JP2004088882A - Controller for main spindle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To use maximum torque with positional loop control contained in a controller and to prevent the occurrence of overshoot as much as possible, in the controller for a main spindle motor. <P>SOLUTION: This controller for the main spindle motor, structured so as to perform position/speed control for the main spindle motor by containing the positional loop control, speed loop control, and current loop control, controls a positional deviation amount so as to make a speed command relative to a target speed meet the target speed or a feedback speed when the feedback speed reaches a level within a prescribed speed range after acceleration or deceleration. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a spindle motor control device configured to execute position / speed control of a spindle motor by combining position loop control, speed loop control, and current loop control.
[0002]
[Problems to be solved by the invention]
Since the spindle motor greatly reduces the torque in the high-speed range, the two-stage acceleration / deceleration control at the time of the spindle rotation command is executed to control the spindle motor to approach the maximum torque of the spindle motor. FIG. 22 shows an acceleration pattern of this control (a characteristic diagram showing a time change of the spindle speed), and FIG. 23 shows a torque-rotation speed characteristic (a characteristic diagram showing a relationship between the torque and the spindle speed). In the case of the above control, as can be seen from FIG. 23, there is a region where the maximum torque is not yet used (unused region).
[0003]
Therefore, if the time constant 1 and the time constant 2 are shortened in order to shorten the response, that is, the time required for acceleration and deceleration, the area where the required torque is larger than the actual maximum torque increases, so that the actual speed with respect to the command is increased. Delay increases. For this reason, the overshoot amount at which the actual speed exceeds the command speed increases (compared to the overshoot amount shown in FIG. 22), and as a result, the main shaft may be damaged. The overshoot is a phenomenon that occurs when a delay with respect to a command is increased in a case where the position loop control is performed, after the command reaches a steady speed, the delay is recovered. In this case, if the position loop control is not set, this phenomenon does not occur. However, since the spindle needs to be positioned at the orient position at the time of tool change, it is necessary to always set the position loop control.
[0004]
A control method that gives an acceleration / deceleration pattern in accordance with the maximum torque characteristic of the spindle motor is also conceivable. However, in this control method, the maximum torque of the spindle motor decreases when the power supply voltage decreases. In order not to cause the generation, it is necessary to adjust the MIN value of the guaranteed power supply voltage. For this reason, when the power supply voltage is high, an unused area of torque is generated as in the conventional configuration.
[0005]
The present invention has been made in view of the above circumstances, and an object of the present invention is to configure the position loop control, to use the maximum torque, and to minimize the occurrence of overshoot. An object of the present invention is to provide a control device for a spindle motor.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, when the feedback speed with respect to the target speed reaches within a predetermined speed range after acceleration or deceleration, the position deviation amount is operated so that the speed command matches the target speed or the feedback speed. Therefore, even if the configuration is such that the position loop control is configured and the maximum torque is used up, occurrence of overshoot can be prevented as much as possible.
In the case of the above configuration, the position deviation operation amount when the position deviation amount is operated may be stored, and at the time of an orientation command, the command value may be corrected based on the position deviation operation amount.
[0007]
In the case of deceleration, stop, and orientation, when the feedback speed reaches the set speed, the position deviation amount is adjusted so that the speed command does not exceed the feedback speed and approaches the feedback speed. It is preferable to configure so as to perform integer multiplication and subtraction.
[0008]
Furthermore, when adding or subtracting the position deviation amount, the position loop gain may be set to a low value, and thereafter, the position loop gain may be gradually increased.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 is a block diagram illustrating an electrical configuration of a control device 1 for a spindle motor according to the present embodiment. As shown in FIG. 1, a control device 1 for a spindle motor includes a numerical control unit (NC) 2 and a servo amplifier 3.
