A speed control method for a DC motor

Abstract

The invention relates to a speed control method for a DC motor. The purpose is that the rotating speed of the DC motor can be accurately controlled according to the method provided by the invention. The technical scheme of the rotating speed control method for the DC motor is that the rotating speed control method comprises the steps that 1) a pulse width value of driving voltage is calculated, and an instruction is outputted to a pulse generator; 2) the pulse generator outputs driving voltage of high-frequency pulses according to the instruction, and the driving voltage is amplified by a power circuit and then drives the DC motor to rotate; 3) the high-frequency pulses are maintained for a certain period of time and then stop, and the DC motor enters a follow current state; 4) in a period when armature current is zero, a sampling circuit collects a voltage value of induction voltage for at least one time, a sampling result is compared with a voltage value corresponding to a preset rotating speed, and a comparison result is outputted to a main controller; 5) the pulse width value of the high-frequency pulses is calculated, and an instruction is inputted into the pulse generator; and 6) the steps 2)-5) are repeated until the completion of operations of the DC motor.

Description

technical field [0001] The invention relates to the technical field of DC motors, in particular to a speed control method for DC motors. Background technique [0002] In welding equipment, the stability of the wire feeding system directly affects the stability of the welding current and the droplet transfer process, thereby affecting the weld formation and welding quality. Therefore, the DC motor of the wire feeding system will be adjusted in speed during actual use to ensure The stability of the welding process. [0003] When the DC motor of the wire feeding system is working, the DC motor will generate an induced electromotive force during the period when the power supply is cut off, and the induced electromotive force is linearly related to the speed of the DC motor. Therefore, the induced electromotive force of the DC motor is accurately sampled as the rotation speed of the DC motor According to the feedback amount, the rotation speed of the DC motor can be adjusted. ...

AI Technical Summary

Problems solved by technology

[0006] Due to the inductance in the motor itself and the circuit, the current has a continuous flow process after the PWM is turned off. Generally, the continuous flow time is about 50us-150us, so the maximum PWM frequency of the above two traditional PWM control methods is limited to about 3K.

The human sense of hearing is very sensitive to the high-frequency noise generated at a frequency of about 1K-3K, so the traditional control method usually adopts a control frequency of about 100HZ, and at this frequency, although the noise generated by the motor does not have a high-frequency sharp sound, but It is very dull, and the frequency is too low to reduce the control accuracy

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