Engine control unit

Abstract

A technique is provided to reduce the start-up time after a power failure, even if the power failure or similar event occurred while a spindle motor was rotating. A motor control device 1 includes: a speed sensing unit 11, which senses the speed of a spindle motor; an initial speed storage unit 12, which stores an initial speed of the spindle motor immediately after the power supply is switched on; and an initial state determination unit 13, which compares the initial speed of the spindle motor with a zero-speed sensing stage to determine whether the initial state of the spindle motor immediately after the power supply is switched on is a rotating state.a stop determination unit 15, which compares a current rotational speed of the spindle motor with a zero-speed detection stage after the determination result of the initial state determination unit 13 in order to determine a stop of the spindle motor if it is determined that the spindle motor is currently also in the rotating state; and a control stop unit 16, which stops the control of the spindle motor after the determination result of the stop determination unit 15.

Description

Technical field

[0001] The present disclosure relates to an engine control device. Background of the technology

[0002] It is known that if a power outage or similar event occurs while the spindle motor of a machine tool is rotating, the spindle motor continues to rotate due to its inertia and is no longer controlled by the control device. For example, techniques have been disclosed to prevent an excessive rise in DC voltage due to renewable energy in a synchronous motor in such a rotational state (see, for example, patent document 1). Citation list patent document

[0003] Patent document 1: Japanese unexamined patent application, publication no. 2012-249397 Disclosure of the invention

[0004] Problems to be solved by the invention

[0005] In the event of a power outage or similar event during high-speed rotation of the spindle motor, it takes a certain amount of time for the spindle motor to come to a standstill due to its inertia. Even if the motor control device is restarted shortly after power is restored, the spindle motor may still be in rotation. In such a case, it was therefore necessary to wait until the spindle motor came to a standstill on its own before it could be restarted.

[0006] The present disclosure was prepared taking into account the problems described above and aims to provide a technique that can reduce the start-up time after the restoration of the power supply, even in the event of a power failure or similar occurrence while the spindle motor is rotating. Means to solve the problems

[0007] The present disclosure relates to a motor control device configured for controlling a spindle motor of an industrial machine, wherein the motor control device comprises: a speed sensing unit configured for sensing a speed of the spindle motor; an initial speed storage unit configured for storing an initial speed of the spindle motor immediately after being switched on, wherein the initial speed is sensed by the speed sensing unit;an initial state determination unit configured to compare the initial speed of the spindle motor stored in the initial speed storage unit with a defined zero-speed detection stage, which serves as a reference to consider the speed of the spindle motor as zero, thereby determining whether an initial state of the spindle motor immediately after power-up is a rotating state; a stop determination unit configured to compare a current speed of the spindle motor detected by the speed detection unit with the zero-speed detection stage, after a determination result of the initial state determination unit, thereby determining that the spindle motor should be stopped if it is determined that the spindle motor is still in a rotating state;and a control stop unit configured to perform a control stop of the spindle motor after a determination result from the stop determination unit. Effects of the invention

[0008] According to the present disclosure, it is possible to provide a motor control device that is capable of reducing the start-up time after restoration of the power supply, even in the event of a power failure or similar occurrence while the spindle motor is rotating. Brief description of the drawings Fig. 1 is a functional block diagram of an engine control device according to an embodiment of the present disclosure; Fig. 2 is a flowchart illustrating the sequence of control processing by the motor control device according to an embodiment of the present disclosure; Fig. 3 is a flowchart illustrating the process of control stop processing by the engine control device according to an embodiment of the present disclosure; Fig. Figure 4 is a time graph illustrating an example of spindle speed changes for a case where the spindle motor is an induction motor; and Fig. Figure 5 is a time graph that shows an example of changes in spindle speed for the case where the spindle motor is a synchronous motor. Preferred method for carrying out the invention

[0009] In the following, an embodiment of the present disclosure is described in detail with reference to the drawings.

[0010] Fig. Figure 1 is a functional block diagram of a motor control device 1 according to an embodiment of the present disclosure. The motor control device 1 of the present embodiment is a motor control device that is capable of shortening the start-up time after restoration of the power supply by performing a control stop of the spindle motor, even if a power failure or similar event occurs while the spindle motor is rotating.