[0010]
The numerical control section 2 includes a motion command section 4, a deviation operation control section 5, an adder 6, and a position loop gain Kp. The motion command unit 4 is configured to, for example, interpret a machining program to generate a position command Pcom, and send the position command Pcom to the adder 6 and the deviation operation control unit 5. The adder 6 has a function of calculating a position deviation e between the position command Pcom and the actual position, that is, the position feedback Pfb output from the encoder 8 of the spindle motor 7. By multiplying the position deviation e by the position loop gain Kp, a speed command Ncom is calculated, and the speed command Ncom is given to the servo amplifier 3.
[0011]
The deviation operation control unit 5 receives the position command Pcom from the motion command unit 4 and the position feedback Pfb from the encoder 8, and changes (operates) the position deviation e and the position loop gain Kp as described later. Has a function. The deviation operation control unit 5 is configured to obtain speed feedback information by differentiating the input information of the position feedback Pfb.
[0012]
Further, the servo amplifier 3 is configured to control the current of the spindle motor 7 so that the spindle motor 7 operates according to the speed command Ncom from the numerical controller 2. In this case, in the adder 9 of the servo amplifier 3, a speed deviation Ve between the speed command Ncom and the actual speed, that is, the speed feedback Nfb obtained by differentiating the position feedback Pfb from the encoder 8 by the differentiating circuit 10. Is calculated.
[0013]
Then, the current command (proportionality) Ip obtained by multiplying the speed deviation Ve by the speed loop proportional gain Kvp and the speed command Ve are integrated by the integration circuit 11, and the integration result is multiplied by the speed loop integration gain Kvi. The current command (integral) Ii thus obtained is added by the adder 12 to calculate the current command Icom. According to the current command Icom, the main shaft motor 7 is controlled to be energized by the current limiter 13 and the current controller 14. The current limiting unit 13 has a function of limiting the current to a maximum current determined by the spindle motor 7 and the current control unit 14 when an excessive current command is generated. In this case, a certain maximum torque is generated. Due to this characteristic, even when a time constant equal to or greater than the maximum torque of the servo amplifier 3 is set, acceleration and deceleration are performed according to the maximum torque curve.
[0014]
Next, the control contents of the deviation operation control unit 5 will be described with reference to the flowcharts of FIGS. First, the content of the control for operating the position deviation when the spindle motor 7 is accelerated (when accelerating to the target speed) will be described with reference to the flowchart of FIG. In this case, during the acceleration of the spindle motor 7, when the difference between the rotation command (speed command) value of the spindle and the actual speed (feedback speed) becomes smaller than the allowable speed difference (predetermined speed), the position deviation is theoretically calculated. It is configured to execute an operation for replacing with a deviation.
[0015]
Specifically, first, in step S1 of FIG. 2, it is determined whether or not there is a rotation command (speed command) of the main shaft. If there is a spindle rotation command, the process proceeds to "YES" in step S1, and the spindle steady-state deviation correction effective SW is turned on (step S2). If there is no main shaft rotation command, the process proceeds to “NO” in step S1 and returns to the process in step S1. Subsequently, the process proceeds to step S3, where it is determined whether or not the acceleration command for the spindle has been completed. Here, if the spindle acceleration command has been completed, the process proceeds to "YES", and it is determined whether the spindle steady-state deviation correction effective SW is on (step S4).
[0016]
Then, the process proceeds to step S5, and it is determined whether or not the absolute value of the difference between the rotation command (speed command) value of the main shaft and the actual speed (feedback speed) is smaller than a predetermined allowable speed difference 1. In this case, when the absolute value of the difference is smaller than the permissible speed difference 1, the process proceeds to "YES" and proceeds to step S6 to turn off the main shaft steady-state deviation correction effective SW. Subsequently, the theoretical deviation e is calculated by the following equation.
[0017]
e = command rotation speed N [rpm] × encoder resolution [pulse / rev]
X Position loop gain Kp [rad / sec] / 60 [sec / min]
Then, the rotational position deviation Pe amount is calculated by the following equation.
