Servo control device

Abstract

The present invention provides a servo control device for industrial machinery capable of constructing a system with superior power efficiency compared to the past. The servo control device includes: a drive motor (3) for driving industrial machinery; a load detection unit (5) for detecting the load or power consumption of the drive motor (3); a buffer motor (6) for regenerating power to the drive motor (3) based on the detection result of the load detection unit (5); and a base speed setting unit (12) for regenerating power to the drive motor (3) by decelerating the buffer motor (6) from a pre-set fixed first base speed before regenerating power to the drive motor (3), and then restoring it to a second base speed set lower than the first base speed.

Description

Technical Field

[0001] The present invention relates to a servo control device. Background Art

[0002] As is well known, in the field of mechanical work, CNC (Computerized Numerical Control) technology is applied to numerically control the amount of movement, movement speed, etc. by a computer, thereby highly automating the repetition of the same action, complex actions, etc. In addition, servo motors (electric motors) for driving shafts of industrial machines such as presses, injection molding machines, machine tools, robots, etc. are driven and controlled for the amount of rotation, speed, torque, etc.

[0003] On the other hand, for example, when the load such as the torque of the servo motor suddenly increases during stamping in a press, mold clamping in an injection molding machine, or cutting in a machine tool, the power consumption of the servo motor suddenly rises sharply. The higher the peak power, the higher the contract electricity cost (Japanese: 契約電気料金) needs to be set.

[0004] Therefore, the following control has been performed in the past: for example Figure 4 As shown, power is supplied from a common power source to a plurality of servo amplifiers that separately control the driving servo motors, and at the moment when the power consumption of the driving servo motor suddenly rises sharply, power is supplied (regenerated) from the buffer servo motor, thereby reducing the peak power (eliminating the peak).

[0005] At this time, as Figure 5 shown, the buffer servo motor is attached with inertia and rotates at the same preset base speed (base speed 1) to store electricity. When power regeneration is required, the driving speed of the buffer servo motor is reduced to supply power to the driving servo motor. In addition, it is set that the power regeneration to which servo amplifier is performed is determined by communication between a plurality of driving servo amplifiers, thereby efficiently and effectively reducing the power consumption of the driving servo motor. After reducing the peak power, the driving of the buffer servo motor is accelerated to store electricity and return to the base speed (base speed 1).

[0006] For example, Patent Document 1 discloses "an energy storage device comprising: a flywheel; a generator motor coupled to the flywheel; and an inverter, the AC side of which is connected to the generator motor and the DC side of which is connected to a DC link section. The energy storage device supplies and receives electrical energy from the DC link section by controlling the rotational speed of the flywheel by supplying variable-frequency AC power to the generator motor from the inverter. The inverter is characterized by comprising: a voltage detector for detecting the voltage of the DC link section; a voltage command value setting unit for setting the voltage command value of the DC link section to either a first voltage command value or a second voltage command value based on the detected voltage from the voltage detector and the rotational speed of the flywheel; and a maximum speed setting unit for setting the maximum rotational speed of the flywheel to either a first maximum speed or a second maximum speed based on the detected voltage from the voltage detector and the rotational speed of the flywheel."

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Publication No. 2012-114994 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] As described above, the conventional method is to ensure a predetermined energy value by performing the following control: the buffer servo motor is independent of the operation of the drive servo motor, and after the power storage / power supply operation is completed, the buffer servo motor is restored to a fixed base speed (base speed 1).

[0012] However, the following problems exist when controlling a servo motor for buffering in this way: Figure 5 As shown, the greater the inertia of the buffer servo motor, the more rapidly it needs to accelerate after regenerative control to perform power accumulation control using the buffer servo motor. Due to this power accumulation control, the speed of the buffer servo motor becomes too high, resulting in energy loss and consequently reduced efficiency.

[0013] Solutions for solving problems

[0014] One aspect of the servo control device disclosed herein is a servo control device for controlling an electric motor that drives a shaft of industrial machinery. The servo control device is configured to include: a drive motor for driving the shaft; a load detection unit for detecting the load or power consumption of the drive motor; a buffer motor for regenerating power to the drive motor based on the detection result of the load detection unit; and a base speed setting unit for regenerating power to the drive motor by decelerating from a pre-set fixed first base speed of the buffer motor before regenerating power to the drive motor, and then restoring the drive motor to a second base speed set lower than the first base speed.

[0015] The effects of the invention

[0016] According to one aspect of the servo control device disclosed herein, it is possible to prevent the speed of the buffer motor from excessively increasing during regeneration of the drive motor, thereby suppressing the maximum speed of the buffer motor to a low level. This, for example, can suppress power consumption caused by friction associated with the flywheel.

[0017] Furthermore, since the maximum speed of the buffer motor can be suppressed to a low level, the upper limit of the base speed (first base speed) can be set higher than before. That is, the first base speed can be increased to approximately the rated speed of the buffer motor, thereby increasing the power supplied per unit inertia.

[0018] Furthermore, the sum of the power supplied by the buffer motor to the drive motor and the power stored in the drive motor (the sum of the power supplied / stored by the buffer motor) can be reduced, thereby reducing energy loss.

