This application belongs to the field of power supply technology and provides a method for adjusting the open-circuit
voltage of a power supply, a power supply circuit, a power supply device, and a
welding machine. By driving the first power
transistor switching module and the second power
transistor switching module to conduct alternately, the
transformer module operates in a state of extremely low
energy density, thereby achieving the purpose of adjusting the open-circuit
voltage of the power supply over a wide range. By using frequency hopping technology to reduce the equivalent driving frequency of the upper and lower switching transistors in the dual-
transistor forward topology circuit in the power supply, the
energy transfer density of the
transformer is further reduced. The
voltage regulation module controls the equivalent resistance at the output terminal of the power supply, and the auxiliary step-down module provides auxiliary voltage, thereby achieving the purpose of compound adjustment of the open-circuit voltage of the power supply. Finally, the rectification and freewheeling modules rectify and
freewheel the voltage
signal output by the
transformer module. This solves the problem that the open-circuit voltage of existing
welding power supplies is mostly not adjustable, or very rarely adjustable but with a small adjustment range, resulting in poor adaptability to
welding processes.