JPH0866075A - Correction method of current feedback for servo control apparatus - Google Patents

Abstract

PURPOSE: To obtain a correction method in which a smooth control operation can be performed by a method wherein a current amplifier is current-controlled by a waiting current instruction and the delay portion of a current feedback is corrected in the current instruction. CONSTITUTION: An inverter 1 which is composed of a power transistor group and a power transistor-based drive circuit 7 which proportionally integrates and power-amplifies a driving signal from a microcomputer 6 are installed. Then, a delay portion which has been computed this time by subtracting a current feedback is added to a current instruction. The delay portion is multiplied by a current amplification gain K, a motor 2 is driven, and a current (i) which has been delay-compensated flows to the motor 2. The delay portion di1 is added to the current instruction iref as a current-feedback correction portion. In this manner, the delay portion of the current feedback is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for calculating a current fluctuation amount from a current command to obtain a current feedback and correcting a delay amount.

[0002]

2. Description of the Related Art In the conventional current control, as shown in FIG. 3, proportional integration is performed on a current command minus current feedback, and this is used as a command for a transistor constituting an inverter [hereinafter, "Conventional example"].

[0003]

However, in the conventional example as the prior art, when current is digitally controlled by a microcomputer or the like, a delay occurs due to a calculation time or the like, so that the system becomes unstable, There was a problem that vibration etc. would occur. Therefore, it is an object of the present invention to provide a current feedback correction method for a servo control device that corrects a delay amount of current feedback to perform smooth control.

[0004]

In order to solve the above problems, the present invention provides a current feedback correction method in which a servo controller calculates a current delay from a current command and corrects the delay in addition to the current command. Is. That is, it is a current feedback correction method of a servo controller that has a current and performs current control by a current command, and corrects a current feedback delay in the current command, and also subtracts the current feedback i ₁ from the current command i _ref , The delay amount di ₁ calculated this time is added, and this is multiplied by the gain K of the current amplifier, and when the motor driven by the servo controller is driven, the delay amount di ₁ of the current feedback is di ₁ = [K / (R + sL )] Di _ref where R is the resistance of the motor s is the Laplace transform operator L is the current feedback correction method of the servo controller described in the preceding paragraph, which is calculated from the inductance of the motor, and an inverter including a power transistor and this inverter The drive circuit that drives the The current detection circuit for detecting the current flowing from the inverter to the inverter, the A / D converter for A / D converting the motor current detected by the current detection circuit, and the output of the A / D converter are introduced and preset. Based on the current amplifier gain K, the motor resistance R, the motor inductance L, and the current command i _ref given at that time, the current feedback correction component d
The current feedback correction method for a servo control device according to the preceding paragraph, further comprising a CPU for calculating i ₁ and driving the motor based on a deviation between the current command and a current feedback correction amount and the current feedback.

[0005]

According to the present invention, since the delay amount of the current feedback can be corrected by the above means, the system becomes unstable and the vibration etc. can be suppressed.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a concrete circuit configuration of an embodiment of the present invention. In FIG. 1, 1 is an inverter composed of a power transistor group, 2 is a motor, 4 is a current detection circuit, 5 is an A / D converter, 6 is a microcomputer (CPU), and 7 is a drive signal from the microcomputer 6. It is a power transistor base drive circuit that integrates and amplifies power. The operation of the circuit configured as described above will be described with reference to the control block diagram of FIG. First, the current feedback is subtracted from the current command, and the delay amount calculated this time is added. By multiplying this by the current amplifier gain K and driving the motor 2, the delay-compensated current i flows through the motor 2. The delay calculated here is calculated by the following equation. di ₁ = [K / (R + sL)] di _ref …………………… (1) where i ₁ is current feedback K is current amplifier gain R is motor resistance s is Laplace transform operator L is motor The inductance i _ref of the current command is added to the current command i _ref as the delay di ₁ as a current feedback correction amount. In this way, the current feedback delay is corrected.

[0007]

As described above, according to the present invention, the delay of the current can be corrected. Therefore, even when the current is changing, the current follows, and an extra current flows or vibrations occur. It is possible to exert a special effect of being able to hold down.

[Brief description of drawings]

FIG. 1 is a block diagram showing a circuit configuration of an embodiment of the present invention.

FIG. 2 is a control block diagram according to an embodiment of the present invention.

FIG. 3 is a control block diagram of Conventional Example 1.

[Explanation of symbols]

 1 power transistor 2 motor 4 current detection circuit 5 A / D converter 6 microcomputer [CPU] 7 power transistor base drive circuit

Claims (3)

[Claims] 1. A current feedback correction method for a servo control device, comprising a current amplifier, performing current control according to a current command, and correcting a current feedback delay in the current command. 2. The current feedback i ₁ is subtracted from the current command i _ref and the delay di ₁ calculated this time is added,
When this is multiplied by the gain K of the current amplifier to drive the motor driven by the servo control device,
2. The current feedback delay di ₁ is calculated as di ₁ = [K / (R + sL)] di _ref , where R is the resistance of the motor, s is the Laplace transform operator, and L is the inductance of the motor. A method for correcting current feedback in a servo control device as described above. 3. An inverter comprising a power transistor, a drive circuit for driving the inverter, a motor driven by the inverter, and a current detection circuit for detecting a current flowing from the inverter to the motor.
An A / D converter for A / D converting the motor current detected from the current detection circuit, and the current amplifier gain K, the motor resistance R, and the motor resistance R preset by introducing the A / D converter output. An inductance L and a CPU for calculating the current feedback correction amount di ₁ based on the current command i _ref given at that time are respectively provided, and the current feedback and the current feedback correction amount are added to the current command. 3. The current feedback correction method for a servo controller according to claim 2, wherein the motor is driven by a deviation.