[0019] Therefore, the servo control device for industrial machinery according to this disclosure can be used to build a system with better power efficiency than before. Attached Figure Description

[0020] Figure 1 This is a diagram illustrating one type of servo control device.

[0021] Figure 2 This is a block diagram illustrating one type of servo control device.

[0022] Figure 3 This diagram illustrates a method for driving and controlling a buffered servo motor using a servo control device.

[0023] Figure 4 This diagram illustrates how regeneration from the buffer servo motor reduces the power consumption of the drive servo motor.

[0024] Figure 5 This diagram illustrates a conventional method for driving and controlling a servo motor used for buffering.

[0025] Explanation of reference numerals in the attached figures

[0026] 1: Servo control device for industrial machinery; 2: CNC (NC); 3: Servo motor (electric motor) for drive; 4: Servo amplifier for drive; 5: Load detection unit; 6: Servo motor (electric motor) for buffer; 7: Servo amplifier for buffer; 8: Common power supply (power supply); 9: Power consumption tolerance setting unit; 10: Power consumption determination unit; 11: Regenerated power distribution unit; 12: Base speed setting unit. Detailed Implementation

[0027] Below, refer to Figures 1 to 3 This will illustrate a servo control device according to one embodiment.

[0028] Here, the servo control device of this embodiment is a servo control device that can reduce the power consumption of the drive servo motor (electric motor) used to drive the shaft of industrial machinery under high loads such as high torque.

[0029] In addition, industrial machinery refers to industrial machinery that generates a sharp increase in load when driven. Representative examples include stamping presses, presses, die-casting machines, injection molding machines, cutting machines, machine tools, and robots. Of course, it can also include conveyors, measuring instruments, testing devices, printing presses, food processing machinery, packaging machines, welding machines, cleaning machines, painting machines, assembly devices, installation machines, woodworking machinery, sealing devices, and other industrial machinery.

[0030] Incidentally, for example, in a stamping press, during the stamping process, the servo motor used for driving is subjected to a sudden load, resulting in a sharp increase in power consumption.

[0031] like Figure 1 and Figure 2As shown, the servo control device 1 for industrial machinery in this embodiment includes: a CNC (NC) 2 serving as an instruction unit; multiple servo motors (electric motors) 3 for driving; multiple servo amplifiers 4 for driving, which control the driving of each servo motor 3 based on instructions from the CNC 2; a load detection unit 5 for detecting the load or power consumption (power consumption and power regeneration) of each servo motor 3; a buffer servo motor (electric motor) 6 for regenerating power for the servo motor 3 based on the detection results of the load detection unit 5; a buffer servo amplifier 7 for controlling the driving of the buffer servo motor 6; and a common power supply (power source) for supplying power to the buffer servo motor 6 and the multiple servo motors 3.

[0032] Furthermore, the servo control device 1 for industrial machinery in this embodiment is configured to include: a power consumption tolerance setting unit 9, which is used to set the tolerance range (consumption-side threshold and regeneration-side threshold) of the power consumption of the drive servo motor 3; a power consumption determination unit 10, which is used to determine whether the power consumption of the drive servo motor 3 is within the tolerance range; a regeneration power distribution unit 11, which is used to distribute the regeneration power generated by the buffer servo motor 6; and a base speed setting unit 12, which is used to... Figure 3 ( Figure 1 , Figure 2 As shown, before regenerating power from the servo motor 3 for driving, the buffer servo motor 6 has a pre-set fixed first base speed. Figure 3 ( Figure 5 After regenerating power to the servo motor 3 by slowing down the base speed 1) in the first base speed, it returns to the second base speed, which was set to be lower than the first base speed. Figure 3 (Base velocity 2).

[0033] The servo motor 3 for driving and the servo motor 6 for buffering are, for example, rotary electric motors. However, the servo motor 3 for driving can also be other electric motors such as linear motors.

[0034] Preferably, the base speed setting unit 12 sets the second base speed to be restored in accordance with the previous power supply and power storage operation of the drive servo motor 3. Furthermore, it is preferable to set the first base speed to a speed slightly lower than the rated speed (approximate rated speed) of the drive servo motor 3.

[0035] In the servo control device 1 of the industrial machinery of this embodiment, configured as described above, commands are sent from the CNC 2 to the drive servo amplifier 4 and the buffer servo amplifier 7, and the servo amplifiers 4 and 7 drive and control the drive servo motor 3 and the buffer servo motor 6. Furthermore, the drive servo amplifier 4, the buffer servo amplifier 7, the drive servo motor 3, and the buffer servo motor 6 are powered by a common power supply 8 for operation.

[0036] The buffer servo motor 6 is given inertia. When the load acting on the drive servo motor 3 is within the allowable range set by the power consumption allowable range setting unit 9, the power consumption determination unit 10 determines the situation and drives the buffer servo motor 6 to rotate at a fixed first base speed (base speed 1) set by the base speed setting unit 12 to accumulate power.

