【摘要】 对变极性TIG焊电源的输出功率进行研究,发现其输出功率随变极性周期和占空比变化而变化,EP(钨极接正)时的功率远大于EN(钨极接负)时的功率.这种周期性变化输出功率会导致弧焊电源周期性地从电网抽取能量.当采用常规的PFC(功率因数校正)电路和控制策略也会给输入电流带来奇次谐波、偶次谐波、间谐波、直流分量、三相不平衡等"污染."提出了一种基于负载观测器(load observer,LOB)的PFC控制策略,有效解决变极性焊接电弧这类负载周期性变化电源的PFC控制问题.结果表明,该方法可以抑制由于周期性负载导致的谐波"污染",使整机接近于单位功率因数.更多还原

【Abstract】 The output power of variable polarity TIG welding power supply was studied.The results show the output power changes with the period and duty radio of variable polarity welding,and the output power in electrode positive is far large than that in electrode negative.The periodically changing output power will cause the variable polarity TIG welding power supply to absorb power from power grid periodically.The input current of the power supply was distorted seriously by using normal PFC (power factor correction) circuit and control strategy.A new PFC control strategy based on load observer is presented to reduce the harmonics of variable polarity inverter arc welding power supply.Experiments result shows that this control strategy is available and near unity power factor is obtained.更多还原