[0011] The motor control device 1 of the present embodiment controls a spindle motor of an industrial machine (not shown). The industrial machine can be, for example, a machine tool or a robot. An induction motor or a synchronous motor can be used as the spindle motor, i.e., as the main spindle motor of such industrial machines.

[0012] The motor control device 1 of the present embodiment is configured using a computer, which includes, for example, a memory such as ROM (read-only memory) or RAM (working memory), a CPU (central processing unit), and an operating control unit, all of which are interconnected via a bus. The functions and operations of the respective functional units described below are achieved through the interaction between the CPU and the memory built into the computer, as well as a control program stored in that memory. The motor control device 1 may include a numerical control device (CNC: computer numerical controller), a PLC (programmable logic controller), or the like, and may be connected to a higher-level computer that outputs a machining program, machining conditions such as rotational speed, etc.

[0013] As in Fig. As shown in Figure 1, the motor control device 1 comprises as functional units a speed detection unit 11, an initial speed storage unit 12, an initial state determination unit 13, a motor type determination unit 14, a stop determination unit 15, a control stop unit 16 with a shock damping unit 17, a counter-electromotive voltage calculation unit 18 and a counter-electromotive voltage determination unit 19.

[0014] The speed detection unit 11 detects the speed of the spindle motor. In particular, the speed detection unit 11 detects signals from sensors, such as an encoder provided on the spindle motor, and determines the speed (rotational speed) of the spindle motor based on these signals.

[0015] The initial speed storage unit 12 stores the initial speed of the spindle motor immediately after the power supply is switched on, with the speed being detected by the speed sensing unit 11. More precisely, the initial speed storage unit 12 stores as the initial speed the speed of the spindle motor detected by the speed sensing unit 11 immediately after power is supplied to devices such as the numerical control device or the amplifier after a power failure or the like.

[0016] The initial state determination unit 13 compares the initial velocity of the spindle motor stored in the initial velocity storage unit 12 with a zero-speed detection stage and thereby determines whether the initial state of the spindle motor is a rotating state immediately after being switched on. More precisely, if the initial velocity of the spindle motor stored in the initial velocity storage unit 12 is greater than the zero-speed detection stage, the initial state determination unit 13 determines that the initial state of the spindle motor is a rotating state immediately after being switched on.

[0017] The fact that the spindle motor is in a rotating state immediately after being switched on indicates that, due to a power failure or similar event, the spindle motor is rotating under inertia without being controlled by the motor control device 1. The motor control device 1 of the present embodiment controls a control stop unit 16, described below, to execute a control stop of the spindle motor without waiting for such inertial rotation to come to a standstill naturally. It should be noted that such inertial rotation is referred to as a coasting state (freewheeling state) in the case of an induction motor.In contrast to an induction motor, a synchronous motor has a permanent magnet embedded in its rotor. If the motor rotates due to inertia after a power outage or similar event, the synchronous motor acts as a generator, generating a high voltage at the power line terminals. Therefore, a dynamic braking circuit is incorporated as a safety feature in synchronous motors. This circuit slows the motor's rotation by converting rotational energy into heat (joules) through resistive short-circuiting of the power lines, comprising a multitude of windings. When this dynamic braking circuit is activated, the aforementioned rotating state is referred to as dynamic braking operation.

[0018] The zero-speed sensing stage serves as a reference for considering the spindle motor speed as zero and is predefined based on experiments or similar methods. This is because even when the spindle motor has come to a complete standstill, it may still exhibit vibrations or slight rotation due to external disturbances or other influences. Therefore, the speed of the spindle motor in such a completely stopped state is predefined, and the zero-speed sensing stage is set based on this measured speed. By comparing this zero-speed sensing stage with the initial speed, the rotating state of the spindle motor can be determined more accurately.

[0019] The motor type determination unit 14 determines the type of spindle motor. In particular, the motor type determination unit 14 determines whether the spindle motor is an induction motor or a synchronous motor. For example, the motor type determination unit 14 makes the decision as to whether the spindle motor is an induction motor or a synchronous motor based on a machining program, user input, or an external signal.

