JP2002272153A - Motor control device - Google Patents

Abstract

(57) [Problem] To provide a motor control device which is inexpensive and can be used with smaller power supply equipment. In a motor control device that drives a plurality of motors, when a plurality of motors accelerate at the same timing, a motor acceleration or a motor speed is set so that the sum of the motor outputs of the respective axes accelerated at the same timing is less than the power supply power. And a motor output limiting unit that limits at least one of the two.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for supplying power to a plurality of motors from the same power supply.

[0002]

2. Description of the Related Art FIG. 6 is a block diagram showing an example of a conventional motor control device. This motor control device includes a numerical control unit 10, servo control units 20x, 20y, 20 for each axis.
z, AC power supply 30, converter unit 40, motor 5 for each axis
0x, 50y, 50z. The numerical control unit 10 includes a program input unit 11, a program interpretation unit 1,
2. It comprises a maximum speed storage unit 13 for each axis, a maximum acceleration storage unit 14 for each axis, and a function generation unit (A) 15, and the servo control units 20x, 20y, 20z are position / speed control units 21x, 21y. , 21z, inverter control units 22x, 2
2y, 22z. The servo control unit of each axis can independently drive the motor of each axis.

The numerical control unit 10 includes a program input unit 1
The program interpreting unit 12 generates the target position / rotational speed command data MD from the contents of the machining program input to 1. The function generator (A) 15 includes a maximum speed unit amount Nx, Ny, Nz for each axis set in the maximum speed storage unit 13 and an acceleration unit amount Ax, Ax,
Ay, Az and target position / rotational speed command data MD
The speed unit quantities MPx, MPy, MPz of each axis are calculated.
The servo control units 20x, 20y, and 20z calculate the speed unit amount M
A position command value is generated by time-integrating Px, MPy, MPz, and torque command values MTx, MTy, MTz are obtained from position detection values sent from position detectors attached to motors 50x, 50y, 50z of each axis. The motor 50 is generated through the inverter control units 22x, 22y, and 22z.
The motor is driven by supplying it to x, 50y, and 50z. The converter unit 40 converts the three-phase AC power supply 30 into a DC voltage, and controls the inverter control units 22x, 22y, 22z.
To supply. The maximum speed unit amount is a motor speed per unit time, and the acceleration unit amount is a change of the speed unit amount per unit time.

[0004] The following equation 1 represents the motors 50x, 50y, 5 of the x, y, z axes in the motor control device shown in FIG.
It shows the output generated at the time of acceleration when 0z is operated.

[0005]

## EQU1 ## Pn = (2π · Nn / 60) × ｛(2π · Nn
/ 60) × Jn / tn + Dn} where n indicates the axis name. Pn: Output during acceleration of n-axis [W] Nn: Motor speed of n-axis [/ min] Jn: Total inertia of n-axis [Kg · m ＾ 2] tn: Acceleration time of n-axis [sec] Dn: n-axis Friction torque [Nm]

[0006] The motor output when a plurality of axes are simultaneously accelerated is the sum of the electric powers calculated by equation (1).
The output when the y- and z-axis motors are accelerated simultaneously is given by the following equation (2).

[0007]

## EQU2 ## Pa = ΣPn = Px + Py + Pz

FIG. 7 is a diagram showing outputs generated by the motors when three motors are simultaneously accelerated and decelerated.
(A) is a graph showing the speed of the x-axis motor when the x-axis is accelerated / decelerated, and tn (n is the axis name) is the acceleration time of the motor. (B) is a graph showing the output torque of the x-axis motor, and (c) is a graph showing the power of the x-axis motor. (D) is a graph showing the total output of the x, y, and z-axis motors. From this graph, the output generated at the timing of the end of acceleration has the maximum value. The symbols shown in FIG. 7 are as follows. ΣPn (t): Sum of motor outputs of each axis [W] Px (t), Py (t), Pz (t): Motor output of each axis [W] Tx (t), Ty (t), Tz ( t): Motor torque of each axis [N · m] Nx (t), Ny (t), Nz (t): Motor speed of each axis [rad / sec]

[0009]

The above-described conventional motor control device drives the motor at a preset speed and acceleration. Therefore, when a plurality of motors are driven at the same time, it is necessary to supply a large amount of electric power during acceleration. Yes, it is necessary to regenerate a large amount of power to the power source during deceleration. Therefore, the converter unit that supplies power to the conventional motor control device needs to be able to supply the maximum output generated when a plurality of motors are driven at the same time. Equipment that can supply power is required. Therefore, when the number of simultaneously driven axes increases, there is a problem in that the cost must be increased by increasing the maximum power supply capability of the converter unit, the size of the device must be increased, and the capacity of the power supply equipment must be increased. .

