Medium frequency inverter rectifier welding machine, which includes a medium frequency transformer and a resistance welding controller. This welding machine features an Automatic Current Compensation (ACC) function, which compensates for changes in grid voltage and variations in secondary circuit impedance to ensure the welding quality of the workpiece. It also has an automatic counting function, allowing for the setup of welding methods such as preheating, welding, post-heating, and multi-pulse. It is equipped with fault diagnosis and automatic protection functions and can store 16 sets of standard parameters for recall. Two units can be interlocked for control. The control system consists of a PLC, touchscreen, stepper motor, and other components. Electrical components are selected from well-known brands. Welding parameter standards, welding speed, and PLC control programs can be set and modified via the human-machine interface. The system offers automatic, manual, and individual stepper control modes. In case of faults or abnormalities, the entire machine stops, accompanied by audible and visual alarms. Depending on the pipe diameter, fin size, and pitch, welding processes can be preset and configured on the touchscreen. The welding process can be fully automated or operated in jog mode. By setting standard parameters, welding spatter is minimized as much as possible.