[0020] The stop determination unit 15 compares the current speed or rotational speed of the spindle motor, as detected by the speed detection unit 11, with the zero-speed detection stage based on the determination result of the initial state determination unit 13, and thereby determines that the spindle motor should be stopped. More precisely, if the current speed of the spindle motor, as detected by the speed detection unit 11, is greater than the zero-speed detection stage, the stop determination unit 15 determines that the spindle motor is still in a rotating state and determines that the spindle motor should be stopped.This configuration makes it possible to avoid a situation in which the control stop unit 16 described later unnecessarily performs a control stop even though the spindle motor is no longer in the rotational state, if the initial state determination unit 13 has previously determined that the spindle motor was in the rotational state immediately after being switched on.

[0021] The control stop unit 16 executes a control stop of the spindle motor according to the determination result of the stop determination unit 15. Specifically, the control stop unit 16 executes a control stop of the spindle motor by stimulating the spindle motor with a speed command value of zero. This causes the spindle motor to immediately switch from a rotating state to a stopped state. The control stop unit 16 includes a shock absorption unit 17, which reduces shocks (excessive loads) generated in the spindle motor during the execution of the control stop. The shock absorption unit 17 will be described in detail later.

[0022] Furthermore, if the motor type determination unit 14 determines that the spindle motor is a synchronous motor, the control stop unit 16 performs a control stop of the spindle motor based on the determination results of both the stop determination unit 15 and a counter-electromotive voltage determination unit 19. The counter-electromotive voltage determination unit 19 will be described later.

[0023] The shock absorption unit 17 reduces the shock (excessive load) exerted on the spindle motor when a control stop is performed. Specifically, the shock absorption unit 17 reduces the shock to the spindle motor by limiting the torque command value for the spindle motor. For example, the shock absorption unit 17 can reduce the shock to the spindle motor by initially setting a small torque command value for the spindle motor and then gradually increasing the torque command value. Alternatively, the shock absorption unit 17 can reduce the shock by decelerating the spindle motor using a time constant based on the current speed of the spindle motor as detected by the speed sensing unit 11.

[0024] The counter-electromotive voltage calculation unit 18 calculates the counter-electromotive voltage of the spindle motor at the current speed or rotational speed based on the current speed of the spindle motor detected by the speed detection unit 11 and the counter-electromotive voltage constant of the spindle motor according to the determination result of the initial state determination unit 13. Here, the counter-electromotive voltage constant of the spindle motor is a value that represents the ratio of the counter-electromotive voltage generated by the speed or rotational speed per unit of rotational speed and is specific to each spindle motor. This counter-electromotive voltage constant is acquired, for example, from a machining program, user input, or an external signal.

[0025] The counter-electromotive voltage determination unit 19 compares the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit 18 at the current speed of the spindle motor with the capacitor voltage rating of the motor drive unit (amplifier) ​​that drives the spindle motor, and thereby determines whether a control stop of the spindle motor is permissible. In particular, if the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit 18 at the current speed of the spindle motor is less than the capacitor voltage rating, the counter-electromotive voltage determination unit 19 determines that a control stop of the spindle motor is permissible.This prevents amplifier failure due to the application of a high voltage exceeding the capacitor's voltage rating, which can occur when the control stop is executed while the spindle motor is still rotating at high speed and the counter-electromotive voltage proportional to the speed exceeds the capacitor's voltage rating.

[0026] Here, the capacitor voltage rating of the motor drive unit (amplifier) ​​is a value specific to each amplifier. This capacitor voltage rating can be determined, for example, from user input or an external signal.

[0027] Next, the control processing performed by the motor control device 1 of the present embodiment, which comprises the functional units described above, will be described with reference to the flowcharts in Fig. 2 and Fig. 3 described in detail. Fig. Figure 2 is a flowchart that represents the control processing operation performed by the motor control device 1 of the present embodiment. Fig. Figure 3 is a flowchart illustrating the control stop processing operation performed by the engine control unit 1 of the present embodiment. The Fig. 2 and Fig. The processing shown in step 3 is initiated and executed in response to the occurrence of a power outage.

