JP2001251879A - Motor control unit and its control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem where constitution and algorithm are complicated, when external disturbance of viscosity loss, cable tension, etc., exist with respect to an object of control, in a motor control unit and its control method, where a load is driven by a compound power amplifier capable of switching linear control and PWM control. SOLUTION: This control unit is equipped with a position deviation calculation means 21, which calculates position deviation/speed command from an aimed position 50 and a position of a control object 5, a detected speed value calculating means 22, which calculates a detected speed value of the object 5 from its position, and a speed deviation calculating means 22, which calculates a speed deviation/thrust command from the position deviation/speed command and the detected speed value. A motor 4, connected with the object 5, is driven with the output of the power amplifier 3, where a linear amplifier means 31 and a PWM amplifier means 32 can switch operations. On the basis of the detected speed value and the detected speed change amount in a specified time, a changeover judging means 33 judges changeover of the means where the power amplifier 3 operates. On the basis of the judgment from the changeover judging means 33, a switching means switches the means where the power amplifier 3 operates.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for switching a current control device and a motor control device for implementing the method, and more particularly to a method and a device for switching a power amplifier whose operation method can be switched.

[0002]

2. Description of the Related Art Conventionally, applications requiring high-efficiency and high-resolution current control include positioning accuracy in a system, that is, high-precision positioning accuracy, and constant-speed feeding in a system. Accuracy at the time, that is, one that requires low speed ripple and low thrust ripple, or one that requires both of them is general. As a power amplifier whose operating means used in such an application can be switched, for example, when a large output is generated, a high-efficiency switching method (hereinafter, referred to as “high-power switching method”)
"PWM control") is selected, and a composite power amplifier in which a low-noise, high-resolution amplification method (hereinafter, "linear control") is selected when a small output is generated is mainly used. In this composite power amplifier, the operation method is switched according to the input thrust command value, thereby improving the energy efficiency and increasing the accuracy of the system. According to Japanese Patent Application Laid-Open No. 9-238031 by the present applicant, a conventional motor control device using a composite type power amplifier and a method of switching the motor control device have a constant thrust command value input to the power amplifier. The operation method is switched depending on whether or not the threshold value is exceeded (hereinafter, referred to as “conventional example 1”). Further, in a stage control device that drives a motor connected to a stage using a composite power amplifier disclosed in Japanese Patent Application Laid-Open No. H10-177949, the operation state of the stage is determined based on the deviation position, and the operation state is determined according to the operation state. Or, in accordance with the stage position and the driving thrust of the motor, the thrust command value supplied to the power amplifier is corrected, or the thrust threshold is changed to switch the operation method of the power amplifier (hereinafter, referred to as
"Conventional example 2").

[0003]

FIG. 2 is a block diagram showing a schematic circuit configuration of a motor control device according to a first embodiment of the prior art, and FIG. 3 is a schematic diagram for explaining a problem in the first prior art. Represent. 2 and 3, the control target 5 is shown in FIG.
It is assumed that the driving is performed at the speed pattern Vb, and the thrust command at that time is Fb in FIG. 3 (b). In the first conventional example, the operation method of the power amplifier 3 is switched depending on whether or not a predetermined threshold value is exceeded. Therefore, PWM control is performed when the controlled object is accelerated and decelerated, and linear control is performed when the controlled object is at a constant speed. Can be driven. Here, consider the case where the electric motor has a viscous loss proportional to the speed. In such an electric motor, a can is provided to suppress a rise in temperature due to a loss of the motor winding, and a cooling medium flows through the can to cool the motor winding. The viscosity loss refers to an eddy current loss or the like generated by the can and the magnet. In this case, a certain control target is set to a speed pattern Va larger than the constant speed Fb [FIG.
(a)], the viscosity loss increases with a constant speed increase. This means that a disturbance force called viscous loss is acting on the controlled object, and therefore, at a constant speed of the controlled object, a thrust command Fa larger than the thrust command Fb sufficient to overcome the disturbance force is required. . Conventional example 1 does not include a means for such a disturbance force, and therefore, the thrust command F
Regardless of whether a is the acceleration / deceleration / constant speed of the control target, the motor exceeds the predetermined threshold value, so that the motor is always driven by PWM control, and the accuracy of constant speed feed in the system, that is, For applications requiring low speed ripple and low thrust ripple, there is a problem that accuracy is deteriorated and influence of switching noise is increased.

