电阻焊机主电路中(图1),可控硅一般采用脉冲触发。这种方法具有触发功率小,脉冲变压器体积小,电路简单,而且精确等优点。但由于电阻焊机是一种感性负载,回路电流总是滞后于电压,因此用这种脉冲触发将存在着下面问题:当触发脉冲的移相角小于配用焊机功率因数角时(即前半波可控硅导通未截止时),就输入下半波的触发脉冲,则下半波 Resistance welding machine main circuit (Figure 1), SCR commonly used pulse trigger. This method has the advantages of small trigger power, small pulse transformer, simple circuit, and accurate. However, the resistance welding machine is an inductive load, the loop current is always lagging behind the voltage, so with this pulse trigger there will be the following problems: When the trigger pulse phase angle is less than the welding power factor with the angle (ie, the first half Wave SCR conduction is not cut-off), the input half-wave trigger pulse, the next half-wave