摘要逆变焊机的最主要组成部分是逆变弧焊电源，它的功能是把工频交流电整流，再通过功率晶体管的开关逆变成高频交流方波，然后通过变压器降压，整流二极管整流，通过焊枪和工件产生焊接电弧，包括恒压、恒流外特性。在我国，逆变式焊机的研究工作始于上个世纪八十年代初，紧跟国际研究开发的进程，水平差距也不大，已形成3代产品。随着Si半导体功率开关器件性能趋近于其理论极限，逆变焊接电源的进一步发展受到限制，因此需要寻找一种新型的频率更高容量更大的开关器件来代替逆变焊接电源中传统的Si半导体开关器件。本文研究了一种基于WBG（Wide Band Gap）半导体功率器件的焊条电弧焊（Shielded Metal-Arc Welding）逆变电源，其开关频率为50kHz，额定焊接电流160A，相比于传统的SMAW逆变电源，其具有体积更小，质量更轻，节能省材等优点，而且控制性能优越， 动态响应更加迅速，利于实时控制焊接过程。87015

本文对WBG半导体材料的物理特性以及SiC MOSFET和Si IGBT之间的可替代性进行了分析。另外，本文根据SMAW外特性要求和焊接工艺特点设计了基于UC3846的外特性控制电路，主要包括电流给定电路、电流采样电路、推力电流电路、比例积分电路和过流过热保护电路，实现了恒流带外拖的外特性控制。

最后，本文对UC3846的PWM波形、驱动波形进行了测试，并采集了所设计的逆变电源的外特性，试验证明外特性控制电路满足设计要求。

毕业论文关键词： WBG；逆变电源；功率变换；外特性；驱动电路

Abstract Inverter arc welding power source is the main component of inverter welding machine, its function is to power frequency alternating current rectifier, the power transistor switching reverse into high frequency AC square wave, and then through a step-down transformer, rectifier diode rectifier, the torch and workpiece produce electric arc welding, including constant voltage, constant current characteristic。 In our country, the research work of inverter welding machine began in the early eighty's of last century, followed by the international research and development process, the level of the gap is not big, has formed the 3 generation of products。 With the Si semiconductor power switch device performance approaches the theoretical limit, further development of inverter welding power supply is limited。 Therefore, it is necessary to find a new frequency higher capacity greater switching devices to replace the inverter welding power supply in traditional Si semiconductor switching device。 In this paper, we study a based on the WBG (wide band gap semiconductor power device of electrode arc welding (shielded Metal-Arc welding) is inverter, the switching frequency is 50KHz, rated welding current 160A, compared to the traditional SMAW inverter, which has a smaller, lighter, energy saving, material saving, etc。, and the control performance is superior, dynamic response more quickly, to real-time control of welding process。

In this paper, the physical properties of WBG semiconductor materials and the substitution between MOSFET Si and IGBT SiC were analyzed。 In addition, this paper according to the SMAW and performance requirements and characteristics of welding process design based on UC3846 external characteristic control circuit, including the current given circuit, current sampling circuit, thrust current circuit, proportional integral circuit and protection circuit of thermal flow, realize constant current band drag the external characteristic control。

Finally, this paper tests the PWM waveform and the driving waveform of UC3846, and collects the external characteristics of the designed inverter。 The test proves that the external characteristic control circuit meets the design requirements。

Keywords: WBG; inverter power; power conversion; external characteristic; driving circuit