[0018]
Pe = Remainder ((current deviation-theoretical deviation) / encoder resolution)
Further, it is configured to execute a process of replacing the spindle position deviation with the theoretical deviation e calculated above.
Subsequently, the process proceeds to step S7, where a speed command given to the servo amplifier 3 of the spindle motor 7 is calculated. Further, the process proceeds to step S8, and the calculated speed command of the spindle motor 7 is transmitted to the servo amplifier 3. Thereafter, the process returns to step S1, and the above-described processing is repeatedly executed.
[0019]
Further, in each of the determination steps S3 and S5, if "NO" in each case, the process proceeds to step S7. If it is determined as "NO" in step S4, the acceleration deviation process is terminated.
[0020]
In this embodiment having such a configuration, FIGS. 4 and 5 show the results obtained by measuring the speed change during acceleration and the used torque by an experiment (simulation) when a time constant exceeding the maximum torque is given. In FIG. 4, a line P1 is a time derivative of a position command, a line P2 is a feedback speed Nfb, a line P3 is a speed command Ncom, a line P4 is a position deviation e, and a line P5 is a current command Icom. In FIG. 5, a line P6 represents the required torque calculated backward from the position command, a line P7 represents the actual use torque, and a line P8 represents the servo maximum torque.
[0021]
According to FIGS. 4 and 5, when the feedback speed falls within a predetermined allowable speed error 1 (for example, 0 in this embodiment) with respect to the target speed, the position deviation is forcibly set to the theoretical position. By substituting the deviation, it can be seen that the speed command matches the target speed, so that overshoot does not occur and the time required for rising is shorter (earlier).
[0022]
In the present embodiment, it is preferable to comprehend (store) one rotation deviation from the operation amount at the time of the deviation operation, and correct the deviation during the deceleration orientation. In the above embodiment, the allowable speed error 1 was set to 0. Instead, the allowable speed error 1 was set to a value other than 0, the deviation operation was performed at an early timing, and the speed command was set to the current feedback. The deviation operation may be configured to be equal to the speed. With this configuration, the response of the current command accumulated in the integral term of the speed loop becomes slow, which is effective for preventing overshoot in the speed loop.
[0023]
Here, FIG. 6 and FIG. 7 show the results obtained by measuring the speed change and the used torque at the time of acceleration in the case of controlling by the conventional technique (see FIG. 22 and FIG. 23) by experiment (simulation). The lines P1 to P8 in FIGS. 6 and 7 are the same as the lines P1 to P8 in FIGS. According to FIGS. 6 and 7, since a time constant that does not exceed the maximum torque is given as much as possible in order to prevent overshoot from occurring, it can be understood that a considerable time is required for the rise. .
[0024]
In such a conventional control, the speed change and the used torque during acceleration when a time constant exceeding the maximum torque (the same time constant as in FIGS. 4 and 5 of the present embodiment) is given are experimentally (simulated). 8) and 9) show the results of the measurement. The lines P1 to P8 in FIGS. 8 and 9 are the same as the lines P1 to P8 in FIGS. According to FIGS. 8 and 9, even when the feedback speed reaches the target speed, a large overshoot occurs to recover the position loop delay.
[0025]
Next, a description will be given of the content of the control for operating the position deviation when the spindle motor 7 is decelerated and stopped (when the orientation motor is stopped). First, the position loop gain Kp when the spindle motor 7 is decelerated and stopped will be considered.
[0026]
In order to perform the orientation of the spindle motor 7 in a short time, it is effective to increase the position loop gain Kp. In this embodiment, the position loop gain Kp is also operated when the position deviation amount is operated immediately before the stop of the spindle motor 7 (specifically, when the speed command approaches the feedback speed). When the position loop gain Kp is high and the position loop gain Kp is high, overshoot occurs. Hereinafter, the operation in this case will be described theoretically.