FIG. 4 is a block diagram showing a schematic circuit configuration of a stage control device according to a second embodiment of the related art. FIG. 5 is a schematic diagram for explaining a problem in the second conventional example.
5A is a characteristic diagram of a speed / thrust, FIG. 5B is a characteristic diagram of a position command / detected position, and FIG. 4 and 5, when the stage of FIG. 4 which is the control target 5a is driven by the position command [see FIG. 5 (b)] and the speed pattern [see FIG. 5 (a)] shown in FIG. In the type 1 servo system of the device, the detected position and thrust are as shown in FIGS. 5 (a) and 5 (b), and the positional deviation [see FIG. 5 (c)], which is the difference between the position command and the detected position, is , Depending on the speed. In Conventional Example 2, the operation state of the stage is determined based on the position deviation, and the thrust command value supplied to the power amplifier is corrected according to the operation state. Even in this case, when it is determined that the position of the stage is being settled, the thrust command value is corrected with respect to a predetermined fixed threshold value, the operation method of the power amplifier can be switched, and desired stage driving can be performed. However, in Conventional Example 2, it is only possible to determine that the operation state of the stage is accelerating and positioning is being set (during deceleration), and it is not possible to reliably determine whether the stage is moving at a constant speed. Accuracy, that is, effective for applications that require high-precision positioning accuracy, but accuracy at constant feed rate in the system, that is, low ripple
There is a problem that it cannot be applied to applications requiring low thrust ripple.

[0005] Further, in Conventional Example 2, the thrust command is corrected to a predetermined threshold value or the thrust threshold value is requested in accordance with the stage position and the driving thrust of the electric motor.
Even if the thrust command value changes due to some disturbance,
The driving method of the power amplifier can be switched, and desired stage driving can be performed. However, in Conventional Example 2, the driving thrust, which is the actual thrust, is calculated from the current value detected by the current detector, and the disturbance force is estimated. Therefore, the thrust of the driving thrust is such as offset or temperature drift of the current detector. There is a problem that it is easily affected by characteristics. Here, the viscous loss proportional to the speed of the motor is taken as an example of the disturbance force, but the disturbance force may be a disturbance force with respect to a control target such as a tension of a wiring for supplying power to the motor or a pipe for cooling or the like.

Here, the present invention has been made to solve the above problems, and the object thereof is as follows.
Drive efficiency by switching the operation method of the composite power amplifier for applications that require accuracy during positioning in the system, applications that require accuracy at a constant feed rate in the system, or applications that require both. It is an object of the present invention to provide a motor control device and a switching method thereof that can be appropriately performed from the viewpoint of the above.

[0007]

According to a first aspect of the present invention, a position deviation or a speed command is calculated based on a target position from a host device and a position of a control target. Position deviation calculating means, detected speed value calculating means for calculating a detected speed value that is the speed of the controlled object based on the position of the controlled object, speed deviation based on the position deviation or speed command and the detected speed value Or a motor control for driving a motor connected to the control object by power output from a power amplifier in which a speed deviation calculating means for calculating a thrust command is provided, and the linear amplifier means and the PWM amplifier means are capable of switching operations. A switching judging means for judging a switching of the means for operating the power amplifier based on the detected speed value and a detected speed change per fixed time; Based on the judgment of the switching judgment unit, a motor control device and having a switching means for switching said means for operation of the power amplifier. Thus, according to the first aspect of the present invention, the following special effects can be obtained. [1] When a disturbance force is acting on the control target, the determination of switching to the operation method of the composite power amplifier, either the linear amplifier or the PWM amplifier, is not affected by the disturbance force. Suitable for applications that require positioning accuracy, applications that require accuracy at a constant feed rate in the system, or applications that require both, from the viewpoint of drive efficiency Can be done. [2] When a disturbance force is acting on the control target, the means for defending the disturbance force is not used, so the switching decision of the operation method of the composite power amplifier does not affect the characteristics such as offset and temperature drift. I will not receive it. [3] When a disturbance force is acting on the control target, the configuration and algorithm can be simplified because a means for estimating the disturbance force is not used.

