电焊设备中的送丝、焊车行走和转胎运转,一般常使用50～200瓦直流电动机拖动,为了适应焊接所需要的多种速度,就必须无级调节直流电动机的转数。过去多采用自耦调压器来改变给进电压,经硅整流组整流后控制直流电动机的转数。此法虽可以方便地调节电机转数,但由于所采用的自耦调压器重量大,体积大,而且当需要电机转数稳定时,需加上笨重的铁磁稳压器。故 Welding equipment in the wire, welding car walking and tire operation, usually used 50 ~ 200 watts DC motor drive, in order to meet the welding needs of a variety of speed, you must steplessly adjust the DC motor speed. In the past, the use of autotransformer to change the feed voltage, rectified by the silicon rectifier group to control the DC motor speed. Although this method can easily adjust the motor speed, but due to the use of autotransformer weight, large size, and when the need for stable motor speed, the need to add bulky ferromagnetic voltage regulator. Therefore