[0027]
Maximum inertia Jmax [kgm ² ], When the guaranteed value of the instantaneous torque that can be output (low speed range) is Tmax [Nm], the deceleration that can be output α [rad / s] ² ] Is as follows.
[0028]
α [rad / s ² ] = Tmax [Nm] / Jmax [kgm ² ] (1)
Assuming that the resolution of the encoder 8 is RESO [pulse / rev], the deceleration αp [pulse / s] obtained by unit-converting the above equation (1) from the rad system to the pulse system ² ] Is as follows.
[0029]
αp [pulse / s ² ] = Α [rad / s ² ] × RESO [pulse / rev] / (2π [rad / rev]) = RESO × Tmax / (2π · Jmax) (2)
Therefore, when an attempt is made to decelerate to a stop with the maximum torque, the vehicle decelerates at a gradient determined by the equation (2) (it is impossible to decelerate at a gradient greater than this). Now, it is assumed that the number of rotations (rotation speed) when the position deviation is operated during deceleration is set to Nx [pulse / s], and the speed command is made equal to Nx by the position deviation operation. In this case, the time required from the time of the operation to the stop when the deceleration stop is performed by continuously outputting the maximum torque is αp / Nx at the shortest.
[0030]
The area of the triangle shown in FIG. 10 is the total feedback pulse ΔP [pulse] from the deviation operation to the stop when decelerating and stopping at the maximum torque, and is represented by the following equation.
[0031]
ΣP [pulse] = 1/2 · Nx · Nx / αp
= Nx ² / (2 · αp) (3)
Further, if the position loop gain after the deviation operation is Kpx [rad / s] and the deviation operation is performed after the position command becomes 0, if the speed command is equal to the feedback speed during the deviation operation, , The position loop deviation ex immediately after the deviation operation is expressed by the following equation.
[0032]
ex [pulse] = Nx [pulse / s] / Kpx [rad / s]
Here, at the time of the deviation operation, since the position command has already become 0, if the position deviation ex at the time of the deviation operation is not larger than the total feedback pulse ΔP after the deviation operation, the position deviation becomes the sign reverse (that is, Overshoot) occurs.
[0033]
Therefore, the conditions for preventing the occurrence of overshoot are as follows.
[0034]
ex> $ P (5)
Nx / Kpx> Nx ² / (2 · αp)
Nx <2 · αp / Kpx
<2 · (RESO × Tmax / (2π · Jmax)) / Kpx
<RESO · Tmax / (π · Jmax · Kpx)
When converting Nx [pulse / s] to [rpm], 60 / RESO may be applied to both sides.
Nx [rpm] <60 · Tmax [Nm] / (π · Jmax [kgm ² ] · Kpx [rad / s]) (6)
In this case, Jmax and Tmax are fixed values that are uniquely determined when the servo specifications and mechanical specifications are determined. Therefore, according to the above equation (6), the timing for operating the deviation is determined by the value of the position loop gain. You can see that it is decided. In order to perform the orientation quickly, it is better that the position loop gain Kp is large. However, in that case, the position deviation operation must be performed at a rotational speed close to the stop.
[0035]
In the description so far, it is assumed that the speed command is made to match the feedback speed by the position deviation operation. However, in reality, the position deviation operation at the time of deceleration stop to the orient position is different from the position deviation operation at the time of acceleration, and has the following restrictions.
[0036]
In order not to cause an orientation shift, the position deviation manipulated variable must be an integral multiple (N times) of the resolution.
[0037]
After recognizing the orientation deceleration stop in the program, the numerical control unit 2 operates the time constant given by the parameter, the current position command, and the one-rotation error generated by operating the position deviation during acceleration ((the deviation operation amount during acceleration). A position command up to the orientation stop is generated in consideration of the remainder of (/ resolution). Since the deviation operation at the time of deceleration stop is performed after all of the position commands are distributed, if the deviation amount is replaced so that the speed command becomes equal to the speed feedback as in the case of acceleration, the position is shifted.