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for driving a plurality of motors at the same time according to the power supply capability of a power supply device. Another object of the present invention is to provide a motor control device which limits acceleration and can be used at low cost and with a smaller power supply device.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a motor control device for supplying power to a plurality of motors from the same power supply.
The object of the present invention is to limit at least one of the motor acceleration and the motor speed such that when a plurality of motors accelerate at the same timing, the sum of the motor outputs of the respective axes that accelerate at the same timing is lower than the power supply power. Can be achieved.

In the present invention, the speed and acceleration of the motor are limited according to the sum of the outputs of the motors driven at the same time, so that the power supply device can be easily reduced in size.

[0013]

FIG. 1 is a block diagram showing an example of a motor control device having a motor output restricting unit according to a second aspect of the present invention. The same components as those of the conventional example shown in FIG. The description is omitted. In the motor control device according to the present embodiment, the numerical control unit 10 includes an output restriction execution unit 16, an output restriction condition storage unit 17 that stores conditions for performing output restriction,
A maximum speed storage unit (B) 18 for storing the maximum speed amount used at the time of output restriction and a maximum acceleration storage unit (B) 19 for storing the maximum acceleration amount used at the time of output restriction are newly set.

FIG. 2 shows an example of an operation flowchart of the output restriction execution section 16. Output restriction execution unit 1
6 detects an axis to which a start command has been given at the same time from the contents of the target position / rotational speed command MD given via the program interpretation unit 12 based on the program input to the program input unit 11 (step). S1). For example, when the program of the N101 line is input to the program input unit 11, the axes to which the start command is given at the same time are detected as the x, y, and z axes. Also, N10
When the program of three lines is input, the axes to which the start command is given at the same time are detected as the x and y axes. N100 G01 F100 X500 Y300 N101 G00 X0 Y0 Z0 N102 G01 F100 X400 Z400 N103 G00 X50 Y50 N104 G04 F2 N **: Program row index X **: Target coordinate of X axis Y **: Target coordinate of Y axis Z ***: Target coordinate of Z axis G01 F ***: Cutting feed command at *** mm / min G00: Rapid feed command G04 F ***: Pause command for *** seconds

Further, the output restriction execution section 16 determines whether or not the axes for which simultaneous activation has been detected match the output restriction conditions set in the output restriction condition storage section 17 (step S).
2) If they match, the speed N1n (n
Is supplied to the function generator (A) 15 (step S3), and if the axes for which simultaneous activation has been detected do not match the output restriction condition,
The conventional speed Nn (n is the axis name) and acceleration An (n is the axis name) are supplied to the function generator (A) 15 (step S).
4). In other words, if the output limiting condition is x-axis, y-axis, z-axis
In the case of the axis, the output restriction is executed when the program of the N101 line is input, but the output restriction is not executed when the program of the N103 line is input.

When the output is limited, the sum of the motor output of each axis is
From Equations 1 and 2, Equation 3 below is obtained.

[0017]

P1a = {P1n P1n = (2π · N1n / 60) × ｛(2π · N1n /
60) × Jn / t1n + Dn} where n indicates the axis name. P1a: Sum of motor outputs of each axis when output is restricted [W] P1n: Output during n-axis acceleration when output is restricted N1n: Motor speed of n-axis when output is restricted [/ min] t1n: Output restriction N-axis acceleration time [sec]

From the equation (3), the motor speed N1n at the time of output limitation is obtained.
Is set smaller than the conventional motor speed Nn and the acceleration time t1n when the output is limited is set to be longer than the conventional acceleration time tn, so that the sum of the motor outputs when the output is limited is smaller than the sum of the conventional motor outputs. can do.

