JP2004350433A - Voltage correction method for servo amplifier - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a stable dynamic characteristic of a servo motor even when power fluctuates by connecting a power voltage correction part to a PWM amplifier gain part. <P>SOLUTION: This voltage correction method for the servo motor is constituted such that the power voltage correction part (20) is connected to the PWM amplifier gain part (Ka2), and the gain of the PWM amplifier gain part (Ka2) is adjusted by a correction amount (C) from the power voltage correction part (20). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a voltage correction method for a servo amplifier, and more particularly to controlling a fluctuation of a motor applied voltage by adjusting a gain using a power supply voltage correction unit when a variable power supply voltage using a battery or the like is used. Related to new improvements.
[0002]
[Prior art]
Conventionally, as a method of driving a servo motor of this type, a patent document or the like showing the method is not disclosed for in-house production, but the configuration shown in FIG. 3 is adopted.
That is, in FIG. 3, what is indicated by reference numeral 1 is a servo amplifier for driving the servo motor 2, and the speed command ωcmd is input to the first subtraction unit 3 of the servo amplifier 1, and the speed gain unit Kv is The current command Icmd is input to the second subtractor 4 via the current gain section Ka1 and the adder 5, and is sent to the PWM amplifier gain section Ka2. The gain is adjusted and then applied to the servomotor 2 as the motor applied voltage V. You.
[0003]
In the servo motor 2, the motor applied voltage V is converted into a current I through a third subtraction unit 6 and a control constant unit 7 as an equivalent DC machine torque constant unit Kt, a speed ω via a torque subtraction unit 8 and an inertia unit 9. It is configured to be obtained.
[0004]
The speed ω is fed back to the third subtraction unit 6 via the equivalent DC machine voltage constant unit Ke and directly to the first subtraction unit 3.
This speed ω is fed back to the adding unit 5 via the back electromotive voltage compensating unit Kb, and the current I is fed back to the second subtracting unit 4.
[0005]
Therefore, a feedback loop indicated by an arrow A shown in FIG. 3 is formed by each of the above-described feedbacks, and the speed ω of the servo motor 2 is controlled to be a predetermined speed.
[0006]
[Problems to be solved by the invention]
Since the conventional servo motor driving method is configured as described above, the following problems exist.
That is, since the speed of the servo motor is only fed back to the adder via the back electromotive force compensator, when the motor drive voltage (motor applied voltage) changes about 1/2 to 2 times, this voltage is reduced. The fluctuation affects the gain of the PWM amplifier gain section. When the fluctuation becomes higher than the specified voltage, the frequency response of the current loop increases, and the servo motor enters an oscillation state in which the servo motor vibrates. Conversely, when the voltage becomes lower than the specified value, the frequency response is lowered and the operation of the servo motor is stabilized, but the difference between the command (Icmd) and the feedback (I) becomes large, and the control accuracy is deteriorated. I was
[0007]
The present invention has been made in order to solve the above-described problems, and particularly when a variable power supply voltage using a battery or the like is used, the gain is adjusted by using a power supply voltage correction unit to apply a motor. It is an object of the present invention to provide a voltage correction method for a servo amplifier that controls voltage fluctuation.
[0008]
[Means for Solving the Problems]
The voltage correction method for a servo amplifier according to the present invention is the case where a feedback motor-controlled voltage is applied to a servo motor based on a speed command input to the servo amplifier to control the servo motor to a predetermined speed. A power supply voltage correction unit is connected to a PWM amplifier gain unit that controls the motor application voltage, and the fluctuation of the motor application voltage that drives the servomotor is changed by the gain of the PWM amplifier gain unit according to the correction amount from the power supply voltage correction unit. It is a method of adjusting.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of a servo amplifier voltage correction method according to the present invention will be described with reference to the drawings. The same or equivalent parts as those in the conventional example will be described with the same reference numerals.
In FIG. 1, reference numeral 1 denotes a servo amplifier for driving a servo motor 2. A speed command ωcmd is input to a first subtraction unit 3 of the servo amplifier 1, and a current command is passed through a speed gain unit Kv. It is input to the second subtraction unit 4 as Icmd, sent to the PWM amplifier gain unit Ka2 via the current gain unit Ka1 and the addition unit 5, and is applied to the servomotor 2 as the motor application voltage V after gain adjustment.
[0010]
A power supply voltage correction section 20 is connected to the PWM amplifier gain section Ka2. The power supply voltage correction section 20 has a power supply voltage correction table for correcting a power supply voltage of a back electromotive voltage described later (even with other automatic control means). And the power supply voltage can be controlled within a specified range based on the correction amount C in the performance guarantee range B based on the reference value A.
[0011]
In the servo motor 2, the motor applied voltage V is converted into a current I through a third subtraction unit 6 and a control constant unit 7 as an equivalent DC machine torque constant unit Kt, a speed ω via a torque subtraction unit 8 and an inertia unit 9. It is configured to be obtained.
[0012]
The speed ω is fed back to the third subtraction unit 6 via the equivalent DC machine voltage constant unit Ke and directly to the first subtraction unit 3.
This speed ω is fed back to the adding unit 5 via the back electromotive voltage compensating unit Kb, and the current I is fed back to the second subtracting unit 4.
[0013]
Therefore, in the above configuration, when the power supply voltage fluctuates, the power supply voltage of the back electromotive voltage can be corrected in both the positive and negative directions from the reference value A along the correction amount C in the performance guarantee range B of FIG.
With the above-described correction, the gain correction of the PWM amplifier gain section Ka2 is performed, and even if the power supply voltage fluctuates, control is performed based on the speed command ωcmd so that the motor speed ω of the specified speed can be maintained.
[0014]
【The invention's effect】
The voltage correction method for a servo amplifier according to the present invention is configured as described above, so that the following effects can be obtained.
That is, since the power supply voltage correction unit connected to the PWM amplifier gain unit of the servo amplifier corrects the motor applied voltage to the servo motor when the power supply voltage fluctuates, the stable dynamic characteristics of the motor when the power supply voltage fluctuates. Obtainable.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a voltage correction method for a servo amplifier according to the present invention.
FIG. 2 is an explanatory diagram showing correction contents of a power supply voltage correction unit in FIG. 1;
FIG. 3 is a block diagram showing a conventional servo motor driving method.
[Explanation of symbols]
Reference Signs List 1 servo amplifier 2 servo motor ωcmd speed command V motor applied voltage Ka2 PWM amplifier gain unit 20 power supply voltage correction unit C correction amount

Claims (1)

An electric motor application voltage (V) that is feedback-controlled based on a speed command (ωcmd) input to the servo amplifier (1) is applied to the servo motor (2), and the servo motor (2) is set to a predetermined speed. When controlling, a power supply voltage correction section (20) is connected to a PWM amplifier gain section (Ka2) for controlling the motor applied voltage (V), and a fluctuation of the motor applied voltage (V) for driving the servo motor (2). Adjusting the gain of the PWM amplifier gain section (Ka2) according to the correction amount (C) from the power supply voltage correction section (20).

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