According to a second aspect of the present invention, the switching determining means determines whether or not the controlled object is accelerating or decelerating based on a comparison between the detected speed value and a predetermined fixed detected speed threshold value. It is a means for judging whether or not the control target is at a constant speed based on a comparison between the detected speed change per fixed time and a predetermined fixed detected speed change threshold. The electric motor control device according to claim 1, wherein

According to a third aspect of the present invention, the switching means transmits the operation of the power amplifier to the linear amplifying means when the content of the determination by the switching determining means is during positioning stabilization or during constant speed. During switching or acceleration / deceleration,
2. The motor control device according to claim 1, wherein the operation of the power amplifier is switched to a PWM amplifier.

According to a fourth aspect of the present invention, a position deviation or speed command is calculated by a position deviation calculating means on the basis of a target position and a position of a control target from a host device, and detection is performed based on the position of the control target. A speed value calculating means calculates a detected speed value which is the speed of the controlled object, and a speed deviation calculating means calculates a speed deviation or a thrust command based on the position deviation or speed command and the detected speed value, In the switching method of the motor control device that drives the motor connected to the control object by the power output from the power amplifier in which the operation of the amplification unit and the PWM amplifier unit is enabled, the detection speed value and the fixed time On the basis of the change in the detected speed of the hit, the switching determination means determines the switching of the means on which the power amplifier operates, and determines the switching from the switching determination means. Zui and a switching method of a motor control device characterized by switching said means for operation of the power amplifier by the switching means. Thus, according to the invention of claim 4 of the present invention, the following remarkable effects can be exerted. That is, in the control method of the motor control device that drives the motor by the composite power amplifier that can switch between the linear control and the PWM control, conventionally, (1)
When there is disturbance such as viscosity loss and cable tension for the control target, switching is performed based on the comparison between the thrust command value and the threshold value, so that appropriate switching cannot be performed due to the influence of the disturbance.
(2) The configuration and algorithm are complicated because a means for estimating and correcting the disturbance force is required. (3) The state of the controlled object is determined and switched based on the position deviation. There was a problem that it could not be applied to applications requiring precision. According to the invention of claim 4 of the present invention, based on the speed of the control target and the threshold value A, the change in the speed of the control target and the threshold value B, the switching is performed by the logical sum of the combinations of the respective judgment results. Can be provided, and a control method of a motor control device capable of appropriately switching operation means of a composite power amplifier from the viewpoint of drive efficiency can be provided.

According to a fifth aspect of the present invention, the switching of the operating means of the power amplifier is determined based on a comparison between the detected speed value and a predetermined fixed detected speed threshold value. It is determined whether the target is accelerating or decelerating, and based on a comparison between the detected speed change per fixed time and a predetermined fixed detected speed change threshold, whether the control target is in a constant speed. The switching method of the motor control device according to claim 4, wherein

According to a sixth aspect of the present invention, in order to perform the switching of the operating means of the power amplifier, when the determination by the switching determining means is during positioning stabilization or during constant speed, 5. The method according to claim 4, wherein the operation of the power amplifier is switched to the linear amplification means, and the operation of the power amplifier is switched to the PWM amplifier means during acceleration / deceleration.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The same reference numerals in all drawings indicate the same or equivalent means. FIG. 1A is a block diagram showing a schematic circuit configuration according to an embodiment of the present invention. In FIG. 1A, the motor control device 1
Is a means that generally forms a speed loop / position loop servo system and controls the position and speed of the control target 5 via the electric motor 4. The motor control device 1 includes a power amplifier 3 that generates a drive current to be supplied to the motor 4, a CPU 2 that performs various calculations described below, and the like. The power amplifier 3 is a composite power amplifier whose operation method can be switched between PWM control and linear control, and includes a PWM amplifier 32 based on PWM control and a linear amplifier based on linear control.
A switching unit 33 including an analog switch for switching between the PWM amplifier 32 and the linear amplifier 31;
A drive current corresponding to the input thrust command is supplied to the electric motor 4.

