Automatic voltage regulation (AVR) singlechip control-based thick wire electric-gas vertical welding machine and control method

The invention relates to an automatic voltage regulation (AVR) singlechip control-based thick wire electric-gas vertical welding machine and a control method. The welding machine comprises a three-way trolley travelling set circuit, a swing front and back stop set circuit, a swing amplitude and speed set circuit, a welding torch centering swing control set circuit, a welding start/end control circuit, a digital display circuit, a welding mode selection control circuit, a welding start/stop control circuit, an optocoupler isolation circuit, a travelling motor control drive circuit, a swinging motor control drive circuit and a motor voltage current feedback circuit. In the method, welding voltage is sampled to serve as a feedback control signal of automatic climbing of a trolley and the change of wire feeding speed; when the arc length is increased by interference in the automatic welding process, the arc voltage is increased and the wire feeding speed is increased, so that the arc length is reduced, and the sp