[0028] Step S1 determines whether the spindle motor is in a rotating state immediately after being switched on. Specifically, it determines whether the initial speed v0 of the spindle motor is greater than the zero-speed detection stage v. sstIf the condition is YES, it is determined that the initial state of the spindle motor is a rotating state, and processing continues with step S2. If the condition is NO, it is determined that the initial state of the spindle motor is not a rotating state, and control processing is terminated.

[0029] Step S2 determines whether the emergency stop of the spindle motor has been released and whether the industrial machine is ready for operation. Specifically, it determines whether the emergency stop signal of the spindle motor has been switched from OFF to ON by the user pressing the emergency stop cancel button or similar, and whether a machine readiness signal has also been switched from OFF to ON, indicating that the machine is ready for operation. If the result is YES, processing continues with step S3; if NO, the control processing is terminated.

[0030] Step S3 determines whether the spindle motor is an induction motor. If the answer is YES, processing continues with step S5; if NO, processing continues with step S4.

[0031] In step S4, it is determined whether the back electromotive voltage v is smaller than the capacitor voltage rating v. limit Because the spindle motor is a synchronous motor. If the determination is YES, the control stop can be safely executed, as no voltage exceeding the capacitor's voltage rating will be applied to the amplifier, and processing will continue with step S5. If the determination is NO, processing will be terminated, as executing the control stop would result in a high voltage exceeding the capacitor's voltage rating being applied to the amplifier.

[0032] In step S5, it is determined whether the spindle motor is still in a rotating state. Specifically, it is determined whether the current speed or rotational speed v of the spindle motor is greater than the zero-speed detection stage v. sst If the condition is YES, it is determined that the spindle motor is still in the rotating state, and processing continues with step S6 to execute the control stop. If the condition is NO, it is determined that the spindle motor is currently in a stopped state, and processing continues with step S7, terminating the control processing without executing the control stop processing.

[0033] Step S5 determines whether the spindle motor is still in a rotating state. Specifically, it determines whether the current speed or rotational speed v of the spindle motor is greater than the zero-speed detection stage v.sst If the determination is YES, it is determined that the spindle motor is still in a rotating state, and processing continues with step S6 to execute the control stop processing. If the determination is NO, it is determined that the spindle motor is currently in a stopped state, and processing continues with step S7, terminating the control processing without executing the control stop processing.

[0034] As in Fig. As shown in Figure 3, the control stop processing in step S6 is carried out by the procedures in steps S61 to S63.

[0035] In step S61, the speed command is set to zero. This changes the spindle motor from an inertial rotation state to a state controlled by the motor control device 1. Step S62 then proceeds.

[0036] In step S62, a torque limit is set. Specifically, the torque command value for the spindle motor can initially be set to a low value and then gradually increased. Alternatively, the spindle motor can be decelerated from its current speed using a time constant. This reduces the load (excessive load) exerted on the spindle motor. Step S63 is then performed.

[0037] In step S63, the excitation of the spindle motor is switched on. This immediately brings the spindle motor to a controlled standstill. Subsequently, the control stop processing is terminated.

[0038] Next, the change in speed or rotational speed of the spindle motor, which is brought to a standstill by the motor control device 1 of the present embodiment after the occurrence of a power failure or the like, is determined with reference to the timing diagrams of Fig. 4 and Fig. 5 described in detail. Fig. Figure 4 is a time diagram showing an example of the change in spindle speed or rotational speed after a power failure or the like, when the spindle motor is an induction motor. Fig. Figure 5 is a time diagram showing an example of the change in spindle speed or rotational speed after a power failure or the like, when the spindle motor is a synchronous motor.

[0039] First, with reference to Fig. 4 describes an example of the change in spindle speed or rotational speed after a power failure or the like, when the spindle motor is an induction motor (induction spindle motor).

