023] Fig. 4 is a speed-output characteristic graph used for calculating the braking distance by speed control. The method for calculating the braking distance by speed control will be described below. When the motor M has a speed-output characteristic as shown in Fig. 4, the time t [sec] required for deceleration by speed control from speed Nm to 0 is calculated in the output change regions (1) to (3) (Jall: total inertia at the motor end [kgfms 2 , Pf, Pm: output [kw], Nb, Nf, Nm: speed [min -1 ).

[0024] Here, the deceleration times t1 to t3 are represented by the following formulas. (1) Deceleration time (t1) in the constant torque region (0 to Nb) t1 = 0.10754 * (Jall * Nb 2 ) / (Pf * 1000) [sec] (2) Deceleration time (t2) in the constant output region (Nb to Nf) t2 = 0.10754 * (Jall * (Nf 2 -Nb 2 )) / (2 * Pf * 1000) [sec] (3) Deceleration time (t3) in the output reduction region (Nf to Nm) t3 = 0.10754 * (Jall * (Nm - Nf)) / ((Pm - Pf) * 1000) * {(Nm - Nf) - (((Pf * Nm) - (Pm * Nf)) / (Pm - Pf)) * ln(Pm / Pf)} [sec]

[0025] Then, using the t values ​​obtained in the regions (1) to (3) corresponding to deceleration, the distance traveled D[rev] when decelerating from N0 to N1 is calculated as D = (N0+N1) / 2*t / 2 / 60. This is done in an appropriate number of divisions from N0 to the stop (N0,N1,N2...Nn-1,Nn,0).

[0026] Figure 5 is a block diagram showing the configuration of a motor control device 1 according to a modified example of this embodiment. The same reference numerals indicate the same or equivalent parts. In this modified example, there is a synchronization control determination means 40 that determines whether or not there is another motor performing synchronization control with the motor M to be stopped.

[0027] Figure 6 is a flowchart showing the procedure for the motor stop control 2 according to this embodiment. In step S20, the abnormality detection unit 30 determines whether or not an abnormality has been detected in the motor control device 1. If the determination in step S20 is positive, the process proceeds to step S21, where the braking distance calculation unit 31 calculates the braking distance for each of the stopping means.

[0028] In the following step S22, the stopping means selection unit 32 selects the stopping means with the shortest braking distance from among the applicable stopping means, and the process proceeds to step S23. In step S23, the synchronization control determination means 40 determines whether the motor M to be stopped is under synchronous control with another motor and whether stopping control by the position control unit A is possible. If the determination in step S23 is positive, the process proceeds to step S25, where the position control unit A is re-selected as the stopping means regardless of the stopping means selected in step S22, and the process proceeds to step S24.

[0029] Then, in step S24, the motor control unit 1 executes motor stop control using the selected stopping means, and the series of controls ends. If a negative determination is made in step S20, the control ends there.

[0030] As described above, according to the motor control device 1 of this modified example, when motor M is performing synchronous control with another motor, motor M is stopped by the position control unit A, which can maintain the synchronous control. For example, by stopping only one of two motors performing synchronous control, twisting of the shaft, etc., can be prevented. This prevents secondary damage such as breakage of the shaft, etc., due to twisting.

[0031] Figure 7 is a block diagram showing the configuration of the motor control device 1 according to a second modified example of this embodiment. The same reference numerals indicate the same or equivalent parts. In this modified example, there is an emergency stop necessity determination means 50 that determines whether or not it is necessary to emergency stop the motor M that is to be stopped when an abnormality is detected.

[0032] Figure 8 is a flowchart showing the procedure of the motor stop control 3 according to this embodiment. In step S30, the abnormality detection unit 30 determines whether or not an abnormality has been detected in the motor control device 1. If the determination in step S30 is positive, the process proceeds to step S31, where the braking distance calculation unit 31 calculates the braking distance for each of the stopping means.

[0033] In the following step S32, the stopping means selection unit 32 selects the stopping means with the shortest braking distance from among the applicable stopping means, and the process proceeds to step S33. In step S33, the emergency stop necessity determination means 50 determines whether or not it is necessary to immediately stop the motor M to be stopped. If the determination in step S33 is positive, that is, if it is determined that the motor M does not need to be stopped immediately because it is a machine configuration in which safety is guaranteed, the process proceeds to step S35, where, regardless of the stopping means selected in step S32, a stopping means that does not consume power through dynamic braking or free running is re-selected, and the process proceeds to step S34.

[0034] Then, in step S34, the motor control unit 1 executes motor stop control using the selected stopping means, and the series of controls ends. If a negative determination is made in step S30, the control ends there.

