数字化逆变弧焊电源采样策略研究

Study on the sampling strategy of digital welding inverter

针对常规数字化逆变电源焊接电流采样可能出现的问题,提出了一种PWM三角波载波顶点同步采样焊接电流的方法,既避免了开关管开关的信号干扰,又可得到每个PWM控制周期的焊接平均电流,保证了焊接电流采样的准确性。同时分析了焊接电缆等效电感对电弧电压测量的影响,提出了两种易实现的电弧电压采样方法,确保电弧电压测量准确。整个控制系统采用离散PI调节器进行电流控制,应用所提出的电流电压采样策略,通过试验验证了该方案可以确保焊接电流稳定,响应速度快,超调小,测量电弧电压准确、稳定。

In order to solve sampling problems of normal digital inverter welding supply,triangle carrier wave PWM is presented in this paper.The sampling point is set at the peak of carrier wave,thus the welding-current average value can be captured without the power switeh＇s disturbing signal.The equivalent inductor influences measurement of are voltage,and it is analyzed.Than two precision measurements are presented to sample arc vohage.A digital PI controller with these sample strategies is employed to control welding inverter, and the experimental results verified its validity.