[0040] As indicated by the dashed arrow A in Fig. As indicated by symbol 4, after a power failure or similar event, the spindle emergency stop signal is switched from OFF to ON by the user pressing the emergency stop cancel button, and the machine ready signal is also switched from OFF to ON accordingly. Then, as indicated by the dashed arrow B, the motor control device 1 initiates a controlled stop, and the spindle motor transitions from a freewheeling state to a controlled stop state, resulting in a gradual deceleration of the spindle motor speed under torque limitation. Subsequently, as indicated by the dashed arrow C, when the spindle motor speed reaches the zero-speed detection stage, it is determined that the spindle motor has stopped, and the zero-speed detection signal is switched from OFF to ON.Then, as indicated by the dashed arrow D, the forward rotation command signal and the S command (spindle number command) are switched from OFF to ON, and normal operation is carried out.

[0041] Next, with reference to Fig. 5. An example of the change in spindle speed after the occurrence of a power failure or the like is described in a case where the spindle motor is a synchronous motor (synchronous spindle motor).

[0042] As indicated by the dashed arrow A in Fig.As indicated by indicator 5, after a power failure or similar event, the spindle emergency stop signal is switched from OFF to ON by the user pressing the emergency stop cancel button, and correspondingly, the machine ready signal is switched from OFF to ON. At this point, the back EMF voltage gradually decreases at the current spindle motor speed and eventually reaches the capacitor voltage rating. Then, as indicated by the dashed arrow B, the motor control device 1 initiates a controlled stop, and the spindle motor transitions from dynamic braking to a controlled stop state. Accordingly, the spindle motor speed is gradually reduced under torque limitation.Subsequently, as indicated by the dashed arrow C, when the spindle motor speed reaches the zero-speed detection stage, it is determined that the spindle motor has stopped, and the zero-speed detection signal is switched from OFF to ON. Then, as indicated by the dashed arrow D, the forward rotation command signal and the S command (spindle number command) are switched from OFF to ON, and normal operation commences.

[0043] As described above, the motor control device 1 according to the present embodiment offers the following advantages.

[0044] The present embodiment comprises: the initial velocity storage unit 12, which is configured to store the initial velocity or rotational speed of the spindle motor immediately after power-up, as detected by the velocity detection unit 11; the initial state determination unit 13, which is configured to compare the initial velocity of the spindle motor with a zero-speed detection stage and thereby determine whether the initial state of the spindle motor is a rotating state immediately after power-up; the stop determination unit 15, which is configured to compare the current velocity of the spindle motor with the zero-speed detection stage after the determination result of the initial state determination unit 13 and thereby determine that the spindle motor should be stopped if it is determined that the spindle motor is still in a rotating state;and the control stop unit 16, which is configured to execute a control stop of the spindle motor based on the determination result of the stop determination unit 15. This configuration executes a control stop of the spindle motor without waiting for the inert rotation to cease naturally, even if a power failure or similar event occurs while the spindle motor is rotating, thereby reducing the start-up time after power is restored.

[0045] Furthermore, the present embodiment comprises: the motor type determination unit 14, which is configured to determine the type of spindle motor; the back EMF calculation unit 18, which is configured to calculate the back EMF at the current speed of the spindle motor based on the current speed and the back EMF voltage constant of the spindle motor according to the determination result of the initial state determination unit 13; and the back EMF determination unit 19, which is configured to compare the back EMF voltage at the current speed of the spindle motor with the capacitor voltage rating of the motor drive unit that drives the spindle motor in order to determine whether a control stop of the spindle motor is permissible.If the spindle motor is determined to be a synchronous motor, the control stop unit 16 is configured to execute a control stop of the spindle motor based on the determination results of both the stop determination unit 15 and the back EMF determination unit 19. This configuration prevents amplifier failure due to the application of a high voltage exceeding the capacitor's voltage rating, which could otherwise result from executing a control stop while the spindle motor is still rotating at high speed and the resulting back EMF exceeds the capacitor's voltage rating.

[0046] Furthermore, according to the present embodiment, the control stop unit 16 is configured to perform a control stop of the spindle motor by exciting the spindle motor with a speed command value of zero. In addition, the control stop unit includes the shock damping unit 17, which is configured to reduce the shock to the spindle motor when a control stop is performed by limiting the torque command value for the spindle motor, for example, by initially setting the torque command value to a small value and gradually increasing it, or by decelerating the motor from its current speed using a time constant.This configuration makes it possible to avoid a situation where, after the power supply is restored, when a large delay torque is output while the spindle motor is rotating due to its inertia, the current feedback becomes excessive and causes a shock (excessive load) on the spindle motor.