The CPU 2 calculates a position deviation (speed command) based on the position of the control target 5 with the target position 50 from the host device, a position deviation (speed command) and a detected speed value to be described later. A speed deviation calculating unit 22 for calculating a speed deviation (thrust command) based on the detected speed value; a detected speed value calculating unit 23 for calculating a detected speed value which is the speed of the controlled object 5 based on the position of the controlled object 5; And a switching determination unit 24 for determining whether to switch the operation method of the power amplifier 3 based on the detected speed change per fixed time.

The switching determination unit 24 determines whether or not the controlled object 5 is accelerating or decelerating based on a comparison between the detected speed value and a predetermined fixed detection speed threshold value. It is determined whether or not the control target 5 is at a constant speed based on a comparison between the change and a predetermined threshold value for a predetermined detected speed change. Here, when the detected speed value is larger than a predetermined fixed detection speed threshold (hereinafter, referred to as “determination result A”), when the detected speed value is smaller than a predetermined fixed detection speed threshold (hereinafter, “ If the detected speed change per fixed time is larger than a predetermined fixed detected speed change threshold (hereinafter referred to as “decision C”), the detected speed change per fixed time is referred to as “determined result B”. If the minute is larger than a predetermined threshold value for a change in the detected speed (hereinafter, referred to as “determination result D”),
FIG. 1 (b) shows the operating state of the control target 5 and the results of each determination, and the associated operating method of the power amplifier 3. Finally, OR (logical sum) by the combination (A / B, C / D) of each judgment result
Is determined by the switching unit 33 constituting the power amplifier 3.
The switching unit 33 switches the operation method of the power amplifier 3 according to the determination result.

[0016]

As described above, according to the present invention, the following special effects can be obtained. [1] When a disturbance force is acting on the control target, the determination of switching to the operation method of the composite power amplifier, either the linear amplifier or the PWM amplifier, is not affected by the disturbance force. Suitable for applications that require positioning accuracy, applications that require accuracy at a constant feed rate in the system, or applications that require both, from the viewpoint of drive efficiency Can be done. [2] When a disturbance force is acting on the control target, the means for defending the disturbance force is not used, so the switching decision of the operation method of the composite power amplifier does not affect the characteristics such as offset and temperature drift. I will not receive it. [3] When a disturbance force is acting on the control target, the configuration and algorithm can be simplified because a means for estimating the disturbance force is not used. That is, linear control and PW
In a control method of a motor control device that drives a motor by a composite type power amplifier that can be switched to M control, in a conventional example and the like, (1) When there is disturbance such as viscous loss or cable tension with respect to the control target, The switching is performed based on the comparison between the command value and the threshold, so that appropriate switching cannot be performed due to the influence of disturbance. (2) A means for estimating and correcting the disturbance force is required, which complicates the configuration and algorithm. (3)
Since the state of the control target is determined and switched based on the position deviation, there is a problem that the method cannot be applied to an application requiring accuracy at a constant speed feed. However, according to the present invention, based on the speed of the control object and the threshold value A, the change in the speed of the control object and the threshold value B, the switching is performed by the logical sum based on the combination of the respective judgment results. A remarkable effect is provided in that a motor control device and a control method thereof that can appropriately switch the operation mode of the type power amplifier from the viewpoint of drive efficiency are provided.

[Brief description of the drawings]

1A and 1B are diagrams illustrating an embodiment of the present invention. FIG. 1A is a block diagram illustrating a schematic circuit configuration, and FIG. 1B is a diagram illustrating an operation state of a control target and an operation method of a power amplifier according to each determination result. Figure

FIG. 2 is a block diagram showing a schematic circuit configuration of a motor control device according to an example of Conventional Example 1 [Japanese Patent Laid-Open No. 9-238031].

