【作者】 章宁；

【导师】 于有生；

【作者基本信息】 武汉理工大学 ， 材料学， 2007， 硕士

【摘要】 随着微机技术及DSP在焊接领域的应用不断深入，采用精细控制尤其是波控技术应用于CO₂焊接电源是当今解决CO₂焊飞溅问题的一大方向。本课题以波控技术为基本指导思想，应用DSP，将CO₂焊短路过渡过程细分为七个阶段。在短路初期以低电压低电流促进溶池形成稳固的短路桥；然后提高电流上升速度，促进颈缩形成；在短路过渡后期降低电流，使液桥在低能量下爆断，依靠表面张力完成熔滴过渡，实现小飞溅甚至无飞溅的短路过渡。专门设计短路信号检测电路判断焊接短路开始与结束，颈缩检测电路检测短路中期du／dt设定值，同时通过实时电流／电压采样电路，把状态信号输送到DSP，由DSP的EVA（事件管理器模块）输出占空比可变的PWM波来控制短路过渡各段的电流电压波形。本文精确分析CO₂焊飞溅产生机理，在此基础上探讨了短路过渡过程的控制策略。采用抗不平衡能力强的半桥逆变式主电路，精心设计的硬件电路实时、准确地检测CO₂短路始末状态、液桥颈缩爆断时刻以及各细分阶段的电弧参数值，并利用DSP控制的快速性和准确性的特点，根据PWM原理输出不同占空比的信号来驱动主回路中的两个大功率开关器件（IGBT）处于交替开关状态，得到符合CO₂焊短路过渡细分各阶段的电源外特性的电压／电流波形。数字控制系统选用美国TI公司的TMS320LF2407 DSP作为控制CPU，利用DSP特有资源，如XINT1，XINT2外部中断入口，PDPINTA及PDPINTB功率驱动保护中断输入引脚，A／D转换模块，PWM输出EVA（事件管理器模块）等。另设有驱动电路，键盘和显示接口电路，保护报警电路等，保证系统正常运行。软件设计采用模块技术，除主程序外，引入中断向量表，各功能都编有相应子程序，中断时直接跳到相应子程序。此外，硬件设计采用Multisim 8进行模拟仿真，减少损失，节约时间，优化了电路功能；同时系统在软硬件方面都采用了抗于扰措施，有力地保证了系统稳定。经示波器实测的各波形结果及后续分析，证明该焊机主电路响应速度快，硬件电路简单可靠，系统软件高效稳定。该CO₂弧焊电源数字控制系统是可行的。更多还原

【Abstract】 With the further application of microcomputer and DSP in the weldingfield, the precise control especially the wave controlled technic in newwelding machine exploits a mainstream method. In this paper, the new powersource for short circuiting transfer was researched and based on the technologyof DSP and wave control. In terms of the character of short circuit transfer ofCO₂ welding, the process was divided into seven subsections. At the beginninglower electric current with low voltage promoting dissolving pool forms thefirm short circuit bridge; then rising the current velocity cause the neck ofmetal coming into being. Then, the welding current is detracted, so as to makethe bridge braking at the low energy and finish the transfer without splash. Theshort circuit signal detecting circuit specially designed for judging the start andend of welding short circuit, and neck forming detecting circuit especiallydesigned for detecting setting value of du/dt, During the process, the real timecurrent and voltage values information are obtained with sensor and sent to theDSP for processing, then the wave of current and voltage was controlled bythe PWM of DSP’S EVA.This paper, based on analyzing of the reasons for splashing of CO₂welding, made discussing about short circuiting transfer controlling strategy.The semi bridge inverter IGBT type main circuit which have ability resistingno-balance was applied. Well designed hardware circuit can obtain all phase’sarc parameter of CO₂ welding process. According to PWM principle, IGBT ismade to works in a on-off statue with the high-speed and precise controlling ofDSP, out character voltage and current wave of the power source that comesup to every subsection of short circuit transfer of CO₂ welding was obtained.The digital control system takes TI company’s TMS320LF2407 as thecontrolling CPU, some DSP’S special port and module such as XINT1,XINT2, PDPINTA and PDPINTB also including A/D,EVA module are used. Inorder to keep system’s normal working, driving circuit, keyboard and displaycircuit,protecting and alarm circuit etc are all designed. Applying themoduling skills in software designing, except the main program, the interrupting vector table introduced,every function has its subprogram, so thehappening of interrupt will swift to corresponding subprogram. The hardwaredesign adopts Multisim 8 for circuit’s simulating,this process can reduce thelose and save the time as well as optimize circuit function. In order to improvethe system stability, hardware and software synthesis measures are adopted forthe disturbance problem.After the analysis of every wave detected by oscilloscope, It can beconcluded that the project is workable for main circuit responding quickly,hardware are simple and stable,software with great stability and efficiency.更多还原