[0047] The present disclosure has been described in detail; however, it is not limited to the individual embodiments described above. These embodiments may be subjected to various additions, substitutions, modifications, partial deletions, and the like without departing from the spirit of the present disclosure, provided that such changes fall within the scope of the claims or the spirit derived from their equivalents. These embodiments may also be implemented in combination. For example, in the embodiments described above, the sequence of operations or processing steps is merely illustrative and not limiting. The same applies to all numerical values ​​or equations used in the descriptions of the embodiments mentioned above.

[0048] Furthermore, the following additional remarks are disclosed with regard to the above-mentioned embodiments and modifications. [Additional Note 1]

[0049] A motor control device (1) configured to control a spindle motor of an industrial machine, the motor control device comprising: a speed sensing unit (11) configured to detect the speed or rotational speed of the spindle motor; an initial velocity storage unit (12) configured to store an initial velocity of the spindle motor immediately after being switched on, wherein the initial velocity is detected by the velocity sensing unit (11); an initial state determination unit (13) configured to compare the initial speed of the spindle motor stored in the initial speed storage unit (12) with a defined zero speed detection stage, which serves as a reference for considering the speed of the spindle motor as zero, thereby determining whether an initial state of the spindle motor immediately after being switched on is a rotating state; a stop determination unit (15) configured to compare the current speed or rotational speed of the spindle motor detected by the speed detection unit (11) with the zero speed detection stage after a determination result of the initial state determination unit (13), and thereby determine that the spindle motor should be stopped if it is determined that the spindle motor is still in a rotating state; and a control stop unit (16) configured to perform a control stop of the spindle motor after a determination result of the stop determination unit (15). [Additional Note 2]

[0050] The motor control device (1) as described above, wherein the initial state determination unit (13) determines that the initial state of the spindle motor is a rotational state immediately after being switched on, in a case where the initial velocity of the spindle motor stored in the initial velocity storage unit (12) is greater than the standstill detection stage. [Additional Note 3]

[0051] The motor control device (1), as described above, wherein the stop determination unit (15) determines that the spindle motor is still in a rotating state and determines that the spindle motor should be stopped when the current speed or rotational speed of the spindle motor detected by the speed detection unit (11) is greater than the zero speed detection level. [Additional Note 4]

[0052] The motor control device (1), as described above, further comprising: a motor type determination unit (14) configured to determine a type of spindle motor; a counter-electromotive voltage calculation unit (18) configured to calculate a counter-electromotive voltage at the current speed or rotational speed of the spindle motor based on the current speed or rotational speed detected by the speed detection unit (11) and a counter-electromotive voltage constant of the spindle motor according to the determination result of the initial state determination unit (13); and a counter-electromotive voltage determination unit (19) configured to compare the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit (18) at the current speed or rotational speed of the spindle motor with the capacitor voltage rating of a motor drive unit driving the spindle motor, and thereby determine whether a control stop of the spindle motor is permissible, wherein the control stop unit (16) is configured to perform a control stop of the spindle motor according to the determination results of the stop determination unit (15) and the counter-electromotive voltage determination unit (19) when the motor type determination unit (14) determines that the spindle motor is a synchronous motor. [Additional Note 5]

[0053] The motor control device (1) as described above, wherein the counter-electromotive voltage determination unit (19) is configured to determine that a control stop of the spindle motor is permissible when the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit (18) at the current speed or rotational speed of the spindle motor is less than the capacitor voltage rating. [Additional Note 6]

[0054] The motor control device (1) as described above, wherein the control stop unit (16) is configured to perform a control stop of the spindle motor by exciting the spindle motor with a speed command value of zero. [Additional Note 7]

[0055] The motor control device (1) as described above, wherein the control stop unit (16) includes a shock absorption unit (17) configured to reduce shocks to the spindle motor when a control stop of the spindle motor is performed. [Additional Note 8]

[0056] The motor control device (1) as described above, wherein the shock absorption unit (17) is configured to limit a torque command value for the spindle motor. [Additional Note 9]