[0037] On the other hand, such as Figure 3 As shown, for example, in the stamping process performed by a stamping press, the load acting on the drive servo motor 3 increases. When the detection result of the load detection unit 5 reaches the power consumption threshold of the drive servo motor 3 set by the power consumption allowable range setting unit 9, the power consumption determination unit 10 determines the situation. The buffer servo amplifier 7, which is communicatively connected to multiple drive servo amplifiers 4, receives the result, performs deceleration control on the buffer servo motor 6, and supplies the stored power to the drive servo motor 3.

[0038] At this time, the power consumption determination unit 10 determines which of the multiple drive servo motors 3 should regenerate power, and to what extent each drive servo motor 3 should regenerate power. Based on its determination result, the power regeneration distribution unit 11 distributes and supplies power to each drive servo motor 3. Thus, power stored by the buffer servo motor 6 is supplied to the drive servo motor 3 that is set to have increased load and whose power consumption has reached the consumption side threshold, so that the power consumption is lower than the consumption side threshold, that is, within the allowable range, thereby reducing peak power (eliminating peaks).

[0039] On the other hand, as the stamping process of the press proceeds, when the load of the drive servo motor 3 decreases and the power consumption is lower than the consumption threshold (when it stabilizes within the allowable range), the buffer servo motor 6 is accelerated and power accumulation begins again.

[0040] When the power storage starts operating again, in the servo control device 1 of the industrial machinery in this embodiment, the base speed setting unit 12 restores the second base speed (base speed 2) which is set to be lower than the first base speed (base speed 1), and drives the buffer servo motor 6 at the lower set second base speed to store power. The first base speed is the speed of the buffer servo motor 6 that was preset before the drive servo motor 3 regenerates power (e.g., the previous time).

[0041] Furthermore, when the load on the drive servo motor 3 further decreases, thereby reducing power consumption and reaching the regeneration threshold, the power consumption determination unit 10 determines this situation. The buffer servo amplifier 7, which is communicatively connected to multiple drive servo amplifiers 4, receives this result and performs acceleration control on the buffer servo motor 6. Additionally, when the regeneration threshold is exceeded (when it stabilizes within an acceptable range), the buffer servo motor 6 is gradually accelerated. This gradual acceleration restores the speed of the buffer servo motor 6 to the first base speed. Therefore, unlike in the past, the speed of the buffer servo motor 6 does not rise sharply during the recovery operation to the first base speed.

[0042] Therefore, in the servo control device 1 for industrial machinery of this embodiment, it is possible to prevent the speed of the buffer servo motor 6 from increasing excessively when the drive servo motor 3 is regenerating, thereby suppressing the maximum speed of the buffer servo motor 6 to a low level. As a result, for example, it is possible to suppress the power consumption generated by the friction of the flywheel.

[0043] Furthermore, in the servo control device 1 for industrial machinery of this embodiment, since the maximum speed of the buffer servo motor 6 can be suppressed to a low level, the base speed upper limit setting (first base speed) can be set higher than before. That is, the first base speed can be increased to approximately the rated speed of the buffer servo motor 6, thereby increasing the power supplied per unit inertia.

[0044] Furthermore, in the servo control device 1 for industrial machinery of this embodiment, the sum of the power supplied by the buffer servo motor 6 to the drive servo motor 3 and the power of the regenerated power of the drive servo motor 3 (the sum of the power supplied / stored by the buffer servo motor 6) can be reduced, and as a result, energy loss can also be reduced.

[0045] Therefore, the servo control device 1 for industrial machinery according to this embodiment can be used to build a system with better power efficiency than before.

[0046] The above describes one embodiment of the servo control device for industrial machinery. However, the present invention is not limited to the above embodiment and can be appropriately modified without departing from its spirit.

Claims

1. A servo control device, comprising: An electric motor for driving industrial machinery; A load detection unit is used to detect the load or power consumption of the drive motor. A buffer motor that regenerates power to the drive motor based on the detection results of the load detection unit; and Base speed setting unit in, When the load acting on the drive motor is within the allowable range set by the power consumption allowable range setting unit, the buffer motor rotates at a fixed first base speed set by the base speed setting unit. When the detection result of the load detection unit reaches the power consumption threshold of the drive motor set by the power consumption tolerance setting unit, the buffer motor is decelerated. When the load of the drive motor decreases and the power consumption is lower than the consumption-side threshold, the buffer motor is accelerated by the base speed setting unit and restored to a second base speed that is lower than the first base speed. When the load on the drive motor further decreases, thereby reducing power consumption and reaching the regeneration threshold, the buffer motor is slowly accelerated, and the speed of the buffer motor is restored to the first base speed.

2. The servo control device according to claim 1, characterized in that, The base speed setting unit sets the second base speed in accordance with the previous power supply and energy storage operation of the drive motor.

3. The servo control device according to claim 1, characterized in that, The first base speed is set to approximately the rated speed of the motor used for buffering.

4. The servo control device according to claim 2, characterized in that, The first base speed is set to approximately the rated speed of the motor used for buffering.

5. The servo control device according to any one of claims 1 to 4, characterized in that, The industrial machinery mentioned is a stamping machine.

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