[0035] As described above, according to the motor control device 1 according to this modification example, when an abnormality is detected by the abnormality detection unit 30 and it is not necessary to immediately stop the motor M, a stop means that does not consume power to stop the motor M is reselected, and the motor M is stopped by the reselected stop means. Therefore, by applying a dynamic brake circuit or a free run that does not consume power, the motor M can be stopped without consuming unnecessary power.

[0036] FIG. 9 is a block diagram showing the configuration of the motor control device 1 according to the third modification example of the present embodiment. The same reference numerals as above indicate the same or equivalent parts. In this modification example, a motor temperature detection unit 60 for detecting the temperature of the motor M is provided.

[0037] Generally, in industrial machines and machine tools, the stop control by the speed control unit has a shorter braking distance than the stop control by the dynamic brake circuit. However, since current flows through the switching element and the motor in the stop control by the speed control unit, there is a possibility that overheating may occur in the motor M due to the temperature rise of these components.

[0038] On the other hand, the dynamic brake circuit can change the distance required for stopping by changing the circuit constants regardless of the acceleration / deceleration specifications of the motor. And since no current flows through the switching element and the motor, overheating does not occur due to the temperature rise of these components.

[0039] FIG. 10 is a flowchart showing the procedure of the motor stop control 4 according to the present embodiment. In step S40, it is determined whether an abnormality of the motor control device 1 is detected by the abnormality detection unit 30. If an affirmative determination is made in step S40, the process proceeds to step S41, and the braking distance calculation unit 31 calculates the braking distance of each stop means.

[0040] In the subsequent step S42, the stop means selection unit 32 selects the stop means with the shortest braking distance among the applicable stop means and proceeds to step S43. In step S43, it is determined whether the temperature detected by the motor temperature detection unit 60 exceeds the threshold value. If an affirmative determination is made in step S43, that is, if it is determined that there is a possibility that the motor M overheats because the motor temperature exceeds the threshold value, the process proceeds to step S45, and regardless of the stop means selected in step S42, a stop means that does not increase the temperature of the motor M by dynamic braking or free run is reselected, and the process proceeds to step S44.

[0041] Then, in step S44, the motor control unit 1 executes motor stop control by the selected stop means and ends a series of controls. If a negative determination is made in step S40, the control is ended as it is.

[0042] As described above, according to the motor control device 1 according to this modification example, when an abnormality is detected by the abnormality detection unit 30, or when the temperature of the motor M exceeds the threshold value after the stop control of the motor M is started, a stop means that does not increase the temperature of the motor M is reselected, and the motor M is stopped by the reselected stop means. Therefore, by applying a dynamic braking circuit or free run that does not increase the temperature of the motor M, it is possible to avoid overheating of the motor M and stop the motor M.

[0043] The motor control device can be composed of a single or a plurality of control units and storage units. Here, the control unit is a processor such as a CPU (Central Processing Unit), and realizes various functions by executing a program stored in the storage unit. The storage unit consists of a ROM (Read Only Memory) that stores an OS (Operating System), application programs, etc., a RAM (Random Access Memory), and a storage device such as a hard disk drive or SSD (Solid State Drive) that stores various other information.

[0044] According to the motor control device described above, a motor control method can be obtained in which the abnormality detection unit 30 is used as an abnormality detection means, the position control unit A is used as a position control means, the speed control units B and C are used as speed control means, the dynamic brake circuit D is used as a dynamic brake circuit means, the braking distance calculation unit 31 is used as a braking distance calculation means, and the stopping means selection unit 32 is used as a stopping means selection means.

[0045] The motor control device and motor control method described above can be implemented by hardware, software, or a combination thereof. Here, implementation by software means that it is implemented by a computer loading and executing a program.

[0046] Programs can be stored and supplied to a computer using various types of non-transitor computer-readable media. Non-transitor computer-readable media include various types of tangible storage media. Examples of non-transitor computer-readable media include magnetic recording media (e.g., hard disk drives), magneto-optical recording media (e.g., magneto-optical disks), CD-ROMs (Read Only Memory), CD-Rs, CD-R / Ws, and semiconductor memory (e.g., mask ROMs, PROMs (Programmable ROMs), EPROMs (Erasable PROMs), flash ROMs, and RAMs (random access memory)).

[0047] Furthermore, while the embodiments described above are preferred embodiments of the present invention, the scope of the present invention is not limited to these embodiments alone. Various modifications can be made to the present invention without departing from its spirit.

[0048] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto.

[0049] The motor control device and motor control method relating to this disclosure can be applied to various machine tools and industrial machinery.

