JPH02146978A - Controller for revolution of motor - Google Patents

Abstract

PURPOSE:To compensate the drift of an analog circuit by storing a driving current value at a time when a driving command to a motor is stopped and the motor is rested and using the driving current value as the base of control. CONSTITUTION:Currents driving a motor are detected by a current sensor 7, and input to a computer 1 through a filter 72, an amplifier 73, a sample holder 74 and an A/D converter 8. The computer 1 checks a motor driving command to an inverter 3 and an output from a revolution detector 6, and reads a current value at a time when there is no motor driving command and the motor 5 is not turned and stores the current value in a storage device 4, and the stored value is used as the reference value of the control of the revolution of the motor.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application] The present invention relates to a motor rotation control device, and more particularly to a motor rotation control device that uses a drive current value when the motor is at rest as a reference for control.

[Prior art] In order to accurately control motors in robots, automatic guided vehicles, NC control devices, etc., it is necessary to determine the output value of the drive current detection circuit when the drive current is zero and the detection value of the drive current detection circuit of the current drive current. It is necessary to compare the values and determine the next command excitation current value in accordance with the difference. To detect the drive current in a digital control device such as a computer, the motor drive current is detected by a current sensor such as a Hall element, amplified to an appropriate value, sampled and held, and the output is sent to an A/D converter. is converted into a digital value by To obtain the output value of the drive current detection circuit described above when the drive current is zero, the output value of the A/D converter is stored in the digital main storage device when the motor drive current is zero before startup, and the digital value is controlled. Although used as a standard for processing, the first stored standard value is not rewritten and is fixed during operation of the device.

[Problems to be Solved by the Invention] However, in the conventional reference value storage method for motor control described above, the value when the motor drive current is zero is first stored, and then the stored contents are not rewritten. However, the analog circuit and sample-hold circuit for processing the drive current fluctuate during control processing due to temperature drift, etc., so the digital conversion value of the zero drive current is fluctuating. There is a problem in that using the value as it is as a reference for control reduces control accuracy.

The present invention has focused on the above-mentioned conventional problems, and an object of the present invention is to provide a motor rotation control device that is highly accurate even when the reference measurement value of the motor drive current fluctuates due to the drift of the analog circuit.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a motor rotation control device according to the present invention stores the drive current value of the motor when the motor is not operating, and stores the drive current value of the motor when the motor is not operating. In a motor rotation control device that uses rotation control as a reference, the drive current value is measured when the drive command to the motor is a stop command and the motor rotation is stopped, and the By rewriting the stored value, it is possible to provide a motor rotation control device with high accuracy even if the reference measured value of the motor drive current fluctuates due to the drift of the analog circuit.

According to the above configuration, the drive current value is measured when the drive command to the motor is a stop command and the motor is stopped, and the stored value is rewritten based on the current value. Therefore, even if the reference measurement value of the motor drive current fluctuates due to the drift of the analog circuit, the reference value used for control when stopping the motor rotation does not fluctuate, making it possible to provide a highly accurate motor rotation control device.

[Embodiment 1] Hereinafter, an embodiment of a motor rotation control device according to the present invention will be described in detail with reference to the drawings. Fig. 1 shows the configuration of the motor current detection circuit of the motor rotation control device, and Fig. 2 shows a flowchart of the detected current correction method. In Fig. 1, 5 is the motor to be controlled, and 6 is the rotation speed of the motor. It is a rotation detector such as an encoder that detects the rotation angle, and inputs the detected value to a computer l which is a control device. 7 is a motor drive current detection device, 71 is a current sensor, 72 is a filter, 73 is an amplifier, 74 is a sample holder that latches the amplified signal, and its output is passed through the A/D converter 8. It is input to the computer 1. A motor drive signal from the computer 1 passes through a D/A converter 2 and an inverter 3, becomes a motor drive current, and drives a motor 5. A storage device 4 stores information necessary for the computer 1 to operate.

Next, the operation of this embodiment will be explained with reference to FIGS. 1 and 2.

The current that drives the motor is detected by the current sensor 7, and after unnecessary noise is removed by the filter 72, it is amplified to an appropriate value by the amplifier 73, and then sampled based on timing instructions from the computer l. Absolute level is temporarily latched. The latched current detection value is input to the computer 1 after being converted by the A/D converter 8 into a digital signal suitable for input to the computer.

The rotation speed of the motor is detected by a rotation detector 6 such as an encoder, and is input to the computer 1 in the same manner as the drive current value.

The processing means carried out in the computer according to the present invention will be explained with reference to the flowchart shown in FIG.

When this flow is started by the main program of the computer, it first checks the motor drive signal command value to the inverter 3, and if a drive command is issued, the flow returns to the start, but if there is no drive command, it proceeds to the next step and starts rotating the motor. Check the content of the speed signal. If there is a speed signal, that is, the motor is rotating, the flow is returned to the start, and if the speed signal is zero, that is, the motor is completely stopped, the flow goes to the next step and A/
The D-converted drive current value from the current sensor 7 is read into the computer 1. The computer 1 rewrites the output value of the motor drive drive current detection device, which represents the standard of the motor rest current value stored in the storage device 4, and then reads the current value. Return to the start of the flow. The computer 1 manages this flow using a main program that controls the entire device, and executes other control programs when the flow returns to the start.

As described above, according to the present invention, since the stored value of the measured motor drive current value is always corrected to the latest value, highly accurate motor control is possible.

In the explanation of the flowchart in Figure 2, it was explained that the flow is started by a command from the main program of the computer, but for example, if the flow is started when it detects that the motor rotation has become zero, and the conditions are satisfied, it is stored. The reference current value within the device may be rewritten, and the control device may be controlled by an appropriate control circuit instead of a computer.

[Effects of the Invention] As explained above, the present invention has the above-mentioned configuration, and measures the immediate current value when the drive command to the motor is a stop command and the motor is stopped. Since the stored value is rewritten according to the current value, even if the reference measured value of the motor drive current fluctuates due to the drift of the analog circuit, the reference value used for control when motor operation is stopped does not fluctuate, resulting in high accuracy. A motor rotation control device can be provided.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram of a motor rotation control device according to an embodiment. FIG. 2 is a flowchart of the motor rotation control device according to the embodiment. ■・・・Computer 2...D/A converter 3...Inverter 4...Storage device 5...Motor 6...- - Rotation detector 7... Drive current detection device 71... Current sensor 72... Filter 73... Amplifier 74... Sample holder

Claims (1)

[Claims] In a motor rotation control device that stores a motor drive current value when the motor is not operating, and uses the stored value as a reference for rotation control, the drive command to the motor is an operation stop command, and A motor rotation control device, characterized in that a drive current value is measured when the rotation of the motor is stopped, and the stored value is rewritten based on the current value.