JPH06315288A - Control method for servo motor - Google Patents

Abstract

PURPOSE:To provide a method for controlling servo motors wherein a regenerating circuit and an inverter circuit are used to stop the servo motor without any special brake circuits. CONSTITUTION:A rectifier circuit 1 supplies direct current power, and an inverter circuit 5 and a regenerating circuit 3 and 4 control the speed and position of a servo motor. When stopping the servo motor, the operation of the rectifier circuit 1 is stopped, and the inverter circuit 5 or regenerating circuit 3 and 4 is driven at an appropriate time ratio to use up the rotational energy of the servo motor. This stops the motor in accordance with desired characteristic curves.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo motor control method in which direct current power is supplied from a rectifier circuit and the speed and position of the servo motor are controlled by an inverter circuit and a regenerative processing circuit.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional servo motor control circuit. Rectifier circuit 2 composed of thyristor
1 inputs commercial AC power supply, and DC power supply lines VL and GL
Supply DC power to. The main capacitor 22 smoothes the DC power supply supplied to the DC power supply lines VL and GL.
The regenerative transistor 23 is on / off controlled, and when in the on state, the regenerative resistor 24 consumes the power that appears in the DC power supply lines VL and GL. The inverter circuit 25 is supplied with DC power from the DC power supply lines VL and GL, generates AC power according to the drive signal DS of the base drive circuit 27, and drives the servomotor 10. The control circuit 26 is composed of a microcomputer, memory, etc.
And the regenerative transistor 23 and the base drive circuit 27. Further, the control circuit 26
When an emergency stop of the servo motor 30 is required, the relay drive transistor 31 is turned on, the relay coil 32 is driven, and the relay contact 33 is turned on in order to instruct the DB operation. When the relay contact 33 is turned on, the dynamic brake circuit 28 (hereinafter abbreviated as the DB circuit 28) connects the brake resistor 34 to the servo motor 30 as a load and brakes the servo motor 30.

[0003]

In the conventional dynamic brake stopping method described above, the resistance value of the brake resistor 34 must be changed in order to change the stopping method such as the time until the stop and the changing process until the stop. And change is not easy. In view of the above problems, the present invention provides a brake resistor 34.
An object of the present invention is to provide a servo motor control method that can change the method of stopping the servo motor without changing the.

[0004]

A servo motor control method of the present invention, which is supplied with DC power from a rectifier circuit and controls the speed and position of a servo motor by an inverter circuit and a regenerative processing circuit, is for stopping the servo motor. ,
The operation of the rectifier circuit is stopped and the inverter circuit or the regenerative processing circuit is driven at an appropriate time ratio to consume the rotational energy of the servo motor.

[0005]

The inverter circuit and the regenerative processing circuit differ in the characteristics relating to the load applied to the servo motor according to the rotation speed of the servo motor. Therefore, depending on which of the inverter circuit and the regenerative processing circuit is driven longer to apply a load to the servo motor, the time until the servo motor stops and the speed change until the servo motor stops change.

[0006]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a circuit diagram showing a servo motor control circuit to which the servo motor control method of the present invention is applied. FIG. 2 is a flow chart showing the operation of the embodiment of FIG. 1, and FIG. 3 is a characteristic diagram showing DB stop characteristics by the regenerative processing circuit and the inverter circuit of the embodiment of FIG. The rectifier circuit 1 including a thyristor inputs a commercial AC power source and is controlled by a control signal CS1 applied thereto, and the DC power source lines VL and GL are controlled.
Supply DC power to. The main capacitor 2 smoothes the DC power supplied to the DC power lines VL and GL. The regenerative transistor 3 is on / off controlled by the control signal CS3, and when in the on state, the regenerative resistor 4 consumes the power that appears in the DC power supply lines VL and GL. The inverter circuit 5 includes freewheeling diodes D1, D2, ..., Which are connected in parallel to the transistors Q1, Q2, ..., Q6 and the transistors Q1, Q2 ,.
D6, which is supplied with DC power from DC power supply lines VL and GL, and which is a drive signal D from the base drive circuit 7.
AC power is generated according to S, and AC power lines UL, V
The servo motor 10 is driven via L and WL.

The control circuit 6 is composed of a microcomputer, a memory and the like, and controls the rectifier circuit 1 and the regenerative transistor 3 and the base drive circuit 7 by control signals CS1 and CS2, respectively. Further, the control circuit 6 determines whether or not a dynamic brake operation (hereinafter abbreviated as DB operation) is instructed (step S
1). When the DB operation is instructed, the main power supply is cut off to stop the operation of the rectifier circuit 1 (step S2). After the operation of the rectifier circuit 1 is stopped, the regenerative transistor 3 or the transistors Q1, Q2, ...
6 is turned on at an appropriate time ratio to stop the servomotor 10 (step S3). The braking characteristic showing the change of the motor rotation speed until the servo motor is stopped by the regeneration transistor 3 or the transistors Q1, Q2, to Q6 of the inverter circuit 5 is as shown in FIG. In some places, the inverter circuit 5
If the on-time of the transistor is increased to increase the on-time of the regenerative transistor 3 at a place where the motor rotation speed is small, the time until the servomotor is stopped is extended as compared with the other cases. On the contrary, when the motor rotation speed is high, the on-time of the regeneration transistor 3 is increased,
When the motor speed is low, the inverter circuit 5
If the on time of the transistor is increased, the time until the servomotor stops can be shortened compared to other cases. Further, in the case of the embodiment shown in FIG. 1, the DB circuit required in FIG. 4 is not necessary and the circuit becomes simple.

[0008]

As described above, according to the present invention, DC power is supplied from the rectifier circuit, and the speed and position of the servo motor are controlled by the inverter circuit and the regenerative processing circuit. However, when the servo motor is stopped, By stopping the operation of the rectifier circuit and driving the inverter circuit or regenerative processing circuit at an appropriate time ratio to consume the rotational energy of the servo motor, the servo motor can be stopped freely according to the desired curve corresponding to the time ratio. can do. Further, there is also an effect that the circuit configuration is simplified because the dynamic brake circuit is not required.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a servo motor control circuit to which a servo motor control method of the present invention is applied.

FIG. 2 is a flowchart showing the operation of the embodiment of FIG.

FIG. 3 is a characteristic diagram showing DB stop characteristics by the regeneration processing circuit and the inverter circuit of the embodiment of FIG.

FIG. 4 is a circuit diagram showing a conventional servo motor control circuit.

[Explanation of symbols]

 1 Rectifier circuit 2 Main capacitor 3 Regenerative resistor 4 Regenerative transistor 5 Inverter circuit 6 Control circuit 7 Base drive circuit 8 DB circuit 10 Servo motor Q1, Q2, ~, Q6 Transistor D1, D2, ~, D6 Diode

Claims (1)

[Claims] 1. A servomotor control method in which direct current power is supplied from a rectifier circuit and speed and position control of the servomotor is performed by an inverter circuit and a regenerative processing circuit. In order to stop the servomotor, an operation of the rectifier circuit is performed. Is stopped, and the inverter circuit or the regenerative processing circuit is driven at an appropriate time ratio to consume the rotational energy of the servo motor.