[0038]
Therefore, it is necessary to perform addition and subtraction of N times the resolution (that is, addition and subtraction of an integral multiple of the pulse amount of one spindle rotation) at the time of deceleration in order to prevent a position shift. Become. In other words, if the deviation operation timing is set when the feedback speed has reached a certain value or less (that is, if the deviation operation timing is made in accordance with the feedback speed), the deviation operation timing is sometimes changed after that. The speed command will vary. If the speed command after the operation is not set to the feedback speed or less, the maximum torque for continuously decelerating is not generated (that is, if the speed command exceeds the feedback speed, the current command is changed from the deceleration state to the acceleration state). Inversion), and a loss of stop time occurs. Therefore, the speed command after the deviation operation is controlled to be equal to or less than the feedback speed. From the above, since the speed command after the deviation operation is shifted by the maximum Kpx resolution, it varies within the range of the following equation (7).
[0039]
Feedback speed-Resolution x Kp <Speed command after deviation operation ≤ Feedback speed (7)
From this equation (7), it can be seen that when the position loop gain Kp is large, the variation of the speed command immediately after the deviation operation becomes large. Considering this result together with the result of the above equation (6), if the position loop gain Kp is increased to shorten the orientation time, it is necessary to set the position deviation operation timing to a low rotation speed. According to the above equation (7), it can be seen that the dispersion is increased, and in the worst case, the speed command may be reversed.
[0040]
Let's find this with a formula. If the feedback speed falls below the possible amount during the deviation operation, from equation (5),
ex-RESO> ΣP
Nx / Kpx-RESO> Nx ² / (2 · αp)
Nx ² / (2 · αp) -Nx / Kpx + RESO <0 (8)
, Which is a quadratic equation of Nx. In this equation (8), the condition that Nx of the equation in which the inequality sign is replaced with an equal has a real root is a quadratic equation ax ² From the discriminant b2-4ac> 0 of the root of + bx + c = 0, the following is obtained.
[0041]
(1 / Kpx) ² -4 · RESO / (2 · αp)> 0
Kpx <(αp / (2 · RESO)) ^1/2 (9)
By substituting equation (2) into equation (9), the following equation is obtained.
[0042]
Kpx <(Tmax / (4π · Jmax)) ^1/2 (10)
That is, the maximum value of the position loop gain Kp is determined by Jmax and Tmax determined by the mechanical conditions. This is expressed as Jmax = 0.00055 [kgm ² ], And a specific example applied to a system with Tmax = 43 [Nm] will be described below.
[0043]
First, the maximum rotational speed Nx of the deviation operation for each Kpx when the speed command is matched with the speed feedback at the time of the deviation operation, and how much the speed command corresponds when there is a deviation of the resolution at the time of the deviation operation at each Kpx. FIG. 11 is a graph showing the relationship. In FIG. 11, a solid line L1 indicates the maximum rotational speed Nx of the deviation operation, and a broken line L2 indicates a speed command amount with a deviation corresponding to the resolution.
[0044]
When the position loop gain Kp is low, the deviation operation rotational speed is also 7500 rpm or less, and even if there is a deviation of the resolution, the amount that appears in the speed command is as small as 1200 rpm. However, when the position loop gain Kp is high, the operation timing also becomes low, and the influence of the deviation of the resolution on the speed command increases.
[0045]
Next, the case where the speed command is not made to coincide with the feedback speed during the deviation operation will be considered. When the position loop gain Kp = 20 and there is a deviation of the resolution (that is, one rotation), the left side of the above equation (8) is set to the vertical axis, and the deviation operation maximum rotation speed Nx is set to the horizontal axis Drawing a graph as shown in FIG. Nx where the parabola Q1 in FIG. 12 becomes 0 or less satisfies the expression (8).