[0057] The motor control device (1) as described above, wherein the shock absorption unit (17) is configured to gradually increase a torque command value for the spindle motor. [Additional Note 10]

[0058] The motor control device (1) as described above, wherein the shock absorption unit (17) is configured to decelerate the spindle motor based on a time constant from the current speed detected by the speed sensing unit (11). Explanation of reference symbols 1 Engine control unit 11 Speed ​​or velocity detection unit 12 Initial velocity storage unit 13 Initial state determination unit 14 Engine type determination unit 15 Stop determination unit 16 Control stop unit 17 Shock absorption unit 18 Counter-electromotive voltage calculation unit 19 Counter-electromotive voltage determination unit QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2012-249397

[0003]

Claims

[1] A motor control device configured to control a spindle motor of an industrial machine, the motor control device comprising: a speed sensing unit configured to detect the speed or rotational speed of the spindle motor; an initial speed storage unit configured to store an initial speed of the spindle motor immediately after power-on, wherein the initial speed is detected by the speed sensing unit; an initial state determination unit configured to compare the initial speed of the spindle motor stored in the initial speed storage unit with a defined zero speed detection stage, which serves as a reference for considering the speed of the spindle motor as zero, thereby determining whether an initial state of the spindle motor immediately after being switched on is a rotating state; a stop determination unit configured to compare the current speed or rotational speed of the spindle motor, as detected by the speed detection unit, with the zero speed detection stage after a determination result from the initial state determination unit, and thereby determine that the spindle motor should be stopped if it is determined that the spindle motor is still in a rotating state; and a control stop unit configured to perform a control stop of the spindle motor after a determination result of the stop determination unit. [2] The motor control device according to claim 1, wherein the initial state determination unit determines that the initial state of the spindle motor is a rotational state immediately after being switched on, in a case where the initial speed of the spindle motor stored in the initial speed storage unit is greater than the standstill detection stage. [3] The motor control device according to claim 1 or 2, wherein the stop determination unit determines that the spindle motor is still in a rotating state and determines that the spindle motor should be stopped when the current speed or rotational speed of the spindle motor detected by the speed detection unit is greater than the zero speed detection level. [4] The motor control device according to any one of claims 1 to 3, further comprising: a motor type determination unit configured to determine the type of spindle motor; a counter-electromotive voltage calculation unit configured to calculate a counter-electromotive voltage at the current speed or rotational speed of the spindle motor based on the current speed or rotational speed detected by the speed sensing unit and a counter-electromotive voltage constant of the spindle motor according to the determination result of the initial state determination unit; and a counter-electromotive voltage determination unit configured to compare the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit at the current speed or rotational speed of the spindle motor with the capacitor voltage rating of a motor drive unit driving the spindle motor, and thereby determine whether a control stop of the spindle motor is permissible. wherein the control stop unit is configured to perform a control stop of the spindle motor according to the determination results of the stop determination unit and the counter-electromotive voltage determination unit, when the motor type determination unit determines that the spindle motor is a synchronous motor. [5] The motor control device according to claim 4, wherein the counter-electromotive voltage determination unit is configured to determine that a control stop of the spindle motor is permissible if the counter-electromotive voltage calculated by the counter-electromotive voltage calculation unit at the current speed or rotational speed of the spindle motor is less than the capacitor voltage rating. [6] The motor control device according to any one of claims 1 to 5, wherein the control stop unit is configured to perform a control stop of the spindle motor by exciting the spindle motor with a speed command value of zero. [7] The motor control device according to any one of claims 1 to 6, wherein the control stop unit includes a shock absorption unit configured to reduce shocks to the spindle motor when a control stop of the spindle motor is performed. [8] The motor control device according to claim 7, wherein the shock absorption unit is configured to limit a torque command value for the spindle motor. [9] The motor control device according to claim 7, wherein the shock absorption unit is configured to gradually increase a torque command value for the spindle motor. [10] The motor control device according to claim 7, wherein the shock absorption unit is configured to decelerate the spindle motor based on a time constant from the current speed detected by the speed sensing unit.

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