[0050] With respect to the above embodiments and modifications, the following additional notes are disclosed. (Addendum 1) A motor control device (1) for controlling a motor (M) that drives a machine tool or industrial machine, comprising: an abnormality detection unit (30) for detecting an abnormality related to the driving of the motor (M); a position control unit (A) including a stopping means for stopping the motor (M) by position control; speed control units (B, C) including a stopping means for stopping the motor (M) by speed control; a dynamic brake circuit (D) including a stopping means for stopping the motor (M) by heat consumption; a braking distance calculation unit (31) for calculating the braking distance required to stop the motor (M) by the position control unit (A), the speed control units (B, C) and the dynamic brake circuit (D), respectively; and a stopping means selection unit (32) for selecting the stopping means that shortens the braking distance, wherein when an abnormality is detected by the abnormality detection unit (30), the motor control device stops the motor (M) with the stopping means that shortens the braking distance.

[0051] (Note 2) The motor control device according to Note 1, wherein if the motor (M) is being controlled synchronously with another motor, the motor (M) is stopped by the stopping means (A) which can maintain the synchronousness of the synchronous control.

[0052] (Note 3) When an abnormality is detected by the abnormality detection unit (30), if it is not necessary to immediately stop the motor (M), the motor control device according to Note 1 further selects a stopping means that does not consume power to stop the motor (M), and stops the motor (M) with the newly selected stopping means.

[0053] (Note 4) The motor control device according to Note 1, wherein when an abnormality is detected by the abnormality detection unit (30), or when the temperature of the motor (M) exceeds a threshold after the motor (M) stop control has been started, a stop means that does not raise the temperature of the motor (M) is re-selected, and the motor (M) is stopped by the re-selected stop means.

[0054] (Note 5) A motor control method for controlling a motor (M) that drives a machine tool or industrial machine, comprising: an abnormality detection means for detecting an abnormality related to the driving of the motor (M); a position control means including a stopping means for stopping the motor (M) by position control; a speed control means including a stopping means for stopping the motor (M) by speed control; a dynamic brake circuit means including a stopping means for stopping the motor (M) by heat consumption; a braking distance calculation means for calculating the braking distance required to stop the motor (M) by the position control unit (A), the speed control units (B, C), and the dynamic brake circuit (D), respectively; and a stopping means selection means for selecting the stopping means that results in the shortest braking distance, wherein when an abnormality is detected by the abnormality detection unit (30), the motor (M) is stopped by the stopping means that results in the shortest braking distance.

[0055] 1 Motor control device 10 Numerical control device 20 Amplifier 30 Anomaly detection unit 31 Braking distance calculation unit 32 Stopping means selection unit 40 Synchronization control determination means 50 Emergency stop necessity determination means 60 Motor temperature detection unit A Position control unit (stopping means) B Speed ​​control unit on the numerical control device side (stopping means) C Speed ​​control unit on the amplifier side (stopping means) D Dynamic brake circuit (stopping means) M Motor

Claims

1. A motor control device for controlling a motor that drives a machine tool or industrial machine, comprising: an abnormality detection unit for detecting an abnormality related to the drive of the motor; a position control unit including a stopping means for stopping the motor by position control; a speed control unit including a stopping means for stopping the motor by speed control; a dynamic brake circuit including a stopping means for stopping the motor by heat consumption; a braking distance calculation unit for calculating the braking distance required to stop the motor by the position control unit, the speed control unit, and the dynamic brake circuit, respectively; and a stopping means selection unit for selecting the stopping means that results in the shortest braking distance, wherein when an abnormality is detected by the abnormality detection unit, the motor is stopped by the stopping means that results in the shortest braking distance.

2. If the motor is being controlled synchronously with other motors, the motor is stopped by the stopping means capable of maintaining the synchronous control, as described in claim 1.

3. When an abnormality is detected by the abnormality detection unit, if it is not necessary to immediately stop the motor, the motor control device further selects a stopping means that does not consume power to stop the motor, and stops the motor using the re-selected stopping means, as described in claim 1.

4. When an abnormality is detected by the abnormality detection unit, or when the motor temperature exceeds a threshold after the motor stop control has started, the motor control device re-selects a stop means that does not raise the motor temperature, and stops the motor using the re-selected stop means, as described in claim 1.

5. A motor control method for controlling a motor that drives a machine tool or industrial machine, comprising: an abnormality detection means for detecting an abnormality related to the driving of the motor; position control means including a stopping means for stopping the motor by position control; speed control means including a stopping means for stopping the motor by speed control; dynamic brake circuit means including a stopping means for stopping the motor by heat consumption; braking distance calculation means for calculating the braking distance required to stop the motor by the position control unit, the speed control unit, and the dynamic brake circuit, respectively; and a stopping means selection means for selecting the stopping means that results in the shortest braking distance, wherein when an abnormality is detected by the abnormality detection unit, the motor is stopped by the stopping means that results in the shortest braking distance.

Images