FIG. 3 shows the motor output generated during acceleration / deceleration when the three motors are started simultaneously in the motor control device shown in FIG. 1 and the output limit is executed, and the conventional motor shown in FIG. It is the figure which compared the motor output in a control device. (A) is a graph showing the speed of the x-axis motor when the x-axis is accelerated / decelerated, (b) is a graph showing the output torque of the x-axis motor, (c) is a graph showing the power of the x-axis motor, ( d) is a graph showing the total output of the x, y, and z axis motors. The thick line in the figure is the result when the output is limited, and the thin line is the result of the conventional control. From these graphs, the motor output generated when the output restriction is executed is smaller than that of the conventional motor control device, and it can be easily achieved to be equal to or less than the maximum power supply output value Pb. In addition,
The symbols shown in FIG. 3 are as follows. P1a (t): Sum of motor outputs of each axis [W] P1x (t), P1y (t), P1z (t): Motor output of each axis when output is limited [W] T1x (t), T1y (t ), T1z (t): Motor torque of each axis when output is limited [N · m] N1x (t), N1y (t), N1z (t): Motor speed of each axis when output is limited [rad / sec] T1n: acceleration time of the n-axis at the time of output limitation [sec]

FIG. 4 is a block diagram showing an example of a motor control device having a motor output limiting unit according to the third aspect. The same components as those in the conventional example shown in FIG. I do. In the motor control device according to the present embodiment, the numerical control unit 10 includes a function generation unit (B) 60, a maximum output calculation unit 61, an output ratio calculation unit 62, and a maximum speed calculation unit 6.
3. A maximum acceleration calculator 64 is added.

FIG. 5 is a flowchart showing the operation of the numerical controller 10 of the present invention. The function generator (B) 60
Based on the contents of the target position / rotational speed command MD given via the program interpreting unit 12, the axes to which the start command is given at the same time are detected from the program input to the program input unit 11 (step S21). For example, when the program of the N101 line is input to the program input unit 11, the axes to which the start command is given at the same time are detected as the x, y, and z axes. N100 G01 F100 X500 Y300 N101 G00 X0 Y0 Z0 N102 G04 F2 N **: Program row index X **: X-axis target coordinate Y **: Y-axis target coordinate Z **: Z-axis target Coordinates G01 F ***: Cutting feed command at *** mm / min G00: Rapid feed command G04 F ***: Pause command for *** seconds

Further, the function generator (B) 60 outputs the target position / rotational speed command MD and the motor speed and acceleration time of the axis to which the start command is given at the same time from the maximum speed storage unit 13 and the maximum acceleration storage unit 14. To determine. The maximum output calculation unit 61 calculates the maximum output during acceleration of the shaft to which the start command has been given at the same time according to Equation 1 using the total inertia Jn and the friction torque Dn which are the parameters of the shaft given in advance. (Step S22). Further, Pa, which is the sum of the maximum outputs, is calculated according to Equation 2 (Step S23). Using the maximum power supply output value Pb of the power supply device given in advance as a parameter, the output ratio calculation unit 62 calculates the allowable power over ratio V according to the following Expression 4 (Step S24).

[0023]

V = Pb / Pa

It is determined whether the calculated value V is larger or smaller than 1 (step S25).
The value is reset to = 1 (step S26).

Either the maximum speed calculator 63 or the maximum acceleration calculator 64 operates based on the calculation result of the output ratio calculator 62. It is determined whether or not to change the speed (step S2).
7) When changing the speed, the maximum speed calculation unit 63 operates (step S28). The maximum speed calculation unit 63 calculates the following Expression 5 and determines a maximum speed unit amount Nn ′ (n is an axis name) used in the function generation unit (A) 15. However, the acceleration unit amount at this time uses An (n is an axis name) which is a value of the maximum acceleration storage unit 14.

