Metallic joints are created in multivariable gas metal arc welding process by maintaining a balance between the quantum of heat generated and the feeding rate of electrode metal to the weld gap. The wire feeding control is often independently handled. The wire feeder unit should be simple, low cost, and capable of producing accurate speed. Arc welding controllers are often kept in clumsy conditions and the wire feeder unit is located close to the welder, could be much away from the controller. To reduce interconnections, separate sensing element for speed feedback should be avoided. Due to their negligible electrical and mechanical time constant, the pancake-type permanent magnet dc motor is suitable for wire feeding, where sensing of back electromotive force (EMF) for feedback is easy. When high frequency pulsewidth modulation (PWM) controller is used, the sensing of back EMF gets complicated. This paper explores the constraints on the choice of PWM frequency along with its maximum pulsewidth for different types of dc motors. It further elaborates comparatively on the choice of suitable control function for generating accurate speed control of wire feeding using back EMF as feedback. Finally, this paper also details the experimental results using the proposed control function.

中文翻译：

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使用反电动势实现 GMAW 精确送丝的稳健 PMDC 电机控制


在多变量气体保护金属电弧焊过程中，通过保持产生的热量和电极金属向焊缝间隙的供给速率之间的平衡来形成金属接头。送丝控制通常是独立处理的。送丝装置应该简单、成本低并且能够产生准确的速度。弧焊控制器通常处于笨拙的环境中，送丝机单元靠近焊机，可能距离控制器很远。为了减少互连，应避免使用单独的速度反馈传感元件。由于其电气和机械时间常数可忽略不计，薄饼型永磁直流电机适用于送丝，其中很容易感测反电动势（EMF）以进行反馈。当使用高频脉宽调制（PWM）控制器时，反电动势的感测变得复杂。本文探讨了不同类型直流电机的 PWM 频率及其最大脉冲宽度选择的限制。进一步比较阐述了如何选择合适的控制函数，以反电动势作为反馈来实现精确的送丝速度控制。最后，本文还详细介绍了使用所提出的控制函数的实验结果。