JPH10111720A - Ac servo mortor and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the speed control with high accuracy and infinite resolution and with no time lag by feeding directly the output signal of a brushless tachogenerator that is provided on the same shaft as an AC servo motor back to a speed amplifier. SOLUTION: When the voltage is turned on and a position command (a) is inputted to an AC servo driver 20, a drive current (i) is supplied to an AC servo motor 7 via a position amplifier 1, a speed amplifier 2, a communication generation circuit 3, a current amplifier 4 and an amplifier 6. Thus, the motor 7 is driven. At the same time, the rotation detection signal (b) received from a rotation detection circuit 8 is inputted to the amplifier 1 and the circuit 3 which undergo the known feedback control. The output signal (d) received from a brushless tachogenerator 9 is fed back to the amplifier 2 which undergoes the feedback control. The signal (d) directly uses the voltage that is supplied from the tachogenerator 9. As a result, the speed control is attained with high accuracy and in a wide range between 1rpm and 0.1rpm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC servomotor and a method of driving the same, and more particularly, to detecting a rotation angle (commutation) and position by a rotation detection signal of a rotation detector, and by controlling an output signal of a brushless tachogenerator. The present invention relates to a novel improvement for enabling a speed control of 1 rpm or less.

[0002]

2. Description of the Related Art Conventionally, a structure shown in FIG. 2 has been adopted as an AC servomotor of this type which has been used. That is, an AC servo driver 20 is connected to the AC servomotor 7 having a rotation detector 8 formed of a resolver or an encoder on the same axis, and a position command a is input to the AC servo driver 20. The position command a is input to the position amplifier 1, the position output C of the position amplifier 1 is input to the speed amplifier 2, and the speed output e of the speed amplifier 2 is a well-known commutation generation for detecting the rotation angle. It is input to the circuit 3. The output f of the commutation generation circuit 3 is input to the current amplifier 4, and the current output h of the current amplifier 4 is input to the AC servomotor 7 as the drive current i via the amplifier 6. The obtained current value g is fed back to the input side of the current amplifier 4 as a feedback current for control.
The rotation detection signal b from the rotation detector 8 is fed back to the input side of the position amplifier 1 and input to the commutation generation circuit 3. Further, the rotation detection signal b is converted into a voltage d by an F / V converter 10 that converts a frequency into a voltage, and is fed back to the speed amplifier 2.
Further, the drive current i of the amplifier 6 is detected by the current sensor 5, and the detected current value g is fed back to the current amplifier 4.

[0003]

Since the conventional AC servomotor is configured as described above, the following problems exist. That is, since the rotation detection signal from the rotation detector is F / V converted and used for the feedback control of the speed, the resolution is limited, and in the low speed control of 1 rpm or less, the accuracy is very poor, and Control at .1 rpm or less was almost impossible. Also, a time lag occurs in the feedback input to the speed amplifier due to the F / V conversion, and a delay in speed control has occurred.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. In particular, the present invention performs rotation angle detection (commutation) and position control based on a rotation detection signal of a rotation detector, and outputs the output of a brushless tachometer. An object of the present invention is to provide an AC servomotor capable of controlling a speed of 1 rpm or less by a signal and a driving method thereof.

[0005]

An AC servomotor according to the present invention is a method for driving an AC servomotor which drives an AC servomotor via a position amplifier, a speed amplifier and a current amplifier based on a position command. AC
In this method, a rotation angle is detected and a position is controlled by a rotation detection signal of a rotation detector linked to a servomotor, and a speed control is performed by using an output signal of a brushless tachogenerator linked to the AC servomotor.

A method of driving an AC servomotor according to the present invention is directed to an AC servomotor that drives the AC servomotor via a position amplifier, a speed amplifier, a commutation generation circuit and a current amplifier based on a position command. A rotation detector connected to the input side of the amplifier and the commutation generation circuit, and a brushless tachogenerator connected to the input side of the speed amplifier;
The speed is controlled using the output signal of the brushless tachogenerator.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
A preferred embodiment of the C servomotor and its driving method will be described. It should be noted that the same reference numerals are used for the conventional example and earth depressions or equivalent parts. In FIG. 1, an AC servo driver 20 is connected to an AC servomotor 7 having a rotation detector 8 composed of a resolver or an encoder and a brushless tachogenerator 9 on the same axis.
The position command a is input to the servo driver 20.
The position command a is input to the position amplifier 1, the position output c of the position amplifier 1 is input to the speed amplifier 2, and the speed output e of the speed amplifier 2 is used as a commutation generation circuit 3 for detecting the rotation angle. Has been entered.

The output f of the commutation generation circuit 3
Is input to the current amplifier 4, the current output h of the current amplifier 4 is input to the AC servomotor 7 as the drive current i via the amplifier 6, and the current value g obtained by the current sensor 5 is used for control. The current is fed back to the input side of the current amplifier 4 as a feedback current. The rotation detection signal b from the rotation detector 8 is fed back to the input side of the position amplifier 1 and is also input to the commutation generation circuit 3. An output signal d composed of a voltage output from the brushless tach generator 9 is input to the input side of the speed amplifier 2.

Next, the operation will be described. First, when the voltage is turned on and the position command a is input to the AC servo driver 20, the drive current i becomes AC via the position amplifier 1, speed amplifier 2, commutation generation circuit 3, current amplifier 4 and amplifier 6. The AC servo motor 7 is supplied to the servo motor 7 and is driven. In this case, the rotation detection signal b from the rotation detector 8 is input to the position amplifier 1 and the commutation generation circuit 3, and a well-known feedback control is performed.

Further, the output signal d from the brushless tacho generator 9 is fed back to the speed amplifier 2 and feedback-controlled. Since this output signal d directly uses the voltage from the brushless tacho generator 9, the output signal d / V
There is no time lag that occurs during conversion, and the resolution is infinite, unlike conventional resolvers or encoders. , Difficult 1rp
Control at m and below 0.1 rpm is also possible.

[0011]

The AC servomotor and the method of driving the same according to the present invention are constructed as described above, so that the following effects can be obtained. That is, since the output signal (voltage) of the brushless tachometer provided on the same axis as the AC servomotor is directly fed back to the speed amplifier, it is not necessary to use a conventional F / V converter, and the time lag is reduced. Speed control with high accuracy and infinite resolution can be performed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an AC servomotor and a driving method thereof according to the present invention.

FIG. 2 is a configuration diagram showing a conventional AC servomotor and a driving method thereof.

[Explanation of symbols]

 Reference Signs List 1 position amplifier 2 speed amplifier 3 commutation generation circuit 4 current amplifier 7 AC servomotor 8 rotation detector 9 brushless tachogenerator a position command b rotation detection signal d output signal

Claims (2)

[Claims] An AC servomotor driving method for driving an AC servomotor (7) via a position amplifier (1), a speed amplifier (2) and a current amplifier (4) based on a position command (a). In the above, the rotation angle detection and the position control are performed by the rotation detection signal (b) of the rotation detector (8) interlocked with the AC servomotor (7), and the brushless tachogenerator (9) interlocked with the AC servomotor (7). A) a method for driving an AC servomotor, wherein the speed control is performed using the output signal (d). An AC servomotor (7) is driven via a position amplifier (1), a speed amplifier (2), a commutation generation circuit (3) and a current amplifier (4) based on a position command (a). In the AC servomotor described above, a rotation detector (8) connected to the input side of the position amplifier (1) and the commutation generation circuit (3), and a brushless motor connected to the input side of the speed amplifier (2). An AC servomotor, comprising: a tach generator (9), wherein the speed is controlled using an output signal (d) of the brushless tach generator (9).