新型弧焊发电机的研制

【作者】 王永锋；

【导师】 朱亮；

【作者基本信息】 兰州理工大学 ， 材料加工工程， 2003， 硕士

【摘要】 本文研制了适用于油气管道、铁路、桥梁等野外焊接施工作业，由柴油机驱动的具有交流发电和直流弧焊两种功能的新型弧焊发电机。它采用三次谐波励磁的同步发电机，由发电机电枢中的单相绕组发出空载50～70V的工频交流电，经过单相桥式全波整流之后直接用于焊接，而不需要变压器；发电机中的三相发电绕组发出380V的三相交流电，作为辅助电源。该弧焊发电机具有引弧容易、电弧力大、动态响应速度快的特点。 控制系统只采用一套控制电路即可实现对焊接电源特性的控制，以及起到发电输出电压的自动调节器作用。控制电路采用“定频率调脉冲宽度”的控制方法，通过对焊接电源输出电压及焊接电流的瞬时波形，而非平均值进行采样及处理，经过调制，形成控制脉冲，控制发电机励磁控制单元IGBT的占空比，从而控制发电机励磁，通过调节发电机励磁来调节焊接电流。采用这种控制方法，直接对采样的电压和电流信号进行调制，不存在滤波滞后，这样更及时、快速地反映了焊接过程中焊接参数的变化，使控制电路能够做出快速的反应，及时调节焊接规范，从而大大提高了在焊接过程中，当弧长变化时控制系统的动态响应速度，改善了焊接过程的动态性能。很好地解决了油气管道的纤维素焊条下向焊工艺中，采用小电流(60～90A)规范进行焊接时，出现的电弧不稳定，容易发生断弧、熄弧、粘条等问题。 最后，利用Matlab软件建立了弧焊发电机控制电路及电弧负载的动态仿真模型，对弧焊发电机的焊接动特性进行了仿真；分析了当弧长变化时焊接电流的响应过程及其控制过程，以及焊接回路的直流电感对焊接动态性能的影响，比较了不同数值的电感对焊接电流的影响；根据仿真得到的动态波形来分析电源设计的正确性；在仿真的基础上实现对弧焊发电机控制电路的计算机辅助优化设计。 该机特别适用于油气管道焊接中普遍采用的纤维素焊条下向焊工艺，并在试用中获得了良好的焊接工艺效果。此外，发电机提供的380V三相交流电，作为辅助电源可带动打磨机、空气压缩机等电动工具。更多还原

【Abstract】 Develop a new type AC Generating-DC Arc Welding dual use welding generator driven by diesel, which can be applied to the field welding-operation such as the building of the pipeline, the railway, the bridge, etc. It adopts a triple frequency harmonic-excited synchronous generator. And it can generate a 50~75V alternating-current through a single-phase welding-winding, and through a rectifier it can be used to welding, and need not the transformer; It can generate a 380V alternating-current as accessional power source through a three-phase winding. The welding generator has the characteristic of striking easily, a big arc force, and rapid dynamic response velocity.The welding generator can control the volt-ampere characteristics of welding power source and regulate the voltage automatically through the same control circuit. The control circuit is based on the method of PWM, which is modulating the width of the control pulse but not changing the frequency, and it samples and processes the instantaneous wave (but not the average value) of the output voltage and the welding-current when welding, and creates the control pulse which can control the generator’s excitation through modulate the width of the pulse of the controlling cell-IGBT; It regulates the welding current through controlling the excitation of the generator. The method can reflect the changes of the welding parameter really and quickly through modulating the sample signals directly but not through the filter which can make a delaying, and it is helpful for the control circuit to make a rapid response, and it can improve the dynamic response velocity of the control system when the arc length changes, and improve the dynamic performance of the welding process, and it can solve the questions of arc breaking off, arc extinguishing ,etc, well when welding using a small welding-current(60~90A) in the downward welding of the cellulose electrode.At last, makes a simulation to the dynamic characteristic of the welding generator with the mathematics software-Matlab through building the model of the welding generator and the arc load; Analyses the influence of the DC inductance to the welding dynamic characteristic, the dynamic response velocity of the control system when the arc length changes and the control process; Compares the influence of the different inductance to the response velocity of welding current; Prove the correctness of the power source designing and optimizes the control circuit of the welding generator on the basis of the simulation.Experiments show that the welding generator fits for the welding of the cellulose electrode very much, which is adopted largely in the downward welding of the oil and gas pipeline, and it has gotten a well welding technical effect in tryout. In addition, the generator can provide a steady 380V three-phase alternating-current, which can drive heavy load tools such as a polishes an air-compressor and so on.更多还原