[0046]
In the case of FIG. 11, that is, when the speed command is made to coincide with the feedback speed, if Nx is 7500 rpm or less when Kp = 20, no overshoot is generated, but in the case of FIG. If the deviation operation is not performed between 1500 and 6000 rpm, an overshoot will occur. As Kp is increased from 20, the parabola in FIG. 12 shifts upward and does not cross 0 at a certain Kp. The value is obtained from equation (10). In the case of the present embodiment, Kp = 24.9. FIG. 13 shows a graph in this case.
[0047]
In other words, when Kp = 24.9, if there is a deviation corresponding to the resolution, an overshoot always occurs when a deviation operation is performed with Nx other than 3000 rpm. Further, when Kp is 24.9 or more, overshoot always occurs regardless of the deviation operation rotational speed when a deviation corresponding to the resolution occurs.
[0048]
In order to solve this problem, in the present embodiment, when performing the deviation operation, first, the position loop gain Kp is set low, and then the gain is gradually increased to a predetermined high gain with a certain time constant. It is configured to go. As a result, deceleration stop control that does not cause overshoot at any time and that ends the orientation positioning early is realized.
[0049]
Next, the specific contents of the control of the position deviation operation at the time of deceleration stop of the spindle motor 7 of this embodiment will be described with reference to the flowchart of FIG. First, in step S11 of FIG. 3, it is determined whether or not there is a spindle stop command (speed command). If there is a spindle stop command, the process proceeds to "YES" in step S11, and the spindle-stop deviation correction effective SW is turned on (step S12). On the other hand, if there is no spindle stop command in step S11, the process proceeds to "NO" and returns to the process in step S11. Subsequently, the process proceeds to step S13, where it is determined whether or not the spindle deceleration command has been completed. Here, if the spindle deceleration command has been completed, the process proceeds to "YES", and it is determined whether or not the spindle steady-state deviation correction effective SW is on (step S14).
[0050]
Then, the process proceeds to step S15, and it is determined whether or not the absolute value of the actual speed (feedback speed) of the spindle is smaller than a predetermined allowable speed difference 2. In this case, when the absolute value of the actual speed is smaller than the permissible speed difference 2, the process proceeds to "YES" and proceeds to step S16 to turn off the main shaft stop time deviation correction effective SW.
[0051]
Subsequently, the process proceeds to step S17, in which the rotational position deviation Pe during main shaft acceleration is corrected to the main shaft position deviation. Then, the position loop gain is switched. In this case, the previous gain Kp1 is switched to the stop-time initial gain Kp2 (a gain smaller than Kp1). Further, the spindle deviation is added or subtracted by an integral multiple of the encoder resolution so that the speed command given to the servo amplifier does not exceed and approaches the spindle feedback speed. Further, the gain switch SW is turned on.
[0052]
Then, the process proceeds to a step S18, and it is determined whether or not the gain switching SW is on. If it is ON, the process proceeds to step S19, and it is determined whether or not the time for gain switching time constant tKp3 has elapsed. If it has elapsed, the process proceeds to step S20, and it is determined whether the high gain Kp3 holding time has elapsed. If it has elapsed, the process proceeds to step S21, where the orientation time gain Kp4 is set to the main shaft position loop gain Kp, and the gain switching SW is turned off. If it has not elapsed in step S20, the process proceeds to step S25, and the high gain Kp3 is set as the main shaft position loop gain Kp.
[0053]
After the execution of step S21, the process proceeds to step S22, in which a spindle speed command given to the servo amplifier 3 is calculated. Then, the process proceeds to step S23, where the calculated spindle speed command is transmitted to the servo amplifier 3, and then the process is terminated.
[0054]
If it is determined in step S19 that the time for gain switching time constant tKp3 has not elapsed, the process proceeds to step S24, where the increment of the spindle position loop gain is added. In this case, the increment is as follows.
