【作者】 左敦桂；

【导师】 华学明； 吴毅雄；

【作者基本信息】 上海交通大学 ， 材料加工工程， 2007， 硕士

【摘要】 脉冲MIG焊是一种焊接电流周期性变化的熔化极气体保护焊。MIG焊通过控制脉冲峰值电流大小和峰值电流时间,有效控制脉冲能量,使脉冲MIG焊具有在很大的电流范围内获得射滴过渡,轴向性好,飞溅小,适于全位置焊接,焊缝成形美观的优点。因此对脉冲MIG焊接电源的研究具有很大的实际意义。论文建立了基于DSP的数字化脉冲MIG焊接电源系统。系统采用高性能的TMS320F240为核心,配以集成度高的专用芯片进行控制,使系统具有很高的控制精度,同时基值电流和峰值电流控制期间的稳态精度高。同时可以通过改变软件,对脉冲电流波形进行控制。并且针对传统脉冲焊接弧长控制的特点,提出了双闭环弧长控制方案,即内环电流环严格控制峰值电流和基值电流大小,保证稳定的熔滴过渡;外环电压环通过弧压反馈控制基值时间来稳定弧长,保证电弧在焊接过程中遇到外界干扰能快速进行调节。论文针对目前仿真研究中以固定频率和幅值的脉冲信号作为峰值电流、峰值时间、基值电流及基值时间的给定信号,而没有考虑实际焊接过程中对焊接电压的实时控制,仿真结果与实际相差较大的缺点,论文利用Matlab/Simulink扩展工具S函数建立基于双闭环弧长控制方案的脉冲MIG焊接电源-电弧系统数学模型,并且对系统在电弧受到弧长阶跃干扰时进行仿真,仿真表明建立的模型具有很好的动态响应特性。通过仿真结果分析和实验验证,表明系统抗干扰能力的仿真结果与焊接实验结果基本吻合,控制系统具有良好的动态响应能力和抗干扰能力。表明所设计的脉冲MIG焊接双闭环弧长控制方案的合理性以及建立在控制方案基础上的仿真模型的正确性,对脉冲MIG焊接电源的设计提供了理论分析工具。更多还原

【Abstract】 Pulsed MIG welding as one kind of GMAW(Gas Metal Arc Welding) is with its welding current changes periodically, which can control pulsed energy effectively through adjusting peak current and peak time. It is developed widely for its good direction transition, less splashed material and nice figure. So research on the Pulsed MIG welding power source becomes more and more important.In the paper,Pulsed MIG welding power source system is designed based on DSP. The system control the welding process based on TMS320F240 of high performance with high integrated level special chip, and use many anti-interference and protection measures. So the system has high control accuracy and high stabilization accuracy in base current and peak current. Meanwhile the system is with high flexibility and high superiority of digital control through modifying the software. And based on traditional arc length control means, the paper put forward to the double closed loop control: inner loop is current loop which controls peak current and base current precisely to assure stable droplet transform; outer loop is voltage loop which controls base time to assure arc length adjustment quickly in external disturbance through welding voltage feedback to reach arc length stable.The present models of Pulsed MIG welding system based on input signals of peak current, peak time, base current and base time with fixed frequency and magnitude, not taking into account real-time control in welding voltage, so the simulation results is not consistent well with the experimental one. The paper established the dynamic simulation model of Pulsed MIG welding power source-arc system based on S-function of Matlab/Simulink extension tool. The results of simulation display good dynamic performance in step change.更多还原