变极性GMAW焊接电源仿真建模与设计

Simulation and design of variable polarity GMAW welding power source

针对焊接过程中热输入大、薄板易熔穿等问题,研制了一种基于STM32F405单片机的高效变极性熔化极气体保护焊(variable-polarity gas metal arc welding, VP GMAW)焊接系统,可以通过调整焊接电流正负极性的时间以及电流的大小来控制焊接工件的热输入量.通过分析带耦合电感的半桥式二次逆变电路电流换向状态,建立相应的数学模型.针对变极性焊接过程中存在的问题,设计理想的控制波形并制定相应的控制策略.以上述的数学模型和控制方案为基础,建立变极性熔化极气体保护焊(gas metal arc welding, GMAW)焊接系统仿真模型,验证控制策略的可行性.将仿真结果与实际测量波形进行对比分析.结果表明,所建立的仿真模型符合实际预期,可以为变极性电源设计提供较好的参考模型.最后在焊接平台上使用制造的VP GMAW焊接样机在1 mm薄钢板进行堆焊试验.结果表明,焊缝表面光洁、成形规则,即使在变极性下依然能够实现薄板的稳定焊接.

A variable-polarity gas metal arc welding(VP GMAW) welding power supply based on STM32 F405 is built to solve the problems of high-heat input and easy deformation for the metal sheet, which is applied to adjust the heat input through modulating the duration of EN/EP and the amplitude of output current. The mathematical model of a second inverting stage with coupling inductance is established based on the analysis of the commutation of the output current.Besides, ideal output waveforms and a control method are developed to solve some problems in the process of variablepolarity(VP) welding. On the basis of the research above, a simulation model for verifying the feasibility of the control method provided is carried out to work as a good reference model for the design of a VP power supply. Compared with the experimental waveforms, the results show it lives up to the factual expectation. Finally, an experimental prototype of VP GMAW power supply is developed to perform a bead welding experiment on an 1 mm thick metal sheet. The result shows that the weld surface is smooth and regular, and there is still an effective and stable welding progress in case of the commutation of output current polarity.