[0026]

Nn ′ = V ＾ 2 × Nn

To change the acceleration, the maximum acceleration calculator 64 operates (step S29). The maximum acceleration calculation unit 64 performs the calculation of the following Expression 6, and a function generation unit (A)
The maximum acceleration unit amount An '(n is the axis name) used in 15
To determine. However, the speed unit quantity at this time uses Nn (n is the axis name) which is the value of the maximum speed storage unit 13.

[0028]

## EQU6 ## An '= V ＾ 2 × An

In the numerical control unit 10, the program input unit 1
The program interpreting unit 12 generates the target position / rotational speed command data MD from the contents of the machining program input to 1. The function generating unit (A) 15 includes Nn ′ (n is an axis name) calculated by the maximum speed calculating unit 63, An ′ (n is an axis name) calculated by the maximum acceleration calculating unit 64, and target position / rotational speed command data. By MD, the speed unit quantity MPx, MPy,
Calculate MPz. Thereby, the motor control device shown in FIG. 4 can change the speed unit amount and the acceleration unit amount so that the total Pa of the motor output becomes the maximum power supply output Pb of the power supply device. can do.

[0030]

As described above, according to the motor control device according to the present invention, when a plurality of motors accelerate at the same timing, the sum of the motor outputs of the respective axes accelerated at the same timing is lower than the power supply power. Therefore, the instantaneous output can be minimized since at least one of the motor acceleration and the motor speed is limited. As a result, the motor control device according to the present invention can be inexpensive and can provide smaller power supply equipment than the conventional motor control device.

[Brief description of the drawings]

FIG. 1 is a block diagram of a motor control device showing an example of an embodiment of the present invention.

FIG. 2 is an example of an operation flowchart of an output restriction execution unit shown in FIG. 1;

FIG. 3 is a diagram illustrating the effect of the present invention.

FIG. 4 is a block diagram of a motor control device showing an example of an embodiment of the present invention.

5 is an example of an operation flowchart of an output restriction execution unit shown in FIG. 4;

FIG. 6 is a block diagram illustrating an example of a conventional motor control device.

FIG. 7 is an explanatory diagram of electric power generated by a motor.

[Explanation of symbols]

 Reference Signs List 10 Numerical control unit 11 Program input unit 12 Program interpretation unit 13 Maximum speed storage unit 14 Maximum acceleration storage unit 15 Function generation unit (A) 16 Output restriction execution unit 17 Output restriction condition storage unit 18 Maximum speed storage unit (B) 19 Maximum Acceleration storage unit (B) 20x X-axis servo control unit 20y Y-axis servo control unit 20z Z-axis servo control unit 21x X-axis position / speed control unit 21y Y-axis position / speed control unit 21z Z-axis position Speed controller 22x Inverter controller 22x for driving X-axis motor 22y Inverter controller for driving Y-axis motor 22z Inverter controller for driving Z-axis motor 30 AC power supply 40 Converter unit 50x X-axis motor 50y Y Axis motor 50z Z-axis motor 60 Function generator (B) 61 Maximum output calculator 62 Output ratio calculator 6 Maximum speed calculator 64 maximum acceleration calculator

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference)

Claims (3)

[Claims] In a motor control device for supplying power to a plurality of motors from the same power supply device, when the plurality of motors accelerate at the same timing, the sum of the motor outputs of the respective axes accelerated at the same timing is lower than the power supply power. And a motor output limiting unit for limiting at least one of the motor acceleration and the motor speed. 2. The motor output limiting section is configured to reduce the motor acceleration or motor speed to a preset motor acceleration or motor speed in accordance with a combination of motors that accelerate at the same timing. The motor control device according to claim 1, wherein: 3. The motor output limiting unit calculates a maximum value Pn (n is an axis name) of a motor output required at the time of acceleration of each axis, and the motor output of each axis accelerated at the same timing. Means for adding the maximum value Pn (Pa = ΣP
n), means for setting the maximum power supply output value Pb of the power supply device, calculating Pb / Pa from the calculated value Pa and the set value Pb, and the acceleration of each axis according to the calculated value of Pb / Pa. 2. The motor control device according to claim 1, further comprising: acceleration changing means for changing a set value or speed changing means for changing the speed of each axis according to the calculated value of Pb / Pa.