[0055]
(Kp3-Kp2) / (tKp3 / processing cycle)
Then, the increment may be added to the main shaft position loop gain Kp. Thereafter, the process proceeds to step S26 to calculate a spindle speed command to be given to the servo amplifier 3. Then, the process proceeds to step S27, in which the calculated spindle speed command is transmitted to the servo amplifier 3. Thereafter, the process returns to step S13.
[0056]
Further, after the step S25 is executed, the process proceeds to the step S27. Also, in step S18, even when the gain switch SW is not on, the process proceeds to step S27. Furthermore, even if the spindle deceleration command is not completed in the determination step S13, the process proceeds to the step S27.
[0057]
FIGS. 14 and 15 show experimental results (simulations) of the speed change and the used torque at the time of deceleration stop when a time constant exceeding the maximum torque is applied in the present embodiment having such a configuration. The lines P1 to P8 in FIGS. 14 and 15 are the same as the lines P1 to P8 in FIGS. According to FIGS. 14 and 15, when the feedback speed reaches the preset allowable speed error 2 with respect to the target speed, the position deviation is added or subtracted by N times the resolution, and the speed command is set to the feedback speed. It can be seen that the vehicle was stopped smoothly without overshooting because the control was performed so as to approach them.
[0058]
FIG. 16 is a characteristic diagram in which the stop portion in FIG. 14 is enlarged and a change in the position loop gain Kp is added. In FIG. 16, P9 indicates a position loop gain Kp. In FIG. 16, the deviation operation speed (that is, the speed allowable error 2) is set to 2000 rpm, the initial position loop gain at the time of the deviation operation is set to 20, and then the position loop gain is gradually increased to 100 with a time constant of 50 ms. After the high gain is maintained for 100 ms, the normal gain at the time of orientation is controlled to return to 30. According to this control, at the time of the position deviation operation, the gain is set to a low value of 20, and thereafter, the gain is gradually increased, so that the deviation converges to the orient position smoothly without overshooting. are doing.
[0059]
On the other hand, FIG. 17 shows a control in which the position loop gain Kp is immediately switched to a high gain during the deviation operation. In this case, it can be seen that overshoot occurs.
[0060]
FIGS. 18 and 19 show experimental results (simulations) of the speed change and the used torque at the time of deceleration stop when controlled by the conventional technique (see FIGS. 22 and 23). The lines P1 to P8 in FIGS. 18 and 19 are the same as the lines P1 to P8 in FIGS. According to FIGS. 18 and 19, since a long time constant that does not exceed the maximum torque is given as much as possible in order to prevent overshoot from occurring, it takes a long time to stop (this embodiment ( 14 and FIG. 15).
[0061]
In such a conventional control, the speed change and the used torque at the time of deceleration stop when the time constant exceeding the maximum torque (the same short time constant as in the case of FIGS. 14 and 15 of the present embodiment) is given are tested. 20 and 21 show the results measured by (simulation). The lines P1 to P8 in FIGS. 20 and 21 are the same as the lines P1 to P8 in FIGS. According to FIGS. 20 and 21, it can be seen that a large overshoot has occurred.
[0062]
On the other hand, in the present embodiment, the acceleration / deceleration pattern is applied to, for example, a configuration in which a two-stage acceleration / deceleration pattern is executed. The invention may be applied and there is no problem. In the case of this one-stage acceleration / deceleration, the deviation during the deviation operation becomes abnormally large.
[0063]
Normally, servo control utilizes the fact that the position deviation becomes large at the time of motor lock or mechanical collision, monitors the position deviation with a value that has a margin for the theoretical deviation at the highest speed, and exceeds the value. If an error occurs, it is determined that an error has occurred and the alarm is stopped. Therefore, in terms of the deviation abnormality detection, it is preferable that the command torque is not too far from the maximum servo torque. Therefore, it is desirable to provide an acceleration / deceleration pattern that slightly exceeds the maximum torque of the servo.