FIGS. 3A and 3B are schematic diagrams for explaining a problem in the conventional example 1, in which FIG. 3A is a speed pattern diagram, and FIG. 3B is a diagram showing distribution of thrust commands and corresponding linear control.
Diagram explaining switching of PWM control

FIG. 4 is a block diagram showing a schematic circuit configuration of a motor control device according to an example of Conventional Example 2 [Japanese Patent Laid-Open No. 10-177949].

5A and 5B are schematic diagrams for explaining a problem in Conventional Example 2 [Japanese Patent Laid-Open No. 10-177949], where FIG. 5A is a pattern diagram of speed and thrust, and FIG. 5B is a characteristic diagram of a position command and a corresponding detected position. (c) is an explanatory diagram for determining the operating state according to the positional deviation between the position command and the detected position in (b).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor control device 1a Stage control device 2 CPU 21 Position deviation calculation part 22 Speed deviation calculation part 23 Detected speed value calculation part 24 Switching judgment part 3 Power amplifier 31 Linear amplifier 32 PWM amplifier 33 Switching part 4 Motor 5 Control target 5a Stage 6 Position detector 7 Position deviation calculation unit 8 Position deviation / thrust conversion unit 9 Adder 10 Operation state judgment unit 11 Thrust correction calculation unit 12 Current / thrust conversion unit 13 Current detector

Claims (6)

[Claims] 1. A position deviation calculating means for calculating a position deviation or a speed command based on a target position from a host device and a position of a control target, and a detection speed which is a speed of the control target based on the position of the control target. Detection speed value calculation means for calculating a value, and speed deviation calculation means for calculating a speed deviation or thrust command based on the position deviation or speed command and the detected speed value, wherein the linear amplification means and the PWM amplifier means operate. An electric motor control device that drives an electric motor connected to the control object by using a power output from a power amplifier that can be switched, wherein the power amplifier is controlled based on the detected speed value and a detected speed change per fixed time. Switching determining means for determining switching of the means operating, and the power amplifier operating based on the determination from the switching determining means. Motor control device characterized by having a switching means for switching the stage. 2. The switching determination unit determines whether the controlled object is accelerating or decelerating based on a comparison between the detected speed value and a predetermined fixed detection speed threshold value. 2. A means for judging whether or not the controlled object is at a constant speed based on a comparison between the detected speed change amount and a preset fixed detected speed change threshold value. Motor control device. 3. The switching means switches the operation of the power amplifier to a linear amplifying means when the determination by the switching determination means is during positioning stabilization or during a constant speed. 2. The motor control device according to claim 1, wherein in the case, the operation of the power amplifier is switched to a PWM amplifier. 4. A position deviation or speed command is calculated by a position deviation calculating means based on a target position from a host device and a position of a control object, and the control is performed by a detected speed value calculating means based on the position of the control object. A detected speed value, which is a target speed, is calculated, and a speed deviation or thrust command is calculated based on the position deviation or speed command and the detected speed value by speed deviation calculating means, and the linear amplification means and the PWM amplifier means A method for switching an electric motor control device that drives an electric motor connected to the control object by a power output from a power amplifier enabled to switch an operation, wherein the detected speed value and a detected speed change amount per fixed time are based on the detected speed value. The switching determining means determines switching of the means for operating the power amplifier, and based on the determination from the switching determining means, Switching method of a motor control device characterized by switching said means for operation of the power amplifier. 5. A method for determining whether to switch the operation means of the power amplifier, comprising: determining whether the control target is accelerating or decelerating based on a comparison between the detected speed value and a predetermined fixed detected speed threshold value. Determining whether or not the control target is at a constant speed based on a comparison between the detected speed change per fixed time and a predetermined fixed detected speed change threshold. A method for switching a motor control device according to claim 4. 6. A method for switching the operation means of the power amplifier, comprising: when the switching judgment means determines that the position is settled or during a constant speed, the operation of the power amplifier is transmitted to the linear amplification means. 5. The method according to claim 4, wherein the operation of the power amplifier is switched to a PWM amplifier during switching or acceleration / deceleration.