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

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TL4 94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IFR95 30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 342V变到 4 18V ,负载从 2 5N变到 5 0N时 ,送丝速度的变化率小于 5 % ,符合JB/T95 33- 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。

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 25 N to 50N and the source voltage changes from 342 V to 418 V. Under proper conditions, the variation ratio of velocity may be zero.