[0064]
【The invention's effect】
As is apparent from the above description, the present invention operates the position deviation amount so that the speed command matches the target speed or the feedback speed when the feedback speed with respect to the target speed reaches within a predetermined speed range after acceleration or deceleration. With such a configuration, the maximum torque can be used up while the position loop control is formed, and the overshoot can be prevented from occurring as much as possible.
[Brief description of the drawings]
FIG. 1 is a block diagram of a control device for a spindle motor showing one embodiment of the present invention.
FIG. 2 is a flowchart for acceleration.
FIG. 3 is a flowchart at the time of deceleration stop.
FIG. 4 is a characteristic diagram showing a change in speed during acceleration, and the like.
FIG. 5 is a characteristic diagram showing a used torque and the like during acceleration.
FIG. 6 is a diagram corresponding to FIG. 4 of a conventional configuration.
FIG. 7 is a diagram corresponding to FIG. 5 of a conventional configuration.
FIG. 8 is a diagram corresponding to FIG. 4 of another conventional configuration.
FIG. 9 is a diagram corresponding to FIG. 5 of another conventional configuration.
FIG. 10 is a characteristic diagram showing a change in rotation speed.
FIG. 11 is a characteristic diagram showing a relationship between a deviation operation maximum rotation speed and a position loop gain.
FIG. 12 is a characteristic diagram showing the relationship between the left side of equation (8) and the maximum rotational speed of the deviation operation.
FIG. 13 is a diagram corresponding to FIG. 12 for different position loop gains;
FIG. 14 is a characteristic diagram showing a speed change and the like at the time of deceleration stop.
FIG. 15 is a characteristic diagram showing a used torque and the like at the time of deceleration stop.
FIG. 16 is an enlarged view showing a stop portion in FIG. 14;
FIG. 17 is a diagram corresponding to FIG. 16 showing a control for suddenly switching the position loop gain Kp to a high gain at the time of a deviation operation.
FIG. 18 is a diagram corresponding to FIG. 14 of a conventional configuration.
FIG. 19 is a diagram corresponding to FIG. 15 of a conventional configuration.
FIG. 20 is a diagram corresponding to FIG. 14 of another conventional configuration.
FIG. 21 is a diagram corresponding to FIG. 15 of another conventional configuration.
FIG. 22 is a characteristic diagram of an acceleration pattern having a conventional configuration.
FIG. 23 is a characteristic diagram showing a relationship between torque and rotation speed of a conventional configuration.
[Explanation of symbols]
1 is a control device, 2 is a numerical control unit, 3 is a servo amplifier, 4 is a motion command unit, 5 is a deviation operation control unit, 6 is an adder, 7 is a spindle motor, 8 is an encoder, 9 is an adder, and 12 is An adder, 13 indicates a current limiting unit, and 14 indicates a current control unit.

Claims (4)

In a spindle motor control device configured to perform position / speed control of the spindle motor by combining position loop control, speed loop control, and current loop control,
A spindle motor control device characterized in that when a feedback speed with respect to a target speed reaches a predetermined speed range after acceleration or deceleration, a position deviation amount is operated so as to make a speed command coincide with the target speed or the feedback speed. While storing the position deviation operation amount when operating the position deviation amount,
2. The spindle motor control device according to claim 1, wherein at the time of the orientation command, the command value is corrected based on the position deviation operation amount. In a spindle motor control device configured to perform position / speed control of the spindle motor by combining position loop control, speed loop control, and current loop control,
In the case of deceleration, stop, and orientation, when the feedback speed reaches the set speed, the position deviation amount is set to an integral multiple of the spindle rotation pulse amount so that the speed command does not exceed the feedback speed and approaches the feedback speed. A control device for a spindle motor, which is configured to perform addition and subtraction. 4. The spindle motor control device according to claim 3, wherein when adding or subtracting the position deviation amount, the position loop gain is set to a low value, and thereafter, the position loop gain is gradually increased.

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