基于TL494的PWM等速送丝电路的设计

Circuit design of feeding wire system based on TL494 by pulse width modulation technology

关键词:  脉宽调制  等速送丝  调速系统  CO₂焊机

Key words:  pulse width modulation  constant speed wire feeding  speed regulation system  CO₂ are welding machine

摘要:

分析了电压负反馈配合电流正反馈的送丝调速系统的传递函数,得到了与转速负反馈调速系统性能相同的等效条件。设计了一种基于TL494芯片的电压负反馈配合电流正反馈的CO₂焊机送丝调速电路。该电路采用场效应管IFR9530驱动,通过脉宽调制(PWM),实现转速的均匀调节,并具有过电流截止保护功能。试验表明,当电源电压由342 V变到418 V,负载从25 N变到50 N时,送丝速度的变化率小于5%,符合JB/T9533-1999专业标准要求,并得到在上述条件下,送丝速度的变化率为零的送丝速度。

Abstract:

The voltage negative feedback system with the current positive feedback system is analyzed, and the equivalent efficiency condition is derived that the velocity negative feedback system is the same as the voltage negative feedback system with the current positive feedback system. A wire feeding system based on TL494 which is used in CO₂ arc welding machine is designed. Because pulse width modulation technology is used in the system, the motor driven by IRF9530 in the system can run smoothly at adjustable velocity. The system can be protected if current is overloaded. The system stability is tested and the variation ratio of velocity is lower than 5% when the load changes from 25N to 50N and source voltage from 342V to 418V. Under proper conditions, the variation ratio of velocity may be zero.