逆变式变极性TIG焊电源的研究.pdf

摘 要 I论文题目：逆变式变极性论文题目：逆变式变极性 TIG 焊电源的研究焊电源的研究 专专 业：材料加工工程业：材料加工工程 研研 究究 生：陈玉喜生：陈玉喜 指导教师：朱锦洪指导教师：朱锦洪 摘 要摘 要 针对铝及其合金对焊接设备及工艺的特殊要求，铝合金交流TIG焊的发展先后经历了正弦波交流TIG、方波交流TIG和变极性TIG几个阶段变极性TIG焊具有输出电流频率、占空比、正负半波电流幅值均可独立调节的特点，能满足阴极雾化作用和减少钨极烧损的要求，成为当前TIG焊中用于铝及其合金材料焊接的最佳方法基于此，本文设计了逆变式变极性TIG焊电源，对电源系统进行了调试，并对调试过程的波形进行了分析 电源的主电路采用输出功率较大的全桥式双逆变结构，选取绝缘栅极型晶体管 IGBT 为主控开关功率转换器件。

主电路系统由输入整流滤波电路、一次全桥逆变电路、高频变压器、输出整流滤波电路、二次全桥逆变电路组成文中对主电路各个组成部分涉及的元件进行了详尽的参数设计和选取，并对二次逆变电路的工作过程进行了分析 针对逆变式变极性 TIG 焊电源的特点进行控制电路的设计一次逆变控制采用脉宽调制型调节(PWM)方式控制输出电流的大小，对输出电流的采样结果经运算放大器 LM324 放大比较，完成 PI 调节后的控制量送入脉冲宽度控制器TL494，经脉宽调制控制电路输出两路互不重叠的触发脉冲，再送入驱动电路，经 IGBT 专用驱动模块 EXB841 进行功率放大后触发一次逆变功率开关管，获得平滑的直流输出，以实现前级恒流源的功能二次逆变控制采用 555 时基电路构成脉冲发生器，产生频率和正负半波导通时间分别独立调节的方波信号，经反相电路产生两路相位差为 180°的方波信号，再经死区时间控制电路和正负半波幅值调节电路，得到两路频率、正负半波导通时间及幅值独立可调且具有一定死区时间要求的触发脉冲，送入驱动电路，经功率放大后驱动二次逆变开关管的开通与关断，实现电流波形的转换，得到满足焊接工艺要求的变极性波形针对IGBT 的过热和过流保护问题，本文设计了相应的保护电路。

通过系统调试，对该电源的主电路及控制电路中的相应波形进行了测试分析，对一次逆变部分的外特性进行了实验研究，对实际焊接过程中的波形进行了测试分析，结果表明，该电源可获得电流频率、占空比、正负半波幅值均可独立摘要 II可调的变极性波形，设计结构合理，器件工作可靠，控制系统运行良好，达到了预期设计目标最后对焊后试样的金相组织、成形状况和钨极烧损情况进行了观察，结果表明，在焊接参数选取适当的情况下，电源能满足阴极雾化作用和减少钨极烧损，降低焊接缺陷发生 关关 键键 词：词：钨极氩弧焊，变极性，双逆变，IGBT 论文类型：论文类型：应用研究 摘要 IIISubject: Research on the Variable Polarity Inverter TIG Welding Supply Specialty: Materials Process Engineering Name: Chen Yu-xi Supervisor: Zhu Jin-hong ABSTRACT In order to satisfy the special technological demands of welding of aluminum and aluminum alloys, the development of aluminum AC TIG welding experienced three stages such as the sine wave AC TIG welding, the square wave AC TIG welding and the variable polarity TIG welding. As a special square-wave AC power supply, the variable polarity power TIG welding can be adjusted separately including the output current frequency, duty cycle and current amplitude. In the welding of the aluminum alloy, it not only can guarantee clean-up role of the cathode, but also can minimize the damage of tungsten electrode, so it become the best approach for TIG welding. Because of this reason, the variable polarity inverter TIG welding supply was designed in this paper. Then, the power system was debugged and the waveforms of the actual welding process were tested. Full-bridge dual inverter structure was used in the main circuit. IGBT was chosen as switch component to perform energy transfer and power conversion. The main circuit was made up of rectifier, filter, the first inverter, high-frequency transformer and the latter inverter. Each part of the elements involved in the main circuit was designed and selected. The working process of the second inverter circuit was also analyzed. TIG welding control circuit was designed according to the characteristics of the variable polarity inverter TIG welding supply. The pulse width modulation (PWM) regulating mode was used in the first inverter to control the value of the output current. Then, the sampling result of the output current was input to the op-amp LM324. Finally, the output of PI regulator was sent into the TL494 modulating IC. A two-way non-overlapping pulse was trigged. The pulses were used to trigger IGBTs after they were magnified by EXB841, and DC output was achieved. The second inverter part was designed based on circuit 555 which can output square wave. The reversed-phase circuit, the dead zone control circuit, and positive and negative half-wave amplitude adjustment circuit were also designed. Two ways of pulses were used to trigger the 摘要 IVswitch components of the second inverter after they were magnified. The waveforms of the current can meet the requirements of variable polarity welding. The protection circuits which were used to solve the problem of the over-heat and over-current protection for the IGBT were also designed. Through the debugging, waveforms were attained and analyzed. The experiments results showed that following parameters of the power supply can be adjusted separately including the output current frequency, duty cycle and current amplitude. The structure design was rational, the devices worked reliably, the control system run well and the expected goal can be achieved. Finally, the metallographic structure of the test specimens, appearance of welds, tungsten electrode ablating were investigated. The experiment results showed that the welding source can not only meet the requirements of negative-pole atomization effects but also reduce tungsten electrode ablating and welding defect under suitable welding parameters. KEY WORDS: argon tungsten-arc welding, variable polarity, dual inverter, IGBT Dissertation Type: Application research 第 1 章 绪论 1第1章 绪论第1章 绪论 1.1 选题意义选题意义 铝及铝合金具有较高的比强度和导热性、良好的耐腐蚀性以及在低温下能保持良好的力学性能等特点，适应现代科技及高新工程发展的需要，成为宇航、化工、交。